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[libpng16] Revise man page to demonstrate dealing with unknown chunk

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handling in libpng.1.5.x and with bugs in libpng-1.4.x and earlier.
This commit is contained in:
Glenn Randers-Pehrson 2013-04-28 20:48:37 -05:00
parent 49f9c24910
commit 61946e0f56
2 changed files with 66 additions and 34 deletions
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46
libpng-manual.txt
View File

@ -1,6 +1,6 @@
libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.6.3beta03 - April 27, 2013
libpng version 1.6.3beta03 - April 29, 2013
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2013 Glenn Randers-Pehrson
@ -11,7 +11,7 @@ libpng-manual.txt - A description on how to use and modify libpng
Based on:
libpng versions 0.97, January 1998, through 1.6.3beta03 - April 27, 2013
libpng versions 0.97, January 1998, through 1.6.3beta03 - April 29, 2013
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2013 Glenn Randers-Pehrson
@ -3104,17 +3104,33 @@ Here is an example of writing two private chunks, prVt and miNE:
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
/* Set unknown chunk data */
png_unknown_chunk unkc[2];
png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS, NULL, 0);
strcpy((char *) unkc[0].name, "prVt";
unkc[0].data = (unsigned char *) "PRIVATE CHUNK DATA";
unkc[0].size = strlen(unkc[0].data)+1;
unkc[0].location = PNG_HAVE_IHDR;
strcpy((char *) unkc[1].name, "miNE";
unkc[1].data = (unsigned char *) "MY CHUNK DATA";
unkc[1].size = strlen(unkc[0].data)+1;
unkc[1].location = PNG_AFTER_IDAT;
png_set_unknown_chunks(png, info, unkc, 2);
png_unknown_chunk unk_chunk[2];
strcpy((char *) unk_chunk[0].name, "prVt";
unk_chunk[0].data = (unsigned char *) "PRIVATE DATA";
unk_chunk[0].size = strlen(unk_chunk[0].data)+1;
unk_chunk[0].location = PNG_HAVE_IHDR;
strcpy((char *) unk_chunk[1].name, "miNE";
unk_chunk[1].data = (unsigned char *) "MY CHUNK DATA";
unk_chunk[1].size = strlen(unk_chunk[0].data)+1;
unk_chunk[1].location = PNG_AFTER_IDAT;
png_set_unknown_chunks(write_ptr, write_info_ptr,
unk_chunk, 2);
/* Needed because miNE is not safe-to-copy */
png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS,
(png_bytep) "miNE", 1);
# if PNG_LIBPNG_VER < 10600
/* Deal with unknown chunk location bug in 1.5.x and earlier */
png_set_unknown_chunk_location(png, info, 0, PNG_HAVE_IHDR);
png_set_unknown_chunk_location(png, info, 1, PNG_AFTER_IDAT);
# endif
# if PNG_LIBPNG_VER < 10500
/* PNG_AFTER_IDAT writes two copies of the chunk prior to libpng-1.5.0,
* one before IDAT and another after IDAT, so don't use it; only use
* PNG_HAVE_IHDR location. This call resets the location previously
* set by assignment and png_set_unknown_chunk_location() for chunk 1.
*/
png_set_unknown_chunk_location(png, info, 1, PNG_HAVE_IHDR);
# endif
#endif
The high-level write interface
@ -4965,7 +4981,7 @@ We no longer include string.h in png.h. The include statement has been moved
to pngpriv.h, where it is not accessible by applications. Applications that
need access to information in string.h must add an '#include <string.h>'
directive. It does not matter whether this is placed prior to or after
the '"#include png.h"' directive.
the '#include "png.h"' directive.
The following API are now DEPRECATED:
png_info_init_3()
@ -5181,7 +5197,7 @@ Other rules can be inferred by inspecting the libpng source.
XVI. Y2K Compliance in libpng
April 27, 2013
April 29, 2013
Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.

