[master] Updated documentation
Merged libpng-1.2.41.txt with libpng-1.4.0.txt where appropriate.
This commit is contained in:
Glenn Randers-Pehrson
parent
2e8aa25844
commit
da9b591621
1
ANNOUNCE
1
ANNOUNCE
@ -89,6 +89,7 @@ version 1.2.41beta09 [November 1, 2009]
|
||||
More bugfixes and improvements to CMakeLists.txt (Philip Lowman)
|
||||
Moved CMakeLists.txt from scripts into the main libpng directory.
|
||||
Apply png_user_chunk_cache_max within png_decompress_chunk().
|
||||
Merged libpng-1.2.41.txt with libpng-1.4.0.txt where appropriate.
|
||||
|
||||
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
|
||||
|
||||
|
||||
1
CHANGES
1
CHANGES
@ -2519,6 +2519,7 @@ version 1.2.41beta09 [November 1, 2009]
|
||||
More bugfixes and improvements to CMakeLists.txt (Philip Lowman)
|
||||
Moved CMakeLists.txt from scripts into the main libpng directory.
|
||||
Apply png_user_chunk_cache_max within png_decompress_chunk().
|
||||
Merged libpng-1.2.41.txt with libpng-1.4.0.txt where appropriate.
|
||||
|
||||
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
|
||||
(subscription required; visit
|
||||
|
||||
@ -1,6 +1,6 @@
|
||||
libpng.txt - A description on how to use and modify libpng
|
||||
|
||||
libpng version 1.2.41beta09 - October 30, 2009
|
||||
libpng version 1.2.41beta09 - November 1, 2009
|
||||
Updated and distributed by Glenn Randers-Pehrson
|
||||
<glennrp at users.sourceforge.net>
|
||||
Copyright (c) 1998-2009 Glenn Randers-Pehrson
|
||||
@ -11,7 +11,7 @@ libpng.txt - A description on how to use and modify libpng
|
||||
|
||||
Based on:
|
||||
|
||||
libpng versions 0.97, January 1998, through 1.2.41beta09 - October 30, 2009
|
||||
libpng versions 0.97, January 1998, through 1.2.41beta09 - November 1, 2009
|
||||
Updated and distributed by Glenn Randers-Pehrson
|
||||
Copyright (c) 1998-2009 Glenn Randers-Pehrson
|
||||
|
||||
@ -410,6 +410,19 @@ If you need to retrieve the limits that are being applied, use
|
||||
width_max = png_get_user_width_max(png_ptr);
|
||||
height_max = png_get_user_height_max(png_ptr);
|
||||
|
||||
The PNG specification sets no limit on the number of ancillary chunks
|
||||
allowed in a PNG datastream. You can impose a limit on the total number
|
||||
of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
|
||||
|
||||
png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
|
||||
|
||||
where 0x7fffffffL means unlimited. You can retrieve this limit with
|
||||
|
||||
chunk_cache_max = png_get_chunk_cache_max(png_ptr);
|
||||
|
||||
This limit also applies to the number of buffers that can be allocated
|
||||
by png_decompress_chunk().
|
||||
|
||||
The high-level read interface
|
||||
|
||||
At this point there are two ways to proceed; through the high-level
|
||||
@ -437,6 +450,8 @@ you want to do are limited to the following set:
|
||||
PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
|
||||
to transparency
|
||||
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
|
||||
PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
|
||||
to RGB (or GA to RGBA)
|
||||
|
||||
(This excludes setting a background color, doing gamma transformation,
|
||||
dithering, and setting filler.) If this is the case, simply do this:
|
||||
@ -680,6 +695,10 @@ into the info_ptr is returned for any complex types.
|
||||
string for unknown).
|
||||
text_ptr[i].lang_key - keyword in UTF-8
|
||||
(empty string for unknown).
|
||||
Note that the itxt_length, lang, and lang_key
|
||||
members of the text_ptr structure only exist
|
||||
when the library is built with iTXt chunk support.
|
||||
|
||||
num_text - number of comments (same as
|
||||
num_comments; you can put NULL here
|
||||
to avoid the duplication)
|
||||
@ -859,6 +878,43 @@ things.
|
||||
As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
|
||||
added. It expands the sample depth without changing tRNS to alpha.
|
||||
|
||||
As of libpng version 1.2.41beta09, not all possible expansions are supported.
|
||||
|
||||
In the following table, the 01 means grayscale with depth<8, 31 means
|
||||
indexed with depth<8, other numerals represent the color type, "T" means
|
||||
the tRNS chunk is present, A means an alpha channel is present, and O
|
||||
means tRNS or alpha is present but all pixels in the image are opaque.
|
||||
|
||||
FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
|
||||
TO
|
||||
01 -
|
||||
31 -
|
||||
0 1 -
|
||||
0T -
|
||||
0O -
|
||||
2 GX -
|
||||
2T -
|
||||
2O -
|
||||
3 1 -
|
||||
3T -
|
||||
3O -
|
||||
4A T -
|
||||
4O -
|
||||
6A GX TX TX -
|
||||
6O GX TX -
|
||||
|
||||
Within the matrix,
|
||||
"-" means the transformation is not supported.
|
||||
"X" means the transformation is obtained by png_set_expand().
|
||||
"1" means the transformation is obtained by
|
||||
png_set_expand_gray_1_2_4_to_8
|
||||
"G" means the transformation is obtained by
|
||||
png_set_gray_to_rgb().
|
||||
"P" means the transformation is obtained by
|
||||
png_set_expand_palette_to_rgb().
|
||||
"T" means the transformation is obtained by
|
||||
png_set_tRNS_to_alpha().
|
||||
|
||||
PNG can have files with 16 bits per channel. If you only can handle
|
||||
8 bits per channel, this will strip the pixels down to 8 bit.
|
||||
|
||||
@ -1916,6 +1972,10 @@ width, height, bit_depth, and color_type must be the same in each call.
|
||||
empty for unknown).
|
||||
text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
|
||||
or empty for unknown).
|
||||
Note that the itxt_length, lang, and lang_key
|
||||
members of the text_ptr structure only exist
|
||||
when the library is built with iTXt chunk support.
|
||||
|
||||
num_text - number of comments
|
||||
|
||||
png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
|
||||
@ -3146,7 +3206,7 @@ source.
|
||||
|
||||
XIII. Y2K Compliance in libpng
|
||||
|
||||
October 30, 2009
|
||||
November 1, 2009
|
||||
|
||||
Since the PNG Development group is an ad-hoc body, we can't make
|
||||
an official declaration.
|
||||
|
||||
Reference in New Issue
Block a user