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libpng/libpng.3

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Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
.TH LIBPNG 3 "December 4, 2001"
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.SH NAME
Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
libpng \- Portable Network Graphics (PNG) Reference Library 1.2.1rc2
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.SH SYNOPSIS
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fB#include <png.h>\fP
\fI\fB
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
\fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBint png_check_sig (png_bytep \fP\fIsig\fP\fB, int \fInum\fP\fB);\fP
\fI\fB
\fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
\fI\fB
\fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
\fI\fB
\fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP
\fI\fB
\fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP
\fI\fB
\fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP
\fI\fB
\fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
\fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
\fBpng_structp png_create_read_struct_2(png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
\fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
\fBpng_structp png_create_write_struct_2(png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
\fI\fB
\fBint png_debug(int \fP\fIlevel\fP\fB, png_const_charp \fImessage\fP\fB);\fP
\fI\fB
\fBint png_debug1(int \fP\fIlevel\fP\fB, png_const_charp \fP\fImessage\fP\fB, \fIp1\fP\fB);\fP
\fI\fB
\fBint png_debug2(int \fP\fIlevel\fP\fB, png_const_charp \fP\fImessage\fP\fB, \fP\fIp1\fP\fB, \fIp2\fP\fB);\fP
\fI\fB
\fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
\fI\fB
\fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_free_default(png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
\fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fI\fB
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
\fBpng_uint_32 png_get_asm_flags (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_byte png_get_bit_depth (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP
\fI\fB
\fBpng_byte png_get_channels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, double \fP\fI*green_y\fP\fB, double \fP\fI*blue_x\fP\fB, double \fI*blue_y\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fBpng_uint_32 png_get_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_uint_32 \fP\fI*green_x\fP\fB, png_uint_32 \fP\fI*green_y\fP\fB, png_uint_32 \fP\fI*blue_x\fP\fB, png_uint_32 \fI*blue_y\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_byte png_get_color_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_byte png_get_compression_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_byte png_get_copyright (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBpng_voidp png_get_error_ptr (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBpng_byte png_get_filter_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fBpng_uint_32 png_get_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5c.tar
1999-11-27 16:22:33 +00:00
\fBpng_byte png_get_header_ver (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_byte png_get_header_version (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fBpng_uint_32 png_get_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_charpp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, int \fP\fI*compression_type\fP\fB, int \fI*filter_type\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_image_height (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_image_width (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_byte png_get_interlace_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5c.tar
1999-11-27 16:22:33 +00:00
\fBpng_byte png_get_libpng_ver (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_voidp png_get_mem_ptr(png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
\fBpng_byte png_get_mmx_bitdepth_threshold (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_mmx_flagmask (int \fP\fIflag_select\fP\fB, int \fI*compilerID\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_mmx_rowbytes_threshold (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_charp \fP\fI*units\fP\fB, png_charpp \fI*params\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
\fI\fB
\fBfloat png_get_pixel_aspect_ratio (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBpng_voidp png_get_progressive_ptr (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBpng_uint_32 png_get_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_byte png_get_rgb_to_gray_status (png_structp \fIpng_ptr)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_rowbytes (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
\fBpng_bytepp png_get_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_bytep png_get_signature (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
\fBpng_uint_32 png_get_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fI*intent\fP\fB);\fP
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_values\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fBpng_uint_32 png_get_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fBpng_voidp png_get_user_chunk_ptr (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_voidp png_get_user_transform_ptr (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_valid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
\fBpng_int_32 png_get_x_offset_microns (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
\fBpng_int_32 png_get_x_offset_pixels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_x_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
\fBpng_int_32 png_get_y_offset_microns (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
\fBpng_int_32 png_get_y_offset_pixels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_uint_32 png_get_y_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
\fBpng_uint_32 png_get_compression_buffer_size (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.2.0beta3.tar
2001-05-18 09:54:50 +00:00
\fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.2.0beta3.tar
2001-05-18 09:54:50 +00:00
\fBDEPRECATED: void png_info_init (png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBDEPRECATED: void png_info_init_2 (png_infopp \fP\fIptr_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_voidp png_malloc_default(png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoidp png_memcpy (png_voidp \fP\fIs1\fP\fB, png_voidp \fP\fIs2\fP\fB, png_size_t \fIsize\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_voidp png_memcpy_check (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIs1\fP\fB, png_voidp \fP\fIs2\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoidp png_memset (png_voidp \fP\fIs1\fP\fB, int \fP\fIvalue\fP\fB, png_size_t \fIsize\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBpng_voidp png_memset_check (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIs1\fP\fB, int \fP\fIvalue\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
\fBint png_mmx_support \fI(void\fP\fB);\fP
\fI\fB
Imported from libpng-1.2.0beta3.tar
2001-05-18 09:54:50 +00:00
\fBDEPRECATED: void png_permit_empty_plte (png_structp \fP\fIpng_ptr\fP\fB, int \fIempty_plte_permitted\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_read_destroy (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_infop \fIend_info_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.7beta11.tar
2000-05-06 19:09:57 +00:00
\fBDEPRECATED: void png_read_init (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.2.0beta3.tar
2001-05-18 09:54:50 +00:00
\fBDEPRECATED: void png_read_init_2 (png_structpp \fP\fIptr_ptr\fP\fB, png_const_charp \fP\fIuser_png_ver\fP\fB, png_size_t \fP\fIpng_struct_size\fP\fB, png_size_t \fIpng_info_size\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.7beta11.tar
2000-05-06 19:09:57 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
\fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
\fBpng_set_asm_flags (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIasm_flags\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_dither (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_dither\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_gray_1_2_4_to_8(png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_charp \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.7beta14.tar
2000-05-17 22:39:34 +00:00
\fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fIfilter_type\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_mem_fn(png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
\fBpng_set_mmx_thresholds (png_structp \fP\fIpng_ptr\fP\fB, png_byte \fP\fImmx_bitdepth_threshold\fP\fB, png_uint_32 \fImmx_rowbytes_threshold\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_palette_to_rgb(png_structp \fIpng_ptr\fP\fB);\fP
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
\fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP
\fI\fB
\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_fixed_point \fP\fIred\fP\fB, png_fixed_point \fIgreen\fP\fB);\fP
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fI\fB
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
\fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP
\fI\fB
\fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
\fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIintent\fP\fB);\fP
\fI\fB
\fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIintent\fP\fB);\fP
\fI\fB
\fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
\fBvoid png_set_strip_error_numbers (png_structp \fIpng_ptr,
\fBpng_uint_32 \fIstrip_mode\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP
\fI\fB
\fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
\fI\fB
\fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_values\fP\fB);\fP
\fI\fB
\fBvoid png_set_tRNS_to_alpha(png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
\fBvoid png_set_unknown_chunk_location(png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP
\fI\fB
\fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP
\fI\fB
\fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP
\fI\fB
\fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
\fBvoid png_set_compression_buffer_size(png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP
\fI\fB
\fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
\fI\fB
\fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
\fI\fB
\fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
\fI\fB
\fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
\fI\fB
\fBvoid png_write_destroy (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_write_destroy_info (png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
\fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.7beta11.tar
2000-05-06 19:09:57 +00:00
\fBDEPRECATED: void png_write_init (png_structp \fIpng_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.2.0beta3.tar
2001-05-18 09:54:50 +00:00
\fBDEPRECATED: void png_write_init_2 (png_structpp \fP\fIptr_ptr\fP\fB, png_const_charp \fP\fIuser_png_ver\fP\fB, png_size_t \fP\fIpng_struct_size\fP\fB, png_size_t \fIpng_info_size\fP\fB);\fP
Imported from libpng-1.0.7beta11.tar
2000-05-06 19:09:57 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.5c.tar
1999-11-27 16:22:33 +00:00
\fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fI\fB
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
\fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
\fI\fB
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
\fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP
\fI\fB
\fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
\fI\fB
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.SH DESCRIPTION
The
.I libpng
library supports encoding, decoding, and various manipulations of
the Portable Network Graphics (PNG) format image files. It uses the
.IR zlib(3)
compression library.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Following is a copy of the libpng.txt file that accompanies libpng.
.SH LIBPNG.TXT
libpng.txt - A description on how to use and modify libpng
Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
libpng version 1.2.1rc2 - December 4, 2001
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Updated and distributed by Glenn Randers-Pehrson
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
<randeg@alum.rpi.edu>
Imported from libpng-1.0.12beta1.tar
2001-05-14 14:20:53 +00:00
Copyright (c) 1998-2001 Glenn Randers-Pehrson
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
For conditions of distribution and use, see copyright
notice in png.h.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
based on:
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
libpng 1.0 beta 6 version 0.96 May 28, 1997
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Updated and distributed by Andreas Dilger
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Copyright (c) 1996, 1997 Andreas Dilger
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
libpng 1.0 beta 2 - version 0.88 January 26, 1996
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
For conditions of distribution and use, see copyright
notice in png.h. Copyright (c) 1995, 1996 Guy Eric
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
Schalnat, Group 42, Inc.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Updated/rewritten per request in the libpng FAQ
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
Copyright (c) 1995, 1996 Frank J. T. Wojcik
December 18, 1995 & January 20, 1996
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
.SH I. Introduction
This file describes how to use and modify the PNG reference library
(known as libpng) for your own use. There are five sections to this
file: introduction, structures, reading, writing, and modification and
configuration notes for various special platforms. In addition to this
file, example.c is a good starting point for using the library, as
it is heavily commented and should include everything most people
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
will need. We assume that libpng is already installed; see the
INSTALL file for instructions on how to install libpng.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Libpng was written as a companion to the PNG specification, as a way
of reducing the amount of time and effort it takes to support the PNG
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
file format in application programs.
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
The PNG-1.2 specification is available at <http://www.libpng.org/pub/png>
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
and at <ftp://ftp.uu.net/graphics/png/documents/>.
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
The PNG-1.0 specification is available
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
as RFC 2083 <ftp://ftp.uu.net/graphics/png/documents/> and as a
W3C Recommendation <http://www.w3.org/TR/REC.png.html>. Some
additional chunks are described in the special-purpose public chunks
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
documents at <ftp://ftp.uu.net/graphics/png/documents/>.
Other information
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
about PNG, and the latest version of libpng, can be found at the PNG home
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
page, <http://www.libpng.org/pub/png/>
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
and at <ftp://ftp.uu.net/graphics/png/>.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Most users will not have to modify the library significantly; advanced
users may want to modify it more. All attempts were made to make it as
complete as possible, while keeping the code easy to understand.
Currently, this library only supports C. Support for other languages
is being considered.
Libpng has been designed to handle multiple sessions at one time,
to be easily modifiable, to be portable to the vast majority of
machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
to use. The ultimate goal of libpng is to promote the acceptance of
the PNG file format in whatever way possible. While there is still
work to be done (see the TODO file), libpng should cover the
majority of the needs of its users.
Libpng uses zlib for its compression and decompression of PNG files.
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Further information about zlib, and the latest version of zlib, can
Imported from libpng-1.0.9beta3.tar
2000-11-23 17:51:42 +00:00
be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The zlib compression utility is a general purpose utility that is
useful for more than PNG files, and can be used without libpng.
See the documentation delivered with zlib for more details.
You can usually find the source files for the zlib utility wherever you
find the libpng source files.
Libpng is thread safe, provided the threads are using different
instances of the structures. Each thread should have its own
png_struct and png_info instances, and thus its own image.
Libpng does not protect itself against two threads using the
Imported from libpng-1.2.0beta5.tar
2001-08-08 03:25:59 +00:00
same instance of a structure. Note: thread safety may be defeated
by use of some of the MMX assembler code in pnggccrd.c, which is only
compiled when the user defines PNG_THREAD_UNSAFE_OK.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
.SH II. Structures
There are two main structures that are important to libpng, png_struct
and png_info. The first, png_struct, is an internal structure that
will not, for the most part, be used by a user except as the first
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
variable passed to every libpng function call.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The png_info structure is designed to provide information about the
PNG file. At one time, the fields of png_info were intended to be
directly accessible to the user. However, this tended to cause problems
with applications using dynamically loaded libraries, and as a result
Imported from libpng-1.0.7beta11.tar
2000-05-06 19:09:57 +00:00
a set of interface functions for png_info (the png_get_*() and png_set_*()
functions) was developed. The fields of png_info are still available for
older applications, but it is suggested that applications use the new
interfaces if at all possible.
Applications that do make direct access to the members of png_struct (except
for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
and applications that make direct access to the members of png_info must
be recompiled if they were compiled or loaded with libpng version 1.0.6,
in which the members were in a different order. In version 1.0.7, the
members of the png_info structure reverted to the old order, as they were
in versions 0.97c through 1.0.5. Starting with version 2.0.0, both
structures are going to be hidden, and the contents of the structures will
only be accessible through the png_get/png_set functions.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The png.h header file is an invaluable reference for programming with libpng.
And while I'm on the topic, make sure you include the libpng header file:
#include <png.h>
.SH III. Reading
We'll now walk you through the possible functions to call when reading
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
in a PNG file sequentially, briefly explaining the syntax and purpose
of each one. See example.c and png.h for more detail. While
progressive reading is covered in the next section, you will still
need some of the functions discussed in this section to read a PNG
file.
.SS Setup
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
You will want to do the I/O initialization(*) before you get into libpng,
so if it doesn't work, you don't have much to undo. Of course, you
will also want to insure that you are, in fact, dealing with a PNG
file. Libpng provides a simple check to see if a file is a PNG file.
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
To use it, pass in the first 1 to 8 bytes of the file to the function
png_sig_cmp(), and it will return 0 if the bytes match the corresponding
bytes of the PNG signature, or nonzero otherwise. Of course, the more bytes
you pass in, the greater the accuracy of the prediction.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
If you are intending to keep the file pointer open for use in libpng,
you must ensure you don't read more than 8 bytes from the beginning
of the file, and you also have to make a call to png_set_sig_bytes_read()
with the number of bytes you read from the beginning. Libpng will
then only check the bytes (if any) that your program didn't read.
(*): If you are not using the standard I/O functions, you will need
to replace them with custom functions. See the discussion under
Customizing libpng.
FILE *fp = fopen(file_name, "rb");
if (!fp)
{
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
fread(header, 1, number, fp);
Imported from libpng-1.0.2b.tar
1999-01-07 03:50:16 +00:00
is_png = !png_sig_cmp(header, 0, number);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
if (!is_png)
{
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (NOT_PNG);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
Next, png_struct and png_info need to be allocated and initialized. In
order to ensure that the size of these structures is correct even with a
dynamically linked libpng, there are functions to initialize and
allocate the structures. We also pass the library version, optional
pointers to error handling functions, and a pointer to a data struct for
use by the error functions, if necessary (the pointer and functions can
be NULL if the default error handlers are to be used). See the section
on Changes to Libpng below regarding the old initialization functions.
