libpng.txt - A description on how to use and modify libpng
libpng version 1.2.41 - December 3, 2009
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2009 Glenn Randers-Pehrson
This document is released under the libpng license.
For conditions of distribution and use, see the disclaimer
and license in png.h
Based on:
libpng versions 0.97, January 1998, through 1.2.41 - December 3, 2009
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2009 Glenn Randers-Pehrson
libpng 1.0 beta 6 version 0.96 May 28, 1997
Updated and distributed by Andreas Dilger
Copyright (c) 1996, 1997 Andreas Dilger
libpng 1.0 beta 2 - version 0.88 January 26, 1996
For conditions of distribution and use, see copyright
notice in png.h. Copyright (c) 1995, 1996 Guy Eric
Schalnat, Group 42, Inc.
Updated/rewritten per request in the libpng FAQ
Copyright (c) 1995, 1996 Frank J. T. Wojcik
December 18, 1995 & January 20, 1996
I. Introduction
This file describes how to use and modify the PNG reference library
(known as libpng) for your own use. There are five sections to this
file: introduction, structures, reading, writing, and modification and
configuration notes for various special platforms. In addition to this
file, example.c is a good starting point for using the library, as
it is heavily commented and should include everything most people
will need. We assume that libpng is already installed; see the
INSTALL file for instructions on how to install libpng.
For examples of libpng usage, see the files "example.c", "pngtest.c",
and the files in the "contrib" directory, all of which are included in
the libpng distribution.
Libpng was written as a companion to the PNG specification, as a way
of reducing the amount of time and effort it takes to support the PNG
file format in application programs.
The PNG specification (second edition), November 2003, is available as
a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at
<http://www.w3.org/TR/2003/REC-PNG-20031110/
The W3C and ISO documents have identical technical content.
The PNG-1.2 specification is available at
<http://www.libpng.org/pub/png/documents/>. It is technically equivalent
to the PNG specification (second edition) but has some additional material.
The PNG-1.0 specification is available
as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
Some additional chunks are described in the special-purpose public chunks
documents at <http://www.libpng.org/pub/png/documents/>.
Other information
about PNG, and the latest version of libpng, can be found at the PNG home
page, <http://www.libpng.org/pub/png/>.
Most users will not have to modify the library significantly; advanced
users may want to modify it more. All attempts were made to make it as
complete as possible, while keeping the code easy to understand.
Currently, this library only supports C. Support for other languages
is being considered.
Libpng has been designed to handle multiple sessions at one time,
to be easily modifiable, to be portable to the vast majority of
machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
to use. The ultimate goal of libpng is to promote the acceptance of
the PNG file format in whatever way possible. While there is still
work to be done (see the TODO file), libpng should cover the
majority of the needs of its users.
Libpng uses zlib for its compression and decompression of PNG files.
Further information about zlib, and the latest version of zlib, can
be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
The zlib compression utility is a general purpose utility that is
useful for more than PNG files, and can be used without libpng.
See the documentation delivered with zlib for more details.
You can usually find the source files for the zlib utility wherever you
find the libpng source files.
Libpng is thread safe, provided the threads are using different
instances of the structures. Each thread should have its own
png_struct and png_info instances, and thus its own image.
Libpng does not protect itself against two threads using the
same instance of a structure.
II. Structures
There are two main structures that are important to libpng, png_struct
and png_info. The first, png_struct, is an internal structure that
will not, for the most part, be used by a user except as the first
variable passed to every libpng function call.
The png_info structure is designed to provide information about the
PNG file. At one time, the fields of png_info were intended to be
directly accessible to the user. However, this tended to cause problems
with applications using dynamically loaded libraries, and as a result
a set of interface functions for png_info (the png_get_*() and png_set_*()
functions) was developed. The fields of png_info are still available for
older applications, but it is suggested that applications use the new
interfaces if at all possible.
Applications that do make direct access to the members of png_struct (except
for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
and applications that make direct access to the members of png_info must
be recompiled if they were compiled or loaded with libpng version 1.0.6,
in which the members were in a different order. In version 1.0.7, the
members of the png_info structure reverted to the old order, as they were
in versions 0.97c through 1.0.5. Starting with version 2.0.0, both
structures are going to be hidden, and the contents of the structures will
only be accessible through the png_get/png_set functions.
The png.h header file is an invaluable reference for programming with libpng.
And while I'm on the topic, make sure you include the libpng header file:
#include <png.h>
III. Reading
We'll now walk you through the possible functions to call when reading
in a PNG file sequentially, briefly explaining the syntax and purpose
of each one. See example.c and png.h for more detail. While
progressive reading is covered in the next section, you will still
need some of the functions discussed in this section to read a PNG
file.
Setup
You will want to do the I/O initialization(*) before you get into libpng,
so if it doesn't work, you don't have much to undo. Of course, you
will also want to insure that you are, in fact, dealing with a PNG
file. Libpng provides a simple check to see if a file is a PNG file.