54
libpng.3
View File

@ -1,4 +1,4 @@
.TH LIBPNG 3 "April 27, 2013"
.TH LIBPNG 3 "April 29, 2013"
.SH NAME
libpng \- Portable Network Graphics (PNG) Reference Library 1.6.3beta03
.SH SYNOPSIS
@ -504,7 +504,7 @@ Following is a copy of the libpng-manual.txt file that accompanies libpng.
.SH LIBPNG.TXT
libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.6.3beta03 - April 27, 2013
libpng version 1.6.3beta03 - April 29, 2013
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2013 Glenn Randers-Pehrson
@ -515,7 +515,7 @@ libpng-manual.txt - A description on how to use and modify libpng
Based on:
libpng versions 0.97, January 1998, through 1.6.3beta03 - April 27, 2013
libpng versions 0.97, January 1998, through 1.6.3beta03 - April 29, 2013
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2013 Glenn Randers-Pehrson
@ -3608,17 +3608,33 @@ Here is an example of writing two private chunks, prVt and miNE:
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
/* Set unknown chunk data */
png_unknown_chunk unkc[2];
png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS, NULL, 0);
strcpy((char *) unkc[0].name, "prVt";
unkc[0].data = (unsigned char *) "PRIVATE CHUNK DATA";
unkc[0].size = strlen(unkc[0].data)+1;
unkc[0].location = PNG_HAVE_IHDR;
strcpy((char *) unkc[1].name, "miNE";
unkc[1].data = (unsigned char *) "MY CHUNK DATA";
unkc[1].size = strlen(unkc[0].data)+1;
unkc[1].location = PNG_AFTER_IDAT;
png_set_unknown_chunks(png, info, unkc, 2);
png_unknown_chunk unk_chunk[2];
strcpy((char *) unk_chunk[0].name, "prVt";
unk_chunk[0].data = (unsigned char *) "PRIVATE DATA";
unk_chunk[0].size = strlen(unk_chunk[0].data)+1;
unk_chunk[0].location = PNG_HAVE_IHDR;
strcpy((char *) unk_chunk[1].name, "miNE";
unk_chunk[1].data = (unsigned char *) "MY CHUNK DATA";
unk_chunk[1].size = strlen(unk_chunk[0].data)+1;
unk_chunk[1].location = PNG_AFTER_IDAT;
png_set_unknown_chunks(write_ptr, write_info_ptr,
unk_chunk, 2);
/* Needed because miNE is not safe-to-copy */
png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS,
(png_bytep) "miNE", 1);
# if PNG_LIBPNG_VER < 10600
/* Deal with unknown chunk location bug in 1.5.x and earlier */
png_set_unknown_chunk_location(png, info, 0, PNG_HAVE_IHDR);
png_set_unknown_chunk_location(png, info, 1, PNG_AFTER_IDAT);
# endif
# if PNG_LIBPNG_VER < 10500
/* PNG_AFTER_IDAT writes two copies of the chunk prior to libpng-1.5.0,
* one before IDAT and another after IDAT, so don't use it; only use
* PNG_HAVE_IHDR location. This call resets the location previously
* set by assignment and png_set_unknown_chunk_location() for chunk 1.
*/
png_set_unknown_chunk_location(png, info, 1, PNG_HAVE_IHDR);
# endif
#endif
.SS The high-level write interface
@ -5470,7 +5486,7 @@ We no longer include string.h in png.h. The include statement has been moved
to pngpriv.h, where it is not accessible by applications. Applications that
need access to information in string.h must add an '#include <string.h>'
directive. It does not matter whether this is placed prior to or after
the '"#include png.h"' directive.
the '#include "png.h"' directive.
The following API are now DEPRECATED:
png_info_init_3()
@ -5686,7 +5702,7 @@ Other rules can be inferred by inspecting the libpng source.
.SH XVI. Y2K Compliance in libpng
April 27, 2013
April 29, 2013
Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.
@ -5963,7 +5979,7 @@ possible without all of you.
Thanks to Frank J. T. Wojcik for helping with the documentation.
Libpng version 1.6.3beta03 - April 27, 2013:
Libpng version 1.6.3beta03 - April 29, 2013:
Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
@ -5986,7 +6002,7 @@ this sentence.
This code is released under the libpng license.
libpng versions 1.2.6, August 15, 2004, through 1.6.3beta03, April 27, 2013, are
libpng versions 1.2.6, August 15, 2004, through 1.6.3beta03, April 29, 2013, 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
@ -6085,7 +6101,7 @@ certification mark of the Open Source Initiative.
Glenn Randers-Pehrson
glennrp at users.sourceforge.net
April 27, 2013
April 29, 2013
.\" end of man page