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
The structure allocation functions quietly return NULL if they fail to
create the structure, so your application should check for that.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_structp png_ptr = png_create_read_struct
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
user_error_fn, user_warning_fn);
if (!png_ptr)
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr,
(png_infopp)NULL, (png_infopp)NULL);
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
png_infop end_info = png_create_info_struct(png_ptr);
if (!end_info)
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
If you want to use your own memory allocation routines,
define PNG_USER_MEM_SUPPORTED and use
png_create_read_struct_2() instead of png_create_read_struct():
png_structp png_ptr = png_create_read_struct_2
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn, (png_voidp)
user_mem_ptr, user_malloc_fn, user_free_fn);
The error handling routines passed to png_create_read_struct()
and the memory alloc/free routines passed to png_create_struct_2()
are only necessary if you are not using the libpng supplied error
handling and memory alloc/free functions.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
When libpng encounters an error, it expects to longjmp back
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
to your routine. Therefore, you will need to call setjmp and pass
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
your png_jmpbuf(png_ptr). If you read the file from different
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
routines, you will need to update the jmpbuf field every time you enter
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
a new routine that will call a png_*() function.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
See your documentation of setjmp/longjmp for your compiler for more
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
information on setjmp/longjmp. See the discussion on libpng error
handling in the Customizing Libpng section below for more information
on the libpng error handling. If an error occurs, and libpng longjmp's
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
back to your setjmp, you will want to call png_destroy_read_struct() to
free any memory.
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
if (setjmp(png_jmpbuf(png_ptr)))
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
{
png_destroy_read_struct(&png_ptr, &info_ptr,
&end_info);
fclose(fp);
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
If you would rather avoid the complexity of setjmp/longjmp issues,
you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
errors will result in a call to PNG_ABORT() which defaults to abort().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Now you need to set up the input code. The default for libpng is to
use the C function fread(). If you use this, you will need to pass a
valid FILE * in the function png_init_io(). Be sure that the file is
opened in binary mode. If you wish to handle reading data in another
way, you need not call the png_init_io() function, but you must then
implement the libpng I/O methods discussed in the Customizing Libpng
section below.
png_init_io(png_ptr, fp);
If you had previously opened the file and read any of the signature from
the beginning in order to see if this was a PNG file, you need to let
libpng know that there are some bytes missing from the start of the file.
png_set_sig_bytes(png_ptr, number);
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Setting up callback code
You can set up a callback function to handle any unknown chunks in the
input stream. You must supply the function
read_chunk_callback(png_ptr ptr,
png_unknown_chunkp chunk);
{
/* The unknown chunk structure contains your
chunk data: */
png_byte name[5];
png_byte *data;
png_size_t size;
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
/* Note that libpng has already taken care of
the CRC handling */
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
/* put your code here. Return one of the
following: */
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
return (-n); /* chunk had an error */
return (0); /* did not recognize */
return (n); /* success */
}
(You can give your function another name that you like instead of
"read_chunk_callback")
To inform libpng about your function, use
png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
read_chunk_callback);
This names not only the callback function, but also a user pointer that
you can retrieve with
png_get_user_chunk_ptr(png_ptr);
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
At this point, you can set up a callback function that will be
called after each row has been read, which you can use to control
a progress meter or the like. It's demonstrated in pngtest.c.
You must supply a function
Imported from libpng-1.0.12beta1.tar
2001-05-14 14:20:53 +00:00
void read_row_callback(png_ptr ptr, png_uint_32 row,
int pass);
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
{
/* put your code here */
}
(You can give it another name that you like instead of "read_row_callback")
To inform libpng about your function, use
png_set_read_status_fn(png_ptr, read_row_callback);
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Unknown-chunk handling
Now you get to set the way the library processes unknown chunks in the
input PNG stream. Both known and unknown chunks will be read. Normal
behavior is that known chunks will be parsed into information in
various info_ptr members; unknown chunks will be discarded. To change
this, you can call:
png_set_keep_unknown_chunks(png_ptr, info_ptr, keep,
chunk_list, num_chunks);
keep - 0: do not keep
1: keep only if safe-to-copy
2: keep even if unsafe-to-copy
chunk_list - list of chunks affected (a byte string,
five bytes per chunk, NULL or '\0' if
num_chunks is 0)
num_chunks - number of chunks affected; if 0, all
unknown chunks are affected
Unknown chunks declared in this way will be saved as raw data onto a
list of png_unknown_chunk structures. If a chunk that is normally
known to libpng is named in the list, it will be handled as unknown,
according to the "keep" directive. If a chunk is named in successive
instances of png_set_keep_unknown_chunks(), the final instance will
take precedence.
.SS The high-level read interface
At this point there are two ways to proceed; through the high-level
read interface, or through a sequence of low-level read operations.
You can use the high-level interface if (a) you are willing to read
the entire image into memory, and (b) the input transformations
you want to do are limited to the following set:
PNG_TRANSFORM_IDENTITY No transformation
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
PNG_TRANSFORM_STRIP_16 Strip 16-bit samples to
8 bits
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
samples to bytes
PNG_TRANSFORM_PACKSWAP Change order of packed
pixels to LSB first
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
PNG_TRANSFORM_EXPAND Perform set_expand()
PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
PNG_TRANSFORM_SHIFT Normalize pixels to the
sBIT depth
PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
to BGRA
PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
to AG
PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
to transparency
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
(This excludes setting a background color, doing gamma transformation,
dithering, and setting filler.) If this is the case, simply do this:
png_read_png(png_ptr, info_ptr, png_transforms, NULL)
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
where png_transforms is an integer containing the logical OR of
some set of transformation flags. This call is equivalent to png_read_info(),
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
followed the set of transformations indicated by the transform mask,
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
then png_read_image(), and finally png_read_end().
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
(The final parameter of this call is not yet used. Someday it might point
to transformation parameters required by some future input transform.)
After you have called png_read_png(), you can retrieve the image data
with
row_pointers = png_get_rows(png_ptr, info_ptr);
where row_pointers is an array of pointers to the pixel data for each row:
png_bytep row_pointers[height];
If you know your image size and pixel size ahead of time, you can allocate
row_pointers prior to calling png_read_png() with
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
row_pointers = png_malloc(png_ptr,
height*sizeof(png_bytep));
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
for (int i=0; i<height, i++)
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
row_pointers[i]=png_malloc(png_ptr,
width*pixel_size);
Imported from libpng-1.0.9beta3.tar
2000-11-23 17:51:42 +00:00
png_set_rows(png_ptr, info_ptr, &row_pointers);
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
Alternatively you could allocate your image in one big block and define
row_pointers[i] to point into the proper places in your block.
If you use png_set_rows(), the application is responsible for freeing
row_pointers (and row_pointers[i], if they were separately allocated).
If you don't allocate row_pointers ahead of time, png_read_png() will
do it, and it'll be free'ed when you call png_destroy_*().
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS The low-level read interface
If you are going the low-level route, you are now ready to read all
the file information up to the actual image data. You do this with a
call to png_read_info().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_read_info(png_ptr, info_ptr);
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
This will process all chunks up to but not including the image data.
.SS Querying the info structure
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
Functions are used to get the information from the info_ptr once it
has been read. Note that these fields may not be completely filled
in until png_read_end() has read the chunk data following the image.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_get_IHDR(png_ptr, info_ptr, &width, &height,
&bit_depth, &color_type, &interlace_type,
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
&compression_type, &filter_method);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
width - holds the width of the image
in pixels (up to 2^31).
height - holds the height of the image
in pixels (up to 2^31).
bit_depth - holds the bit depth of one of the
image channels. (valid values are
1, 2, 4, 8, 16 and depend also on
the color_type. See also
significant bits (sBIT) below).
color_type - describes which color/alpha channels
are present.
PNG_COLOR_TYPE_GRAY
(bit depths 1, 2, 4, 8, 16)
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
PNG_COLOR_TYPE_GRAY_ALPHA
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
(bit depths 8, 16)
PNG_COLOR_TYPE_PALETTE
(bit depths 1, 2, 4, 8)
PNG_COLOR_TYPE_RGB
(bit_depths 8, 16)
PNG_COLOR_TYPE_RGB_ALPHA
(bit_depths 8, 16)
PNG_COLOR_MASK_PALETTE
PNG_COLOR_MASK_COLOR
PNG_COLOR_MASK_ALPHA
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
filter_method - (must be PNG_FILTER_TYPE_BASE
for PNG 1.0, and can also be
PNG_INTRAPIXEL_DIFFERENCING if
the PNG datastream is embedded in
a MNG-1.0 datastream)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
compression_type - (must be PNG_COMPRESSION_TYPE_BASE
for PNG 1.0)
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
interlace_type - (PNG_INTERLACE_NONE or
PNG_INTERLACE_ADAM7)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Any or all of interlace_type, compression_type, of
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
filter_method can be NULL if you are
not interested in their values.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
channels = png_get_channels(png_ptr, info_ptr);
channels - number of channels of info for the
color type (valid values are 1 (GRAY,
PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
4 (RGB_ALPHA or RGB + filler byte))
rowbytes = png_get_rowbytes(png_ptr, info_ptr);
rowbytes - number of bytes needed to hold a row
signature = png_get_signature(png_ptr, info_ptr);
signature - holds the signature read from the
file (if any). The data is kept in
the same offset it would be if the
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
whole signature were read (i.e. if an
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
application had already read in 4
bytes of signature before starting
libpng, the remaining 4 bytes would
be in signature[4] through signature[7]
(see png_set_sig_bytes())).
width = png_get_image_width(png_ptr,
info_ptr);
height = png_get_image_height(png_ptr,
info_ptr);
bit_depth = png_get_bit_depth(png_ptr,
info_ptr);
color_type = png_get_color_type(png_ptr,
info_ptr);
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
filter_method = png_get_filter_type(png_ptr,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
info_ptr);
compression_type = png_get_compression_type(png_ptr,
info_ptr);
interlace_type = png_get_interlace_type(png_ptr,
info_ptr);
These are also important, but their validity depends on whether the chunk
has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
data has been read, or zero if it is missing. The parameters to the
png_get_<chunk> are set directly if they are simple data types, or a pointer
into the info_ptr is returned for any complex types.
png_get_PLTE(png_ptr, info_ptr, &palette,
&num_palette);
palette - the palette for the file
(array of png_color)
num_palette - number of entries in the palette
png_get_gAMA(png_ptr, info_ptr, &gamma);
gamma - the gamma the file is written
at (PNG_INFO_gAMA)
png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
srgb_intent - the rendering intent (PNG_INFO_sRGB)
The presence of the sRGB chunk
means that the pixel data is in the
sRGB color space. This chunk also
implies specific values of gAMA and
cHRM.
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_get_iCCP(png_ptr, info_ptr, &name,
&compression_type, &profile, &proflen);
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
name - The profile name.
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
compression - The compression type; always
PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
You may give NULL to this argument to
ignore it.
profile - International Color Consortium color
profile data. May contain NULs.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
proflen - length of profile data in bytes.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_get_sBIT(png_ptr, info_ptr, &sig_bit);
sig_bit - the number of significant bits for
(PNG_INFO_sBIT) each of the gray,
red, green, and blue channels,
whichever are appropriate for the
given color type (png_color_16)
png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans,
&trans_values);
trans - array of transparent entries for
palette (PNG_INFO_tRNS)
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
trans_values - graylevel or color sample values of
the single transparent color for
non-paletted images (PNG_INFO_tRNS)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
num_trans - number of transparent entries
(PNG_INFO_tRNS)
png_get_hIST(png_ptr, info_ptr, &hist);
(PNG_INFO_hIST)
hist - histogram of palette (array of
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
png_uint_16)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_get_tIME(png_ptr, info_ptr, &mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_get_bKGD(png_ptr, info_ptr, &background);
background - background color (PNG_VALID_bKGD)
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
valid 16-bit red, green and blue
values, regardless of color_type
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
num_comments = png_get_text(png_ptr, info_ptr,
&text_ptr, &num_text);
num_comments - number of comments
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
text_ptr - array of png_text holding image
comments
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].compression - type of compression used
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
on "text" PNG_TEXT_COMPRESSION_NONE
PNG_TEXT_COMPRESSION_zTXt
PNG_ITXT_COMPRESSION_NONE
PNG_ITXT_COMPRESSION_zTXt
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].key - keyword for comment. Must contain
1-79 characters.
text_ptr[i].text - text comments for current
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
keyword. Can be empty.
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].text_length - length of text string,
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
after decompression, 0 for iTXt
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].itxt_length - length of itxt string,
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
after decompression, 0 for tEXt/zTXt
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].lang - language of comment (empty
string for unknown).
text_ptr[i].translated_keyword - keyword in UTF-8
(empty string for unknown).
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
num_text - number of comments (same as
num_comments; you can put NULL here
to avoid the duplication)
Note while png_set_text() will accept text, language,
and translated keywords that can be NULL pointers, the
structure returned by png_get_text will always contain
regular zero-terminated C strings. They might be
empty strings but they will never be NULL pointers.
num_spalettes = png_get_sPLT(png_ptr, info_ptr,
&palette_ptr);
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
palette_ptr - array of palette structures holding
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
contents of one or more sPLT chunks
read.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
num_spalettes - number of sPLT chunks read.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
&unit_type);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
offset_x - positive offset from the left edge
of the screen
offset_y - positive offset from the top edge
of the screen
unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
&unit_type);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
res_x - pixels/unit physical resolution in
x direction
res_y - pixels/unit physical resolution in
x direction
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
unit_type - PNG_RESOLUTION_UNKNOWN,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
PNG_RESOLUTION_METER
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_get_sCAL(png_ptr, info_ptr, &unit, &width,
&height)
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
unit - physical scale units (an integer)
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
width - width of a pixel in physical scale units
height - height of a pixel in physical scale units
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
(width and height are doubles)
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
&height)
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
height - height of a pixel in physical scale units
(width and height are strings like "2.54")
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
num_unknown_chunks = png_get_unknown_chunks(png_ptr,
info_ptr, &unknowns)
unknowns - array of png_unknown_chunk
structures holding unknown chunks
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
unknowns[i].name - name of unknown chunk
unknowns[i].data - data of unknown chunk
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
unknowns[i].size - size of unknown chunk's data
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
unknowns[i].location - position of chunk in file
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
The value of "i" corresponds to the order in which the
chunks were read from the PNG file or inserted with the
png_set_unknown_chunks() function.
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The data from the pHYs chunk can be retrieved in several convenient
forms:
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
res_x = png_get_x_pixels_per_meter(png_ptr,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
info_ptr)
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
res_y = png_get_y_pixels_per_meter(png_ptr,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
info_ptr)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
res_x_and_y = png_get_pixels_per_meter(png_ptr,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
info_ptr)
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
res_x = png_get_x_pixels_per_inch(png_ptr,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
info_ptr)
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
res_y = png_get_y_pixels_per_inch(png_ptr,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
info_ptr)
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
res_x_and_y = png_get_pixels_per_inch(png_ptr,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
info_ptr)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
info_ptr)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
(Each of these returns 0 [signifying "unknown"] if
the data is not present or if res_x is 0;
res_x_and_y is 0 if res_x != res_y)
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
The data from the oFFs chunk can be retrieved in several convenient
forms:
x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
(Each of these returns 0 [signifying "unknown" if both
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
x and y are 0] if the data is not present or if the
chunk is present but the unit is the pixel)
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
For more information, see the png_info definition in png.h and the
PNG specification for chunk contents. Be careful with trusting
rowbytes, as some of the transformations could increase the space
needed to hold a row (expand, filler, gray_to_rgb, etc.).
See png_read_update_info(), below.
