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[libpng16] Updated the documentation about CRC and ADLER32 handling.

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Glenn Randers-Pehrson
2016-09-26 10:32:24 -05:00
parent 394be58371
commit 04dab1e82d
4 changed files with 14 additions and 4 deletions
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8
libpng-manual.txt
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@@ -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
chunk.
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