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Guy Schalnat 1995-11-28 11:22:13 -06:00 committed by Glenn Randers-Pehrson
parent 51f0eb4584
commit 0f71645dfe
16 changed files with 1233 additions and 475 deletions
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48
example.c
View File

@ -79,9 +79,19 @@ void read_png(char *file_name)
png_info_init(info_ptr);
png_read_init(png_ptr);
/* set up the input control */
/* set up the input control for the default input and message functions.
* If we were to replace both the input and message functions we don't
* need to call png_init_io first. */
png_init_io(png_ptr, fp);
/* if you are using replacement read functions, here you would call */
io_ptr = (user_io_struct *)malloc(sizeof(user_io_struct));
png_set_read_fn(png_ptr, (void *)io_ptr, user_read_fn);
/* if you are using replacement message functions, here you would call */
msg_ptr = (user_msg_struct *)malloc(sizeof(user_msg_struct));
png_set_read_fn(png_ptr, (void *)msg_ptr, user_error_fn, user_warning_fn);
/* read the file information */
png_read_info(png_ptr, info_ptr);
@ -146,8 +156,7 @@ void read_png(char *file_name)
png_set_invert(png_ptr);
/* shift the pixels down to their true bit depth */
if (info_ptr->valid & PNG_INFO_sBIT &&
info_ptr->bit_depth > info_ptr->sig_bit)
if (info_ptr->valid & PNG_INFO_sBIT)
png_set_shift(png_ptr, &(info_ptr->sig_bit));
/* pack pixels into bytes */
@ -212,6 +221,11 @@ void read_png(char *file_name)
in info_ptr */
png_read_end(png_ptr, info_ptr);
/* if you had allocated any memory structures for custom input or
messaging routines you need to free them before png_read_destroy */
free(png_get_io_ptr(png_ptr));
free(png_get_msg_ptr(png_ptr));
/* clean up after the read, and free any memory allocated */
png_read_destroy(png_ptr, info_ptr, (png_info *)0);
@ -269,9 +283,19 @@ void write_png(char *file_name, ... other image information ...)
png_info_init(info_ptr);
png_write_init(png_ptr);
/* set up the output control */
/* set up the output control for the default output and message functions.
* If we were to replace both the output and message functions we don't
* need to call png_init_io first. */
png_init_io(png_ptr, fp);
/* if you are using replacement write functions, here you would call */
io_ptr = (user_io_struct *)malloc(sizeof(user_io_struct));
png_set_write_fn(png_ptr, (void *)io_ptr, user_write_fn, user_flush_fn);
/* if you are using replacement message functions, here you would call */
msg_ptr = (user_msg_struct *)malloc(sizeof(user_msg_struct));
png_set_read_fn(png_ptr, (void *)msg_ptr, user_error_fn, user_warning_fn);
/* set the file information here */
info_ptr->width = ;
info_ptr->height = ;
@ -285,9 +309,16 @@ void write_png(char *file_name, ... other image information ...)
/* optional significant bit chunk */
info_ptr->valid |= PNG_INFO_sBIT;
info_ptr->sig_bit = true_bit_depth;
/* if we are dealing with a grayscale image then */
info_ptr->sig_bit.gray = true_bit_depth;
/* otherwise, if we are dealing with a color image then */
info_ptr->sig_bit.red = true_red_bit_depth;
info_ptr->sig_bit.green = true_green_bit_depth;
info_ptr->sig_bit.blue = true_blue_bit_depth;
/* if the image has an alpha channel then */
info_ptr->sig_bit.alpha = true_alpha_bit_depth;
/* optional gamma chunk */
/* optional gamma chunk is a good idea if you can write one */
info_ptr->valid |= PNG_INFO_gAMA;
info_ptr->gamma = gamma;
@ -347,6 +378,11 @@ void write_png(char *file_name, ... other image information ...)
/* write the rest of the file */
png_write_end(png_ptr, info_ptr);
/* if you had allocated any memory structures for custom output or
messaging routines you need to free them before png_write_destroy */
free(png_get_io_ptr(png_ptr));
free(png_get_msg_ptr(png_ptr));
/* clean up after the write, and free any memory allocated */
png_write_destroy(png_ptr);

250
libpng.txt
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@ -45,22 +45,22 @@ The 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 the general user except as
the first variable passed to every png function call.
the first variable passed to every PNG function call.
The png_info structure is designed to provide information about the
png file. All of it's fields are intended to be examined or modified
by the user. See png.h for a good description of the png_info fields.
And while I'm on the topic, make sure you include the png header file:
And while I'm on the topic, make sure you include the PNG header file:
#include <png.h>
Checking PNG files:
Libpng provides a simple check to see if a file is a png file. To
Libpng provides a simple check to see if a file is a PNG file. To
use it, pass in the first 1 to 8 bytes of the file, and it will return
true or false (1 or 0) depending on whether the bytes could be part
of a png file. Of course, the more bytes you pass in, the greater
of a PNG file. Of course, the more bytes you pass in, the greater
the accuracy of the prediction.
fread(header, 1, number, fp);
@ -95,6 +95,11 @@ much to undo.
return;
}
If you are not using the standard IO functions to do input and
output, and/or not using stderr for your output messages, you will
have the ability to change the functions that libpng uses once
you have allocated the libpng data structures below.
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
@ -103,10 +108,11 @@ read the file from different routines, you will need to update
the jmpbuf field every time you enter a new routine that will
call a png_ function. See your documentation of setjmp/longjmp
for your compiler for more information on setjmp/longjmp. See
the discussion on png error handling in the Customizing Libpng
section below for more information on the png error handling.
If an error occurs, and libpng longjmp's back to your setjmp,
you will want to call png_read_destroy() to free any memory.
the discussion on libpng error handling in the Customizing Libpng
section below for more information on how to change the behaviour
of libpng error handling. If an error occurs, and libpng longjmp's
back to your setjmp, you will want to call png_read_destroy() to
free any memory.
if (setjmp(png_ptr->jmpbuf))
{
@ -132,9 +138,8 @@ would be bad.
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, see the discussion on png i/o handling in the
Customizing Libpng section below.
the file is opened in binary mode. Otherwise, you should see the
section below on Customizing libpng I/O functions.
png_init_io(png_ptr, fp);
@ -159,7 +164,7 @@ to read the file. Some of the more important parts of the png_info are:
PNG_INFO_<chunk name> define.
palette and num_palette - the palette for the file
gamma - the gamma the file is written at
sig_bit and sig_bit_number - the number of significant bits
sig_bit - the number of significant bits for red, green, blue, grey, alpha
trans, trans_values, and number_trans - transparency info
hist - histogram of palette
text and num_text - text comments in the file.
@ -174,14 +179,26 @@ suggested keywords, there is no requirement to restrict the use
to these strings. There is a requirement to have at least one
character for a keyword. It is strongly suggested that keywords
be sensible to humans (that's the point), so don't use abbreviations.
See the png specification for more details. There is no requirement
to have text after the keyword on tEXt chunks. However, you must
have text after the keyword on zTXt chunks, as only the text gets
compressed, and compressing nothing will result in an error.
Some suggested keywords for tEXT (or zTXt) chunks are:
There is no maximum length on the keyword, and nothing
prevents you from duplicating the keyword. The text field is an
array of png_text structures, each holding pointer to a keyword
Title Short (one line) title or caption for image
Author Name of image's creator
Copyright Copyright notice (possibly long)
Description Description of image (possibly long)
Software Software used to create the image
Disclaimer Legal disclaimer (possibly long)
Warning Warning of nature of content
Source Device used to create the image
Comment Miscellaneous comment; conversion from GIF comment
Created When the image or source file was created
There is no requirement to have text after the keyword on tEXt chunks.
However, you must have text after the keyword on zTXt chunks, as only
the text gets compressed, and compressing nothing will result in an error.
The maximum length of the keyword is limited to 80 characters. It is
possible to use the same keyword any number of times. The text field
is an array of png_text structures, each holding pointer to a keyword
and a pointer to a text string. Only the text string may be null.
The keyword/text pairs are put into the array in the order that
they are received. However, some or all of the text chunks may be
@ -200,7 +217,7 @@ check to see if it has data that it can do somthing with, you should
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.
This transforms bit depths of less then 8 to 8 bits, changes paletted
This transforms bit depths of less than 8 to 8 bits, changes paletted
images to rgb, and adds an alpha channel if there is transparency
information in a tRNS chunk. This is probably most useful on grayscale
images with bit depths of 2 or 4 and tRNS chunks.
@ -239,7 +256,8 @@ This handles gamma transformations of the data. Pass both the file
gamma and the desired screen gamma. If the file does not have a
gamma value, you can pass one anyway if you wish. Note that file
gammas are inverted from screen gammas. See the discussions on
gamma in the PNG specification for more information.
gamma in the PNG specification for more information. It is strongly
reccommended that viewers support gamma correction.
if (info_ptr->valid & PNG_INFO_gAMA)
png_set_gamma(png_ptr, screen_gamma, info_ptr->gamma);
@ -506,9 +524,11 @@ setjmp and pass the jmpbuf field of your png_struct. If you
write the file from different routines, you will need to update
the jmpbuf field every time you enter a new routine that will
call a png_ function. See your documentation of setjmp/longjmp
for your compiler for more information on setjmp/longjmp. See
the discussion on png error handling in the Customizing Libpng
section below for more information on the png error handling.
for your compiler for more information on setjmp/longjmp. If you
don't want to use stderr for error output, or you want to use a
method other than setjmp()/longjmp() to handle errors, see the
Customizing Libpng section below for more information on libpng
error handling.
if (setjmp(png_ptr->jmpbuf))
{
@ -535,7 +555,7 @@ Now you need to set up the input 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. If you wish to handle writing
data in another way, see the discussion on png i/o handling in the
data in another way, see the discussion on PNG I/O handling in the
Customizing Libpng section below.
png_init_io(png_ptr, fp);
@ -543,7 +563,7 @@ Customizing Libpng section below.
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 certain special cases, like if you need to
write png files extremely fast and are willing to give up some
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, as it has been
@ -553,12 +573,34 @@ See the compression library for more details.
/* turn on or off filtering (1 or 0) */
png_set_filtering(png_struct *png_ptr, 1);
/* compression level (0 - none, 6 - default, 9 - maximum) */
png_set_compression_level(png_ptr, Z_DEFAULT_COMPRESSION);
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);
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 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 on line 75, unless png_write_flush is
called earlier. If nrows is too small (less than about 10 lines) the
image compression may decrease dramatically (although this 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.
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
@ -581,7 +623,7 @@ parts of the png_info are:
appropriate PNG_INFO_<chunk name> define.
palette and num_palette - the palette for the file
gamma - the gamma the file is written at
sig_bit and sig_bit_number - the number of significant bits
sig_bit - the number of significant bits for red, green, blue, grey, alpha
trans, trans_values, and number_trans - transparency info
hist - histogram of palette
text and num_text - text comments in the file.
@ -614,13 +656,20 @@ 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
PNG supports MODIFICATION time via the png_time structure. Two
conversion routines are proved, png_convert_from_time_t() for
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.
instead of your local time. Note that the year number is the full
year number (ie 1995 rather than 95).
Since the CREATION time of an image is somewhat ambiguous, it is not
sensible to store an exact time like the tIME chunk above (ie when was
a scanned photo of neanderthal art created?). However, a text chunk
with a "Created" keyword can hold this information, in a form which is
useful (ie "Painted circa 40000 BC, photographed 1971, scanned 1996").
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().
@ -782,29 +831,43 @@ 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.
All of the memory allocation, input/output, and error handling in libpng
goes through the routines in pngstub.c. The file as plenty of comments
describing each function and how it expects to work, so I will just
summarize here. See pngstub.c for more details.
All of the memory allocation in libpng is done in pngmem.c. Memory
allocation is done through the functions png_large_malloc(), png_malloc(),
png_realloc(), png_large_free(), and png_free(). These currently just
call the standard C functions. The large functions must handle at least
64K, but they don't have to handle more then that. If your pointers can't
access more then 64K at a time, you will want to set MAXSEG_64K in zlib.h.
Memory allocation is done through the functions png_large_malloc(),
png_malloc(), png_realloc(), png_large_free(), and png_free().
These currently just call the standard C functions. The large
functions must handle exactly 64K, but they don't have to handle
more then that. If 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 functions must be modified
or replaced to change their behaviour. If you only need to add new tests or
flags to have the compiler choose the correct function calls, please forward
these changes to the libpng author, so they can be added into the library
for the benefit of others.
Input/Output in libpng is done throught 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
this, make the appropriate changes in pngstub.c and png.h. Make sure you
change the function prototype for png_init_io() if you are no longer
using a FILE *.
All of the input/output, and error handling in libpng go through the
routines in pngio.c by default. The file has plenty of comments describing
each function and how it expects to work. It is possible to supply different
I/O and error handling methods at run time with the png_set_msg_fn(),
png_set_read_fn(), and png_set_write_fn() calls.
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 it's caller. Currently, this is handled via
setjmp() and longjmp(), but you could change this to do things like
Input/Output in libpng is done throught png_read_data() and png_write_data(),
which currently just call fread() and fwrite(). The error and warning
functions png_error() and png_warning() use stderr to output any messages,
and png_error() uses longjmp to return from an error. These default
functions are set by via png_init_io().
If you wish to change some or all of these functions, it is possible to
do so at runtime, and without modifying the libpng library code. The
application must supply replacement functions which have the same arguments
and are functionally equivalent to the default functions. If you are
replacing both the I/O and message functions, the call to png_init_io()
is not needed.
Error handling in libpng is done through png_error() and png_warning() by
default. Errors handled through png_error() are fatal, meaning that
png_error() should never return to it's caller. Currently, this is handled
via setjmp() and longjmp(), but you could change this to do things like
exit() if you should wish. Similarly, both png_error() and png_warning()
print a message on stderr, but that can also be changed. The motivation
behind using setjmp() and longjmp() is the C++ throw and catch exception
@ -815,6 +878,71 @@ a longjmp, so the user may want to be careful about doing anything after
setjmp returns non zero besides returning itself. Consult your compiler
documentation for more details.
The replacement message functions should have parameters as follows:
void user_error_fn(png_struct png_ptr, char *error_msg);
void user_warning_fn(png_struct png_ptr, char *warning_msg);
These functions can be attached to a PNG stream with a call
png_set_msg_fn(png_ptr, msg_ptr, user_error_fn, user_warning_fn);
If NULL is supplied for user_error_fn, then the error function will not
print any error messages, and will return via longjmp(png_ptr->jmpbuf,1) to
the last location setjmp(png_ptr->jmpbuf) was previously called. If NULL is
supplied for user_warning_fn then no warning messages will be printed.
In order to make it possible to have multiple PNG files open at the same
time, the replacement message functions should not modify any global
variables. In order to have any message information available to the
libpng streams, there is a pointer available to for a user variable or
structure. If more than one variable or structure of needs to be kept
with each stream, then you must create a structure which holds all the
relevant data. The pointer to this data is set in the initial png_set_msg_fn
call, and can be accessed with:
msg_ptr = (user_msg_type *)png_get_msg_ptr(png_ptr);
The replacement I/O functions should have prototypes as follows:
void user_read_data(png_struct *png_ptr,png_bytef *data,png_uint_32 length);
void user_write_data(png_struct *png_ptr,png_bytef *data,png_uint_32 length);
where the routine will read or write "length" bytes into or out of "data".
If the routines are unable to read or write the correct number of bytes, they
should call (*(png_ptr->error_fn))(png_ptr, "Error message"); to abort.
void user_output_flush(png_struct *png_ptr);
will flush any data from the buffer used by the output device. Note that
the flush function is purely to output any data being stored by the write
function, and has no control over any data buffered inside the compressor.
These functions can be attached to a PNG stream by calling one of
png_set_read_fn(png_ptr, io_ptr, user_read_data);
png_set_write_fn(png_ptr, io_ptr, user_write_data, user_output_flush);
You should only call one of these two functions for a single PNG stream.
It is a fatal error to read from a write stream, and vice-versa. If the
output method you are using does not buffer any data, or you have chosen
not to compile libpng with PNG_WRITE_FLUSH_SUPPORTED, NULL may be supplied
instead of a function name for user_output_flush, and an empty function will
be used. Note that even if the output method being used does not buffer
output, during compression data is buffered by the compressor. If an
application wants to guarantee that all pending output data has been written,
it should call png_write_flush, which will flush the compression buffers,
and in turn call the user_output_flush function.
As with the message functions, the replacement I/O functions should not
modify any global variables. Therse is a separate pointer available to for
an I/O variable or structure. If more than one variable or structure of
needs to be kept with each stream, then you must create a structure which
holds all the relevant data. The pointer to this data is set in the initial
set_xxx_fn call, and can be accessed with:
io_ptr = (user_io_type *)png_get_io_ptr(png_ptr);
If you need to read or write custom chunks, you will need to get deeper
into the libpng code. First, read the PNG specification, and have
a first level of understanding of how it works. Pay particular
@ -822,7 +950,9 @@ attention to the sections that describe chunk names, and look
at how other chunks were designed, so you can do things similar.
Second, check out the sections of libpng that read and write chunks.
Try to find a chunk that is similar to yours, and copy off of it.
More details can be found in the comments inside the code.
More details can be found in the comments inside the code. If you are
truly ambitious, you can modify the libpng code to handle unknown chunks
in a general way and send the code to the libpng author.
If you wish to write your own transformation for the data, look
through the part of the code that does the transformations, and check
@ -833,8 +963,8 @@ itself.
Configuring for 16 bit platforms:
You will probably need to change the png__large_malloc() and
png_large_free() routines in pngstub.c, as these are requred
You will probably need to change the png_large_malloc() and
png_large_free() routines in pngmem.c, as these are required
to allocate 64K. Also, you will want to look into zconf.h to tell
zlib (and thus libpng) that it cannot allocate more then 64K at a
time. Even if you can, the memory won't be accessable. So limit zlib
@ -842,11 +972,12 @@ and libpng to 64K by defining MAXSEG_64K.
Configuring for gui/windowing platforms:
You will need to change the error message display in png_error() and
png_warning() to display a message instead of fprinting it to stderr.
You may want to write a single function to do this and call it something
like png_message(). On some compliers, you may have to change the
memory allocators (png_malloc, etc.).
You will need to supply new message display functions for png_error() and
png_warning() (through png_set_message_fn() to display a message in a window
instead of fprinting it to stderr. You may want to write a single function
to do this and call it something like png_message() (although the error
function should still call longjmp or otherwise handle the error without
returning).
Configuring for compiler xxx:
@ -858,9 +989,9 @@ files in libpng proper only include png.h.
Removing unwanted object code:
There are a bunch of #define's in png.h that control what parts of
There are a bunch of #define's in pngconf.h that control what parts of
libpng are compiled. All the defines end in _SUPPORT. If you are
not using an ability, you can change the #define to #undef and
never going to use an ability, you can change the #define to #undef and
save yourself code and data space. All the reading and writing
specific code are in seperate files, so the linker should only grab
the files it needs. However, if you want to make sure, or if you
@ -868,4 +999,3 @@ 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.