A quick word about text_ptr and num_text. PNG stores comments in
keyword/text pairs, one pair per chunk, with no limit on the number
of text chunks, and a 2^31 byte limit on their size. While there are
suggested keywords, there is no requirement to restrict the use to these
strings. It is strongly suggested that keywords and text be sensible
to humans (that's the point), so don't use abbreviations. Non-printing
symbols are not allowed. See the PNG specification for more details.
There is also no requirement to have text after the keyword.
Keywords should be limited to 79 Latin-1 characters without leading or
trailing spaces, but non-consecutive spaces are allowed within the
keyword. It is possible to have the same keyword any number of times.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
The text_ptr is an array of png_text structures, each holding a
pointer to a language string, a pointer to a keyword and a pointer to
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
a text string. The text string, language code, and translated
keyword may be empty or NULL pointers. The keyword/text
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
pairs are put into the array in the order that they are received.
However, some or all of the text chunks may be after the image, so, to
make sure you have read all the text chunks, don't mess with these
until after you read the stuff after the image. This will be
mentioned again below in the discussion that goes with png_read_end().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Input transformations
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
After you've read the header information, you can set up the library
to handle any special transformations of the image data. The various
ways to transform the data will be described in the order that they
should occur. This is important, as some of these change the color
type and/or bit depth of the data, and some others only work on
certain color types and bit depths. Even though each transformation
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
checks to see if it has data that it can do something with, you should
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
make sure to only enable a transformation if it will be valid for the
data. For example, don't swap red and blue on grayscale data.
The colors used for the background and transparency values should be
supplied in the same format/depth as the current image data. They
are stored in the same format/depth as the image data in a bKGD or tRNS
chunk, so this is what libpng expects for this data. The colors are
transformed to keep in sync with the image data when an application
calls the png_read_update_info() routine (see below).
Data will be decoded into the supplied row buffers packed into bytes
unless the library has been told to transform it into another format.
For example, 4 bit/pixel paletted or grayscale data will be returned
2 pixels/byte with the leftmost pixel in the high-order bits of the
byte, unless png_set_packing() is called. 8-bit RGB data will be stored
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
in RGB RGB RGB format unless png_set_filler() is called to insert filler
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
bytes, either before or after each RGB triplet. 16-bit RGB data will
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
be returned RRGGBB RRGGBB, with the most significant byte of the color
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
value first, unless png_set_strip_16() is called to transform it to
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
regular RGB RGB triplets, or png_set_filler() is called to insert
filler bytes, either before or after each RRGGBB triplet. Similarly,
8-bit or 16-bit grayscale data can be modified with png_set_filler()
or png_set_strip_16().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The following code transforms grayscale images of less than 8 to 8 bits,
changes paletted images to RGB, and adds a full alpha channel if there is
transparency information in a tRNS chunk. This is most useful on
grayscale images with bit depths of 2 or 4 or if there is a multiple-image
viewing application that wishes to treat all images in the same way.
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb(png_ptr);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
if (color_type == PNG_COLOR_TYPE_GRAY &&
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
bit_depth < 8) png_set_gray_1_2_4_to_8(png_ptr);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
if (png_get_valid(png_ptr, info_ptr,
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
These three functions are actually aliases for png_set_expand(), added
in libpng version 1.0.4, with the function names expanded to improve code
readability. In some future version they may actually do different
things.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
PNG can have files with 16 bits per channel. If you only can handle
8 bits per channel, this will strip the pixels down to 8 bit.
if (bit_depth == 16)
png_set_strip_16(png_ptr);
If, for some reason, you don't need the alpha channel on an image,
and you want to remove it rather than combining it with the background
(but the image author certainly had in mind that you *would* combine
it with the background, so that's what you should probably do):
if (color_type & PNG_COLOR_MASK_ALPHA)
png_set_strip_alpha(png_ptr);
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
In PNG files, the alpha channel in an image
is the level of opacity. If you need the alpha channel in an image to
be the level of transparency instead of opacity, you can invert the
alpha channel (or the tRNS chunk data) after it's read, so that 0 is
fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
images) is fully transparent, with
png_set_invert_alpha(png_ptr);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
they can, resulting in, for example, 8 pixels per byte for 1 bit
files. This code expands to 1 pixel per byte without changing the
values of the pixels:
if (bit_depth < 8)
png_set_packing(png_ptr);
PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
stored in a PNG image have been "scaled" or "shifted" up to the next
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
higher possible bit depth (e.g. from 5 bits/sample in the range [0,31] to
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
8 bits/sample in the range [0, 255]). However, it is also possible to
convert the PNG pixel data back to the original bit depth of the image.
This call reduces the pixels back down to the original bit depth:
Imported from libpng-1.2.0beta5.tar
2001-08-08 03:25:59 +00:00
png_color_8p sig_bit;
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
png_set_shift(png_ptr, sig_bit);
PNG files store 3-color pixels in red, green, blue order. This code
changes the storage of the pixels to blue, green, red:
if (color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_bgr(png_ptr);
Imported from libpng-1.2.0rc1.tar
2001-08-25 11:46:06 +00:00
PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
into 4 or 8 bytes for windowing systems that need them in this format:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.2.0rc1.tar
2001-08-25 11:46:06 +00:00
if (color_type == PNG_COLOR_TYPE_RGB)
png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
where "filler" is the 8 or 16-bit number to fill with, and the location is
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
you want the filler before the RGB or after. This transformation
Imported from libpng-1.2.0rc1.tar
2001-08-25 11:46:06 +00:00
does not affect images that already have full alpha channels. To add an
opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
will generate RGBA pixels.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
If you are reading an image with an alpha channel, and you need the
data as ARGB instead of the normal PNG format RGBA:
if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_swap_alpha(png_ptr);
For some uses, you may want a grayscale image to be represented as
RGB. This code will do that conversion:
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
with alpha.
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
if (color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
png_set_rgb_to_gray_fixed(png_ptr, error_action,
int red_weight, int green_weight);
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
error_action = 1: silently do the conversion
error_action = 2: issue a warning if the original
image has any pixel where
red != green or red != blue
error_action = 3: issue an error and abort the
conversion if the original
image has any pixel where
red != green or red != blue
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
red_weight: weight of red component times 100000
green_weight: weight of green component times 100000
If either weight is negative, default
weights (21268, 71514) are used.
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
If you have set error_action = 1 or 2, you can
later check whether the image really was gray, after processing
the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
It will return a png_byte that is zero if the image was gray or
1 if there were any non-gray pixels. bKGD and sBIT data
will be silently converted to grayscale, using the green channel
data, regardless of the error_action setting.
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
With red_weight+green_weight<=100000,
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
the normalized graylevel is computed:
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
int rw = red_weight * 65536;
int gw = green_weight * 65536;
int bw = 65536 - (rw + gw);
gray = (rw*red + gw*green + bw*blue)/65536;
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
The default values approximate those recommended in the Charles
Poynton's Color FAQ, <http://www.inforamp.net/~poynton/>
Copyright (c) 1998-01-04 Charles Poynton poynton@inforamp.net
Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
Libpng approximates this with
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
Y = 0.21268 * R + 0.7151 * G + 0.07217 * B
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
which can be expressed with integers as
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
Y = (6969 * R + 23434 * G + 2365 * B)/32768
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
The calculation is done in a linear colorspace, if the image gamma
is known.
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
If you have a grayscale and you are using png_set_expand_depth() or
png_set_expand() to change to
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
a higher bit-depth, you must either supply the background color as a gray
value at the original file bit-depth (need_expand = 1) or else supply the
background color as an RGB triplet at the final, expanded bit depth
(need_expand = 0). Similarly, if you are reading a paletted image, you
must either supply the background color as a palette index (need_expand = 1)
or as an RGB triplet that may or may not be in the palette (need_expand = 0).
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_color_16 my_background;
png_color_16p image_background;
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
if (png_get_bKGD(png_ptr, info_ptr, &image_background))
png_set_background(png_ptr, image_background,
PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
else
png_set_background(png_ptr, &my_background,
PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
The png_set_background() function tells libpng to composite images
with alpha or simple transparency against the supplied background
color. If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
you may use this color, or supply another color more suitable for
the current display (e.g., the background color from a web page). You
need to tell libpng whether the color is in the gamma space of the
display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
know why anyone would use this, but it's here).
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
To properly display PNG images on any kind of system, the application needs
to know what the display gamma is. Ideally, the user will know this, and
the application will allow them to set it. One method of allowing the user
Imported from libpng-1.0.4c.tar
1999-10-01 19:22:25 +00:00
to set the display gamma separately for each system is to check for a
SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be
correctly set.
Note that display_gamma is the overall gamma correction required to produce
pleasing results, which depends on the lighting conditions in the surrounding
environment. In a dim or brightly lit room, no compensation other than
the physical gamma exponent of the monitor is needed, while in a dark room
a slightly smaller exponent is better.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
double gamma, screen_gamma;
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
if (/* We have a user-defined screen
gamma value */)
{
screen_gamma = user_defined_screen_gamma;
}
/* One way that applications can share the same
screen gamma value */
else if ((gamma_str = getenv("SCREEN_GAMMA"))
!= NULL)
{
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
screen_gamma = (double)atof(gamma_str);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
/* If we don't have another value */
else
{
screen_gamma = 2.2; /* A good guess for a
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
PC monitor in a bright office or a dim room */
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
screen_gamma = 2.0; /* A good guess for a
PC monitor in a dark room */
screen_gamma = 1.7 or 1.0; /* A good
guess for Mac systems */
}
The png_set_gamma() function handles gamma transformations of the data.
Pass both the file gamma and the current screen_gamma. If the file does
not have a gamma value, you can pass one anyway if you have an idea what
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
it is (usually 0.45455 is a good guess for GIF images on PCs). Note
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
that file gammas are inverted from screen gammas. See the discussions
on gamma in the PNG specification for an excellent description of what
gamma is, and why all applications should support it. It is strongly
recommended that PNG viewers support gamma correction.
if (png_get_gAMA(png_ptr, info_ptr, &gamma))
png_set_gamma(png_ptr, screen_gamma, gamma);
else
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
png_set_gamma(png_ptr, screen_gamma, 0.45455);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
If you need to reduce an RGB file to a paletted file, or if a paletted
file has more entries then will fit on your screen, png_set_dither()
will do that. Note that this is a simple match dither that merely
finds the closest color available. This should work fairly well with
optimized palettes, and fairly badly with linear color cubes. If you
pass a palette that is larger then maximum_colors, the file will
reduce the number of colors in the palette so it will fit into
maximum_colors. If there is a histogram, it will use it to make
more intelligent choices when reducing the palette. If there is no
histogram, it may not do as good a job.
if (color_type & PNG_COLOR_MASK_COLOR)
{
if (png_get_valid(png_ptr, info_ptr,
PNG_INFO_PLTE))
{
Imported from libpng-1.0.9rc1.tar
2000-12-23 20:27:39 +00:00
png_uint_16p histogram;
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_get_hIST(png_ptr, info_ptr,
&histogram);
png_set_dither(png_ptr, palette, num_palette,
max_screen_colors, histogram, 1);
}
else
{
png_color std_color_cube[MAX_SCREEN_COLORS] =
{ ... colors ... };
png_set_dither(png_ptr, std_color_cube,
MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
NULL,0);
}
}
PNG files describe monochrome as black being zero and white being one.
The following code will reverse this (make black be one and white be
zero):
Imported from libpng-1.2.0beta5.tar
2001-08-08 03:25:59 +00:00
if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
png_set_invert_mono(png_ptr);
This function can also be used to invert grayscale and gray-alpha images:
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_invert_mono(png_ptr);
PNG files store 16 bit pixels in network byte order (big-endian,
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
ie. most significant bits first). This code changes the storage to the
other way (little-endian, i.e. least significant bits first, the
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
way PCs store them):
if (bit_depth == 16)
png_set_swap(png_ptr);
If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
need to change the order the pixels are packed into bytes, you can use:
if (bit_depth < 8)
png_set_packswap(png_ptr);
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
Finally, you can write your own transformation function if none of
the existing ones meets your needs. This is done by setting a callback
with
png_set_read_user_transform_fn(png_ptr,
read_transform_fn);
You must supply the function
void read_transform_fn(png_ptr ptr, row_info_ptr
row_info, png_bytep data)
See pngtest.c for a working example. Your function will be called
after all of the other transformations have been processed.
You can also set up a pointer to a user structure for use by your
callback function, and you can inform libpng that your transform
function will change the number of channels or bit depth with the
function
png_set_user_transform_info(png_ptr, user_ptr,
user_depth, user_channels);
The user's application, not libpng, is responsible for allocating and
freeing any memory required for the user structure.
You can retrieve the pointer via the function
png_get_user_transform_ptr(). For example:
voidp read_user_transform_ptr =
png_get_user_transform_ptr(png_ptr);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The last thing to handle is interlacing; this is covered in detail below,
but you must call the function here if you want libpng to handle expansion
of the interlaced image.
number_of_passes = png_set_interlace_handling(png_ptr);
After setting the transformations, libpng can update your png_info
structure to reflect any transformations you've requested with this
call. This is most useful to update the info structure's rowbytes
field so you can use it to allocate your image memory. This function
will also update your palette with the correct screen_gamma and
background if these have been given with the calls above.
png_read_update_info(png_ptr, info_ptr);
After you call png_read_update_info(), you can allocate any
memory you need to hold the image. The row data is simply
raw byte data for all forms of images. As the actual allocation
varies among applications, no example will be given. If you
are allocating one large chunk, you will need to build an
array of pointers to each row, as it will be needed for some
of the functions below.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Reading image data
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
After you've allocated memory, you can read the image data.
The simplest way to do this is in one function call. If you are
allocating enough memory to hold the whole image, you can just
call png_read_image() and libpng will read in all the image data
and put it in the memory area supplied. You will need to pass in
an array of pointers to each row.
This function automatically handles interlacing, so you don't need
to call png_set_interlace_handling() or call this function multiple
times, or any of that other stuff necessary with png_read_rows().
png_read_image(png_ptr, row_pointers);
where row_pointers is:
png_bytep row_pointers[height];
You can point to void or char or whatever you use for pixels.
If you don't want to read in the whole image at once, you can
use png_read_rows() instead. If there is no interlacing (check
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
interlace_type == PNG_INTERLACE_NONE), this is simple:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_read_rows(png_ptr, row_pointers, NULL,
number_of_rows);
where row_pointers is the same as in the png_read_image() call.
If you are doing this just one row at a time, you can do this with
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
a single row_pointer instead of an array of row_pointers:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
png_bytep row_pointer = row;
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
png_read_row(png_ptr, row_pointer, NULL);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
get somewhat harder. The only current (PNG Specification version 1.2)
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
is a somewhat complicated 2D interlace scheme, known as Adam7, that
breaks down an image into seven smaller images of varying size, based
on an 8x8 grid.
libpng can fill out those images or it can give them to you "as is".
If you want them filled out, there are two ways to do that. The one
mentioned in the PNG specification is to expand each pixel to cover
those pixels that have not been read yet (the "rectangle" method).