To use it, pass in the first 1 to 8 bytes of the file to the function
png_sig_cmp(), and it will return 0 (false) if the bytes match the
corresponding bytes of the PNG signature, or nonzero (true) otherwise.
Of course, the more bytes you pass in, the greater the accuracy of the
prediction.
If you are intending to keep the file pointer open for use in libpng,
you must ensure you don't read more than 8 bytes from the beginning
of the file, and you also have to make a call to png_set_sig_bytes_read()
with the number of bytes you read from the beginning. Libpng will
then only check the bytes (if any) that your program didn't read.
(*): If you are not using the standard I/O functions, you will need
to replace them with custom functions. See the discussion under
Customizing libpng.
FILE *fp = fopen(file_name, "rb");
if (!fp)
{
return (ERROR);
}
fread(header, 1, number, fp);
is_png = !png_sig_cmp(header, 0, number);
if (!is_png)
{
return (NOT_PNG);
}
Next, png_struct and png_info need to be allocated and initialized. In
order to ensure that the size of these structures is correct even with a
dynamically linked libpng, there are functions to initialize and
allocate the structures. We also pass the library version, optional
pointers to error handling functions, and a pointer to a data struct for
use by the error functions, if necessary (the pointer and functions can
be NULL if the defa
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将 BLP 图像文件转换为 PNG 或 TGA 格式的命令行工具。BLP 暴雪游戏使用图像。 支持以下 BLP 格式: * BLP1: - JPEG - 未压缩无 Alpha 通道 - 使用 Alpha 通道(8 位)未压缩 * BLP2: - 未压缩无 Alpha 通道 - 使用 Alpha 通道(1、4 和 8 位)未压缩 - 未压缩的原始 BGRA(称为 RAW3) - 没有 Alpha 通道的 DXT1 - 带 Alpha 通道的 DXT1(1 位) - 带 Alpha 通道的 DXT3(4 位和 8 位) - 带 Alpha 通道的 DXT5(8 位) 适用于 MacOS X 和 Linux。
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将 BLP图像文件转换为 PNG 或 TGA 的命令行工具_C++_代码_下载 (578个子文件)
Authors 986B
libmng_pixels.c 800KB
libmng_chunk_io.c 340KB
libmng_display.c 269KB
libmng_chunk_xs.c 252KB
libmng_object_prc.c 226KB
libmng_chunk_descr.c 193KB
jidctint.c 178KB
jfdctint.c 155KB
pngrtran.c 144KB
libmng_chunk_prc.c 121KB
libmng_hlapi.c 108KB
tif_fax3sm.c 102KB
pngrutil.c 93KB
pngwutil.c 83KB
libmng_trace.c 82KB
libmng_prop_xs.c 81KB
tif_ojpeg.c 73KB
j2k.c 70KB
tif_getimage.c 67KB
deflate.c 63KB
tif_jpeg.c 60KB
libmng_read.c 59KB
tif_dirread.c 58KB
transupp.c 54KB
tcd.c 53KB
pngwrite.c 49KB
jchuff.c 49KB
inflate.c 48KB
jquant2.c 47KB
pngpread.c 46KB
pngread.c 46KB
tif_fax3.c 44KB
libmng_jpeg.c 43KB
trees.c 43KB
jdhuff.c 41KB
tif_luv.c 41KB
jdmarker.c 40KB
jmemmgr.c 40KB
tif_dir.c 39KB
tif_dirwrite.c 38KB
libmng_callback_xs.c 37KB
tif_pixarlog.c 37KB
pngset.c 35KB
tif_dirinfo.c 33KB
png.c 31KB
jquant1.c 31KB
gzio.c 30KB
tif_lzw.c 30KB
libmng_cms.c 30KB
pi.c 29KB
t1.c 29KB
jcarith.c 27KB
jcmaster.c 27KB
libmng_filter.c 25KB
jdcoefct.c 25KB
jdmaster.c 25KB
pngget.c 24KB
jdarith.c 23KB
dwt.c 23KB
t2.c 23KB
tif_write.c 22KB
infback.c 22KB
libmng_zlib.c 22KB
jcparam.c 21KB
tif_read.c 21KB
pngtrans.c 21KB
jdmainct.c 20KB
jcsample.c 19KB
jp2.c 19KB
tif_predict.c 19KB
tif_print.c 18KB
pngmem.c 17KB
jcmarker.c 17KB
pngwtran.c 17KB
libmng_error.c 16KB
tif_open.c 16KB
jccoefct.c 16KB
jcdctmgr.c 15KB
jccolor.c 15KB
jdmerge.c 14KB
mqc.c 14KB
jctrans.c 13KB
inftrees.c 13KB
jdinput.c 13KB
crc32.c 13KB
jidctfst.c 13KB
jdcolor.c 13KB
jdapimin.c 12KB
inffast.c 12KB
jddctmgr.c 12KB
jcprepct.c 12KB
jdsample.c 12KB
pngerror.c 11KB
tif_zip.c 11KB
tif_strip.c 10KB
jdpostct.c 9KB
openjpeg.c 9KB
jdapistd.c 9KB
jcmainct.c 9KB
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