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[libpng15] Updated the documentation of the png_text structure

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(clarifying that the "lang" and "lang_key" fields can be NULL pointers
or might not exist).
This commit is contained in:
Glenn Randers-Pehrson 2011-11-21 17:05:41 -06:00
parent 8e83631361
commit 680da02ade
3 changed files with 51 additions and 30 deletions
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29
libpng-manual.txt
View File

@ -1,6 +1,6 @@
libpng-manual.txt - A description on how to use and modify libpng libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.5.7beta05 - November 18, 2011 libpng version 1.5.7beta05 - November 21, 2011
Updated and distributed by Glenn Randers-Pehrson Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net> <glennrp at users.sourceforge.net>
Copyright (c) 1998-2011 Glenn Randers-Pehrson Copyright (c) 1998-2011 Glenn Randers-Pehrson
@ -11,7 +11,7 @@ libpng-manual.txt - A description on how to use and modify libpng
Based on: Based on:
libpng versions 0.97, January 1998, through 1.5.7beta05 - November 18, 2011 libpng versions 0.97, January 1998, through 1.5.7beta05 - November 21, 2011
Updated and distributed by Glenn Randers-Pehrson Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2011 Glenn Randers-Pehrson Copyright (c) 1998-2011 Glenn Randers-Pehrson
@ -1265,10 +1265,13 @@ pointer into the info_ptr is returned for any complex types.
(empty string for unknown). (empty string for unknown).
Note that the itxt_length, lang, and lang_key Note that the itxt_length, lang, and lang_key
members of the text_ptr structure only exist members of the text_ptr structure only exist when the
when the library is built with iTXt chunk support. library is built with iTXt chunk support. Prior to
Prior to libpng-1.4.0, the default build was libpng-1.4.0 the library was built by default without
without iTXt chunk support. iTXt support. Also note that when iTXt is supported,
they contain NULL pointers when the "compression"
field contains PNG_TEXT_COMPRESSION_NONE or
PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments (same as num_text - number of comments (same as
num_comments; you can put NULL here num_comments; you can put NULL here
@ -2849,11 +2852,15 @@ width, height, bit_depth, and color_type must be the same in each call.
empty for unknown). empty for unknown).
text_ptr[i].translated_keyword - keyword in UTF-8 (NULL text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
or empty for unknown). or empty for unknown).
Note that the itxt_length, lang, and lang_key Note that the itxt_length, lang, and lang_key
members of the text_ptr structure only exist members of the text_ptr structure only exist when the
when the library is built with iTXt chunk support. library is built with iTXt chunk support. Prior to
Prior to libpng-1.4.0 the library was built by default libpng-1.4.0 the library was built by default without
without iTXt support. iTXt support. Also note that when iTXt is supported,
they contain NULL pointers when the "compression"
field contains PNG_TEXT_COMPRESSION_NONE or
PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments num_text - number of comments
@ -4566,7 +4573,7 @@ Other rules can be inferred by inspecting the libpng source.
XIV. Y2K Compliance in libpng XIV. Y2K Compliance in libpng
November 18, 2011 November 21, 2011
Since the PNG Development group is an ad-hoc body, we can't make Since the PNG Development group is an ad-hoc body, we can't make
an official declaration. an official declaration.