This results in a blocky image for the first pass, which gradually
smooths out as more pixels are read. The other method is the "sparkle"
method, where pixels are drawn only in their final locations, with the
rest of the image remaining whatever colors they were initialized to
before the start of the read. The first method usually looks better,
but tends to be slower, as there are more pixels to put in the rows.
If you don't want libpng to handle the interlacing details, just call
png_read_rows() seven times to read in all seven images. Each of the
images is a valid image by itself, or they can all be combined on an
8x8 grid to form a single image (although if you intend to combine them
you would be far better off using the libpng interlace handling).
The first pass will return an image 1/8 as wide as the entire image
(every 8th column starting in column 0) and 1/8 as high as the original
(every 8th row starting in row 0), the second will be 1/8 as wide
(starting in column 4) and 1/8 as high (also starting in row 0). The
third pass will be 1/4 as wide (every 4th pixel starting in column 0) and
1/8 as high (every 8th row starting in row 4), and the fourth pass will
be 1/4 as wide and 1/4 as high (every 4th column starting in column 2,
and every 4th row starting in row 0). The fifth pass will return an
image 1/2 as wide, and 1/4 as high (starting at column 0 and row 2),
while the sixth pass will be 1/2 as wide and 1/2 as high as the original
(starting in column 1 and row 0). The seventh and final pass will be as
wide as the original, and 1/2 as high, containing all of the odd
numbered scanlines. Phew!
If you want libpng to expand the images, call this before calling
png_start_read_image() or png_read_update_info():
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
if (interlace_type == PNG_INTERLACE_ADAM7)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
number_of_passes
= png_set_interlace_handling(png_ptr);
This will return the number of passes needed. Currently, this
is seven, but may change if another interlace type is added.
This function can be called even if the file is not interlaced,
where it will return one pass.
If you are not going to display the image after each pass, but are
going to wait until the entire image is read in, use the sparkle
effect. This effect is faster and the end result of either method
is exactly the same. If you are planning on displaying the image
after each pass, the "rectangle" effect is generally considered the
better looking one.
If you only want the "sparkle" effect, just call png_read_rows() as
normal, with the third parameter NULL. Make sure you make pass over
the image number_of_passes times, and you don't change the data in the
rows between calls. You can change the locations of the data, just
not the data. Each pass only writes the pixels appropriate for that
pass, and assumes the data from previous passes is still valid.
png_read_rows(png_ptr, row_pointers, NULL,
number_of_rows);
If you only want the first effect (the rectangles), do the same as
before except pass the row buffer in the third parameter, and leave
the second parameter NULL.
png_read_rows(png_ptr, NULL, row_pointers,
number_of_rows);
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Finishing a sequential read
After you are finished reading the image through either the high- or
low-level interfaces, you can finish reading the file. If you are
interested in comments or time, which may be stored either before or
after the image data, you should pass the separate png_info struct if
you want to keep the comments from before and after the image
separate. If you are not interested, you can pass NULL.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_read_end(png_ptr, end_info);
When you are done, you can free all memory allocated by libpng like this:
png_destroy_read_struct(&png_ptr, &info_ptr,
&end_info);
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
It is also possible to individually free the info_ptr members that
Imported from libpng-1.0.7beta14.tar
2000-05-17 22:39:34 +00:00
point to libpng-allocated storage with the following function:
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_free_data(png_ptr, info_ptr, mask, seq)
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
mask - identifies data to be freed, a mask
containing the logical OR of one or
more of
PNG_FREE_PLTE, PNG_FREE_TRNS,
PNG_FREE_HIST, PNG_FREE_ICCP,
PNG_FREE_PCAL, PNG_FREE_ROWS,
PNG_FREE_SCAL, PNG_FREE_SPLT,
PNG_FREE_TEXT, PNG_FREE_UNKN,
or simply PNG_FREE_ALL
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
seq - sequence number of item to be freed
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
(-1 for all items)
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.7beta14.tar
2000-05-17 22:39:34 +00:00
This function may be safely called when the relevant storage has
Imported from libpng-1.0.6a.tar
2000-04-02 03:10:05 +00:00
already been freed, or has not yet been allocated, or was allocated
by the user and not by libpng, and will in those
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
cases do nothing. The "seq" parameter is ignored if only one item
of the selected data type, such as PLTE, is allowed. If "seq" is not
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
-1, and multiple items are allowed for the data type identified in
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
the mask, such as text or sPLT, only the n'th item in the structure
is freed, where n is "seq".
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
The default behavior is only to free data that was allocated internally
by libpng. This can be changed, so that libpng will not free the data,
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
or so that it will free data that was allocated by the user with png_malloc()
or png_zalloc() and passed in via a png_set_*() function, with
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
png_data_freer(png_ptr, info_ptr, freer, mask)
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
mask - which data elements are affected
same choices as in png_free_data()
freer - one of
PNG_DESTROY_WILL_FREE_DATA
PNG_SET_WILL_FREE_DATA
PNG_USER_WILL_FREE_DATA
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
This function only affects data that has already been allocated.
You can call this function after reading the PNG data but before calling
any png_set_*() functions, to control whether the user or the png_set_*()
function is responsible for freeing any existing data that might be present,
and again after the png_set_*() functions to control whether the user
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
or png_destroy_*() is supposed to free the data. When the user assumes
responsibility for libpng-allocated data, the application must use
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
png_free() to free it, and when the user transfers responsibility to libpng
for data that the user has allocated, the user must have used png_malloc()
Imported from libpng-1.2.0beta4.tar
2001-06-23 13:03:17 +00:00
or png_zalloc() to allocate it.
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
If you allocated your row_pointers in a single block, as suggested above in
the description of the high level read interface, you must not transfer
responsibility for freeing it to the png_set_rows or png_read_destroy function,
because they would also try to free the individual row_pointers[i].
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
separately, do not transfer responsibility for freeing text_ptr to libpng,
because when libpng fills a png_text structure it combines these members with
the key member, and png_free_data() will free only text_ptr.key. Similarly,
if you transfer responsibility for free'ing text_ptr from libpng to your
application, your application must not separately free those members.
Imported from libpng-1.0.7beta14.tar
2000-05-17 22:39:34 +00:00
The png_free_data() function will turn off the "valid" flag for anything
it frees. If you need to turn the flag off for a chunk that was freed by your
application instead of by libpng, you can use
png_set_invalid(png_ptr, info_ptr, mask);
mask - identifies the chunks to be made invalid,
containing the logical OR of one or
Imported from libpng-1.0.9beta3.tar
2000-11-23 17:51:42 +00:00
more of
Imported from libpng-1.0.7beta14.tar
2000-05-17 22:39:34 +00:00
PNG_INFO_gAMA, PNG_INFO_sBIT,
PNG_INFO_cHRM, PNG_INFO_PLTE,
PNG_INFO_tRNS, PNG_INFO_bKGD,
PNG_INFO_hIST, PNG_INFO_pHYs,
PNG_INFO_oFFs, PNG_INFO_tIME,
PNG_INFO_pCAL, PNG_INFO_sRGB,
PNG_INFO_iCCP, PNG_INFO_sPLT,
PNG_INFO_sCAL, PNG_INFO_IDAT
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
For a more compact example of reading a PNG image, see the file example.c.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Reading PNG files progressively
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The progressive reader is slightly different then the non-progressive
reader. Instead of calling png_read_info(), png_read_rows(), and
png_read_end(), you make one call to png_process_data(), which calls
callbacks when it has the info, a row, or the end of the image. You
set up these callbacks with png_set_progressive_read_fn(). You don't
have to worry about the input/output functions of libpng, as you are
giving the library the data directly in png_process_data(). I will
assume that you have read the section on reading PNG files above,
so I will only highlight the differences (although I will show
all of the code).
png_structp png_ptr;
png_infop info_ptr;
/* An example code fragment of how you would
initialize the progressive reader in your
application. */
int
initialize_png_reader()
{
png_ptr = png_create_read_struct
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
user_error_fn, user_warning_fn);
if (!png_ptr)
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr, (png_infopp)NULL,
(png_infopp)NULL);
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
if (setjmp(png_jmpbuf(png_ptr)))
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
/* This one's new. You can provide functions
to be called when the header info is valid,
when each row is completed, and when the image
is finished. If you aren't using all functions,
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
you can specify NULL parameters. Even when all
three functions are NULL, you need to call
png_set_progressive_read_fn(). You can use
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
any struct as the user_ptr (cast to a void pointer
for the function call), and retrieve the pointer
from inside the callbacks using the function
png_get_progressive_ptr(png_ptr);
which will return a void pointer, which you have
to cast appropriately.
*/
png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
info_callback, row_callback, end_callback);
return 0;
}
/* A code fragment that you call as you receive blocks
of data */
int
process_data(png_bytep buffer, png_uint_32 length)
{
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
if (setjmp(png_jmpbuf(png_ptr)))
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
/* This one's new also. Simply give it a chunk
of data from the file stream (in order, of
course). On machines with segmented memory
models machines, don't give it any more than
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
64K. The library seems to run fine with sizes
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
of 4K. Although you can give it much less if
necessary (I assume you can give it chunks of
1 byte, I haven't tried less then 256 bytes
yet). When this function returns, you may
want to display any rows that were generated
in the row callback if you don't already do
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
so there.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
*/
png_process_data(png_ptr, info_ptr, buffer, length);
return 0;
}
/* This function is called (as set by
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
png_set_progressive_read_fn() above) when enough data
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
has been supplied so all of the header has been
read.
*/
void
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
info_callback(png_structp png_ptr, png_infop info)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
{
/* Do any setup here, including setting any of
the transformations mentioned in the Reading
PNG files section. For now, you _must_ call
either png_start_read_image() or
png_read_update_info() after all the
transformations are set (even if you don't set
any). You may start getting rows before
png_process_data() returns, so this is your
last chance to prepare for that.
*/
}
/* This function is called when each row of image
data is complete */
void
row_callback(png_structp png_ptr, png_bytep new_row,
Imported from libpng-1.0.12beta1.tar
2001-05-14 14:20:53 +00:00
png_uint_32 row_num, int pass)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
{
/* If the image is interlaced, and you turned
on the interlace handler, this function will
be called for every row in every pass. Some
of these rows will not be changed from the
previous pass. When the row is not changed,
the new_row variable will be NULL. The rows
and passes are called in order, so you don't
really need the row_num and pass, but I'm
supplying them because it may make your life
easier.
For the non-NULL rows of interlaced images,
you must call png_progressive_combine_row()
passing in the row and the old row. You can
call this function for NULL rows (it will just
return) and for non-interlaced images (it just
does the memcpy for you) if it will make the
code easier. Thus, you can just do this for
all cases:
*/
png_progressive_combine_row(png_ptr, old_row,
new_row);
/* where old_row is what was displayed for
Imported from libpng-1.0.2.tar
1998-06-14 19:43:31 +00:00
previously for the row. Note that the first
pass (pass == 0, really) will completely cover
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
the old row, so the rows do not have to be
initialized. After the first pass (and only
for interlaced images), you will have to pass
the current row, and the function will combine
the old row and the new row.
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
*/
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
void
end_callback(png_structp png_ptr, png_infop info)
{
/* This function is called after the whole image
has been read, including any chunks after the
image (up to and including the IEND). You
will usually have the same info chunk as you
had in the header, although some data may have
been added to the comments and time fields.
Most people won't do much here, perhaps setting
a flag that marks the image as finished.
*/
}
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
.SH IV. Writing
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Much of this is very similar to reading. However, everything of
importance is repeated here, so you won't have to constantly look
back up in the reading section to understand writing.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Setup
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
You will want to do the I/O initialization before you get into libpng,
so if it doesn't work, you don't have anything to undo. If you are not
using the standard I/O functions, you will need to replace them with
custom writing functions. See the discussion under Customizing libpng.
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
FILE *fp = fopen(file_name, "wb");
if (!fp)
{
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
Next, png_struct and png_info need to be allocated and initialized.
As these can be both relatively large, you may not want to store these
on the stack, unless you have stack space to spare. Of course, you
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
will want to check if they return NULL. If you are also reading,
you won't want to name your read structure and your write structure
both "png_ptr"; you can call them anything you like, such as
"read_ptr" and "write_ptr". Look at pngtest.c, for example.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_structp png_ptr = png_create_write_struct
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
user_error_fn, user_warning_fn);
if (!png_ptr)
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_write_struct(&png_ptr,
(png_infopp)NULL);
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
If you want to use your own memory allocation routines,
define PNG_USER_MEM_SUPPORTED and use
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
png_create_write_struct_2() instead of png_create_write_struct():
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
png_structp png_ptr = png_create_write_struct_2
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn, (png_voidp)
user_mem_ptr, user_malloc_fn, user_free_fn);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
After you have these structures, you will need to set up the
error handling. When libpng encounters an error, it expects to
longjmp() back to your routine. Therefore, you will need to call
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
setjmp() and pass the png_jmpbuf(png_ptr). If you
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
write the file from different routines, you will need to update
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
the png_jmpbuf(png_ptr) every time you enter a new routine that will
call a png_*() function. See your documentation of setjmp/longjmp
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
for your compiler for more information on setjmp/longjmp. See
the discussion on libpng error handling in the Customizing Libpng
section below for more information on the libpng error handling.
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
if (setjmp(png_jmpbuf(png_ptr)))
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
{
Imported from libpng-1.0.7beta15.tar
2000-05-29 13:58:03 +00:00
png_destroy_write_struct(&png_ptr, &info_ptr);
fclose(fp);
return (ERROR);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
}
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
...
return;
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
If you would rather avoid the complexity of setjmp/longjmp issues,
you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
errors will result in a call to PNG_ABORT() which defaults to abort().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Now you need to set up the output code. The default for libpng is to
use the C function fwrite(). If you use this, you will need to pass a
valid FILE * in the function png_init_io(). Be sure that the file is
opened in binary mode. Again, if you wish to handle writing data in
another way, see the discussion on libpng I/O handling in the Customizing
Libpng section below.
png_init_io(png_ptr, fp);
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Write callbacks
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
At this point, you can set up a callback function that will be
called after each row has been written, which you can use to control
a progress meter or the like. It's demonstrated in pngtest.c.
You must supply a function
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
void write_row_callback(png_ptr, png_uint_32 row,
int pass);
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
{
/* put your code here */
}
(You can give it another name that you like instead of "write_row_callback")
To inform libpng about your function, use
png_set_write_status_fn(png_ptr, write_row_callback);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
You now have the option of modifying how the compression library will
run. The following functions are mainly for testing, but may be useful
in some cases, like if you need to write PNG files extremely fast and
are willing to give up some compression, or if you want to get the
maximum possible compression at the expense of slower writing. If you
have no special needs in this area, let the library do what it wants by
not calling this function at all, as it has been tuned to deliver a good
speed/compression ratio. The second parameter to png_set_filter() is
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
the filter method, for which the only valid values are 0 (as of the
July 1999 PNG specification, version 1.2) or 64 (if you are writing
a PNG datastream that is to be embedded in a MNG datastream). The third
parameter is a flag that indicates which filter type(s) are to be tested
for each scanline. See the PNG specification for details on the specific filter
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
types.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
/* turn on or off filtering, and/or choose
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
specific filters. You can use either a single
PNG_FILTER_VALUE_NAME or the logical OR of one
or more PNG_FILTER_NAME masks. */
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_filter(png_ptr, 0,
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
PNG_FILTER_AVE | PNG_FILTER_VALUE_AVE |
PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
PNG_ALL_FILTERS);
If an application
wants to start and stop using particular filters during compression,
it should start out with all of the filters (to ensure that the previous
row of pixels will be stored in case it's needed later), and then add
and remove them after the start of compression.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
If you are writing a PNG datastream that is to be embedded in a MNG
datastream, the second parameter can be either 0 or 64.