190
lpfaq.txt Normal file
View File

@ -0,0 +1,190 @@
libpng FAQ - August 20, 1995
Maintainer:
Guy Eric Schalnat: schalnat@group42.com CompuServe: 75501,1625
Contents:
1) General Questions
1.1) How official is this FAQ?
1.2) How often is this FAQ posted?
1.3) Where can I get this FAQ, libpng, zlib, the PNG
specification, test images, etc.?
1.4) How ready is libpng?
1.5) How portable is libpng?
1.6) When will libpng be out of Beta?
1.7) What remains to be done in libpng for the 1.0 release?
1.8) Can I help?
1.9) Why don't you answer your mail?
2) Libpng questions
2.1) Does the order of functions calls matter?
2.2) When I try to read/write a png image, it doesn't work.
2.3) Do I have to start with example.c?
2.4) What things should I be careful of?
2.5) Why doesn't example.c compile?
3) Critical Patches
No known bugs (for now :-).
4) Non-critical patches
No known bugs (for now :-).
Questions:
1) General Questions
1.1) How official is this FAQ?
As it was written by the author of libpng (that's me :), it's
about offical as one can get. However, it is not ready for
prime time yet, as libpng is still in beta, and thus its
users are of the sort that are willing to deal with beta
software. Thus, I assume all of you reading this have a
basic familiarity with PNG, libpng, and C programming. I'll
write a basic section for libpng later, as well as some quick
stuff on PNG itself (but this will not be the PNG FAQ. I just
don't have that kind of time).
1.2) How often is this FAQ posted?
As often as events warrant. I doubt it'll get stale, and as
it is not (and may never be) actually posted to a newsgroup,
I feel no need to make monthy postings.
1.3) Where can I get this FAQ, libpng, zlib, the PNG
specification, test images, etc.?
Everything should be at ftp://ftp.uu.net/graphics/png and
mirror sites. On CompuServe, it should be at GO GRAPHSUPPORT
in the Png Development library (lib 20). Failing that, try
my ftp site at ftp://ftp.group42.com/pub/png or web site at
http://www.group42.com/ If you have trouble getting to these,
the numerical address is 204.94.158.25
1.4) How ready is libpng?
In its current incarnation (0.8), it still may have a few bugs.
I think I got all of the bugs this time, but one never knows.
Also, the dithering currently in libpng is horrid, so that
needs work. Finally, I have yet to implement medium model
support.
1.5) How portable is libpng?
As portable as I can make it. It needs int's of at least
16 bits, and longs of at least 32 bits. It has not been
tried for char's larger then 8 bits. It should support
any reasonable K&R C compiler, as well as any ANSI C
compiler. The most you should need to do is change the
includes in pngconf.h. So far, I know of no compiler in use
that libpng will not compile on.
1.6) When will libpng be out of Beta?
That depends on my workload here. I'm writing libpng for
free, which generates tons of good will, but doesn't help
put food on the table, so there are times I just can't do
any real work on it. There is still some work to be done
(see question 1.7), so don't expect the official version
before September (and that may be pushing it). I'll try
to get the next (last?) beta version out my early
September. Be warned, I always seem to take twice as
long as I think I will.
1.7) What remains to be done in libpng for the 1.0 release?
Add Tim Wegner's medium memory model support. (Thanks, Tim).
Improve the dithering.
Rewrite libpng.txt, and comment the code better.
Test with a final zlib.
1.8) Can I help?
Sweet words. The most helpful thing you can do for the
1.0 release is help testing on your compiler. After this
release, though, there is a large list of things that ought
to be done to make libpng be more full featured. We'll
talk about this later, as I don't want to add tons of new
code until after 1.0 gets out the door. Please send me
any makefile changes and/or other changes needed to support
your compiler (with a #ifdef for the code changes).
If any of you are good at technical writing, take a look at
libpng.txt and correct it (or rewrite it) as necessary. I
am not a writer, I'm a programmer. It shows.
1.9) Why don't you answer your mail?
I've been busy. I'm sorry about that, and I've got to get
into the habit of at least replying that I got the message.
Also, some of you have sent me problems that I haven't gotten
back to you yet. If it is still a problem, you may want to
give me a short message and remind me that I need to look into
it. Libpng is being tested by more people than I dared hope
(which is a good thing), and I was unprepared to deal with so
many problems so soon.
2) Libpng questions
2.1) Does the order of functions calls matter?
In general, yes. If you stick with the order I used in libpng.txt
and example.c, you should be safe. Be warned, however, that I
messed up the order of png_set_interlace_handling(). It needs
to be called *before* png_start_read_image(), not after. Oops.
The exceptions to this rule are all the png_set ... calls.
They can be done in any order, but they all have to be done
in the area indicated by libpng.txt/example.c.
2.2) When I try to read/write a png image, it doesn't work.
Does zlib's test program work (example.c)? Does libpng's test
program work (testpng.c)? Have you installed the patches at
the end of this FAQ? After all that, if the problem continues,
e-mail me, and we'll try to fix it. If you don't have much
programming experience, be patient about the fix. Code
fragments help, as do *small* images (uuencoded please). If
I don't get back to you right away, give me some time. Thanks.
2.3) Do I have to start with example.c?
No, but most people have had much better luck doing that. Seems
I didn't explain things well in libpng.txt, so things are not
intuitive to people (which could be an api design problem also).
Sometime in the future, we'll revisit the api design, and try
to make it easier to use. I'll rewrite libpng.txt before the
1.0 release.
2.4) What things should I be careful of?
The main gotcha is calling png_read_init() before png_info_init().
Also, always make sure you have a correct setjmp buffer. That's
all I can think of for now.
2.5) Why doesn't example.c compile?
I wrote example.c as a staring point for using libpng. It doesn't
compile because I don't know how you want to do things like allocating
memory to hold the image, so I left that code out. If you go in and
finish it up, it should work fine. The file pngtest.c gives a
very simple example of reading and writing png files.
3) Critical Patches
No known bugs (for now :-).
4) Non-critical patches
No known bugs (for now :-).
That's it so far as I know. If I missed something, yell.
-Guy

