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1README for libpng version 1.2.8 - December 3, 2004 (shared library 12.0)
2See the note about version numbers near the top of png.h
3
4See INSTALL for instructions on how to install libpng.
5
6Libpng comes in several distribution formats. Get libpng-*.tar.gz
7or libpng-*.tar.bz2 if you want UNIX-style line endings in the text
8files, or lpng*.zip if you want DOS-style line endings.
9
10Version 0.89 was the first official release of libpng. Don't let the
11fact that it's the first release fool you. The libpng library has been in
12extensive use and testing since mid-1995. By late 1997 it had
13finally gotten to the stage where there hadn't been significant
14changes to the API in some time, and people have a bad feeling about
15libraries with versions < 1.0. Version 1.0.0 was released in
16March 1998.
17
18****
19Note that some of the changes to the png_info structure render this
20version of the library binary incompatible with libpng-0.89 or
21earlier versions if you are using a shared library. The type of the
22"filler" parameter for png_set_filler() has changed from png_byte to
23png_uint_32, which will affect shared-library applications that use
24this function.
25
26To avoid problems with changes to the internals of png_info_struct,
27new APIs have been made available in 0.95 to avoid direct application
28access to info_ptr. These functions are the png_set_<chunk> and
29png_get_<chunk> functions. These functions should be used when
30accessing/storing the info_struct data, rather than manipulating it
31directly, to avoid such problems in the future.
32
33It is important to note that the APIs do not make current programs
34that access the info struct directly incompatible with the new
35library. However, it is strongly suggested that new programs use
36the new APIs (as shown in example.c and pngtest.c), and older programs
37be converted to the new format, to facilitate upgrades in the future.
38****
39
40Additions since 0.90 include the ability to compile libpng as a
41Windows DLL, and new APIs for accessing data in the info struct.
42Experimental functions include the ability to set weighting and cost
43factors for row filter selection, direct reads of integers from buffers
44on big-endian processors that support misaligned data access, faster
45methods of doing alpha composition, and more accurate 16->8 bit color
46conversion.
47
48The additions since 0.89 include the ability to read from a PNG stream
49which has had some (or all) of the signature bytes read by the calling
50application. This also allows the reading of embedded PNG streams that
51do not have the PNG file signature. As well, it is now possible to set
52the library action on the detection of chunk CRC errors. It is possible
53to set different actions based on whether the CRC error occurred in a
54critical or an ancillary chunk.
55
56The changes made to the library, and bugs fixed are based on discussions
57on the PNG-implement mailing list
58and not on material submitted privately to Guy, Andreas, or Glenn. They will
59forward any good suggestions to the list.
60
61For a detailed description on using libpng, read libpng.txt. For
62examples of libpng in a program, see example.c and pngtest.c. For usage
63information and restrictions (what little they are) on libpng, see
64png.h. For a description on using zlib (the compression library used by
65libpng) and zlib's restrictions, see zlib.h
66
67I have included a general makefile, as well as several machine and
68compiler specific ones, but you may have to modify one for your own needs.
69
70You should use zlib 1.0.4 or later to run this, but it MAY work with
71versions as old as zlib 0.95. Even so, there are bugs in older zlib
72versions which can cause the output of invalid compression streams for
73some images. You will definitely need zlib 1.0.4 or later if you are
74taking advantage of the MS-DOS "far" structure allocation for the small
75and medium memory models. You should also note that zlib is a
76compression library that is useful for more things than just PNG files.
77You can use zlib as a drop-in replacement for fread() and fwrite() if
78you are so inclined.
79
80zlib should be available at the same place that libpng is, or at.
81ftp://ftp.info-zip.org/pub/infozip/zlib
82
83You may also want a copy of the PNG specification. It is available
84as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find
85these at http://www.libpng.org/pub/png/documents/
86
87This code is currently being archived at libpng.sf.net in the
88[DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT)
89at GO GRAPHSUP. If you can't find it in any of those places,
90e-mail me, and I'll help you find it.
91
92If you have any code changes, requests, problems, etc., please e-mail
93them to me. Also, I'd appreciate any make files or project files,
94and any modifications you needed to make to get libpng to compile,
95along with a #define variable to tell what compiler/system you are on.
