path: root/src/3rdparty/libpng/libpng-manual.txt
diff options
Diffstat (limited to 'src/3rdparty/libpng/libpng-manual.txt')
1 files changed, 48 insertions, 17 deletions
diff --git a/src/3rdparty/libpng/libpng-manual.txt b/src/3rdparty/libpng/libpng-manual.txt
index 87eeb2b583..048ba31c06 100644
--- a/src/3rdparty/libpng/libpng-manual.txt
+++ b/src/3rdparty/libpng/libpng-manual.txt
@@ -1,9 +1,9 @@
libpng-manual.txt - A description on how to use and modify libpng
- libpng version 1.6.20 - December 3, 2015
+ libpng version 1.6.28 - January 5, 2017
Updated and distributed by Glenn Randers-Pehrson
<glennrp at>
- Copyright (c) 1998-2015 Glenn Randers-Pehrson
+ Copyright (c) 1998-2016 Glenn Randers-Pehrson
This document is released under the libpng license.
For conditions of distribution and use, see the disclaimer
@@ -11,9 +11,9 @@ libpng-manual.txt - A description on how to use and modify libpng
Based on:
- libpng versions 0.97, January 1998, through 1.6.20 - December 3, 2015
+ libpng versions 0.97, January 1998, through 1.6.28 - January 5, 2017
Updated and distributed by Glenn Randers-Pehrson
- Copyright (c) 1998-2015 Glenn Randers-Pehrson
+ Copyright (c) 1998-2016 Glenn Randers-Pehrson
libpng 1.0 beta 6 - version 0.96 - May 28, 1997
Updated and distributed by Andreas Dilger
@@ -467,8 +467,9 @@ the default, use
The values for png_set_crc_action() say how libpng is to handle CRC errors in
ancillary and critical chunks, and whether to use the data contained
-therein. Note that it is impossible to "discard" data in a critical
+therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
+is handled while reading the IDAT chunk. Note that it is impossible to
+"discard" data in a critical chunk.
Choices for (int) crit_action are
PNG_CRC_DEFAULT 0 error/quit
@@ -485,6 +486,9 @@ Choices for (int) ancil_action are
PNG_CRC_QUIET_USE 4 quiet/use data
PNG_CRC_NO_CHANGE 5 use the current value
+When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
+checksums are not only ignored, but they are not evaluated.
Setting up callback code
You can set up a callback function to handle any unknown chunks in the
@@ -559,7 +563,7 @@ non-interlaced case the row that was just handled is simply one less than the
passed in row number, and pass will always be 0. For the interlaced case the
same applies unless the row value is 0, in which case the row just handled was
the last one from one of the preceding passes. Because interlacing may skip a
-pass you cannot be sure that the preceding pass is just 'pass-1', if you really
+pass you cannot be sure that the preceding pass is just 'pass-1'; if you really
need to know what the last pass is record (row,pass) from the callback and use
the last recorded value each time.
@@ -2230,7 +2234,8 @@ is exactly the same. If you are planning on displaying the image
after each pass, the "rectangle" effect is generally considered the
better looking one.
-If you only want the "sparkle" effect, just call png_read_rows() as
+If you only want the "sparkle" effect, just call png_read_row() or
+png_read_rows() as
normal, with the third parameter NULL. Make sure you make pass over
the image number_of_passes times, and you don't change the data in the
rows between calls. You can change the locations of the data, just
@@ -2239,6 +2244,8 @@ pass, and assumes the data from previous passes is still valid.
png_read_rows(png_ptr, row_pointers, NULL,
+ or
+ png_read_row(png_ptr, row_pointers, NULL);
If you only want the first effect (the rectangles), do the same as
before except pass the row buffer in the third parameter, and leave
@@ -2246,6 +2253,8 @@ the second parameter NULL.
png_read_rows(png_ptr, NULL, row_pointers,
+ or
+ png_read_row(png_ptr, NULL, row_pointers);
If you don't want libpng to handle the interlacing details, just call
png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
@@ -2842,7 +2851,7 @@ filter types.