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
The png_set_compression_*() functions interface to the zlib compression
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
library, and should mostly be ignored unless you really know what you are
doing. The only generally useful call is png_set_compression_level()
which changes how much time zlib spends on trying to compress the image
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
data. See the Compression Library (zlib.h and algorithm.txt, distributed
with zlib) for details on the compression levels.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
/* set the zlib compression level */
png_set_compression_level(png_ptr,
Z_BEST_COMPRESSION);
/* set other zlib parameters */
png_set_compression_mem_level(png_ptr, 8);
png_set_compression_strategy(png_ptr,
Z_DEFAULT_STRATEGY);
png_set_compression_window_bits(png_ptr, 15);
png_set_compression_method(png_ptr, 8);
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
png_set_compression_buffer_size(png_ptr, 8192)
extern PNG_EXPORT(void,png_set_zbuf_size)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Setting the contents of info for output
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
You now need to fill in the png_info structure with all the data you
wish to write before the actual image. Note that the only thing you
are allowed to write after the image is the text chunks and the time
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
the latest PNG specification for more information on that. If you
wish to write them before the image, fill them in now, and flag that
data as being valid. If you want to wait until after the data, don't
fill them until png_write_end(). For all the fields in png_info and
their data types, see png.h. For explanations of what the fields
contain, see the PNG specification.
Some of the more important parts of the png_info are:
png_set_IHDR(png_ptr, info_ptr, width, height,
bit_depth, color_type, interlace_type,
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
compression_type, filter_method)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
width - holds the width of the image
in pixels (up to 2^31).
height - holds the height of the image
in pixels (up to 2^31).
bit_depth - holds the bit depth of one of the
image channels.
(valid values are 1, 2, 4, 8, 16
and depend also on the
color_type. See also significant
bits (sBIT) below).
color_type - describes which color/alpha
channels are present.
PNG_COLOR_TYPE_GRAY
(bit depths 1, 2, 4, 8, 16)
PNG_COLOR_TYPE_GRAY_ALPHA
(bit depths 8, 16)
PNG_COLOR_TYPE_PALETTE
(bit depths 1, 2, 4, 8)
PNG_COLOR_TYPE_RGB
(bit_depths 8, 16)
PNG_COLOR_TYPE_RGB_ALPHA
(bit_depths 8, 16)
PNG_COLOR_MASK_PALETTE
PNG_COLOR_MASK_COLOR
PNG_COLOR_MASK_ALPHA
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
interlace_type - PNG_INTERLACE_NONE or
PNG_INTERLACE_ADAM7
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
compression_type - (must be
PNG_COMPRESSION_TYPE_DEFAULT)
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
filter_method - (must be PNG_FILTER_TYPE_DEFAULT
or, if you are writing a PNG to
be embedded in a MNG datastream,
can also be
PNG_INTRAPIXEL_DIFFERENCING)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_PLTE(png_ptr, info_ptr, palette,
num_palette);
palette - the palette for the file
(array of png_color)
num_palette - number of entries in the palette
png_set_gAMA(png_ptr, info_ptr, gamma);
gamma - the gamma the image was created
at (PNG_INFO_gAMA)
png_set_sRGB(png_ptr, info_ptr, srgb_intent);
srgb_intent - the rendering intent
(PNG_INFO_sRGB) The presence of
the sRGB chunk means that the pixel
data is in the sRGB color space.
This chunk also implies specific
values of gAMA and cHRM. Rendering
intent is the CSS-1 property that
has been defined by the International
Color Consortium
(http://www.color.org).
It can be one of
Imported from libpng-1.0.5c.tar
1999-11-27 16:22:33 +00:00
PNG_sRGB_INTENT_SATURATION,
PNG_sRGB_INTENT_PERCEPTUAL,
PNG_sRGB_INTENT_ABSOLUTE, or
PNG_sRGB_INTENT_RELATIVE.
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
srgb_intent);
srgb_intent - the rendering intent
(PNG_INFO_sRGB) The presence of the
sRGB chunk means that the pixel
data is in the sRGB color space.
This function also causes gAMA and
cHRM chunks with the specific values
that are consistent with sRGB to be
written.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
png_set_iCCP(png_ptr, info_ptr, name, compression_type,
profile, proflen);
name - The profile name.
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
compression - The compression type; always
PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
You may give NULL to this argument to
ignore it.
profile - International Color Consortium color
profile data. May contain NULs.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
proflen - length of profile data in bytes.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_sBIT(png_ptr, info_ptr, sig_bit);
sig_bit - the number of significant bits for
(PNG_INFO_sBIT) each of the gray, red,
green, and blue channels, whichever are
appropriate for the given color type
(png_color_16)
png_set_tRNS(png_ptr, info_ptr, trans, num_trans,
trans_values);
trans - array of transparent entries for
palette (PNG_INFO_tRNS)
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
trans_values - graylevel or color sample values of
the single transparent color for
non-paletted images (PNG_INFO_tRNS)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
num_trans - number of transparent entries
(PNG_INFO_tRNS)
png_set_hIST(png_ptr, info_ptr, hist);
(PNG_INFO_hIST)
hist - histogram of palette (array of
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
png_uint_16)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_tIME(png_ptr, info_ptr, mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_set_bKGD(png_ptr, info_ptr, background);
background - background color (PNG_VALID_bKGD)
png_set_text(png_ptr, info_ptr, text_ptr, num_text);
text_ptr - array of png_text holding image
comments
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].compression - type of compression used
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
on "text" PNG_TEXT_COMPRESSION_NONE
PNG_TEXT_COMPRESSION_zTXt
PNG_ITXT_COMPRESSION_NONE
PNG_ITXT_COMPRESSION_zTXt
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].key - keyword for comment. Must contain
1-79 characters.
text_ptr[i].text - text comments for current
keyword. Can be NULL or empty.
text_ptr[i].text_length - length of text string,
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
after decompression, 0 for iTXt
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].itxt_length - length of itxt string,
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
after decompression, 0 for tEXt/zTXt
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
text_ptr[i].lang - language of comment (NULL or
empty for unknown).
text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
or empty for unknown).
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
num_text - number of comments
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
num_spalettes);
palette_ptr - array of png_sPLT_struct structures
to be added to the list of palettes
in the info structure.
num_spalettes - number of palette structures to be
added.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
unit_type);
offset_x - positive offset from the left
edge of the screen
offset_y - positive offset from the top
edge of the screen
unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
unit_type);
res_x - pixels/unit physical resolution
in x direction
res_y - pixels/unit physical resolution
in y direction
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
unit_type - PNG_RESOLUTION_UNKNOWN,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
PNG_RESOLUTION_METER
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
png_set_sCAL(png_ptr, info_ptr, unit, width, height)
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
height - height of a pixel in physical scale units
(width and height are doubles)
png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
unit - physical scale units (an integer)
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
width - width of a pixel in physical scale units
height - height of a pixel in physical scale units
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
(width and height are strings like "2.54")
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
num_unknowns)
unknowns - array of png_unknown_chunk
structures holding unknown chunks
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
unknowns[i].name - name of unknown chunk
unknowns[i].data - data of unknown chunk
Imported from libpng-1.0.6f.tar
2000-04-14 19:20:47 +00:00
unknowns[i].size - size of unknown chunk's data
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
unknowns[i].location - position to write chunk in file
0: do not write chunk
PNG_HAVE_IHDR: before PLTE
PNG_HAVE_PLTE: before IDAT
PNG_AFTER_IDAT: after IDAT
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
The "location" member is set automatically according to
what part of the output file has already been written.
You can change its value after calling png_set_unknown_chunks()
as demonstrated in pngtest.c. Within each of the "locations",
the chunks are sequenced according to their position in the
structure (that is, the value of "i", which is the order in which
the chunk was either read from the input file or defined with
png_set_unknown_chunks).
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
A quick word about text and num_text. text is an array of png_text
structures. num_text is the number of valid structures in the array.
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
Each png_text structure holds a language code, a keyword, a text value,
and a compression type.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The compression types have the same valid numbers as the compression
types of the image data. Currently, the only valid number is zero.
However, you can store text either compressed or uncompressed, unlike
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
images, which always have to be compressed. So if you don't want the
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
Because tEXt and zTXt chunks don't have a language field, if you
specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
any language code or translated keyword will not be written out.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Until text gets around 1000 bytes, it is not worth compressing it.
After the text has been written out to the file, the compression type
is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
so that it isn't written out again at the end (in case you are calling
png_write_end() with the same struct.
The keywords that are given in the PNG Specification are:
Title Short (one line) title or
caption for image
Author Name of image's creator
Description Description of image (possibly long)
Copyright Copyright notice
Creation Time Time of original image creation
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
(usually RFC 1123 format, see below)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Software Software used to create the image
Disclaimer Legal disclaimer
Warning Warning of nature of content
Source Device used to create the image
Comment Miscellaneous comment; conversion
from other image format
The keyword-text pairs work like this. Keywords should be short
simple descriptions of what the comment is about. Some typical
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
keywords are found in the PNG specification, as is some recommendations
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
on keywords. You can repeat keywords in a file. You can even write
some text before the image and some after. For example, you may want
to put a description of the image before the image, but leave the
disclaimer until after, so viewers working over modem connections
don't have to wait for the disclaimer to go over the modem before
they start seeing the image. Finally, keywords should be full
words, not abbreviations. Keywords and text are in the ISO 8859-1
(Latin-1) character set (a superset of regular ASCII) and can not
contain NUL characters, and should not contain control or other
unprintable characters. To make the comments widely readable, stick
with basic ASCII, and avoid machine specific character set extensions
like the IBM-PC character set. The keyword must be present, but
you can leave off the text string on non-compressed pairs.
Compressed pairs must have a text string, as only the text string
is compressed anyway, so the compression would be meaningless.
PNG supports modification time via the png_time structure. Two
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
conversion routines are provided, png_convert_from_time_t() for
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
time_t and png_convert_from_struct_tm() for struct tm. The
time_t routine uses gmtime(). You don't have to use either of
these, but if you wish to fill in the png_time structure directly,
you should provide the time in universal time (GMT) if possible
instead of your local time. Note that the year number is the full
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
that months start with 1.
If you want to store the time of the original image creation, you should
use a plain tEXt chunk with the "Creation Time" keyword. This is
necessary because the "creation time" of a PNG image is somewhat vague,
depending on whether you mean the PNG file, the time the image was
created in a non-PNG format, a still photo from which the image was
scanned, or possibly the subject matter itself. In order to facilitate
machine-readable dates, it is recommended that the "Creation Time"
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
although this isn't a requirement. Unlike the tIME chunk, the
"Creation Time" tEXt chunk is not expected to be automatically changed
by the software. To facilitate the use of RFC 1123 dates, a function
png_convert_to_rfc1123(png_timep) is provided to convert from PNG
time to an RFC 1123 format string.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Writing unknown chunks
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
You can use the png_set_unknown_chunks function to queue up chunks
for writing. You give it a chunk name, raw data, and a size; that's
all there is to it. The chunks will be written by the next following
png_write_info_before_PLTE, png_write_info, or png_write_end function.
Any chunks previously read into the info structure's unknown-chunk
list will also be written out in a sequence that satisfies the PNG
specification's ordering rules.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS The high-level write interface
At this point there are two ways to proceed; through the high-level
write interface, or through a sequence of low-level write operations.
You can use the high-level interface if your image data is present
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
in the info structure. All defined output
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
transformations are permitted, enabled by the following masks.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
PNG_TRANSFORM_IDENTITY No transformation
PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
PNG_TRANSFORM_PACKSWAP Change order of packed
pixels to LSB first
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
PNG_TRANSFORM_SHIFT Normalize pixels to the
sBIT depth
PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
to BGRA
PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
to AG
PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
to transparency
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
PNG_TRANSFORM_STRIP_FILLER Strip out filler bytes.
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
If you have valid image data in the info structure (you can use
png_set_rows() to put image data in the info structure), simply do this:
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
png_write_png(png_ptr, info_ptr, png_transforms, NULL)
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
where png_transforms is an integer containing the logical OR of some set of
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
transformation flags. This call is equivalent to png_write_info(),
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
followed the set of transformations indicated by the transform mask,
then png_write_image(), and finally png_write_end().
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
(The final parameter of this call is not yet used. Someday it might point
to transformation parameters required by some future output transform.)
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS The low-level write interface
If you are going the low-level route instead, you are now ready to
write all the file information up to the actual image data. You do
this with a call to png_write_info().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_write_info(png_ptr, info_ptr);
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
Note that there is one transformation you may need to do before
png_write_info(). In PNG files, the alpha channel in an image is the
level of opacity. If your data is supplied as a level of
transparency, you can invert the alpha channel before you write it, so
that 0 is fully transparent and 255 (in 8-bit or paletted images) or
65535 (in 16-bit images) is fully opaque, with
png_set_invert_alpha(png_ptr);
This must appear before png_write_info() instead of later with the
other transformations because in the case of paletted images the tRNS
chunk data has to be inverted before the tRNS chunk is written. If
your image is not a paletted image, the tRNS data (which in such cases
represents a single color to be rendered as transparent) won't need to
be changed, and you can safely do this transformation after your
png_write_info() call.
Imported from libpng-1.0.5c.tar
1999-11-27 16:22:33 +00:00
If you need to write a private chunk that you want to appear before
the PLTE chunk when PLTE is present, you can write the PNG info in
two steps, and insert code to write your own chunk between them:
png_write_info_before_PLTE(png_ptr, info_ptr);
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
png_set_unknown_chunks(png_ptr, info_ptr, ...);
Imported from libpng-1.0.5c.tar
1999-11-27 16:22:33 +00:00
png_write_info(png_ptr, info_ptr);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
After you've written the file information, you can set up the library
to handle any special transformations of the image data. The various
ways to transform the data will be described in the order that they
should occur. This is important, as some of these change the color
type and/or bit depth of the data, and some others only work on
certain color types and bit depths. Even though each transformation
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
checks to see if it has data that it can do something with, you should
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
make sure to only enable a transformation if it will be valid for the
data. For example, don't swap red and blue on grayscale data.
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
Imported from libpng-1.0.6a.tar
2000-04-02 03:10:05 +00:00
the library to strip input data that has 4 or 8 bytes per pixel down
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
bytes per pixel).
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
is stored XRGB or RGBX.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
they can, resulting in, for example, 8 pixels per byte for 1 bit files.
If the data is supplied at 1 pixel per byte, use this code, which will
correctly pack the pixels into a single byte:
png_set_packing(png_ptr);
PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
data is of another bit depth, you can write an sBIT chunk into the
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
file so that decoders can recover the original data if desired.