14
makefile
View File

@ -2,25 +2,26 @@
# Copyright (C) 1995 Guy Eric Schalnat, Group 42, Inc.
# For conditions of distribution and use, see copyright notice in png.h
CC=cc
CFLAGS=-I../zlib -O
CC=gcc
CFLAGS=-I../zlib -O2 -Wall -ansi -pedantic
LDFLAGS=-L. -L../zlib/ -lpng -lz -lm
#RANLIB=ranlib
RANLIB=echo
RANLIB=ranlib
#RANLIB=echo
# where make install puts libpng.a and png.h
prefix=/usr/local
prefix=/home/munet-d2/sun/local
OBJS = png.o pngrcb.o pngrutil.o pngtrans.o pngwutil.o \
pngread.o pngio.o pngwrite.o pngrtran.o pngwtran.o \
pngmem.o pngerror.o
pngmem.o
all: libpng.a pngtest
libpng.a: $(OBJS)
ar rc $@ $(OBJS)
$(RANLIB) $@
rcp libpng.a vlsi:bin/lib/libpng.a
pngtest: pngtest.o libpng.a
$(CC) -o pngtest $(CCFLAGS) pngtest.o $(LDFLAGS)
@ -44,7 +45,6 @@ clean:
# DO NOT DELETE THIS LINE -- make depend depends on it.
png.o: png.h pngconf.h
pngerror.o: png.h pngconf.h
pngio.o: png.h pngconf.h
pngmem.o: png.h pngconf.h
pngrcb.o: png.h pngconf.h

98
png.h
View File

@ -267,7 +267,19 @@ typedef struct png_row_info_struct
The only people who need to care about what is inside of this are the
people who will be modifying the library for their own special needs.
*/
typedef struct png_struct_def
typedef struct png_struct_def png_struct;
typedef png_struct FAR png_structf;
/* These are the function types for the I/O functions, and the functions which
* modify the default I/O functions to user I/O functions. The png_msg_ptr
* type should match that of user supplied warning and error functions, while
* the png_rw_ptr type should match that of the user read/write data functions.
*/
typedef void (*png_msg_ptr) PNGARG((png_struct *, char *));
typedef void (*png_rw_ptr) PNGARG((png_struct *, png_bytef *, png_uint_32));
typedef void (*png_flush_ptr) PNGARG((png_struct *));
struct png_struct_def
{
jmp_buf jmpbuf; /* used in png_error */
png_byte mode; /* used to determine where we are in the png file */
@ -314,6 +326,10 @@ typedef struct png_struct_def
png_uint_32 width; /* width of file */
png_uint_32 height; /* height of file */
png_uint_32 num_rows; /* number of rows in current pass */
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
png_uint_32 flush_dist; /* how many rows apart to flush, 0 for no flush */
png_uint_32 flush_rows; /* number of rows written since last flush */
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
png_uint_32 rowbytes; /* size of row in bytes */
png_uint_32 usr_width; /* width of row at start of write */
png_uint_32 iwidth; /* interlaced width */
@ -322,13 +338,14 @@ typedef struct png_struct_def
png_uint_32 idat_size; /* current idat size for read */
png_uint_32 zbuf_size; /* size of zbuf */
png_color *palette; /* files palette */
png_uint_32 do_free; /* flags indicating if libpng should free memory */
#if defined(PNG_READ_DITHER_SUPPORTED)
png_bytef *palette_lookup; /* lookup table for dithering */
#endif
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
png_byte *gamma_table; /* gamma table for 8 bit depth files */
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED)
#if defined(PNG_READ_GAMMA_SUPPORTED)
png_byte *gamma_from_1; /* converts from 1.0 to screen */
png_byte *gamma_to_1; /* converts from file to 1.0 */
#endif
@ -363,7 +380,7 @@ typedef struct png_struct_def
#if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
png_color_8 shift; /* shift for significant bit tranformation */
#endif
#if defined(PNG_READ_GAMMA_SUPPORTED)
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined (PNG_READ_sBIT_SUPPORTED)
png_color_8 sig_bit; /* significant bits in file */
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED)
@ -375,10 +392,17 @@ typedef struct png_struct_def
#endif
png_row_info row_info; /* used for transformation routines */
z_stream zstream_struct; /* decompression structure */
FILE *fp; /* used for png_read and png_write */
} png_struct;
typedef png_struct FAR png_structf;
FILE *fp; /* used for default png_read and png_write */
png_msg_ptr error_fn; /* Function for printing errors and aborting */
png_msg_ptr warning_fn; /* Function for printing warnings */
png_rw_ptr write_data_fn; /* Function for writing output data */
png_rw_ptr read_data_fn; /* Function for reading input data */
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
png_flush_ptr output_flush_fn;/* Function for flushing output */
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
void *io_ptr; /* Pointer to user supplied struct for I/O functions */
void *msg_ptr; /* Pointer to user supplied struct for message functions */
};
/* Here are the function definitions most commonly used. This is not
the place to find out how to use libpng. See libpng.txt for the
@ -403,7 +427,7 @@ extern void png_write_info PNGARG((png_struct *png_ptr, png_info *info));
/* read the information before the actual image data. */
extern void png_read_info PNGARG((png_struct *png_ptr, png_info *info));
#if defined(PNG_READ_tIME_SUPPORTED)
#if defined(PNG_WRITE_tIME_SUPPORTED)
/* convert from a struct tm to png_time */
extern void png_convert_from_struct_tm PNGARG((png_time *ptime,
struct tm *ttime));
@ -500,6 +524,14 @@ extern void png_set_gamma PNGARG((png_struct *png_ptr, double screen_gamma,
double default_file_gamma));
#endif
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
/* Set how many lines between output flushes - 0 for no flushing */
extern void png_set_flush PNGARG((png_struct *png_ptr, int nrows));
/* Flush the current PNG output buffer */
extern void png_write_flush PNGARG((png_struct *png_ptr));
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
/* optional update palette with requested transformations */
extern void png_start_read_image PNGARG((png_struct *png_ptr));
@ -570,21 +602,8 @@ extern void png_set_compression_window_bits PNGARG((png_struct *png_ptr,
extern void png_set_compression_method PNGARG((png_struct *png_ptr,
int method));
/* These next functions are stubs of typical c functions for input/output,
memory, and error handling. They are in the file pngstub.c, and are
set up to be easily modified for users that need to. See the file
pngstub.c for more information */
/* Write the data to whatever output you are using. */
extern void png_write_data PNGARG((png_struct *png_ptr, png_bytef *data,
png_uint_32 length));
/* Read data from whatever input you are using */
extern void png_read_data PNGARG((png_struct *png_ptr, png_bytef *data,
png_uint_32 length));
/* Initialize the input/output for the png file. */
extern void png_init_io PNGARG((png_struct *png_ptr, FILE *fp));
/* These next functions are prototypes of the functions libpng uses for
memory allocation. */
/* Allocate memory in larger chunks. */
extern voidpf png_large_malloc PNGARG((png_structf *png_ptr, png_uint_32 size));
@ -602,12 +621,32 @@ extern void *png_realloc PNGARG((png_struct *png_ptr, void *ptr,
/* free's a pointer allocated by png_malloc() */
extern void png_free PNGARG((png_struct *png_ptr, void *ptr));
/* Fatal error in libpng - can't continue */
extern void png_error PNGARG((png_structf *png_ptr, char *error));
/* Initialize the I/O and message handling for the png file to the defaults. */
extern void png_init_io PNGARG((png_struct *png_ptr, FILE *fp));
/* Non-fatal error in libpng. Can continue, but may have a problem. */
extern void png_warning PNGARG((png_struct *png_ptr, char *message));
/* Replace the error message and abort, and warning functions with user
supplied functions. If no messages are to be printed, NULL can be
supplied for error_fn and warning_fn, although error_fn will still do
a longjmp to the last setjmp location. */
extern void png_set_msg_fn PNGARG((png_struct *png_ptr, void *msg_ptr,
png_msg_ptr error_fn, png_msg_ptr warning_fn));
/* Return the user pointer associated with the message functions */
extern void *png_get_msg_ptr PNGARG((png_struct *png_ptr));
/* Replace the default data output functions with a user supplied one(s).
If buffered output is not used, then output_flush_fn can be set to NULL.
if PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
output_flush_fn will be ignored (but must be supplied for compatability). */
extern void png_set_write_fn PNGARG((png_struct *png_ptr, void *io_ptr,
png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
/* Replace the default data input function with a user supplied one. */
extern void png_set_read_fn PNGARG((png_struct *png_ptr, void *io_ptr,
png_rw_ptr read_data_fn));
/* Return the user pointer associated with the I/O functions */
extern void *png_get_io_ptr PNGARG((png_struct *png_ptr));
/* These next functions are used internally in the code. If you use
them, make sure you read and understand the png spec. More information
@ -646,6 +685,11 @@ extern void png_warning PNGARG((png_struct *png_ptr, char *message));
#define PNG_GRAY_TO_RGB 0x2000
#define PNG_FILLER 0x4000
/* defines for memory alloced by libpng which should be freed */
#define PNG_FREE_TRANS 0x0001
#define PNG_FREE_HIST 0x0002
#define PNG_FREE_PALETTE 0x0004
/* save typing and make code easier to understand */
#define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
abs((int)((c1).green) - (int)((c2).green)) + \

10
pngchang.txt
View File

@ -55,6 +55,16 @@ version 0.8
put all the configurable stuff in pngconf.h
enabled png_set_shift to work with paletted images on read
added png_read_update_info() - updates info structure with transformations
version 0.81
added support for medium memory model
version 0.82
added ability to flush output stream automatically or manually
added ability to change I/O and error functions dynamically
moved pngerror.c into pngio.c to make all the default functions static
when freeing memory in png_read_destroy don't free memory we didn't allocate
added warnings when reading blocks of incorrect length
limit tEXt and zTXt keywords to 80 chars

3
pngconf.h
View File

@ -27,7 +27,7 @@
Unless this gets smaller then the size of a row (compressed),
it should not make much difference how big this is. */
#define PNG_ZBUF_SIZE 8192
#define PNG_ZBUF_SIZE 32768
/* While libpng currently uses zlib for it's compression, it has been designed
to stand on it's own. Towards this end, there are two defines that are
@ -166,6 +166,7 @@
#define PNG_WRITE_SWAP_SUPPORTED
#define PNG_WRITE_INVERT_SUPPORTED
#define PNG_WRITE_FILLER_SUPPORTED
#define PNG_WRITE_FLUSH_SUPPORTED
/* any chunks you are not interested in, you can undef here. The
ones that allocate memory may be expecially important (hIST,

46
pngerror.c
View File

@ -1,46 +0,0 @@
/* pngstub.c - stub functions for i/o and memory allocation
libpng 1.0 beta 2 - version 0.81
For conditions of distribution and use, see copyright notice in png.h
Copyright (c) 1995 Guy Eric Schalnat, Group 42, Inc.
August 24, 1995
This file provides a location for all error handling. Users which
need special error handling are expected to modify the code in this
file to meet their needs. See the instructions at each function. */
#define PNG_INTERNAL
#include "png.h"
/* This function is called whenever there is an error. Replace with
however you wish to handle the error. Note that this function
MUST NOT return, or the program will crash */
void
png_error(png_structf *png_ptr, char *message)
{
fprintf(stderr, "libpng error: %s\n", message);
#ifdef USE_FAR_KEYWORD
{
jmp_buf jmpbuf;
png_memcpy(jmpbuf,png_ptr->jmpbuf,sizeof(jmp_buf));
longjmp(jmpbuf, 1);
}
#else
longjmp(png_ptr->jmpbuf, 1);
#endif
}
/* This function is called when there is a warning, but the library
thinks it can continue anyway. You don't have to do anything here
if you don't want to. In the default configuration, png_ptr is
not used, but it is passed in case it may be useful. */
void
png_warning(png_struct *png_ptr, char *message)
{
if (!png_ptr)
return;
fprintf(stderr, "libpng warning: %s\n", message);
}