96If you needed to add transformations to libpng, or wish libpng would
97provide the image in a different way, drop me a note (and code, if
98possible), so I can consider supporting the transformation.
99Finally, if you get any warning messages when compiling libpng
100(note: not zlib), and they are easy to fix, I'd appreciate the
101fix. Please mention "libpng" somewhere in the subject line. Thanks.
102
103This release was created and will be supported by myself (of course
104based in a large way on Guy's and Andreas' earlier work), and the PNG group.
105
106glennrp at users.sourceforge.net
107png-implement at ccrc.wustl.edu (subscription required; write to
108majordomo at ccrc.wustl.edu with "subscribe png-implement" in the message).
109
110You can't reach Guy, the original libpng author, at the addresses
111given in previous versions of this document. He and Andreas will read mail
112addressed to the png-implement list, however.
113
114Please do not send general questions about PNG. Send them to
115the (png-list at ccrc.wustl.edu, subscription required, write to
116majordomo at ccrc.wustl.edu with "subscribe png-list" in your message).
117On the other hand,
118please do not send libpng questions to that address, send them to me
119or to the png-implement list. I'll
120get them in the end anyway. If you have a question about something
121in the PNG specification that is related to using libpng, send it
122to me. Send me any questions that start with "I was using libpng,
123and ...". If in doubt, send questions to me. I'll bounce them
124to others, if necessary.
125
126Please do not send suggestions on how to change PNG. We have
127been discussing PNG for nine years now, and it is official and
128finished. If you have suggestions for libpng, however, I'll
129gladly listen. Even if your suggestion is not used immediately,
130it may be used later.
131
132Files in this distribution:
133
134 ANNOUNCE => Announcement of this version, with recent changes
135 CHANGES => Description of changes between libpng versions
136 KNOWNBUG => List of known bugs and deficiencies
137 LICENSE => License to use and redistribute libpng
138 README => This file
139 TODO => Things not implemented in the current library
140 Y2KINFO => Statement of Y2K compliance
141 example.c => Example code for using libpng functions
142 libpng.3 => manual page for libpng (includes libpng.txt)