If an application wants to start and stop using particular filters during
compression, it should start out with all of the filters (to ensure that
@@ -4103,6 +4112,13 @@ be written:
Write the image to the named file.
+ int png_image_write_to_memory (png_imagep image, void *memory,
+ png_alloc_size_t * PNG_RESTRICT memory_bytes,
+ int convert_to_8_bit, const void *buffer, ptrdiff_t row_stride,
+ const void *colormap));
+ Write the image to memory.
int png_image_write_to_stdio(png_imagep image, FILE *file,
int convert_to_8_bit, const void *buffer,
png_int_32 row_stride, const void *colormap)
@@ -4380,8 +4396,9 @@ for any images with bit depths less than 8 bits/pixel.
The 'method' parameter sets the main filtering method, which is
currently only '0' in the PNG 1.2 specification. The 'filters'
parameter sets which filter(s), if any, should be used for each
-scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
-to turn filtering on and off, respectively.
+scanline. Possible values are PNG_ALL_FILTERS, PNG_NO_FILTERS,
+or PNG_FAST_FILTERS to turn filtering on and off, or to turn on
+just the fast-decoding subset of filters, respectively.
Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
@@ -4395,12 +4412,19 @@ means the first row must always be adaptively filtered, because libpng
currently does not allocate the filter buffers until png_write_row()
is called for the first time.)
+ filters = PNG_NO_FILTERS;
+ filters = PNG_ALL_FILTERS;
+ filters = PNG_FAST_FILTERS;
+ or
png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
The second parameter can also be
writing a PNG to be embedded in a MNG
@@ -4775,7 +4799,8 @@ There are no substantial API changes between the non-deprecated parts of
the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
members of the main libpng control structures, png_struct and png_info,
deprecated in earlier versions of libpng, has been completely removed from
-libpng 1.5.
+libpng 1.5, and new private "pngstruct.h", "pnginfo.h", and "pngdebug.h"
+header files were created.
We no longer include zlib.h in png.h. The include statement has been moved
to pngstruct.h, where it is not accessible by applications. Applications that
@@ -5015,6 +5040,7 @@ includes the following:
write functions
+ png_image_write_to_memory()
Starting with libpng-1.6.0, you can configure libpng to prefix all exported
@@ -5078,6 +5104,10 @@ enforced. The sRGB chunk is allowed to appear in images with any color type
and is interpreted by libpng to convey a one-tracer-curve gray profile or a
three-tracer-curve RGB profile as appropriate.
+Libpng 1.5.x erroneously used /MD for Debug DLL builds; if you used the debug
+builds in your app and you changed your app to use /MD you will need to
+change it back to /MDd for libpng 1.6.x.
Prior to libpng-1.6.0 a warning would be issued if the iTXt chunk contained
an empty language field or an empty translated keyword. Both of these
are allowed by the PNG specification, so these warnings are no longer issued.
@@ -5309,8 +5339,9 @@ with an even number of lower-case hex digits, and to make them unsigned
We prefer to use underscores rather than camelCase in names, except
for a few type names that we inherit from zlib.h.
-We prefer "if (something != 0)" and "if (something == 0)"
-over "if (something)" and if "(!something)", respectively.
+We prefer "if (something != 0)" and "if (something == 0)" over
+"if (something)" and if "(!something)", respectively, and for pointers
+we prefer "if (some_pointer != NULL)" or "if (some_pointer == NULL)".
We do not use the TAB character for indentation in the C sources.
@@ -5324,7 +5355,7 @@ Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.
This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.20 are Y2K compliant. It is my belief that earlier
+upward through 1.6.28 are Y2K compliant. It is my belief that earlier
versions were also Y2K compliant.
Libpng only has two year fields. One is a 2-byte unsigned integer