307
pngio.c
View File

@ -1,32 +1,31 @@
/* pngstub.c - stub functions for i/o and memory allocation
/* pngio.c - default functions for data I/O and error/warning messages
libpng 1.0 beta 2 - version 0.81
libpng 1.0 beta 3 - version 0.82
For conditions of distribution and use, see copyright notice in png.h
Copyright (c) 1995 Guy Eric Schalnat, Group 42, Inc.
August 24, 1995
Some portions Copyright (C) 1995 Andreas Dilger
Sept 24, 1995
This file provides a location for all input/output. Users which need
special handling are expected to modify the code in this file to meet
their needs. See the instructions at each function. */
special handling are expected to write functions which have the same
arguments as these, and perform similar functions, but possibly have
different I/O methods. Note that you shouldn't change these functions,
but rather write replacement functions and then change them at run
time with png_set_write_fn(...) or png_set_read_fn(...), etc */
#define PNG_INTERNAL
#include "png.h"
/* Write the data to whatever output you are using. The default
routine writes to a file pointer. If you need to write to something
else, this is the place to do it. We suggest saving the old code
for future use, possibly in a #define. Note that this routine sometimes
gets called with very small lengths, so you should implement some kind
of simple buffering if you are using unbuffered writes. This should
never be asked to write more then 64K on a 16 bit machine. The cast
to png_size_t is there for insurance, but if you are having problems
with it, you can take it out. Just be sure to cast length to whatever
fwrite needs in that spot if you don't have a function prototype for
it. */
else, this is a good example of how to do it. Note that this routine
sometimes gets called with very small lengths, so you should implement
some kind of simple buffering if you are using unbuffered writes. This
should never be asked to write more then 64K on a 16 bit machine. The
cast to png_size_t is there for insurance. */
#ifndef USE_FAR_KEYWORD
void
static void
png_write_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
{
png_uint_32 check;
@ -34,7 +33,7 @@ png_write_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
check = fwrite(data, 1, (png_size_t)length, png_ptr->fp);
if (check != length)
{
png_error(png_ptr, "Write Error");
(*(png_ptr->error_fn))(png_ptr, "Write error");
}
}
#else
@ -51,7 +50,7 @@ png_write_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
#include <dos.h>
#endif
void
static void
png_write_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
{
png_uint_32 check;
@ -92,25 +91,22 @@ png_write_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
}
if (check != length)
{
png_error(png_ptr, "Write Error");
(*(png_ptr->error_fn))(png_ptr, "Write error");
}
}
#endif
/* Read the data from whatever input you are using. The default
routine reads from a file pointer. If you need to read from something
else, this is the place to do it. We suggest saving the old code
for future use. Note that this routine sometimes gets called with
very small lengths, so you should implement some kind of simple
buffering if you are using unbuffered reads. This should
never be asked to read more then 64K on a 16 bit machine. The cast
to png_size_t is there for insurance, but if you are having problems
with it, you can take it out. Just be sure to cast length to whatever
fread needs in that spot if you don't have a function prototype for
it. */
else, this is a good example of how to do it. Note that this routine
sometimes gets called with very small lengths, so you should implement
some kind of simple buffering if you are using unbuffered reads. This
should never be asked to read more then 64K on a 16 bit machine. The
cast to png_size_t is there for insurance. */
#ifndef USE_FAR_KEYWORD
void
static void
png_read_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
{
png_uint_32 check;
@ -118,11 +114,11 @@ png_read_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
check = fread(data, 1, (size_t)length, png_ptr->fp);
if (check != length)
{
png_error(png_ptr, "Read Error");
(*(png_ptr->error_fn))(png_ptr, "Read error");
}
}
#else
void
static void
png_read_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
{
png_uint_32 check;
@ -163,18 +159,253 @@ png_read_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
}
if (check != length)
{
png_error(png_ptr, "read Error");
(*(png_ptr->error_fn))(png_ptr, "Read error");
}
}
#endif
/* Initialize the input/output for the png file. If you change
the read and write routines, you will probably need to change
this routine (or write your own). If you change the parameters
of this routine, remember to change png.h also. */
/* This function does nothing, and is used for the write function on
a read, and vice-versa. It is an error if this function is
actually called. */
static void
png_empty_rw(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
{
if (png_ptr->read_data_fn == png_empty_rw)
{
(*(png_ptr->error_fn))(png_ptr, "Invalid read on a write device");
}
else /* if (png_ptr->write_data_fn == png_empty_rw) */
{
(*(png_ptr->error_fn))(png_ptr, "Invalid write on a read device");
}
}
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
/* This function does nothing, and is supplied for user I/O functions which
do not do any buffering. This function is set when NULL is supplied for
the flush function pointer. */
static void
png_empty_flush(png_struct *png_ptr)
{
}
/* Write out any remaining output that is stored in the output buffers.
If you supply a new write routine, you will probably need to supply a
replacement for this routine as well. */
static void
png_output_flush(png_struct *png_ptr)
{
fflush(png_ptr->fp);
}
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
/* This function does nothing, and is called if the user supplies null
when setting the error function. */
static void
png_empty_error(png_structf *png_ptr, char *message)
{
#ifdef USE_FAR_KEYWORD
{
jmp_buf jmpbuf;
png_memcpy(jmpbuf,png_ptr->jmpbuf,sizeof(jmp_buf));
longjmp(jmpbuf, 1);
}
#else
longjmp(png_ptr->jmpbuf, 1);
#endif
}
/* This function is called whenever there is an error. Replace with a
function you wish to handle the error. Note that this function
MUST NOT return, or the program will crash. To be consistent with
the examples for the library and this function, you could call
longjmp(pnt_ptr->jmpbuf) to return to the program at the location of
the last setjmp(png_ptr->jmpbuf) after an error. */
static void
png_error(png_structf *png_ptr, char *message)
{
fprintf(stderr, "libpng error: %s\n", message);
png_empty_error(png_ptr, message);
}
/* This function does nothing, and is called if the user supplies null
when setting the warning function. */
static void
png_empty_warning(png_struct *png_ptr, char *message)
{
}
/* This function is called when there is a warning, but the library
thinks it can continue anyway. You don't have to do anything here
if you don't want to. In the default configuration, png_ptr is
not used, but it is passed in case it may be useful. */
static void
png_warning(png_struct *png_ptr, char *message)
{
fprintf(stderr, "libpng warning: %s\n", message);
}
/* This function allows the application to supply new output functions for
libpng if standard C streams aren't being used. The new write function
should call (*(png_ptr->error_fn))("Error message") to exit and output
any fatal error messages if it cannot output the correct number of bytes.
This function takes as its arguments:
png_ptr - pointer to a png output data structure
io_ptr - pointer to user supplied structure containing info about
the output functions. May be NULL.
write_data_fn - pointer to a new output function which takes as its
arguments a pointer to a png_struct, a pointer to
data to be written, and a 32-bit unsigned int which is
the number of bytes to be written. The new write
function should call (*(png_ptr->error_fn))("Error msg")
to exit and output any fatal error messages.
flush_data_fn - pointer to a new flush function which takes as its
arguments a pointer to a png_struct. After a call to
the flush function, there should be no data in any buffers
or pending transmission. If the output method doesn't do
any buffering of ouput, this parameter can be NULL. If
PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng
compile time, output_flush_fn will be ignored, although
it must be supplied for compatibility. */
void
png_set_write_fn(png_struct *png_ptr, void *io_ptr, png_rw_ptr write_data_fn,
png_flush_ptr output_flush_fn)
{
png_ptr->io_ptr = io_ptr;
if (write_data_fn == NULL)
{
(*(png_ptr->error_fn))(png_ptr, "NULL write function pointer given");
}
png_ptr->write_data_fn = write_data_fn;
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
if (output_flush_fn == NULL)
{
png_ptr->output_flush_fn = png_empty_flush;
}
else
{
png_ptr->output_flush_fn = output_flush_fn;
}
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
/* It is an error to write to a read device */
png_ptr->read_data_fn = png_empty_rw;
}
/* This function allows the application to supply a new input function
for libpng if standard C streams aren't being used. The new read function
should call (*(png_ptr->error_fn))("Error message") to exit and output
any fatal error messages if the desired number of bytes is not available.
This function takes as its arguments:
png_ptr - pointer to a png input data structure
io_ptr - pointer to user supplied structure containing info about
the input functions. May be NULL.
read_data_fn - pointer to a new input function which takes as it's
arguments a pointer to a png_struct, a pointer to
a location where input data can be stored, and a 32-bit
unsigned int which is the number of bytes to be read. */
void
png_set_read_fn(png_struct *png_ptr, void *io_ptr, png_rw_ptr read_data_fn)
{
png_ptr->io_ptr = io_ptr;
if (read_data_fn == NULL)
{
(*(png_ptr->error_fn))(png_ptr, "NULL read function pointer given");
}
png_ptr->read_data_fn = read_data_fn;
/* It is an error to write to a read device */
png_ptr->write_data_fn = png_empty_rw;
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
png_ptr->output_flush_fn = png_empty_flush;
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
}
/* This function returns a pointer to the io_ptr associated with the user
functions. The application should free any memory associated with this
pointer before png_write_destroy and png_read_destroy are called. */
void *
png_get_io_ptr(png_struct *png_ptr)
{
return png_ptr->io_ptr;
}
/* This function is called when the application wants to use another
method of handling errors and warnings. Note that the error function must
NOT return to the calling routine or serious problems will occur. The
error return method used in the default routine calls
longjmp(png_ptr->jmpbuf, 1), or exits if setjmp(png_ptr->jmpbuf) has never
been called. */
void
png_set_msg_fn(png_struct *png_ptr, void *msg_ptr, png_msg_ptr error_fn,
png_msg_ptr warning_fn)
{
png_ptr->msg_ptr = msg_ptr;
if (error_fn == NULL)
{
png_ptr->error_fn = png_empty_error;
}
else
{
png_ptr->error_fn = error_fn;
}
if (warning_fn == NULL)
{
png_ptr->warning_fn = png_empty_warning;
}
else
{
png_ptr->warning_fn = warning_fn;
}
}
/* This function returns a pointer to the msg_ptr associated with the user
functions. The application should free any memory associated with this
pointer before png_write_destroy and png_read_destroy are called. */
void *
png_get_msg_ptr(png_struct *png_ptr)
{
return png_ptr->msg_ptr;
}
/* Initialize the default input/output functions for the png file.
If you change the read, write or message routines, can call
either png_set_read_fn(...), png_set_write_fn(...), etc. to change
individual functions after a call to png_init_io(...). You can also
call one of png_set_read_fn(...) or png_set_write_fn(...), AND
png_set_msg_fn(...) instead of png_init_io(...) if you aren't using
any of the default libpng functions. */
void
png_init_io(png_struct *png_ptr, FILE *fp)
{
png_ptr->fp = fp;
}
png_ptr->error_fn = png_error;
png_ptr->warning_fn = png_warning;
png_ptr->write_data_fn = png_write_data;
png_ptr->read_data_fn = png_read_data;
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
png_ptr->output_flush_fn = png_output_flush;
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
}