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
/* Set the true bit depth of the image data */
if (color_type & PNG_COLOR_MASK_COLOR)
{
sig_bit.red = true_bit_depth;
sig_bit.green = true_bit_depth;
sig_bit.blue = true_bit_depth;
}
else
{
sig_bit.gray = true_bit_depth;
}
if (color_type & PNG_COLOR_MASK_ALPHA)
{
sig_bit.alpha = true_bit_depth;
}
png_set_sBIT(png_ptr, info_ptr, &sig_bit);
If the data is stored in the row buffer in a bit depth other than
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
this will scale the values to appear to be the correct bit depth as
is required by PNG.
png_set_shift(png_ptr, &sig_bit);
PNG files store 16 bit pixels in network byte order (big-endian,
ie. most significant bits first). This code would be used if they are
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
supplied the other way (little-endian, i.e. least significant bits
first, the way PCs store them):
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
if (bit_depth > 8)
png_set_swap(png_ptr);
If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
need to change the order the pixels are packed into bytes, you can use:
if (bit_depth < 8)
png_set_packswap(png_ptr);
PNG files store 3 color pixels in red, green, blue order. This code
would be used if they are supplied as blue, green, red:
png_set_bgr(png_ptr);
PNG files describe monochrome as black being zero and white being
one. This code would be used if the pixels are supplied with this reversed
(black being one and white being zero):
png_set_invert_mono(png_ptr);
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
Finally, you can write your own transformation function if none of
the existing ones meets your needs. This is done by setting a callback
with
png_set_write_user_transform_fn(png_ptr,
write_transform_fn);
You must supply the function
void write_transform_fn(png_ptr ptr, row_info_ptr
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
row_info, png_bytep data)
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
See pngtest.c for a working example. Your function will be called
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
before any of the other transformations are processed.
You can also set up a pointer to a user structure for use by your
callback function.
png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
The user_channels and user_depth parameters of this function are ignored
when writing; you can set them to zero as shown.
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
You can retrieve the pointer via the function png_get_user_transform_ptr().
For example:
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
voidp write_user_transform_ptr =
png_get_user_transform_ptr(png_ptr);
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
It is possible to have libpng flush any pending output, either manually,
or automatically after a certain number of lines have been written. To
flush the output stream a single time call:
png_write_flush(png_ptr);
and to have libpng flush the output stream periodically after a certain
number of scanlines have been written, call:
png_set_flush(png_ptr, nrows);
Note that the distance between rows is from the last time png_write_flush()
was called, or the first row of the image if it has never been called.
So if you write 50 lines, and then png_set_flush 25, it will flush the
output on the next scanline, and every 25 lines thereafter, unless
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
png_write_flush() is called before 25 more lines have been written.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
If nrows is too small (less than about 10 lines for a 640 pixel wide
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
RGB image) the image compression may decrease noticeably (although this
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
may be acceptable for real-time applications). Infrequent flushing will
only degrade the compression performance by a few percent over images
that do not use flushing.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Writing the image data
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
That's it for the transformations. Now you can write the image data.
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
The simplest way to do this is in one function call. If you have the
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
whole image in memory, you can just call png_write_image() and libpng
will write the image. You will need to pass in an array of pointers to
each row. This function automatically handles interlacing, so you don't
need to call png_set_interlace_handling() or call this function multiple
times, or any of that other stuff necessary with png_write_rows().
png_write_image(png_ptr, row_pointers);
where row_pointers is:
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
png_byte *row_pointers[height];
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
You can point to void or char or whatever you use for pixels.
Imported from libpng-1.0.1a.tar
1998-04-21 20:03:57 +00:00
If you don't want to write the whole image at once, you can
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
use png_write_rows() instead. If the file is not interlaced,
this is simple:
png_write_rows(png_ptr, row_pointers,
number_of_rows);
row_pointers is the same as in the png_write_image() call.
If you are just writing one row at a time, you can do this with
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
a single row_pointer instead of an array of row_pointers:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_bytep row_pointer = row;
Imported from libpng-1.0.6.tar
2000-03-21 11:13:06 +00:00
png_write_row(png_ptr, row_pointer);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
When the file is interlaced, things can get a good deal more
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
complicated. The only currently (as of the PNG Specification
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
version 1.2, dated July 1999) defined interlacing scheme for PNG files
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
is the "Adam7" interlace scheme, that breaks down an
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
image into seven smaller images of varying size. libpng will build
these images for you, or you can do them yourself. If you want to
build them yourself, see the PNG specification for details of which
pixels to write when.
If you don't want libpng to handle the interlacing details, just
use png_set_interlace_handling() and call png_write_rows() the
correct number of times to write all seven sub-images.
If you want libpng to build the sub-images, call this before you start
writing any rows:
number_of_passes =
png_set_interlace_handling(png_ptr);
This will return the number of passes needed. Currently, this
is seven, but may change if another interlace type is added.
Then write the complete image number_of_passes times.
png_write_rows(png_ptr, row_pointers,
number_of_rows);
As some of these rows are not used, and thus return immediately,
you may want to read about interlacing in the PNG specification,
and only update the rows that are actually used.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Finishing a sequential write
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
After you are finished writing the image, you should finish writing
the file. If you are interested in writing comments or time, you should
pass an appropriately filled png_info pointer. If you are not interested,
you can pass NULL.
png_write_end(png_ptr, info_ptr);
When you are done, you can free all memory used by libpng like this:
png_destroy_write_struct(&png_ptr, &info_ptr);
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
It is also possible to individually free the info_ptr members that
Imported from libpng-1.0.7beta14.tar
2000-05-17 22:39:34 +00:00
point to libpng-allocated storage with the following function:
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_free_data(png_ptr, info_ptr, mask, seq)
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
mask - identifies data to be freed, a mask
containing the logical OR of one or
more of
PNG_FREE_PLTE, PNG_FREE_TRNS,
PNG_FREE_HIST, PNG_FREE_ICCP,
PNG_FREE_PCAL, PNG_FREE_ROWS,
PNG_FREE_SCAL, PNG_FREE_SPLT,
PNG_FREE_TEXT, PNG_FREE_UNKN,
or simply PNG_FREE_ALL
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
seq - sequence number of item to be freed
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
(-1 for all items)
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.7beta14.tar
2000-05-17 22:39:34 +00:00
This function may be safely called when the relevant storage has
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
already been freed, or has not yet been allocated, or was allocated
by the user and not by libpng, and will in those
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
cases do nothing. The "seq" parameter is ignored if only one item
of the selected data type, such as PLTE, is allowed. If "seq" is not
Imported from libpng-1.0.6a.tar
2000-04-02 03:10:05 +00:00
-1, and multiple items are allowed for the data type identified in
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
the mask, such as text or sPLT, only the n'th item in the structure
is freed, where n is "seq".
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
If you allocated data such as a palette that you passed
in to libpng with png_set_*, you must not free it until just before the call to
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
png_destroy_write_struct().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
The default behavior is only to free data that was allocated internally
by libpng. This can be changed, so that libpng will not free the data,
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
or so that it will free data that was allocated by the user with png_malloc()
or png_zalloc() and passed in via a png_set_*() function, with
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
png_data_freer(png_ptr, info_ptr, freer, mask)
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
mask - which data elements are affected
same choices as in png_free_data()
freer - one of
PNG_DESTROY_WILL_FREE_DATA
PNG_SET_WILL_FREE_DATA
PNG_USER_WILL_FREE_DATA
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
For example, to transfer responsibility for some data from a read structure
to a write structure, you could use
png_data_freer(read_ptr, read_info_ptr,
PNG_USER_WILL_FREE_DATA,
PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
png_data_freer(write_ptr, write_info_ptr,
PNG_DESTROY_WILL_FREE_DATA,
PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
thereby briefly reassigning responsibility for freeing to the user but
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
immediately afterwards reassigning it once more to the write_destroy
function. Having done this, it would then be safe to destroy the read
structure and continue to use the PLTE, tRNS, and hIST data in the write
structure.
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
This function only affects data that has already been allocated.
You can call this function before calling after the png_set_*() functions
to control whether the user or png_destroy_*() is supposed to free the data.
When the user assumes responsibility for libpng-allocated data, the
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
application must use
png_free() to free it, and when the user transfers responsibility to libpng
for data that the user has allocated, the user must have used png_malloc()
or png_zalloc() to allocate it.
If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
separately, do not transfer responsibility for freeing text_ptr to libpng,
because when libpng fills a png_text structure it combines these members with
the key member, and png_free_data() will free only text_ptr.key. Similarly,
if you transfer responsibility for free'ing text_ptr from libpng to your
application, your application must not separately free those members.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
For a more compact example of writing a PNG image, see the file example.c.
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
.SH V. Modifying/Customizing libpng:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.9beta8.tar
2001-01-12 21:13:06 +00:00
There are three issues here. The first is changing how libpng does
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
standard things like memory allocation, input/output, and error handling.
The second deals with more complicated things like adding new chunks,
adding new transformations, and generally changing how libpng works.
Imported from libpng-1.0.9beta8.tar
2001-01-12 21:13:06 +00:00
Both of those are compile-time issues; that is, they are generally
determined at the time the code is written, and there is rarely a need
to provide the user with a means of changing them. The third is a
run-time issue: choosing between and/or tuning one or more alternate
versions of computationally intensive routines; specifically, optimized
assembly-language (and therefore compiler- and platform-dependent)
versions.
Memory allocation, input/output, and error handling
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
All of the memory allocation, input/output, and error handling in libpng
Imported from libpng-1.0.9beta8.tar
2001-01-12 21:13:06 +00:00
goes through callbacks that are user-settable. The default routines are
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
these functions, call the appropriate png_set_*_fn() function.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
Memory allocation is done through the functions png_malloc(), png_zalloc(),
and png_free(). These currently just call the standard C functions. If
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
your pointers can't access more then 64K at a time, you will want to set
MAXSEG_64K in zlib.h. Since it is unlikely that the method of handling
memory allocation on a platform will change between applications, these
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
functions must be modified in the library at compile time. If you prefer
to use a different method of allocating and freeing data, you can use
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_set_mem_fn(png_structp png_ptr, png_voidp mem_ptr,
png_malloc_ptr malloc_fn, png_free_ptr free_fn)
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
This function also provides a void pointer that can be retrieved via
mem_ptr=png_get_mem_ptr(png_ptr);
Your replacement memory functions must have prototypes as follows:
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_voidp malloc_fn(png_structp png_ptr,
Imported from libpng-1.2.1rc1.tar
2001-11-24 20:53:31 +00:00
png_size_t size);
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
void free_fn(png_structp png_ptr, png_voidp ptr);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.11rc1.tar
2001-04-20 15:32:10 +00:00
Your malloc_fn() can return NULL in case of failure. The png_malloc()
function will call png_error() if it receives a NULL from the system
memory allocator or from your replacement malloc_fn().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Input/Output in libpng is done through png_read() and png_write(),
which currently just call fread() and fwrite(). The FILE * is stored in
png_struct and is initialized via png_init_io(). If you wish to change
the method of I/O, the library supplies callbacks that you can set
through the function png_set_read_fn() and png_set_write_fn() at run
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
time, instead of calling the png_init_io() function. These functions
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
also provide a void pointer that can be retrieved via the function
png_get_io_ptr(). For example:
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
png_set_read_fn(png_structp read_ptr,
voidp read_io_ptr, png_rw_ptr read_data_fn)
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
png_set_write_fn(png_structp write_ptr,
voidp write_io_ptr, png_rw_ptr write_data_fn,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_flush_ptr output_flush_fn);
Imported from libpng-1.0.1e.tar
1998-06-06 20:31:35 +00:00
voidp read_io_ptr = png_get_io_ptr(read_ptr);
voidp write_io_ptr = png_get_io_ptr(write_ptr);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
The replacement I/O functions must have prototypes as follows:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
void user_read_data(png_structp png_ptr,
png_bytep data, png_uint_32 length);
void user_write_data(png_structp png_ptr,
png_bytep data, png_uint_32 length);
void user_flush_data(png_structp png_ptr);
Supplying NULL for the read, write, or flush functions sets them back
to using the default C stream functions. It is an error to read from
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
a write stream, and vice versa.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Error handling in libpng is done through png_error() and png_warning().
Errors handled through png_error() are fatal, meaning that png_error()
should never return to its caller. Currently, this is handled via
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
setjmp() and longjmp() (unless you have compiled libpng with
PNG_SETJMP_NOT_SUPPORTED, in which case it is handled via PNG_ABORT()),
but you could change this to do things like exit() if you should wish.
On non-fatal errors, png_warning() is called
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
to print a warning message, and then control returns to the calling code.
By default png_error() and png_warning() print a message on stderr via
Imported from libpng-1.0.6e.tar
2000-04-10 00:06:13 +00:00
fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
(because you don't want the messages) or PNG_NO_STDIO defined (because
fprintf() isn't available). If you wish to change the behavior of the error
functions, you will need to set up your own message callbacks. These
functions are normally supplied at the time that the png_struct is created.
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
It is also possible to redirect errors and warnings to your own replacement
functions after png_create_*_struct() has been called by calling:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_error_fn(png_structp png_ptr,
png_voidp error_ptr, png_error_ptr error_fn,
png_error_ptr warning_fn);
png_voidp error_ptr = png_get_error_ptr(png_ptr);
If NULL is supplied for either error_fn or warning_fn, then the libpng
default function will be used, calling fprintf() and/or longjmp() if a
problem is encountered. The replacement error functions should have
parameters as follows:
void user_error_fn(png_structp png_ptr,
png_const_charp error_msg);
void user_warning_fn(png_structp png_ptr,
png_const_charp warning_msg);
The motivation behind using setjmp() and longjmp() is the C++ throw and
catch exception handling methods. This makes the code much easier to write,
as there is no need to check every return code of every function call.
However, there are some uncertainties about the status of local variables
after a longjmp, so the user may want to be careful about doing anything after
setjmp returns non-zero besides returning itself. Consult your compiler
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
documentation for more details. For an alternative approach, you may wish
to use the "cexcept" facility (see http://cexcept.sourceforge.net).
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Custom chunks
If you need to read or write custom chunks, you may need to get deeper
into the libpng code. The library now has mechanisms for storing
and writing chunks of unknown type; you can even declare callbacks
for custom chunks. Hoewver, this may not be good enough if the
library code itself needs to know about interactions between your
chunk and existing `intrinsic' chunks.
If you need to write a new intrinsic chunk, first read the PNG
specification. Acquire a first level of
understanding of how it works. Pay particular attention to the
sections that describe chunk names, and look at how other chunks were
designed, so you can do things similarly. Second, check out the
sections of libpng that read and write chunks. Try to find a chunk
that is similar to yours and use it as a template. More details can
be found in the comments inside the code. It is best to handle unknown
chunks in a generic method, via callback functions, instead of by
modifying libpng functions.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
If you wish to write your own transformation for the data, look through
the part of the code that does the transformations, and check out some of
the simpler ones to get an idea of how they work. Try to find a similar
transformation to the one you want to add and copy off of it. More details
can be found in the comments inside the code itself.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Configuring for 16 bit platforms
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
You will want to look into zconf.h to tell zlib (and thus libpng) that
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
it cannot allocate more then 64K at a time. Even if you can, the memory
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Configuring for DOS
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
For DOS users who only have access to the lower 640K, you will
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
have to limit zlib's memory usage via a png_set_compression_mem_level()
call. See zlib.h or zconf.h in the zlib library for more information.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Configuring for Medium Model
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Libpng's support for medium model has been tested on most of the popular
compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
defined, and FAR gets defined to far in pngconf.h, and you should be
all set. Everything in the library (except for zlib's structure) is
expecting far data. You must use the typedefs with the p or pp on
the end for pointers (or at least look at them and be careful). Make
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
note that the rows of data are defined as png_bytepp, which is an
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
unsigned char far * far *.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Configuring for gui/windowing platforms:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
You will need to write new error and warning functions that use the GUI
interface, as described previously, and set them to be the error and
Imported from libpng-1.0.5s.tar
2000-02-18 19:48:52 +00:00
warning functions at the time that png_create_*_struct() is called,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
in order to have them available during the structure initialization.
