libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.6.25 - September 1, 2016
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2016 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 1.6.25 - September 1, 2016
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2016 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
TABLE OF CONTENTS
I. Introduction
II. Structures
III. Reading
IV. Writing
V. Simplified API
VI. Modifying/Customizing libpng
VII. MNG support
VIII. Changes to Libpng from version 0.88
IX. Changes to Libpng from version 1.0.x to 1.2.x
X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
XI. Changes to Libpng from version 1.4.x to 1.5.x
XII. Changes to Libpng from version 1.5.x to 1.6.x
XIII. Detecting libpng
XIV. Source code repository
XV. Coding style
XVI. Y2K Compliance in libpng
I. Introduction
This file describes how to use and modify the PNG reference library
(known as libpng) for your own use. 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 configure and 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 15948:2004 (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://png-mng.sourceforge.net/pub/png/spec/1.2/>.
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://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.
Some additional chunks are described in the special-purpose public chunks
documents at <http://www.libpng.org/pub/png/spec/register/>
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://zlib.net/>.
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. Both are internal structures that are no longer exposed
in the libpng interface (as of libpng 1.5.0).
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, and direct access to the png_info fields was
deprecated..
The png_struct structure is the object used by the library to decode a
single image. As of 1.5.0 this structure is also not exposed.
Almost all libpng APIs require a pointer to a png_struct as the first argument.
Many (in particular the png_set and png_get APIs) also require a pointer
to png_info as the second argument. Some application visible macros
defined in png.h designed for basic data access (reading and writing
integers in the PNG format) don't take a png_info pointer, but it's almost
always safe to assume that a (png_struct*) has to be passed to call an API
function.
You can have more than one png_info structure associated with an image,
as illustrated in pngtest.c, one for information valid prior to the
IDAT chunks and another (called "end_info" below) for things after them.
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>
and also (as of libpng-1.5.0) the zlib header file, if you need it:
#include <zlib.h>
Types
The png.h header file defines a number of integral types used by the
APIs. Most of these are fairly obvious; for example types corresponding
to integers of particular sizes and types for passing color values.
One exception is how non-integral numbers are handled. For application
convenience most APIs that take such numbers have C (double) arguments;
however, internally PNG, and libpng, use 32 bit signed integers and encode
the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
which is simply (png_int_32).
All APIs that take (double) arguments also have a matching API that
takes the corresponding fixed point integer arguments. The fixed point
API has the same name as the floating point one with "_fixed" appended.
The actual range of values permitted in the APIs is frequently less than
the full range of (png_fixed_point) (-21474 to +21474). When APIs require
a non-negative argument the type is recorded as png_uint_32 above. Consult
the header file and the text below for more information.
Special care must be take with sCAL chunk handling because the chunk itself
uses non-integral values encoded as strings containing decimal floating point
numbers. See the comments in the header file.
Configuration
The main header file function declarations are frequently protected by C
preprocessing directives of the form:
#ifdef PNG_feature_SUPPORTED
declare-function
#endif
...
#ifdef PNG_feature_SUPPORTED
use-function
#endif
The library can be built without support for t
没有合适的资源?快使用搜索试试~ 我知道了~
Android-tess-two.zip
共2000个文件
c:577个
h:398个
cpp:304个
需积分: 13 0 下载量 115 浏览量
2019-09-17
12:07:27
上传
评论
收藏 17.45MB ZIP 举报
温馨提示
Android-tess-two.zip,android的fork of tesseract工具,安卓系统是谷歌在2008年设计和制造的。操作系统主要写在爪哇,C和C 的核心组件。它是在linux内核之上构建的,具有安全性优势。
资源推荐
资源详情
资源评论
收起资源包目录
Android-tess-two.zip (2000个子文件)
cjpeg.1 14KB
tesseract.1 11KB
jpegtran.1 10KB
djpeg.1 8KB
combine_tessdata.1 7KB
unicharset_extractor.1 3KB
shapeclustering.1 3KB
mftraining.1 3KB
wordlist2dawg.1 3KB
wrjpgcom.1 3KB
dawg2wordlist.1 2KB
cntraining.1 2KB
ambiguous_words.1 2KB
rdjpgcom.1 2KB
libpng.3 264KB
libpngpf.3 764B
makefile.32sunu 8KB
unicharset.5 7KB
unicharambigs.5 3KB
png.5 2KB
makefile.64sunu 8KB
pngstest-1.8 51B
pngstest-1.8-alpha 52B
configure.ac 17KB
configure.ac 16KB
configure.ac 12KB
configure.ac 5KB
makefile.acorn 2KB
makefile.aix 4KB
Makefile.am 13KB
Makefile.am 10KB
Makefile.am 5KB
Makefile.am 5KB
Makefile.am 4KB
Makefile.am 3KB
Makefile.am 3KB
Makefile.am 2KB
Makefile.am 2KB
Makefile.am 2KB
Makefile.am 2KB
Makefile.am 2KB
Makefile.am 2KB
Makefile.am 2KB
Makefile.am 2KB
Makefile.am 1KB
Makefile.am 827B
Makefile.am 794B
Makefile.am 668B
Makefile.am 562B
Makefile.am 483B
Makefile.am 360B
Makefile.am 266B
Makefile.am 232B
Makefile.am 219B
Makefile.am 218B
Makefile.am 166B
Makefile.am 86B
Makefile.am 67B
Makefile.am 56B
Makefile.am 21B
Makefile.am 17B
makefile.amiga 1KB
README.android 682B
ANNOUNCE 1KB
makefile.ansi 12KB
api_config 26B
ar-lib 6KB
tesseract.1.asc 9KB
unicharset.5.asc 5KB
combine_tessdata.1.asc 5KB
unicharambigs.5.asc 2KB
unicharset_extractor.1.asc 2KB
shapeclustering.1.asc 2KB
mftraining.1.asc 2KB
wordlist2dawg.1.asc 1KB
dawg2wordlist.1.asc 976B
ambiguous_words.1.asc 799B
cntraining.1.asc 776B
jmemdosa.asm 8KB
makefile.atari 2KB
AUTHORS 653B
autobuild 93B
options.awk 31KB
checksym.awk 6KB
dfn.awk 6KB
makefile.b32 14KB
boxa2.ba 18KB
boxa3.ba 18KB
boxa4.ba 2KB
boxa1.ba 2KB
showboxes2.baa 1KB
showboxes1.baa 888B
gradlew.bat 2KB
png2pnm.bat 2KB
pnm2png.bat 1KB
pngminus.bat 56B
batch 50B
bazaar 113B
makefile.bc32 4KB
makefile.bcc 14KB
共 2000 条
- 1
- 2
- 3
- 4
- 5
- 6
- 20
资源评论
weixin_38744153
- 粉丝: 346
- 资源: 2万+
上传资源 快速赚钱
- 我的内容管理 展开
- 我的资源 快来上传第一个资源
- 我的收益 登录查看自己的收益
- 我的积分 登录查看自己的积分
- 我的C币 登录后查看C币余额
- 我的收藏
- 我的下载
- 下载帮助
安全验证
文档复制为VIP权益,开通VIP直接复制
信息提交成功