22
pngmem.c
View File

@ -1,5 +1,5 @@
/* pngstub.c - stub functions for i/o and memory allocation
/* pngmem.c - stub functions for memory allocation
libpng 1.0 beta 2 - version 0.81
For conditions of distribution and use, see copyright notice in png.h
@ -61,7 +61,7 @@ png_large_malloc(png_structf *png_ptr, png_uint_32 size)
#ifdef PNG_MAX_MALLOC_64K
if (size > (png_uint_32)65536L)
png_error(png_ptr, "Cannot Allocate > 64K");
(*(png_ptr->error_fn))(png_ptr, "Cannot Allocate > 64K");
#endif
#ifdef __TURBOC__
@ -99,11 +99,11 @@ png_large_malloc(png_structf *png_ptr, png_uint_32 size)
num_save_array = 1;
save_array = malloc(num_save_array * sizeof (borland_seg));
if (!save_array)
png_error(png_ptr, "Out of Memory 1");
(*(png_ptr->error_fn))(png_ptr, "Out of Memory 1");
save_array->mem_ptr = farmalloc(
(unsigned long)(NUM_SEG) * 65536L + 65532L);
if (!save_array->mem_ptr)
png_error(png_ptr, "Out of Memory 2");
(*(png_ptr->error_fn))(png_ptr, "Out of Memory 2");
offset = (unsigned long)(ret);
offset &= 0xffffL;
ptr = save_array->mem_ptr;
@ -141,11 +141,11 @@ png_large_malloc(png_structf *png_ptr, png_uint_32 size)
save_array = realloc(save_array,
(num_save_array + 1) * sizeof (borland_seg));
if (!save_array)
png_error(png_ptr, "Out of Memory 3");
(*(png_ptr->error_fn))(png_ptr, "Out of Memory 3");
save_array[num_save_array].mem_ptr = farmalloc(
(unsigned long)(NUM_SEG) * 65536L + 65532L);
if (!save_array[num_save_array].mem_ptr)
png_error(png_ptr, "Out of Memory 4");
(*(png_ptr->error_fn))(png_ptr, "Out of Memory 4");
offset = (unsigned long)(ret);
offset &= 0xffffL;
ptr = save_array[num_save_array].mem_ptr;
@ -180,7 +180,7 @@ png_large_malloc(png_structf *png_ptr, png_uint_32 size)
if (ret == NULL)
{
png_error(png_ptr, "Out of Memory");
(*(png_ptr->error_fn))(png_ptr, "Out of Memory");
}
return ret;
@ -259,14 +259,14 @@ png_malloc(png_struct *png_ptr, png_uint_32 size)
#ifdef PNG_MAX_MALLOC_64K
if (size > (png_uint_32)65536L)
png_error(png_ptr, "Cannot Allocate > 64K");
(*(png_ptr->error_fn))(png_ptr, "Cannot Allocate > 64K");
#endif
ret = malloc((png_size_t)size);
if (!ret)
{
png_error(png_ptr, "Out of Memory 6");
(*(png_ptr->error_fn))(png_ptr, "Out of Memory 6");
}
return ret;
@ -285,14 +285,14 @@ png_realloc(png_struct *png_ptr, void *ptr, png_uint_32 size,
#ifdef PNG_MAX_MALLOC_64K
if (size > (png_uint_32)65536L)
png_error(png_ptr, "Cannot Allocate > 64K");
(*(png_ptr->error_fn))(png_ptr, "Cannot Allocate > 64K");
#endif
ret = realloc(ptr, (png_size_t)size);
if (!ret)
{
png_error(png_ptr, "Out of Memory 7");
(*(png_ptr->error_fn))(png_ptr, "Out of Memory 7");
}
return ret;

126
pngread.c
View File

@ -38,22 +38,22 @@ png_read_info(png_struct *png_ptr, png_info *info)
png_byte chunk_start[8];
png_uint_32 length;
png_read_data(png_ptr, chunk_start, 8);
(*(png_ptr->read_data_fn))(png_ptr, chunk_start, 8);
if (memcmp(chunk_start, png_sig, 8))
png_error(png_ptr, "Not a Png File");
(*(png_ptr->error_fn))(png_ptr, "Not a PNG File");
while (1)
{
png_uint_32 crc;
png_read_data(png_ptr, chunk_start, 8);
(*(png_ptr->read_data_fn))(png_ptr, chunk_start, 8);
length = png_get_uint_32(chunk_start);
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, chunk_start + 4, 4);
if (!memcmp(chunk_start + 4, png_IHDR, 4))
{
if (png_ptr->mode != PNG_BEFORE_IHDR)
png_error(png_ptr, "Out of Place IHDR");
(*(png_ptr->error_fn))(png_ptr, "Out of Place IHDR");
png_handle_IHDR(png_ptr, info, length);
png_ptr->mode = PNG_HAVE_IHDR;
@ -61,7 +61,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
else if (!memcmp(chunk_start + 4, png_PLTE, 4))
{
if (png_ptr->mode != PNG_HAVE_IHDR)
png_error(png_ptr, "Missing IHDR");
(*(png_ptr->error_fn))(png_ptr, "Missing IHDR");
#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
if (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
@ -82,13 +82,13 @@ png_read_info(png_struct *png_ptr, png_info *info)
}
else if (!memcmp(chunk_start + 4, png_IEND, 4))
{
png_error(png_ptr, "No Image in File");
(*(png_ptr->error_fn))(png_ptr, "No Image in File");
}
#if defined(PNG_READ_gAMA_SUPPORTED)
else if (!memcmp(chunk_start + 4, png_gAMA, 4))
{
if (png_ptr->mode != PNG_HAVE_IHDR)
png_error(png_ptr, "Out of Place PLTE");
(*(png_ptr->error_fn))(png_ptr, "Out of Place PLTE");
png_handle_gAMA(png_ptr, info, length);
}
@ -97,7 +97,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
else if (!memcmp(chunk_start + 4, png_sBIT, 4))
{
if (png_ptr->mode != PNG_HAVE_IHDR)
png_error(png_ptr, "Out of Place sBIT");
(*(png_ptr->error_fn))(png_ptr, "Out of Place sBIT");
png_handle_sBIT(png_ptr, info, length);
}
@ -106,7 +106,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
else if (!memcmp(chunk_start + 4, png_cHRM, 4))
{
if (png_ptr->mode != PNG_HAVE_IHDR)
png_error(png_ptr, "Out of Place cHRM");
(*(png_ptr->error_fn))(png_ptr, "Out of Place cHRM");
png_handle_cHRM(png_ptr, info, length);
}
@ -116,7 +116,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode != PNG_HAVE_IHDR &&
png_ptr->mode != PNG_HAVE_PLTE)
png_error(png_ptr, "Out of Place tRNS");
(*(png_ptr->error_fn))(png_ptr, "Out of Place tRNS");
png_handle_tRNS(png_ptr, info, length);
}
@ -126,7 +126,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode != PNG_HAVE_IHDR &&
png_ptr->mode != PNG_HAVE_PLTE)
png_error(png_ptr, "Out of Place bKGD");
(*(png_ptr->error_fn))(png_ptr, "Out of Place bKGD");
png_handle_bKGD(png_ptr, info, length);
}
@ -135,7 +135,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
else if (!memcmp(chunk_start + 4, png_hIST, 4))
{
if (png_ptr->mode != PNG_HAVE_PLTE)
png_error(png_ptr, "Out of Place hIST");
(*(png_ptr->error_fn))(png_ptr, "Out of Place hIST");
png_handle_hIST(png_ptr, info, length);
}
@ -145,7 +145,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode != PNG_HAVE_IHDR &&
png_ptr->mode != PNG_HAVE_PLTE)
png_error(png_ptr, "Out of Place pHYs");
(*(png_ptr->error_fn))(png_ptr, "Out of Place pHYs");
png_handle_pHYs(png_ptr, info, length);
}
@ -155,7 +155,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode != PNG_HAVE_IHDR &&
png_ptr->mode != PNG_HAVE_PLTE)
png_error(png_ptr, "Out of Place oFFs");
(*(png_ptr->error_fn))(png_ptr, "Out of Place oFFs");
png_handle_oFFs(png_ptr, info, length);
}
@ -165,7 +165,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode == PNG_BEFORE_IHDR ||
png_ptr->mode == PNG_AFTER_IEND)
png_error(png_ptr, "Out of Place tIME");
(*(png_ptr->error_fn))(png_ptr, "Out of Place tIME");
png_handle_tIME(png_ptr, info, length);
}
@ -175,7 +175,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode == PNG_BEFORE_IHDR ||
png_ptr->mode == PNG_AFTER_IEND)
png_error(png_ptr, "Out of Place tEXt");
(*(png_ptr->error_fn))(png_ptr, "Out of Place tEXt");
png_handle_tEXt(png_ptr, info, length);
}
@ -185,7 +185,7 @@ png_read_info(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode == PNG_BEFORE_IHDR ||
png_ptr->mode == PNG_AFTER_IEND)
png_error(png_ptr, "Out of Place zTXt");
(*(png_ptr->error_fn))(png_ptr, "Out of Place zTXt");
png_handle_zTXt(png_ptr, info, length);
}
@ -193,15 +193,15 @@ png_read_info(png_struct *png_ptr, png_info *info)
else
{
if ((chunk_start[4] & 0x20) == 0)
png_error(png_ptr, "Unknown Critical Chunk");
(*(png_ptr->error_fn))(png_ptr, "Unknown Critical Chunk");
png_crc_skip(png_ptr, length);
}
png_read_data(png_ptr, chunk_start, 4);
(*(png_ptr->read_data_fn))(png_ptr, chunk_start, 4);
crc = png_get_uint_32(chunk_start);
if (((crc ^ 0xffffffffL) & 0xffffffffL) !=
(png_ptr->crc & 0xffffffffL))
png_error(png_ptr, "Bad CRC value");
(*(png_ptr->error_fn))(png_ptr, "Bad CRC value");
}
}
@ -310,7 +310,7 @@ png_read_row(png_struct *png_ptr, png_bytef *row, png_byte *dsp_row)
#endif
if (png_ptr->mode != PNG_HAVE_IDAT)
png_error(png_ptr, "invalid attempt to read row data");
(*(png_ptr->error_fn))(png_ptr, "Invalid attempt to read row data");
png_ptr->zstream->next_out = png_ptr->row_buf;
png_ptr->zstream->avail_out = (uInt)png_ptr->irowbytes;
@ -323,19 +323,19 @@ png_read_row(png_struct *png_ptr, png_bytef *row, png_byte *dsp_row)
png_byte buf[4];
png_uint_32 crc;
png_read_data(png_ptr, buf, 4);
(*(png_ptr->read_data_fn))(png_ptr, buf, 4);
crc = png_get_uint_32(buf);
if (((crc ^ 0xffffffffL) & 0xffffffffL) !=
(png_ptr->crc & 0xffffffffL))
png_error(png_ptr, "Bad CRC value");
(*(png_ptr->error_fn))(png_ptr, "Bad CRC value");
png_read_data(png_ptr, buf, 4);
(*(png_ptr->read_data_fn))(png_ptr, buf, 4);
png_ptr->idat_size = png_get_uint_32(buf);
png_reset_crc(png_ptr);
png_crc_read(png_ptr, buf, 4);
if (memcmp(buf, png_IDAT, 4))
png_error(png_ptr, "Not enough image data");
(*(png_ptr->error_fn))(png_ptr, "Not enough image data");
}
png_ptr->zstream->avail_in = (uInt)png_ptr->zbuf_size;
@ -350,12 +350,12 @@ png_read_row(png_struct *png_ptr, png_bytef *row, png_byte *dsp_row)
{
if (png_ptr->zstream->avail_out || png_ptr->zstream->avail_in ||
png_ptr->idat_size)
png_error(png_ptr, "Extra compressed data");
(*(png_ptr->warning_fn))(png_ptr, "Extra compressed data");
png_ptr->mode = PNG_AT_LAST_IDAT;
break;
}
if (ret != Z_OK)
png_error(png_ptr, "Compression Error");
(*(png_ptr->error_fn))(png_ptr, "Compression Error");
} while (png_ptr->zstream->avail_out);
@ -448,6 +448,7 @@ png_read_rows(png_struct *png_ptr, png_bytef **row,
dptr = *dp;
else
dptr = NULL;
png_read_row(png_ptr, rptr, dptr);
if (row)
rp++;
@ -491,70 +492,70 @@ png_read_end(png_struct *png_ptr, png_info *info)
png_uint_32 length;
png_uint_32 crc;
png_read_data(png_ptr, chunk_start, 4);
(*(png_ptr->read_data_fn))(png_ptr, chunk_start, 4);
crc = png_get_uint_32(chunk_start);
if (((crc ^ 0xffffffffL) & 0xffffffffL) !=
(png_ptr->crc & 0xffffffffL))
png_error(png_ptr, "Bad CRC value");
(*(png_ptr->error_fn))(png_ptr, "Bad CRC value");
do
{
png_read_data(png_ptr, chunk_start, 8);
(*(png_ptr->read_data_fn))(png_ptr, chunk_start, 8);
length = png_get_uint_32(chunk_start);
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, chunk_start + 4, 4);
if (!memcmp(chunk_start + 4, png_IHDR, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_PLTE, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_gAMA, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_sBIT, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_cHRM, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_tRNS, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_bKGD, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_hIST, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_IDAT, 4))
{
if (length > 0 || png_ptr->mode != PNG_AT_LAST_IDAT)
png_error(png_ptr, "too many IDAT's found");
(*(png_ptr->error_fn))(png_ptr, "Too many IDAT's found");
}
else if (!memcmp(chunk_start + 4, png_pHYs, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
else if (!memcmp(chunk_start + 4, png_oFFs, 4))
{
png_error(png_ptr, "invalid chunk after IDAT");
(*(png_ptr->error_fn))(png_ptr, "Invalid chunk after IDAT");
}
#if defined(PNG_READ_tIME_SUPPORTED)
else if (!memcmp(chunk_start + 4, png_tIME, 4))
{
if (png_ptr->mode == PNG_BEFORE_IHDR ||
png_ptr->mode == PNG_AFTER_IEND)
png_error(png_ptr, "Out of Place tIME");
(*(png_ptr->error_fn))(png_ptr, "Out of Place tIME");
if (info)
png_handle_tIME(png_ptr, info, length);
@ -567,7 +568,7 @@ png_read_end(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode == PNG_BEFORE_IHDR ||
png_ptr->mode == PNG_AFTER_IEND)
png_error(png_ptr, "Out of Place tEXt");
(*(png_ptr->error_fn))(png_ptr, "Out of Place tEXt");
if (info)
png_handle_tEXt(png_ptr, info, length);
@ -580,7 +581,7 @@ png_read_end(png_struct *png_ptr, png_info *info)
{
if (png_ptr->mode == PNG_BEFORE_IHDR ||
png_ptr->mode == PNG_AFTER_IEND)
png_error(png_ptr, "Out of Place zTXt");
(*(png_ptr->error_fn))(png_ptr, "Out of Place zTXt");
if (info)
png_handle_zTXt(png_ptr, info, length);
@ -594,16 +595,25 @@ png_read_end(png_struct *png_ptr, png_info *info)
}
else
{
if ((chunk_start[4] & 0x20) == 0)
png_error(png_ptr, "Unknown Critical Chunk");
char msg[80];
if ((chunk_start[4] & 0x20) == 0)
{
png_strcpy(msg,"Unknown critical chunk ");
png_memcpy(msg + strlen(msg), chunk_start + 4,4);
(*(png_ptr->error_fn))(png_ptr, msg);
}
png_strcpy(msg,"Unknown extension chunk ");
png_memcpy(msg + strlen(msg), chunk_start + 4,4);
(*(png_ptr->warning_fn))(png_ptr, msg);
png_crc_skip(png_ptr, length);
}
png_read_data(png_ptr, chunk_start, 4);
(*(png_ptr->read_data_fn))(png_ptr, chunk_start, 4);
crc = png_get_uint_32(chunk_start);
if (((crc ^ 0xffffffffL) & 0xffffffffL) !=
(png_ptr->crc & 0xffffffffL))
png_error(png_ptr, "Bad CRC value");
(*(png_ptr->error_fn))(png_ptr, "Bad CRC value");
if (png_ptr->mode == PNG_AT_LAST_IDAT)
png_ptr->mode = PNG_AFTER_IDAT;
} while (png_ptr->mode != PNG_AFTER_IEND);
@ -618,19 +628,19 @@ png_read_destroy(png_struct *png_ptr, png_info *info, png_info *end_info)
if (info)
{
/* I'm not sure I should be freeing this */
if (info->palette != png_ptr->palette)
if (png_ptr->do_free & PNG_FREE_PALETTE)
png_free(png_ptr, info->palette);
/* I'm not sure I should be freeing this */
#if defined(PNG_READ_BACKGROUND_SUPPORTED) && defined(PNG_READ_bKGD_SUPPORTED)
if (info->trans != png_ptr->trans)
if (png_ptr->do_free & PNG_FREE_TRANS)
png_free(png_ptr, info->trans);
#endif
/* I'm not sure I should be freeing this */
#if defined(PNG_READ_hIST_SUPPORTED)
if (info->hist != png_ptr->hist)
if (png_ptr->do_free & PNG_FREE_HIST)
png_free(png_ptr, info->hist);
#endif
#if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
for (i = 0; i < info->num_text; i++)
{
@ -658,17 +668,21 @@ png_read_destroy(png_struct *png_ptr, png_info *info, png_info *end_info)
png_large_free(png_ptr, png_ptr->zbuf);
png_large_free(png_ptr, png_ptr->row_buf);
png_large_free(png_ptr, png_ptr->prev_row);
#if defined(PNG_READ_DITHER_SUPPORTED)
png_large_free(png_ptr, png_ptr->palette_lookup);
png_free(png_ptr, png_ptr->dither_index);
#endif
#if defined(PNG_READ_GAMMA_SUPPORTED)
png_free(png_ptr, png_ptr->gamma_table);
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED)
png_free(png_ptr, png_ptr->gamma_from_1);
png_free(png_ptr, png_ptr->gamma_to_1);
#endif
#if defined(PNG_READ_GAMMA_SUPPORTED)
if (png_ptr->gamma_16_table)
{
@ -678,6 +692,7 @@ png_read_destroy(png_struct *png_ptr, png_info *info, png_info *end_info)
}
}
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED)
png_free(png_ptr, png_ptr->gamma_16_table);
if (png_ptr->gamma_16_from_1)
@ -697,12 +712,15 @@ png_read_destroy(png_struct *png_ptr, png_info *info, png_info *end_info)
}
png_free(png_ptr, png_ptr->gamma_16_to_1);
#endif
#if defined(PNG_READ_BACKGROUND_SUPPORTED)
png_free(png_ptr, png_ptr->trans);
#endif
#if defined(PNG_READ_DITHER_SUPPORTED)
png_free(png_ptr, png_ptr->hist);
#endif
if (!png_ptr->user_palette)
png_free(png_ptr, png_ptr->palette);