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
They can be changed later via png_set_error_fn(). On some compilers,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
you may also have to change the memory allocators (png_malloc, etc.).
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Configuring for compiler xxx:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
All includes for libpng are in pngconf.h. If you need to add/change/delete
an include, this is the place to do it. The includes that are not
needed outside libpng are protected by the PNG_INTERNAL definition,
which is only defined for those routines inside libpng itself. The
files in libpng proper only include png.h, which includes pngconf.h.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Configuring zlib:
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
There are special functions to configure the compression. Perhaps the
most useful one changes the compression level, which currently uses
input compression values in the range 0 - 9. The library normally
uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
have shown that for a large majority of images, compression values in
the range 3-6 compress nearly as well as higher levels, and do so much
faster. For online applications it may be desirable to have maximum speed
(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
specify no compression (Z_NO_COMPRESSION = 0), but this would create
files larger than just storing the raw bitmap. You can specify the
compression level by calling:
png_set_compression_level(png_ptr, level);
Another useful one is to reduce the memory level used by the library.
The memory level defaults to 8, but it can be lowered if you are
short on memory (running DOS, for example, where you only have 640K).
png_set_compression_mem_level(png_ptr, level);
The other functions are for configuring zlib. They are not recommended
for normal use and may result in writing an invalid PNG file. See
zlib.h for more information on what these mean.
png_set_compression_strategy(png_ptr,
strategy);
png_set_compression_window_bits(png_ptr,
window_bits);
png_set_compression_method(png_ptr, method);
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
png_set_compression_buffer_size(png_ptr, size);
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Controlling row filtering
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
If you want to control whether libpng uses filtering or not, which
filters are used, and how it goes about picking row filters, you
can call one of these functions. The selection and configuration
of row filters can have a significant impact on the size and
encoding speed and a somewhat lesser impact on the decoding speed
of an image. Filtering is enabled by default for RGB and grayscale
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
images (with and without alpha), but not for paletted images nor
for any images with bit depths less than 8 bits/pixel.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The 'method' parameter sets the main filtering method, which is
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
currently only '0' in the PNG 1.2 specification. The 'filters'
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
parameter sets which filter(s), if any, should be used for each
scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
to turn filtering on and off, respectively.
Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
Imported from libpng-1.0.6i.tar
2000-05-01 14:31:54 +00:00
ORed together with '|' to specify one or more filters to use.
These filters are described in more detail in the PNG specification. If
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
you intend to change the filter type during the course of writing
the image, you should start with flags set for all of the filters
you intend to use so that libpng can initialize its internal
structures appropriately for all of the filter types.
filters = PNG_FILTER_NONE | PNG_FILTER_SUB
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
PNG_FILTER_UP | PNG_FILTER_AVE |
PNG_FILTER_PAETH | PNG_ALL_FILTERS;
or
filters = one of PNG_FILTER_VALUE_NONE,
PNG_FILTER_VALUE_SUB, PNG_FILTER_VALUE_UP,
PNG_FILTER_VALUE_AVE, PNG_FILTER_VALUE_PAETH
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
filters);
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
The second parameter can also be
PNG_INTRAPIXEL_DIFFERENCING if you are
writing a PNG to be embedded in a MNG
datastream. This parameter must be the
same as the value of filter_method used
in png_set_IHDR().
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
It is also possible to influence how libpng chooses from among the
available filters. This is done in two ways - by telling it how
important it is to keep the same filter for successive rows, and
by telling it the relative computational costs of the filters.
double weights[3] = {1.5, 1.3, 1.1},
costs[PNG_FILTER_VALUE_LAST] =
{1.0, 1.3, 1.3, 1.5, 1.7};
png_set_filter_selection(png_ptr,
PNG_FILTER_SELECTION_WEIGHTED, 3,
weights, costs);
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
The weights are multiplying factors that indicate to libpng that the
row filter should be the same for successive rows unless another row filter
is that many times better than the previous filter. In the above example,
if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
"sum of absolute differences" 1.5 x 1.3 times higher than other filters
and still be chosen, while the NONE filter could have a sum 1.1 times
higher than other filters and still be chosen. Unspecified weights are
taken to be 1.0, and the specified weights should probably be declining
like those above in order to emphasize recent filters over older filters.
The filter costs specify for each filter type a relative decoding cost
to be considered when selecting row filters. This means that filters
with higher costs are less likely to be chosen over filters with lower
costs, unless their "sum of absolute differences" is that much smaller.
The costs do not necessarily reflect the exact computational speeds of
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
the various filters, since this would unduly influence the final image
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
size.
Note that the numbers above were invented purely for this example and
are given only to help explain the function usage. Little testing has
been done to find optimum values for either the costs or the weights.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Removing unwanted object code
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
There are a bunch of #define's in pngconf.h that control what parts of
libpng are compiled. All the defines end in _SUPPORTED. If you are
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
never going to use a capability, you can change the #define to #undef
before recompiling libpng and save yourself code and data space, or
you can turn off individual capabilities with defines that begin with
PNG_NO_.
You can also turn all of the transforms and ancillary chunk capabilities
Imported from libpng-1.0.6g.tar
2000-04-24 04:14:02 +00:00
off en masse with compiler directives that define
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
or all four,
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
along with directives to turn on any of the capabilities that you do
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
the extra transformations but still leave the library fully capable of reading
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
and writing PNG files with all known public chunks
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
Use of the PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
produces a library that is incapable of reading or writing ancillary chunks.
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
If you are not using the progressive reading capability, you can
Imported from libpng-1.0.1c.tar
1998-05-09 15:02:29 +00:00
turn that off with PNG_NO_PROGRESSIVE_READ (don't confuse
Imported from libpng-0.99i.tar
1998-03-07 12:06:55 +00:00
this with the INTERLACING capability, which you'll still have).
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
All the reading and writing specific code are in separate files, so the
linker should only grab the files it needs. However, if you want to
make sure, or if you are building a stand alone library, all the
reading files start with pngr and all the writing files start with
pngw. The files that don't match either (like png.c, pngtrans.c, etc.)
are used for both reading and writing, and always need to be included.
The progressive reader is in pngpread.c
If you are creating or distributing a dynamically linked library (a .so
or DLL file), you should not remove or disable any parts of the library,
as this will cause applications linked with different versions of the
library to fail if they call functions not available in your library.
The size of the library itself should not be an issue, because only
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
those sections that are actually used will be loaded into memory.
Imported from libpng-1.0.5q.tar
2000-02-05 05:40:16 +00:00
.SS Requesting debug printout
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
The macro definition PNG_DEBUG can be used to request debugging
printout. Set it to an integer value in the range 0 to 3. Higher
numbers result in increasing amounts of debugging information. The
information is printed to the "stderr" file, unless another file
name is specified in the PNG_DEBUG_FILE macro definition.
When PNG_DEBUG > 0, the following functions (macros) become available:
png_debug(level, message)
png_debug1(level, message, p1)
png_debug2(level, message, p1, p2)
in which "level" is compared to PNG_DEBUG to decide whether to print
the message, "message" is the formatted string to be printed,
and p1 and p2 are parameters that are to be embedded in the string
according to printf-style formatting directives. For example,
png_debug1(2, "foo=%d\n", foo);
is expanded to
if(PNG_DEBUG > 2)
fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
can still use PNG_DEBUG to control your own debugging:
#ifdef PNG_DEBUG
fprintf(stderr, ...
#endif
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
having level = 0 will be printed. There aren't any such statements in
this version of libpng, but if you insert some they will be printed.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
.SH VI. Runtime optimization
A new feature in libpng 1.2.0 is the ability to dynamically switch between
standard and optimized versions of some routines. Currently these are
limited to three computationally intensive tasks when reading PNG files:
decoding row filters, expanding interlacing, and combining interlaced or
transparent row data with previous row data. Currently the optimized
versions are available only for x86 (Intel, AMD, etc.) platforms with
MMX support, though this may change in future versions. (For example,
the non-MMX assembler optimizations for zlib might become similarly
runtime-selectable in future releases, in which case libpng could be
extended to support them. Alternatively, the compile-time choice of
floating-point versus integer routines for gamma correction might become
runtime-selectable.)
Because such optimizations tend to be very platform- and compiler-dependent,
both in how they are written and in how they perform, the new runtime code
in libpng has been written to allow programs to query, enable, and disable
either specific optimizations or all such optimizations. For example, to
enable all possible optimizations (bearing in mind that some "optimizations"
may actually run more slowly in rare cases):
#if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
png_uint_32 mask, flags;
flags = png_get_asm_flags(png_ptr);
mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
png_set_asm_flags(png_ptr, flags | mask);
#endif
To enable only optimizations relevant to reading PNGs, use PNG_SELECT_READ
by itself when calling png_get_asm_flagmask(); similarly for optimizing
only writing. To disable all optimizations:
#if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
flags = png_get_asm_flags(png_ptr);
mask = png_get_asm_flagmask(PNG_SELECT_READ | PNG_SELECT_WRITE);
png_set_asm_flags(png_ptr, flags & ~mask);
#endif
To enable or disable only MMX-related features, use png_get_mmx_flagmask()
in place of png_get_asm_flagmask(). The mmx version takes one additional
parameter:
#if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
int selection = PNG_SELECT_READ | PNG_SELECT_WRITE;
int compilerID;
mask = png_get_mmx_flagmask(selection, &compilerID);
#endif
On return, compilerID will indicate which version of the MMX assembler
optimizations was compiled. Currently two flavors exist: Microsoft
Visual C++ (compilerID == 1) and GNU C (a.k.a. gcc/gas, compilerID == 2).
On non-x86 platforms or on systems compiled without MMX optimizations, a
value of -1 is used.
Note that both png_get_asm_flagmask() and png_get_mmx_flagmask() return
all valid, settable optimization bits for the version of the library that's
currently in use. In the case of shared (dynamically linked) libraries,
this may include optimizations that did not exist at the time the code was
written and compiled. It is also possible, of course, to enable only known,
specific optimizations; for example:
#if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
flags = PNG_ASM_FLAG_MMX_READ_COMBINE_ROW \
| PNG_ASM_FLAG_MMX_READ_INTERLACE \
| PNG_ASM_FLAG_MMX_READ_FILTER_SUB \
| PNG_ASM_FLAG_MMX_READ_FILTER_UP \
| PNG_ASM_FLAG_MMX_READ_FILTER_AVG \
| PNG_ASM_FLAG_MMX_READ_FILTER_PAETH ;
png_set_asm_flags(png_ptr, flags);
#endif
This method would enable only the MMX read-optimizations available at the
time of libpng 1.2.0's release, regardless of whether a later version of
the DLL were actually being used. (Also note that these functions did not
exist in versions older than 1.2.0, so any attempt to run a dynamically
linked app on such an older version would fail.)
To determine whether the processor supports MMX instructions at all, use
the png_mmx_support() function:
#if defined(PNG_LIBPNG_VER) && (PNG_LIBPNG_VER >= 10200)
mmxsupport = png_mmx_support();
#endif
It returns -1 if MMX support is not compiled into libpng, 0 if MMX code
is compiled but MMX is not supported by the processor, or 1 if MMX support
is fully available. Note that png_mmx_support(), png_get_mmx_flagmask(),
and png_get_asm_flagmask() all may be called without allocating and ini-
tializing any PNG structures (for example, as part of a usage screen or
"about" box).
Imported from libpng-1.2.0.tar
2001-09-01 12:54:01 +00:00
The following code can be used to prevent an application from using the
thread_unsafe features, even if libpng was built with PNG_THREAD_UNSAFE_OK
defined:
#if defined(PNG_USE_PNGGCCRD) && defined(PNG_ASSEMBLER_CODE_SUPPORTED) \
&& defined(PNG_THREAD_UNSAFE_OK)
/* Disable thread-unsafe features of pnggccrd */
if (png_access_version() >= 10200)
{
png_uint_32 mmx_disable_mask = 0;
png_uint_32 asm_flags;
mmx_disable_mask |= ( PNG_ASM_FLAG_MMX_READ_COMBINE_ROW \
| PNG_ASM_FLAG_MMX_READ_FILTER_SUB \
| PNG_ASM_FLAG_MMX_READ_FILTER_AVG \
| PNG_ASM_FLAG_MMX_READ_FILTER_PAETH );
asm_flags = png_get_asm_flags(png_ptr);
png_set_asm_flags(png_ptr, asm_flags & ~mmx_disable_mask);
}
#endif
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
For more extensive examples of runtime querying, enabling and disabling
of optimized features, see contrib/gregbook/readpng2.c in the libpng
source-code distribution.
.SH VII. MNG support
Imported from libpng-1.0.9beta5.tar
2000-12-15 14:54:42 +00:00
The MNG specification (available at http://www.libpng.org/pub/mng) allows
certain extensions to PNG for PNG images that are embedded in MNG datastreams.
Libpng can support some of these extensions. To enable them, use the
png_permit_mng_features() function:
feature_set = png_permit_mng_features(png_ptr, mask)
mask is a png_uint_32 containing the logical OR of the
features you want to enable. These include
PNG_FLAG_MNG_EMPTY_PLTE
PNG_FLAG_MNG_FILTER_64
PNG_ALL_MNG_FEATURES
feature_set is a png_32_uint that is the logical AND of
your mask with the set of MNG features that is
supported by the version of libpng that you are using.
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
It is an error to use this function when reading or writing a standalone
PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
Imported from libpng-1.0.9rc1.tar
2000-12-23 20:27:39 +00:00
in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
and the MHDR and MEND chunks. Libpng does not provide support for these
or any other MNG chunks; your application must provide its own support for
them. You may wish to consider using libmng (available at
http://www.libmng.com) instead.
Imported from libpng-1.0.9beta6.tar
2000-12-18 15:33:57 +00:00
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
.SH VIII. Changes to Libpng from version 0.88
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
It should be noted that versions of libpng later than 0.96 are not
distributed by the original libpng author, Guy Schalnat, nor by
Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
distributed versions 0.89 through 0.96, but rather by another member
of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
still alive and well, but they have moved on to other things.
The old libpng functions png_read_init(), png_write_init(),
Imported from libpng-1.2.0beta3.tar
2001-05-18 09:54:50 +00:00
png_info_init(), png_read_destroy(), and png_write_destroy() have been
Imported from libpng-1.0.7beta11.tar
2000-05-06 19:09:57 +00:00
moved to PNG_INTERNAL in version 0.95 to discourage their use. These
functions will be removed from libpng version 2.0.0.
