[libpng15] Updated the documentation of the png_text structure
(clarifying that the "lang" and "lang_key" fields can be NULL pointers
or might not exist).
diff --git a/libpng-manual.txt b/libpng-manual.txt
index 666c886..4c6e115 100644
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1,6 +1,6 @@
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
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2011 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@
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
Copyright (c) 1998-2011 Glenn Randers-Pehrson
@@ -1265,10 +1265,13 @@
(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.
- Prior to libpng-1.4.0, the default build was
- without iTXt chunk support.
+ members of the text_ptr 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,
+ 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_comments; you can put NULL here
@@ -2849,11 +2852,15 @@
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.
- Prior to libpng-1.4.0 the library was built by default
- without iTXt support.
+ members of the text_ptr 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,
+ they contain NULL pointers when the "compression"
+ field contains PNG_TEXT_COMPRESSION_NONE or
+ PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments
@@ -4566,7 +4573,7 @@
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
an official declaration.
diff --git a/libpng.3 b/libpng.3
index 1324810..3375e83 100644
--- a/libpng.3
+++ b/libpng.3
@@ -1,4 +1,4 @@
-.TH LIBPNG 3 "November 18, 2011"
+.TH LIBPNG 3 "November 21, 2011"
.SH NAME
libpng \- Portable Network Graphics (PNG) Reference Library 1.5.7beta05
.SH SYNOPSIS
@@ -1037,7 +1037,7 @@
.SH LIBPNG.TXT
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
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2011 Glenn Randers-Pehrson
@@ -1048,7 +1048,7 @@
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
Copyright (c) 1998-2011 Glenn Randers-Pehrson
@@ -2302,10 +2302,13 @@
(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.
- Prior to libpng-1.4.0, the default build was
- without iTXt chunk support.
+ members of the text_ptr 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,
+ 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_comments; you can put NULL here
@@ -3886,11 +3889,15 @@
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.
- Prior to libpng-1.4.0 the library was built by default
- without iTXt support.
+ members of the text_ptr 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,
+ they contain NULL pointers when the "compression"
+ field contains PNG_TEXT_COMPRESSION_NONE or
+ PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments
@@ -5604,7 +5611,7 @@
.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
an official declaration.
@@ -5869,7 +5876,7 @@
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.
Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
@@ -5892,7 +5899,7 @@
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
distributed according to the same disclaimer and license as libpng-1.2.5
with the following individual added to the list of Contributing Authors
@@ -5991,7 +5998,7 @@
Glenn Randers-Pehrson
glennrp at users.sourceforge.net
-November 18, 2011
+November 21, 2011
.\" end of man page
diff --git a/png.h b/png.h
index ccee420..1b07769 100644
--- a/png.h
+++ b/png.h
@@ -609,11 +609,18 @@
#ifdef PNG_TEXT_SUPPORTED
/* 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
- * points to a regular zero-terminated C string. The "text", "lang", and
- * "lang_key" fields can be regular C strings, empty strings, or NULL pointers.
+ * points to a regular zero-terminated C string. The "text" fields can be a
+ * regular C string, an empty string, or a NULL pointer.
* However, the structure returned by png_get_text() will always contain
- * regular zero-terminated C strings (possibly empty), never NULL pointers,
- * so they can be safely used in printf() and other string-handling functions.
+ * the "text" field as a regular zero-terminated C string (possibly
+ * 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
{