49
pngrtran.c
View File

@ -572,7 +572,7 @@ png_init_read_transformations(png_struct *png_ptr)
}
#endif
#if defined(PNG_READ_SHIFT_SUPPORTED)
#if defined(PNG_READ_SHIFT_SUPPORTED) && defined(PNG_READ_sBIT_SUPPORTED)
if ((png_ptr->transformations & PNG_SHIFT) &&
png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{
@ -876,19 +876,33 @@ png_do_unshift(png_row_info *row_info, png_bytef *row,
channels = 0;
if (row_info->color_type & PNG_COLOR_MASK_COLOR)
{
shift[channels++] = row_info->bit_depth - sig_bits->red;
shift[channels++] = row_info->bit_depth - sig_bits->green;
shift[channels++] = row_info->bit_depth - sig_bits->blue;
shift[channels++] = row_info->bit_depth - sig_bits->red < 0 ?
0 : row_info->bit_depth - sig_bits->red;
shift[channels++] = row_info->bit_depth - sig_bits->green < 0 ?
0 : row_info->bit_depth - sig_bits->green;
shift[channels++] = row_info->bit_depth - sig_bits->blue < 0 ?
0 : row_info->bit_depth - sig_bits->blue;
}
else
{
shift[channels++] = row_info->bit_depth - sig_bits->gray;
shift[channels++] = row_info->bit_depth - sig_bits->gray < 0 ?
0 : row_info->bit_depth - sig_bits->gray;
}
if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
{
shift[channels++] = row_info->bit_depth - sig_bits->alpha;
shift[channels++] = row_info->bit_depth - sig_bits->alpha < 0 ?
0 : row_info->bit_depth - sig_bits->alpha;
}
value = 1;
for (i = 0; i < channels; i++)
{
if (shift[i] != 0) value = 0;
}
if (value == 1) return;
switch (row_info->bit_depth)
{
case 2:
@ -905,6 +919,7 @@ png_do_unshift(png_row_info *row_info, png_bytef *row,
case 4:
{
png_byte mask;
mask = (png_byte)(((int)0xf0 >> shift[0]) & (int)0xf0) |
((int)0xf >> shift[0]);
for (bp = row, i = 0;
@ -957,17 +972,15 @@ png_do_unshift(png_row_info *row_info, png_bytef *row,
void
png_do_chop(png_row_info *row_info, png_bytef *row)
{
png_bytef *sp, *dp;
png_uint_32 i;
if (row && row_info && row_info->bit_depth == 16)
{
sp = row + 2;
dp = row + 1;
for (i = 1; i < row_info->width * row_info->channels; i++)
png_bytef *sp = row, *dp = row;
png_uint_32 i;
for (i = 0; i < row_info->width * row_info->channels; i++)
{
*dp = *sp;
*dp++ = ((((*sp << 8 | *(sp + 1)) - *sp) + 0x7F) >> 8) & 0xFF;
sp += 2;
dp++;
}
row_info->bit_depth = 8;
row_info->pixel_depth = 8 * row_info->channels;
@ -1147,6 +1160,7 @@ png_build_grayscale_palette(int bit_depth, png_color *palette)
break;
default:
num_palette = 0;
color_inc = 0;
break;
}
@ -2002,7 +2016,7 @@ png_do_background(png_row_info *row_info, png_bytef *row,
you do this after you deal with the trasparency issue on grayscale
or rgb images. If your bit depth is 8, use gamma_table, if it is 16,
use gamma_16_table and gamma_shift. Build these with
build_gamma_table(). If your bit depth < 8, gamma correct a
build_gamma_table(). If your bit depth <= 8, gamma correct a
palette, not the data. */
void
png_do_gamma(png_row_info *row_info, png_bytef *row,
@ -2623,8 +2637,9 @@ png_build_gamma_table(png_struct *png_ptr)
{
double g;
int i, j, shift, num;
int sig_bit;
png_uint_32 ig;
#if defined(PNG_READ_sBIT_SUPPORTED)
int sig_bit;
if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
{
@ -2642,6 +2657,7 @@ png_build_gamma_table(png_struct *png_ptr)
if (sig_bit > 0)
shift = 16 - sig_bit;
else
#endif /* PNG_READ_sBIT_SUPPORTED */
shift = 0;
if (png_ptr->transformations & PNG_16_TO_8)
@ -2685,8 +2701,7 @@ png_build_gamma_table(png_struct *png_ptr)
max = (png_uint_32)(fin * (double)(num << 8));
while (last <= max)
{
png_ptr->gamma_16_table[(int)(last >> 8)]
[(int)(last & 0xff)] =
png_ptr->gamma_16_table[(int)(last >> 8)][(int)(last & 0xff)] =
(png_uint_16)i | ((png_uint_16)i << 8);
last++;
}