The preferred method of creating and initializing the libpng structures is
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
via the png_create_read_struct(), png_create_write_struct(), and
png_create_info_struct() because they isolate the size of the structures
from the application, allow version error checking, and also allow the
use of custom error handling routines during the initialization, which
the old functions do not. The functions png_read_destroy() and
png_write_destroy() do not actually free the memory that libpng
allocated for these structs, but just reset the data structures, so they
can be used instead of png_destroy_read_struct() and
png_destroy_write_struct() if you feel there is too much system overhead
allocating and freeing the png_struct for each image read.
Setting the error callbacks via png_set_message_fn() before
png_read_init() as was suggested in libpng-0.88 is no longer supported
Imported from libpng-1.0.2a.tar
1998-12-29 17:47:59 +00:00
because this caused applications that do not use custom error functions
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
to fail if the png_ptr was not initialized to zero. It is still possible
to set the error callbacks AFTER png_read_init(), or to change them with
Imported from libpng-1.0.7beta11.tar
2000-05-06 19:09:57 +00:00
png_set_error_fn(), which is essentially the same function, but with a new
name to force compilation errors with applications that try to use the old
method.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-1.0.7beta12.tar
2000-05-12 11:19:53 +00:00
Starting with version 1.0.7, you can find out which version of the library
you are using at run-time:
png_uint_32 libpng_vn = png_access_version_number();
The number libpng_vn is constructed from the major version, minor
version with leading zero, and release number with leading zero,
(e.g., libpng_vn for version 1.0.7 is 10007).
You can also check which version of png.h you used when compiling your
application:
png_uint_32 application_vn = PNG_LIBPNG_VER;
Imported from libpng-1.2.0beta1.tar
2001-05-06 10:34:26 +00:00
.SH IX. Y2K Compliance in libpng
Imported from libpng-1.0.3.tar
1999-01-14 04:06:39 +00:00
Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
December 4, 2001
Imported from libpng-1.0.3.tar
1999-01-14 04:06:39 +00:00
Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
This is your unofficial assurance that libpng from version 0.71 and
Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
upward through 1.2.1rc2 are Y2K compliant. It is my belief that earlier
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
versions were also Y2K compliant.
Imported from libpng-1.0.3.tar
1999-01-14 04:06:39 +00:00
Libpng only has three year fields. One is a 2-byte unsigned integer that
will hold years up to 65535. The other two hold the date in text
format, and will hold years up to 9999.
The integer is
"png_uint_16 year" in png_time_struct.
The strings are
"png_charp time_buffer" in png_struct and
"near_time_buffer", which is a local character string in png.c.
There are seven time-related functions:
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
png_convert_to_rfc_1123() in png.c
Imported from libpng-1.0.3.tar
1999-01-14 04:06:39 +00:00
(formerly png_convert_to_rfc_1152() in error)
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
png_convert_from_struct_tm() in pngwrite.c, called
in pngwrite.c
Imported from libpng-1.0.3.tar
1999-01-14 04:06:39 +00:00
png_convert_from_time_t() in pngwrite.c
png_get_tIME() in pngget.c
png_handle_tIME() in pngrutil.c, called in pngread.c
png_set_tIME() in pngset.c
png_write_tIME() in pngwutil.c, called in pngwrite.c
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
All appear to handle dates properly in a Y2K environment. The
Imported from libpng-1.0.3.tar
1999-01-14 04:06:39 +00:00
png_convert_from_time_t() function calls gmtime() to convert from system
clock time, which returns (year - 1900), which we properly convert to
the full 4-digit year. There is a possibility that applications using
libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
function, or that they are incorrectly passing only a 2-digit year
instead of "year - 1900" into the png_convert_from_struct_tm() function,
but this is not under our control. The libpng documentation has always
stated that it works with 4-digit years, and the APIs have been
documented as such.
Imported from libpng-1.0.3.tar
1999-01-14 04:06:39 +00:00
The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
integer to hold the year, and can hold years as large as 65535.
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
zlib, upon which libpng depends, is also Y2K compliant. It contains
no date-related code.
Imported from libpng-1.0.3.tar
1999-01-14 04:06:39 +00:00
Glenn Randers-Pehrson
libpng maintainer
PNG Development Group
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
.SH NOTE
Note about libpng version numbers:
Due to various miscommunications, unforeseen code incompatibilities
and occasional factors outside the authors' control, version numbering
on the library has not always been consistent and straightforward.
The following table summarizes matters since version 0.89c, which was
the first widely used release:
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
source png.h png.h shared-lib
version string int version
------- ------ ----- ----------
0.89c ("beta 3") 0.89 89 1.0.89
0.90 ("beta 4") 0.90 90 0.90
0.95 ("beta 5") 0.95 95 0.95
0.96 ("beta 6") 0.96 96 0.96
0.97b ("beta 7") 1.00.97 97 1.0.1
0.97c 0.97 97 2.0.97
0.98 0.98 98 2.0.98
0.99 0.99 98 2.0.99
0.99a-m 0.99 99 2.0.99
1.00 1.00 100 2.1.0
1.0.0 1.0.0 100 2.1.0
1.0.0 (from here on, the 100 2.1.0
1.0.1 png.h string is 10001 2.1.0
1.0.1a-e identical to the 10002 from here on, the
1.0.2 source version) 10002 shared library is 2.V
1.0.2a-b 10003 where V is the source
1.0.1 10001 code version except as
1.0.1a-e 10002 2.1.0.1a-e noted.
1.0.2 10002 2.1.0.2
1.0.2a-b 10003 2.1.0.2a-b
1.0.3 10003 2.1.0.3
1.0.3a-d 10004 2.1.0.3a-d
1.0.4 10004 2.1.0.4
1.0.4a-f 10005 2.1.0.4a-f
1.0.5 (+ 2 patches) 10005 2.1.0.5
1.0.5a-d 10006 2.1.0.5a-d
1.0.5e-r 10100 2.1.0.5e-r
1.0.5s-v 10006 2.1.0.5s-v
1.0.6 (+ 3 patches) 10006 2.1.0.6
1.0.6d-g 10007 2.1.0.6d-g
1.0.6h 10007 10.6h
1.0.6i 10007 10.6i
1.0.6j 10007 2.1.0.6j
1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14
1.0.7beta15-18 1 10007 2.1.0.7beta15-18
1.0.7rc1-2 1 10007 2.1.0.7rc1-2
1.0.7 1 10007 2.1.0.7
1.0.8beta1-4 1 10008 2.1.0.8beta1-4
1.0.8rc1 1 10008 2.1.0.8rc1
1.0.8 1 10008 2.1.0.8
1.0.9beta1-6 1 10009 2.1.0.9beta1-6
1.0.9rc1 1 10009 2.1.0.9rc1
1.0.9beta7-10 1 10009 2.1.0.9beta7-10
1.0.9rc2 1 10009 2.1.0.9rc2
1.0.9 1 10009 2.1.0.9
Imported from libpng-1.0.10rc1.tar
2001-03-23 11:06:56 +00:00
1.0.10beta1 1 10010 2.1.0.10beta1
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
1.0.10rc1 1 10010 2.1.0.10rc1
Imported from libpng-1.0.10.tar
2001-03-30 12:42:28 +00:00
1.0.10 1 10010 2.1.0.10
Imported from libpng-1.0.11beta3.tar
2001-04-15 01:15:41 +00:00
1.0.11beta1-3 1 10011 2.1.0.11beta1-3
Imported from libpng-1.0.11rc1.tar
2001-04-20 15:32:10 +00:00
1.0.11rc1 1 10011 2.1.0.11rc1
Imported from libpng-1.0.11.tar
2001-04-27 13:29:32 +00:00
1.0.11 1 10011 2.1.0.11
Imported from libpng-1.2.0beta4.tar
2001-06-23 13:03:17 +00:00
1.0.12beta1-2 2 10012 2.1.0.12beta1-2
1.0.12rc1 2 10012 2.1.0.12rc1
1.0.12 2 10012 2.1.0.12
1.1.0a-f - 10100 2.1.1.0a-f abandoned
Imported from libpng-1.2.0beta3.tar
2001-05-18 09:54:50 +00:00
1.2.0beta1-2 2 10200 2.1.2.0beta1-2
Imported from libpng-1.2.1beta1.tar
2001-10-19 01:55:13 +00:00
1.2.0beta3-5 3 10200 3.1.2.0beta3-5
1.2.0rc1 3 10200 3.1.2.0rc1
1.2.0 3 10200 3.1.2.0
Imported from libpng-1.2.1beta4.tar
2001-11-07 13:10:08 +00:00
1.2.1beta-4 3 10201 3.1.2.1beta1-4
Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
1.2.1rc1-2 3 10201 3.1.2.1rc1-2
1.2.1 3 10201 3.1.2.1
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
Henceforth the source version will match the shared-library minor
and patch numbers; the shared-library major version number will be
used for changes in backward compatibility, as it is intended. The
PNG_PNGLIB_VER macro, which is not used within libpng but is available
for applications, is an unsigned integer of the form xyyzz corresponding
to the source version x.y.z (leading zeros in y and z). Beta versions
Imported from libpng-1.0.10rc1.tar
2001-03-23 11:06:56 +00:00
were given the previous public release number plus a letter, until
version 1.0.6j; from then on they were given the upcoming public
release number plus "betaNN" or "rcN".
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.SH "SEE ALSO"
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
libpngpf(3), png(5)
.LP
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.IR libpng :
.IP
ftp://ftp.uu.net/graphics/png
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
http://www.libpng.org/pub/png
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
.LP
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.IR zlib :
.IP
(generally) at the same location as
.I libpng
or at
.br
ftp://ftp.uu.net/pub/archiving/zip/zlib
.br
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
ftp://ftp.info-zip.org/pub/infozip/zlib
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
.LP
.IR PNG specification: RFC 2083
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.IP
(generally) at the same location as
.I libpng
or at
.br
ftp://ds.internic.net/rfc/rfc2083.txt
.br
or (as a W3C Recommendation) at
.br
http://www.w3.org/TR/REC-png.html
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-0.99e.tar
1998-02-28 13:00:24 +00:00
.LP
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
In the case of any inconsistency between the PNG specification
and this library, the specification takes precedence.
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.SH AUTHORS
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
This man page: Glenn Randers-Pehrson
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
<randeg@alum.rpi.edu>
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
The contributing authors would like to thank all those who helped
with testing, bug fixes, and patience. This wouldn't have been
possible without all of you.
Thanks to Frank J. T. Wojcik for helping with the documentation.
Imported from libpng-1.0.5h.tar
1999-12-10 15:43:02 +00:00
Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
Libpng version 1.2.1rc2 - December 4, 2001:
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
Currently maintained by Glenn Randers-Pehrson (randeg@alum.rpi.edu).
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
Supported by the PNG development group
.br
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
(png-implement@ccrc.wustl.edu).
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
.SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
Imported from libpng-1.0.9beta1.tar
2000-11-10 18:26:19 +00:00
(This copy of the libpng notices is provided for your convenience. In case of
any discrepancy between this copy and the notices in the file png.h that is
included in the libpng distribution, the latter shall prevail.)
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
If you modify libpng you may insert additional notices immediately following
this sentence.
Imported from libpng-1.0.4c.tar
1999-10-01 19:22:25 +00:00
Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
libpng versions 1.0.7, July 1, 2000, through 1.2.1rc2, December 4, 2001, are
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
Copyright (c) 2000-2001 Glenn Randers-Pehrson, and are
Imported from libpng-1.0.8.tar
2000-07-24 11:34:14 +00:00
distributed according to the same disclaimer and license as libpng-1.0.6
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
with the following individuals added to the list of Contributing Authors
Simon-Pierre Cadieux
Eric S. Raymond
Gilles Vollant
and with the following additions to the disclaimer:
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
There is no warranty against interference with your
enjoyment of the library or against infringement.
There is no warranty that our efforts or the library
will fulfill any of your particular purposes or needs.
This library is provided with all faults, and the entire
risk of satisfactory quality, performance, accuracy, and
effort is with the user.
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
Copyright (c) 1998, 1999 Glenn Randers-Pehrson
Distributed according to the same disclaimer and license as libpng-0.96,
with the following individuals added to the list of Contributing Authors:
Tom Lane
Glenn Randers-Pehrson
Willem van Schaik
libpng versions 0.89, June 1996, through 0.96, May 1997, are
Copyright (c) 1996, 1997 Andreas Dilger
Distributed according to the same disclaimer and license as libpng-0.88,
with the following individuals added to the list of Contributing Authors:
Imported from libpng-1.0.4c.tar
1999-10-01 19:22:25 +00:00
John Bowler
Kevin Bracey
Sam Bushell
Magnus Holmgren
Greg Roelofs
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
Tom Tanner
libpng versions 0.5, May 1995, through 0.88, January 1996, are
Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
For the purposes of this copyright and license, "Contributing Authors"
is defined as the following set of individuals:
Andreas Dilger
Dave Martindale
Imported from libpng-1.0.4c.tar
1999-10-01 19:22:25 +00:00
Guy Eric Schalnat
Paul Schmidt
Tim Wegner
Imported from libpng-1.0.2b.tar
1999-01-07 03:50:16 +00:00
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
The PNG Reference Library is supplied "AS IS". The Contributing Authors
and Group 42, Inc. disclaim all warranties, expressed or implied,
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
including, without limitation, the warranties of merchantability and of
fitness for any purpose. The Contributing Authors and Group 42, Inc.
assume no liability for direct, indirect, incidental, special, exemplary,
or consequential damages, which may result from the use of the PNG
Reference Library, even if advised of the possibility of such damage.
Imported from libpng-0.99d.tar
1998-02-09 02:56:40 +00:00
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
Permission is hereby granted to use, copy, modify, and distribute this
source code, or portions hereof, for any purpose, without fee, subject
to the following restrictions:
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
1. The origin of this source code must not be misrepresented.
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
2. Altered versions must be plainly marked as such and
must not be misrepresented as being the original source.
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
Imported from libpng-1.0.10beta1.tar
2001-03-14 13:08:39 +00:00
3. This Copyright notice may not be removed or altered from
any source or altered source distribution.
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
The Contributing Authors and Group 42, Inc. specifically permit, without
fee, and encourage the use of this source code as a component to
supporting the PNG file format in commercial products. If you use this
source code in a product, acknowledgment is not required but would be
appreciated.
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
A "png_get_copyright" function is available, for convenient use in "about"
boxes and the like:
printf("%s",png_get_copyright(NULL));
Also, the PNG logo (in PNG format, of course) is supplied in the
Imported from libpng-1.0.8beta4.tar
2000-07-14 13:15:12 +00:00
files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
Imported from libpng-1.0.4-pre1.tar
1999-09-17 17:27:26 +00:00
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a
Imported from libpng-1.0.4c.tar
1999-10-01 19:22:25 +00:00
certification mark of the Open Source Initiative.
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
Glenn Randers-Pehrson
randeg@alum.rpi.edu
Imported from libpng-1.2.1rc2.tar
2001-12-04 12:30:43 +00:00
December 4, 2001
Imported from libpng-1.0.7.tar
2000-07-01 20:37:28 +00:00
Imported from libpng-0.99c.tar
1998-02-07 16:20:57 +00:00
.\" end of man page
Reference in New Issue Copy Permalink