143 libpng.txt => Description of libpng and its functions
144 libpngpf.3 => manual page for libpng's private functions
145 png.5 => manual page for the PNG format
146 png.c => Basic interface functions common to library
147 png.h => Library function and interface declarations
148 pngconf.h => System specific library configuration
149 pngasmrd.h => Header file for assembler-coded functions
150 pngerror.c => Error/warning message I/O functions
151 pngget.c => Functions for retrieving info from struct
152 pngmem.c => Memory handling functions
153 pngbar.png => PNG logo, 88x31
154 pngnow.png => PNG logo, 98x31
155 pngpread.c => Progressive reading functions
156 pngread.c => Read data/helper high-level functions
157 pngrio.c => Lowest-level data read I/O functions
158 pngrtran.c => Read data transformation functions
159 pngrutil.c => Read data utility functions
160 pngset.c => Functions for storing data into the info_struct
161 pngtest.c => Library test program
162 pngtest.png => Library test sample image
163 pngtrans.c => Common data transformation functions
164 pngwio.c => Lowest-level write I/O functions
165 pngwrite.c => High-level write functions
166 pngwtran.c => Write data transformations
167 pngwutil.c => Write utility functions
168 contrib => Contributions
169 gregbook => source code for PNG reading and writing, from
170 Greg Roelofs' "PNG: The Definitive Guide",
171 O'Reilly, 1999
172 msvctest => Builds and runs pngtest using a MSVC workspace
173 pngminus => Simple pnm2png and png2pnm programs
174 pngsuite => Test images
175 visupng => Contains a MSVC workspace for VisualPng
176 projects => Contains project files and workspaces for building DLL
177 beos => Contains a Beos workspace for building libpng
178 c5builder => Contains a Borland workspace for building libpng
179 and zlib
180 visualc6 => Contains a Microsoft Visual C++ (MSVC) workspace
181 for building libpng and zlib
182 netware.txt => Contains instructions for downloading a set of
183 project files for building libpng and zlib on
184 Netware.
185 wince.txt => Contains instructions for downloading a Microsoft
186 Visual C++ (Windows CD Toolkit) workspace for
187 building libpng and zlib on WindowsCE
188 scripts => Directory containing scripts for building libpng:
189 descrip.mms => VMS makefile for MMS or MMK
190 makefile.std => Generic UNIX makefile (cc, creates static libpng.a)
191 makefile.elf => Linux/ELF makefile symbol versioning,
192 gcc, creates libpng12.so.0.1.2.8)
193 makefile.linux => Linux/ELF makefile
194 (gcc, creates libpng12.so.0.1.2.8)
195 makefile.gcmmx => Linux/ELF makefile
196 (gcc, creates libpng12.so.0.1.2.8,
197 uses assembler code tuned for Intel MMX platform)
198 makefile.gcc => Generic makefile (gcc, creates static libpng.a)
199 makefile.knr => Archaic UNIX Makefile that converts files with
200 ansi2knr (Requires ansi2knr.c from
201 ftp://ftp.cs.wisc.edu/ghost)
202 makefile.aix => AIX makefile
203 makefile.cygwin => Cygwin/gcc makefile
204 makefile.darwin => Darwin makefile
205 makefile.dec => DEC Alpha UNIX makefile
206 makefile.freebsd => FreeBSD makefile
207 makefile.hpgcc => HPUX makefile using gcc
208 makefile.hpux => HPUX (10.20 and 11.00) makefile
209 makefile.hp64 => HPUX (10.20 and 11.00) makefile, 64 bit
210 makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2 (static)
211 makefile.intel => Intel C/C++ version 4.0 and later
212 libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later
213 makefile.netbsd => NetBSD/cc makefile, PNGGCCRD, makes libpng.so.
214 makefile.ne12bsd => NetBSD/cc makefile, PNGGCCRD, makes libpng12.so
215 makefile.openbsd => OpenBSD makefile
216 makefile.sgi => Silicon Graphics IRIX (cc, creates static lib)
217 makefile.sggcc => Silicon Graphics
218 (gcc, creates libpng12.so.0.1.2.8)
219 makefile.sunos => Sun makefile
220 makefile.solaris => Solaris 2.X makefile
221 (gcc, creates libpng12.so.0.1.2.8)
222 makefile.so9 => Solaris 9 makefile
223 (gcc, creates libpng12.so.0.1.2.8)
224 makefile.32sunu => Sun Ultra 32-bit makefile
225 makefile.64sunu => Sun Ultra 64-bit makefile
226 makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc
227 makefile.mips => MIPS makefile
228 makefile.acorn => Acorn makefile
229 makefile.amiga => Amiga makefile
230 smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC
231 compiler (Requires SCOPTIONS, copied from
232 scripts/SCOPTIONS.ppc)
233 makefile.atari => Atari makefile
234 makefile.beos => BEOS makefile for X86
235 makefile.bor => Borland makefile (uses bcc)
236 makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode)
237 makefile.tc3 => Turbo C 3.0 makefile
238 makefile.dj2 => DJGPP 2 makefile
239 makefile.msc => Microsoft C makefile
240 makefile.vcawin32=> makefile for Microsoft Visual C++ 5.0 and
241 later (uses assembler code tuned for Intel MMX
242 platform)
243 makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and
244 later (does not use assembler code)
245 makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def)
246 pngos2.def => OS/2 module definition file used by makefile.os2
247 makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model
248 makevms.com => VMS build script
249 SCOPTIONS.ppc => Used with smakefile.ppc
250
251Good luck, and happy coding.
252
253-Glenn Randers-Pehrson (current maintainer)
254 Internet: glennrp at users.sourceforge.net
255
256-Andreas Eric Dilger (former maintainer, 1996-1997)
257 Internet: adilger at enel.ucalgary.ca
258 Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
259
260-Guy Eric Schalnat (original author and former maintainer, 1995-1996)
261 (formerly of Group 42, Inc)
262 Internet: gschal at infinet.com
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