94
pngrutil.c
View File

@ -40,7 +40,7 @@ png_get_uint_16(png_byte *buf)
void
png_crc_read(png_struct *png_ptr, png_bytef *buf, png_uint_32 length)
{
png_read_data(png_ptr, buf, length);
(*(png_ptr->read_data_fn))(png_ptr, buf, length);
png_calculate_crc(png_ptr, buf, length);
}
@ -52,12 +52,12 @@ png_crc_skip(png_struct *png_ptr, png_uint_32 length)
for (i = length; i > png_ptr->zbuf_size; i -= png_ptr->zbuf_size)
{
png_read_data(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
(*(png_ptr->read_data_fn))(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
png_calculate_crc(png_ptr, png_ptr->zbuf, png_ptr->zbuf_size);
}
if (i)
{
png_read_data(png_ptr, png_ptr->zbuf, i);
(*(png_ptr->read_data_fn))(png_ptr, png_ptr->zbuf, i);
png_calculate_crc(png_ptr, png_ptr->zbuf, i);
}
}
@ -73,7 +73,7 @@ png_handle_IHDR(png_struct *png_ptr, png_info *info, png_uint_32 length)
/* check the length */
if (length != 13)
png_error(png_ptr, "Invalid IHDR chunk");
(*(png_ptr->error_fn))(png_ptr, "Invalid IHDR chunk");
png_crc_read(png_ptr, buf, 13);
@ -87,36 +87,36 @@ png_handle_IHDR(png_struct *png_ptr, png_info *info, png_uint_32 length)
/* check for width and height valid values */
if (width == 0 || height == 0)
png_error(png_ptr, "Invalid Width or Height Found");
(*(png_ptr->error_fn))(png_ptr, "Invalid Width or Height Found");
/* check other values */
if (bit_depth != 1 && bit_depth != 2 &&
bit_depth != 4 && bit_depth != 8 &&
bit_depth != 16)
png_error(png_ptr, "Invalid Bit Depth Found");
(*(png_ptr->error_fn))(png_ptr, "Invalid Bit Depth Found");
if (color_type < 0 || color_type == 1 ||
color_type == 5 || color_type > 6)
png_error(png_ptr, "Invalid Color Type Found");
(*(png_ptr->error_fn))(png_ptr, "Invalid Color Type Found");
if (color_type == PNG_COLOR_TYPE_PALETTE &&
bit_depth == 16)
png_error(png_ptr, "Found Invalid Color Type and Bit Depth Combination");
(*(png_ptr->error_fn))(png_ptr, "Found Invalid Color Type and Bit Depth Combination");
if ((color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
bit_depth < 8)
png_error(png_ptr, "Found Invalid Color Type and Bit Depth Combination");
(*(png_ptr->error_fn))(png_ptr, "Found Invalid Color Type and Bit Depth Combination");
if (interlace_type > 1)
png_error(png_ptr, "Found Invalid Interlace Value");
(*(png_ptr->error_fn))(png_ptr, "Found Unsupported Interlace Value");
if (compression_type > 0)
png_error(png_ptr, "Found Invalid Compression Value");
(*(png_ptr->error_fn))(png_ptr, "Found Unsupported Compression Value");
if (filter_type > 0)
png_error(png_ptr, "Found Invalid Filter Value");
(*(png_ptr->error_fn))(png_ptr, "Found Unsupported Filter Value");
/* set internal variables */
png_ptr->width = width;
@ -160,10 +160,12 @@ png_handle_PLTE(png_struct *png_ptr, png_info *info, png_uint_32 length)
png_color *palette;
if (length % 3)
png_error(png_ptr, "Invalid Palette Chunk");
(*(png_ptr->error_fn))(png_ptr, "Invalid Palette Chunk");
num = (int)length / 3;
palette = (png_color *)png_malloc(png_ptr, num * sizeof (png_color));
png_ptr->do_free |= PNG_FREE_PALETTE;
for (i = 0; i < num; i++)
{
png_byte buf[3];
@ -189,6 +191,7 @@ png_handle_gAMA(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != 4)
{
(*(png_ptr->warning_fn))(png_ptr,"Incorrect gAMA chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -210,6 +213,7 @@ void
png_handle_sBIT(png_struct *png_ptr, png_info *info, png_uint_32 length)
{
int slen;
register int index = 0;
png_byte buf[4];
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
@ -219,6 +223,7 @@ png_handle_sBIT(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != (png_uint_32)slen)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect sBIT chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -226,16 +231,28 @@ png_handle_sBIT(png_struct *png_ptr, png_info *info, png_uint_32 length)
png_crc_read(png_ptr, buf, length);
if (png_ptr->color_type & PNG_COLOR_MASK_COLOR)
{
png_ptr->sig_bit.red = buf[0];
png_ptr->sig_bit.green = buf[1];
png_ptr->sig_bit.blue = buf[2];
png_ptr->sig_bit.alpha = buf[3];
png_ptr->sig_bit.red = buf[index++];
png_ptr->sig_bit.green = buf[index++];
png_ptr->sig_bit.blue = buf[index++];
png_ptr->sig_bit.gray = 0;
}
else
{
png_ptr->sig_bit.red = 0;
png_ptr->sig_bit.green = 0;
png_ptr->sig_bit.blue = 0;
png_ptr->sig_bit.gray = buf[0];
png_ptr->sig_bit.alpha = buf[1];
}
if (png_ptr->color_type & PNG_COLOR_MASK_ALPHA)
{
png_ptr->sig_bit.alpha = buf[index++];
}
else
{
png_ptr->sig_bit.alpha = 0;
}
png_read_sBIT(png_ptr, info, &(png_ptr->sig_bit));
}
#endif
@ -250,6 +267,7 @@ png_handle_cHRM(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != 32)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect cHRM chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -299,11 +317,13 @@ png_handle_tRNS(png_struct *png_ptr, png_info *info, png_uint_32 length)
{
if (length > png_ptr->num_palette)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect tRNS chunk length");
png_crc_skip(png_ptr, length);
return;
}
png_ptr->trans = png_malloc(png_ptr, length);
png_ptr->do_free |= PNG_FREE_TRANS;
png_crc_read(png_ptr, png_ptr->trans, length);
png_ptr->num_trans = (int)length;
}
@ -313,6 +333,7 @@ png_handle_tRNS(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != 6)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect tRNS chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -329,6 +350,7 @@ png_handle_tRNS(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != 2)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect tRNS chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -338,7 +360,7 @@ png_handle_tRNS(png_struct *png_ptr, png_info *info, png_uint_32 length)
png_ptr->trans_values.gray = png_get_uint_16(buf);
}
else
png_error(png_ptr, "Invalid tRNS chunk");
(*(png_ptr->error_fn))(png_ptr, "Invalid tRNS chunk");
png_read_tRNS(png_ptr, info, png_ptr->trans, png_ptr->num_trans,
&(png_ptr->trans_values));
@ -361,6 +383,7 @@ png_handle_bKGD(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != (png_uint_32)truelen)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect bKGD chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -389,12 +412,15 @@ png_handle_hIST(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != 2 * png_ptr->num_palette)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect hIST chunk length");
png_crc_skip(png_ptr, length);
return;
}
num = (int)length / 2;
png_ptr->hist = png_malloc(png_ptr, num * sizeof (png_uint_16));
png_ptr->do_free |= PNG_FREE_HIST;
for (i = 0; i < num; i++)
{
png_byte buf[2];
@ -416,6 +442,7 @@ png_handle_pHYs(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != 9)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect pHYS chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -439,6 +466,7 @@ png_handle_oFFs(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != 9)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect oFFs chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -461,6 +489,7 @@ png_handle_tIME(png_struct *png_ptr, png_info *info, png_uint_32 length)
if (length != 7)
{
(*(png_ptr->warning_fn))(png_ptr, "Incorrect tIME chunk length");
png_crc_skip(png_ptr, length);
return;
}
@ -509,7 +538,7 @@ png_handle_zTXt(png_struct *png_ptr, png_info *info, png_uint_32 length)
{
charf *key;
charf *text;
int ret;
int ret = Z_STREAM_END;
png_uint_32 text_size, key_size;
text = NULL;
@ -524,6 +553,7 @@ png_handle_zTXt(png_struct *png_ptr, png_info *info, png_uint_32 length)
/* zTXt can't have zero text */
if (text == key + (png_size_t)length)
{
(*(png_ptr->warning_fn))(png_ptr, "Zero length zTXt chunk");
png_large_free(png_ptr, key);
return;
}
@ -552,6 +582,10 @@ png_handle_zTXt(png_struct *png_ptr, png_info *info, png_uint_32 length)
ret = inflate(png_ptr->zstream, Z_PARTIAL_FLUSH);
if (ret != Z_OK && ret != Z_STREAM_END)
{
if (png_ptr->zstream->msg)
(*(png_ptr->warning_fn))(png_ptr,png_ptr->zstream->msg);
else
(*(png_ptr->warning_fn))(png_ptr,"zTXt decompression error");
inflateReset(png_ptr->zstream);
png_ptr->zstream->avail_in = 0;
png_large_free(png_ptr, key);
@ -1104,19 +1138,19 @@ png_read_finish_row(png_struct *png_ptr)
png_byte buf[4];
png_uint_32 crc;
png_read_data(png_ptr, buf, 4);
(*(png_ptr->read_data_fn))(png_ptr, buf, 4);
crc = png_get_uint_32(buf);
if (((crc ^ 0xffffffffL) & 0xffffffffL) !=
(png_ptr->crc & 0xffffffffL))
png_error(png_ptr, "Bad CRC value");
(*(png_ptr->error_fn))(png_ptr, "Bad CRC value");
png_read_data(png_ptr, buf, 4);
(*(png_ptr->read_data_fn))(png_ptr, buf, 4);
png_ptr->idat_size = png_get_uint_32(buf);
png_reset_crc(png_ptr);
png_crc_read(png_ptr, buf, 4);
if (memcmp(buf, png_IDAT, 4))
png_error(png_ptr, "Not enough image data");
(*(png_ptr->error_fn))(png_ptr, "Not enough image data");
}
png_ptr->zstream->avail_in = (uInt)png_ptr->zbuf_size;
@ -1131,22 +1165,22 @@ png_read_finish_row(png_struct *png_ptr)
{
if (!(png_ptr->zstream->avail_out) || png_ptr->zstream->avail_in ||
png_ptr->idat_size)
png_error(png_ptr, "Extra compressed data");
(*(png_ptr->warning_fn))(png_ptr, "Extra compressed data");
png_ptr->mode = PNG_AT_LAST_IDAT;
break;
}
if (ret != Z_OK)
png_error(png_ptr, "Compression Error");
(*(png_ptr->error_fn))(png_ptr, "Compression Error");
if (!(png_ptr->zstream->avail_out))
png_error(png_ptr, "Extra compressed data");
(*(png_ptr->error_fn))(png_ptr, "Extra compressed data");
} while (1);
png_ptr->zstream->avail_out = 0;
}
if (png_ptr->idat_size || png_ptr->zstream->avail_in)
png_error(png_ptr, "Extra compression data");
(*(png_ptr->warning_fn))(png_ptr, "Extra compression data");
inflateReset(png_ptr->zstream);
@ -1258,13 +1292,13 @@ png_read_start_row(png_struct *png_ptr)
1 + ((max_pixel_depth + 7) >> 3);
#ifdef PNG_MAX_MALLOC_64K
if (rowbytes > 65536L)
png_error(png_ptr, "This image requires a row greater then 64KB");
(*(png_ptr->error_fn))(png_ptr, "This image requires a row greater then 64KB");
#endif
png_ptr->row_buf = (png_bytef *)png_large_malloc(png_ptr, rowbytes);
#ifdef PNG_MAX_MALLOC_64K
if (png_ptr->rowbytes + 1 > 65536L)
png_error(png_ptr, "This image requires a row greater then 64KB");
(*(png_ptr->error_fn))(png_ptr, "This image requires a row greater then 64KB");
#endif
png_ptr->prev_row = png_large_malloc(png_ptr,
png_ptr->rowbytes + 1);

9
pngtest.c
View File

@ -19,7 +19,7 @@
/* input and output filenames */
char inname[] = "pngtest.png";
char outname[] = "pngout.png";
char outname[] = "testout.png";
png_struct read_ptr;
png_struct write_ptr;
@ -79,10 +79,10 @@ int main()
return 1;
}
png_read_init(&read_ptr);
png_write_init(&write_ptr);
png_info_init(&info_ptr);
png_info_init(&end_info);
png_read_init(&read_ptr);
png_write_init(&write_ptr);
png_init_io(&read_ptr, fpin);
png_init_io(&write_ptr, fpout);
@ -97,6 +97,9 @@ int main()
if (info_ptr.color_type & 4)
channels++;
png_set_flush(&write_ptr, 20);
png_set_compression_level(&write_ptr, 9);
rowbytes = ((info_ptr.width * info_ptr.bit_depth * channels + 7) >> 3);
row_buf = (png_byte *)malloc((size_t)rowbytes);
if (!row_buf)