37
libpng.3
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@ -1,4 +1,4 @@
.TH LIBPNG 3 "November 18, 2011" .TH LIBPNG 3 "November 21, 2011"
.SH NAME .SH NAME
libpng \- Portable Network Graphics (PNG) Reference Library 1.5.7beta05 libpng \- Portable Network Graphics (PNG) Reference Library 1.5.7beta05
.SH SYNOPSIS .SH SYNOPSIS
@ -1037,7 +1037,7 @@ Following is a copy of the libpng-manual.txt file that accompanies libpng.
.SH LIBPNG.TXT .SH LIBPNG.TXT
libpng-manual.txt - A description on how to use and modify libpng libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.5.7beta05 - November 18, 2011 libpng version 1.5.7beta05 - November 21, 2011
Updated and distributed by Glenn Randers-Pehrson Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net> <glennrp at users.sourceforge.net>
Copyright (c) 1998-2011 Glenn Randers-Pehrson Copyright (c) 1998-2011 Glenn Randers-Pehrson
@ -1048,7 +1048,7 @@ libpng-manual.txt - A description on how to use and modify libpng
Based on: Based on:
libpng versions 0.97, January 1998, through 1.5.7beta05 - November 18, 2011 libpng versions 0.97, January 1998, through 1.5.7beta05 - November 21, 2011
Updated and distributed by Glenn Randers-Pehrson Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2011 Glenn Randers-Pehrson Copyright (c) 1998-2011 Glenn Randers-Pehrson
@ -2302,10 +2302,13 @@ pointer into the info_ptr is returned for any complex types.
(empty string for unknown). (empty string for unknown).
Note that the itxt_length, lang, and lang_key Note that the itxt_length, lang, and lang_key
members of the text_ptr structure only exist members of the text_ptr structure only exist when the
when the library is built with iTXt chunk support. library is built with iTXt chunk support. Prior to
Prior to libpng-1.4.0, the default build was libpng-1.4.0 the library was built by default without
without iTXt chunk support. iTXt support. Also note that when iTXt is supported,
they contain NULL pointers when the "compression"
field contains PNG_TEXT_COMPRESSION_NONE or
PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments (same as num_text - number of comments (same as
num_comments; you can put NULL here num_comments; you can put NULL here
@ -3886,11 +3889,15 @@ width, height, bit_depth, and color_type must be the same in each call.
empty for unknown). empty for unknown).
text_ptr[i].translated_keyword - keyword in UTF-8 (NULL text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
or empty for unknown). or empty for unknown).
Note that the itxt_length, lang, and lang_key Note that the itxt_length, lang, and lang_key
members of the text_ptr structure only exist members of the text_ptr structure only exist when the
when the library is built with iTXt chunk support. library is built with iTXt chunk support. Prior to
Prior to libpng-1.4.0 the library was built by default libpng-1.4.0 the library was built by default without
without iTXt support. iTXt support. Also note that when iTXt is supported,
they contain NULL pointers when the "compression"
field contains PNG_TEXT_COMPRESSION_NONE or
PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments num_text - number of comments
@ -5604,7 +5611,7 @@ Other rules can be inferred by inspecting the libpng source.
.SH XIV. Y2K Compliance in libpng .SH XIV. Y2K Compliance in libpng
November 18, 2011 November 21, 2011
Since the PNG Development group is an ad-hoc body, we can't make Since the PNG Development group is an ad-hoc body, we can't make
an official declaration. an official declaration.
@ -5869,7 +5876,7 @@ possible without all of you.
Thanks to Frank J. T. Wojcik for helping with the documentation. Thanks to Frank J. T. Wojcik for helping with the documentation.
Libpng version 1.5.7beta05 - November 18, 2011: Libpng version 1.5.7beta05 - November 21, 2011:
Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc. Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net). Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
@ -5892,7 +5899,7 @@ this sentence.
This code is released under the libpng license. This code is released under the libpng license.
libpng versions 1.2.6, August 15, 2004, through 1.5.7beta05, November 18, 2011, are libpng versions 1.2.6, August 15, 2004, through 1.5.7beta05, November 21, 2011, are
Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-1.2.5 distributed according to the same disclaimer and license as libpng-1.2.5
with the following individual added to the list of Contributing Authors with the following individual added to the list of Contributing Authors
@ -5991,7 +5998,7 @@ certification mark of the Open Source Initiative.
Glenn Randers-Pehrson Glenn Randers-Pehrson
glennrp at users.sourceforge.net glennrp at users.sourceforge.net
November 18, 2011 November 21, 2011
.\" end of man page .\" end of man page

15
png.h
View File

@ -609,11 +609,18 @@ typedef png_sPLT_t FAR * FAR * png_sPLT_tpp;
#ifdef PNG_TEXT_SUPPORTED #ifdef PNG_TEXT_SUPPORTED
/* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file, /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
* and whether that contents is compressed or not. The "key" field * and whether that contents is compressed or not. The "key" field
* points to a regular zero-terminated C string. The "text", "lang", and * points to a regular zero-terminated C string. The "text" fields can be a
* "lang_key" fields can be regular C strings, empty strings, or NULL pointers. * regular C string, an empty string, or a NULL pointer.
* However, the structure returned by png_get_text() will always contain * However, the structure returned by png_get_text() will always contain
* regular zero-terminated C strings (possibly empty), never NULL pointers, * the "text" field as a regular zero-terminated C string (possibly
* so they can be safely used in printf() and other string-handling functions. * empty), never a NULL pointer, so it can be safely used in printf() and
* other string-handling functions. Note that the "itxt_length", "lang", and
* "lang_key" members of the structure only exist when the library is built
* with iTXt chunk support. Prior to libpng-1.4.0 the library was built by
* default without iTXt support. Also note that when iTXt *is* supported,
* the "lang" and "lang_key" fields contain NULL pointers when the
* "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
* PNG_TEXT_COMPRESSION_zTXt.
*/ */
typedef struct png_text_struct typedef struct png_text_struct
{ {