107
pngwrite.c
View File

@ -57,25 +57,30 @@ png_write_info(png_struct *png_ptr, png_info *info)
if (info->valid & PNG_INFO_bKGD)
png_write_bKGD(png_ptr, &(info->background), info->color_type);
#endif
#if defined(PNG_WRITE_hIST_SUPPORTED)
if (info->valid & PNG_INFO_hIST)
png_write_hIST(png_ptr, info->hist, info->num_palette);
#endif
#if defined(PNG_WRITE_pHYs_SUPPORTED)
if (info->valid & PNG_INFO_pHYs)
png_write_pHYs(png_ptr, info->x_pixels_per_unit,
info->y_pixels_per_unit, info->phys_unit_type);
#endif
#if defined(PNG_WRITE_oFFs_SUPPORTED)
if (info->valid & PNG_INFO_oFFs)
png_write_oFFs(png_ptr, info->x_offset, info->y_offset,
info->offset_unit_type);
#endif
#if defined(PNG_WRITE_tIME_SUPPORTED)
if (info->valid & PNG_INFO_tIME)
png_write_tIME(png_ptr, &(info->mod_time));
/* Check to see if we need to write text chunks */
#endif
#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
if (info->num_text)
{
@ -84,6 +89,12 @@ png_write_info(png_struct *png_ptr, png_info *info)
/* loop through the text chunks */
for (i = 0; i < info->num_text; i++)
{
if (strlen(info->text[i].key) > 80)
{
(*(png_ptr->warning_fn))(png_ptr,"tEXt keyword more than 80 chars");
continue;
}
/* if chunk is compressed */
if (info->text[i].compression >= 0)
{
@ -104,7 +115,8 @@ png_write_info(png_struct *png_ptr, png_info *info)
}
}
}
#endif
#endif /* PNG_WRITE_tEXt_SUPPORTED || PNG_WRITE_zTXt_SUPPORTED */
png_ptr->mode = PNG_HAVE_IHDR;
}
/* writes the end of the png file. If you don't want to write comments or
@ -114,6 +126,9 @@ png_write_info(png_struct *png_ptr, png_info *info)
void
png_write_end(png_struct *png_ptr, png_info *info)
{
if (info && png_ptr->mode == PNG_AFTER_IEND)
return;
/* see if user wants us to write information chunks */
if (info)
{
@ -122,6 +137,7 @@ png_write_end(png_struct *png_ptr, png_info *info)
if (info->valid & PNG_INFO_tIME)
png_write_tIME(png_ptr, &(info->mod_time));
#endif
#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
/* check to see if we need to write comment chunks */
if (info->num_text)
@ -151,10 +167,12 @@ png_write_end(png_struct *png_ptr, png_info *info)
}
}
}
#endif
#endif /* PNG_WRITE_tEXt_SUPPORTED || PNG_WRITE_zTXt_SUPPORTED */
}
/* write end of png file */
png_write_IEND(png_ptr);
png_ptr->mode = PNG_AFTER_IEND;
}
#if defined(PNG_WRITE_tIME_SUPPORTED)
@ -177,7 +195,7 @@ png_convert_from_time_t(png_time *ptime, time_t ttime)
tbuf = gmtime(&ttime);
png_convert_from_struct_tm(ptime, tbuf);
}
#endif
#endif /* PNG_WRITE_tIME_SUPPORTED */
/* initialize png structure, and allocate any memory needed */
void
@ -243,11 +261,13 @@ void
png_write_row(png_struct *png_ptr, png_bytef *row)
{
/* initialize transformations and other stuff if first time */
if (png_ptr->row_number == 0 && png_ptr->pass == 0)
if (png_ptr->mode < PNG_HAVE_IDAT)
{
png_write_start_row(png_ptr);
}
png_ptr->mode = PNG_HAVE_IDAT;
#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
/* if interlaced and not interested in row, return */
if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
@ -305,7 +325,7 @@ png_write_row(png_struct *png_ptr, png_bytef *row)
break;
}
}
#endif
#endif /* PNG_WRITE_INTERLACE_SUPPORTED */
/* set up row info for transformations */
png_ptr->row_info.color_type = png_ptr->color_type;
@ -334,7 +354,7 @@ png_write_row(png_struct *png_ptr, png_bytef *row)
return;
}
}
#endif
#endif /* PNG_WRITE_INTERLACE_SUPPORTED */
/* handle other transformations */
if (png_ptr->transformations)
@ -367,6 +387,7 @@ png_write_row(png_struct *png_ptr, png_bytef *row)
/* set up the zlib input buffer */
png_ptr->zstream->next_in = png_ptr->row_buf;
png_ptr->zstream->avail_in = (uInt)png_ptr->row_info.rowbytes + 1;
/* repeat until we have compressed all the data */
do
{
@ -378,9 +399,9 @@ png_write_row(png_struct *png_ptr, png_bytef *row)
if (ret != Z_OK)
{
if (png_ptr->zstream->msg)
png_error(png_ptr, png_ptr->zstream->msg);
(*(png_ptr->error_fn))(png_ptr, png_ptr->zstream->msg);
else
png_error(png_ptr, "zlib error");
(*(png_ptr->error_fn))(png_ptr, "zlib error");
}
/* see if it is time to write another IDAT */
@ -396,7 +417,76 @@ png_write_row(png_struct *png_ptr, png_bytef *row)
/* finish row - updates counters and flushes zlib if last row */
png_write_finish_row(png_ptr);
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
png_ptr->flush_rows++;
if (png_ptr->flush_dist > 0 &&
png_ptr->flush_rows >= png_ptr->flush_dist)
{
png_write_flush(png_ptr);
}
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
}
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
/* Set the automatic flush interval or 0 to turn flushing off */
void
png_set_flush(png_struct *png_ptr, int nrows)
{
png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
}
/* flush the current output buffers now */
void
png_write_flush(png_struct *png_ptr)
{
char wrote_IDAT;
if (png_ptr->mode != PNG_HAVE_IDAT)
return;
do
{
int ret;
/* compress the data */
ret = deflate(png_ptr->zstream, Z_SYNC_FLUSH);
wrote_IDAT = 0;
/* check for compression errors */
if (ret != Z_OK)
{
if (png_ptr->zstream->msg)
(*(png_ptr->error_fn))(png_ptr, png_ptr->zstream->msg);
else
(*(png_ptr->error_fn))(png_ptr, "zlib error");
}
if (!png_ptr->zstream->avail_out)
{
/* write the IDAT and reset the zlib output buffer */
png_write_IDAT(png_ptr, png_ptr->zbuf,
png_ptr->zbuf_size);
png_ptr->zstream->next_out = png_ptr->zbuf;
png_ptr->zstream->avail_out = (uInt)png_ptr->zbuf_size;
wrote_IDAT = 1;
}
} while(wrote_IDAT == 1);
/* If there is any data left to be output, write it into a new IDAT */
if (png_ptr->zbuf_size != png_ptr->zstream->avail_out)
{
/* write the IDAT and reset the zlib output buffer */
png_write_IDAT(png_ptr, png_ptr->zbuf,
png_ptr->zbuf_size - png_ptr->zstream->avail_out);
png_ptr->zstream->next_out = png_ptr->zbuf;
png_ptr->zstream->avail_out = (uInt)png_ptr->zbuf_size;
}
png_ptr->flush_rows = 0;
(*(png_ptr->output_flush_fn))(png_ptr);
}
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
/* free any memory used in png struct */
void
@ -416,6 +506,7 @@ png_write_destroy(png_struct *png_ptr)
png_memset(png_ptr, 0, sizeof (png_struct));
png_memcpy(png_ptr->jmpbuf, tmp_jmp, sizeof (jmp_buf));
}
void
png_set_filtering(png_struct *png_ptr, int filter)
{

29
pngwutil.c
View File

@ -39,7 +39,7 @@ png_write_uint_32(png_struct *png_ptr, png_uint_32 i)
buf[1] = (png_byte)((i >> 16) & 0xff);
buf[2] = (png_byte)((i >> 8) & 0xff);
buf[3] = (png_byte)(i & 0xff);
png_write_data(png_ptr, buf, 4);
(*(png_ptr->write_data_fn))(png_ptr, buf, 4);
}
/* write a 16 bit number */
@ -50,7 +50,7 @@ png_write_uint_16(png_struct *png_ptr, png_uint_16 i)
buf[0] = (png_byte)((i >> 8) & 0xff);
buf[1] = (png_byte)(i & 0xff);
png_write_data(png_ptr, buf, 2);
(*(png_ptr->write_data_fn))(png_ptr, buf, 2);
}
/* Write a png chunk all at once. The type is an array of ASCII characters
@ -68,7 +68,7 @@ png_write_chunk(png_struct *png_ptr, png_byte *type,
/* write length */
png_write_uint_32(png_ptr, length);
/* write chunk name */
png_write_data(png_ptr, type, (png_uint_32)4);
(*(png_ptr->write_data_fn))(png_ptr, type, (png_uint_32)4);
/* reset the crc and run the chunk name over it */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, type, (png_uint_32)4);
@ -76,7 +76,7 @@ png_write_chunk(png_struct *png_ptr, png_byte *type,
if (length)
{
png_calculate_crc(png_ptr, data, length);
png_write_data(png_ptr, data, length);
(*(png_ptr->write_data_fn))(png_ptr, data, length);
}
/* write the crc */
png_write_uint_32(png_ptr, ~png_ptr->crc);
@ -92,7 +92,7 @@ png_write_chunk_start(png_struct *png_ptr, png_byte *type,
/* write the length */
png_write_uint_32(png_ptr, total_length);
/* write the chunk name */
png_write_data(png_ptr, type, (png_uint_32)4);
(*(png_ptr->write_data_fn))(png_ptr, type, (png_uint_32)4);
/* reset the crc and run it over the chunk name */
png_reset_crc(png_ptr);
png_calculate_crc(png_ptr, type, (png_uint_32)4);
@ -109,7 +109,7 @@ png_write_chunk_data(png_struct *png_ptr, png_bytef *data, png_uint_32 length)
if (length)
{
png_calculate_crc(png_ptr, data, length);
png_write_data(png_ptr, data, length);
(*(png_ptr->write_data_fn))(png_ptr, data, length);
}
}
@ -126,7 +126,7 @@ void
png_write_sig(png_struct *png_ptr)
{
/* write the 8 byte signature */
png_write_data(png_ptr, png_sig, (png_uint_32)8);
(*(png_ptr->write_data_fn))(png_ptr, png_sig, (png_uint_32)8);
}
/* Write the IHDR chunk, and update the png_struct with the necessary
@ -462,9 +462,9 @@ png_write_zTXt(png_struct *png_ptr, charf *key, charf *text,
{
/* error */
if (png_ptr->zstream->msg)
png_error(png_ptr, png_ptr->zstream->msg);
(*(png_ptr->error_fn))(png_ptr, png_ptr->zstream->msg);
else
png_error(png_ptr, "zlib error");
(*(png_ptr->error_fn))(png_ptr, "zlib error");
}
/* check to see if we need more room */
if (!png_ptr->zstream->avail_out && png_ptr->zstream->avail_in)
@ -508,9 +508,9 @@ png_write_zTXt(png_struct *png_ptr, charf *key, charf *text,
{
/* we got an error */
if (png_ptr->zstream->msg)
png_error(png_ptr, png_ptr->zstream->msg);
(*(png_ptr->error_fn))(png_ptr, png_ptr->zstream->msg);
else
png_error(png_ptr, "zlib error");
(*(png_ptr->error_fn))(png_ptr, "zlib error");
}
/* check to see if we need more room */
@ -689,7 +689,7 @@ png_write_finish_row(png_struct *png_ptr)
/* next row */
png_ptr->row_number++;
/* see if we are done */
if (png_ptr->row_number < png_ptr->num_rows)
if (png_ptr->row_number < png_ptr->num_rows || png_ptr->mode > PNG_HAVE_IDAT)
return;
/* if interlaced, go to next pass */
@ -740,9 +740,9 @@ png_write_finish_row(png_struct *png_ptr)
if (ret != Z_OK && ret != Z_STREAM_END)
{
if (png_ptr->zstream->msg)
png_error(png_ptr, png_ptr->zstream->msg);
(*(png_ptr->error_fn))(png_ptr, png_ptr->zstream->msg);
else
png_error(png_ptr, "zlib error");
(*(png_ptr->error_fn))(png_ptr, "zlib error");
}
/* check to see if we need more room */
if (!png_ptr->zstream->avail_out && ret == Z_OK)
@ -761,6 +761,7 @@ png_write_finish_row(png_struct *png_ptr)
}
deflateReset(png_ptr->zstream);
png_ptr->mode = PNG_AFTER_IDAT;
}
#if defined(PNG_WRITE_INTERLACING_SUPPORTED)