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1 README for libpng 1.2.5rc3 - September 18, 2002 (shared library 12.0)
2 See the note about version numbers near the top of png.h
3
4 See INSTALL for instructions on how to install libpng.
5
6 Libpng comes in two distribution formats. Get libpng-*.tar.gz if you
7 want UNIX-style line endings in the text files, or lpng*.zip if you want
8 DOS-style line endings.
9
10 Version 0.89 was the first official release of libpng. Don't let the
11 fact that it's the first release fool you. The libpng library has been in
12 extensive use and testing since mid-1995. By late 1997 it had
13 finally gotten to the stage where there hadn't been significant
14 changes to the API in some time, and people have a bad feeling about
15 libraries with versions < 1.0. Version 1.0.0 was released in
16 March 1998.
17
18 ****
19 Note that some of the changes to the png_info structure render this
20 version of the library binary incompatible with libpng-0.89 or
21 earlier 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
23 png_uint_32, which will affect shared-library applications that use
24 this function.
25
26 To avoid problems with changes to the internals of png_info_struct,
27 new APIs have been made available in 0.95 to avoid direct application
28 access to info_ptr. These functions are the png_set_<chunk> and
29 png_get_<chunk> functions. These functions should be used when
30 accessing/storing the info_struct data, rather than manipulating it
31 directly, to avoid such problems in the future.
32
33 It is important to note that the APIs do not make current programs
34 that access the info struct directly incompatible with the new
35 library. However, it is strongly suggested that new programs use
36 the new APIs (as shown in example.c and pngtest.c), and older programs
37 be converted to the new format, to facilitate upgrades in the future.
38 ****
39
40 Additions since 0.90 include the ability to compile libpng as a
41 Windows DLL, and new APIs for accessing data in the info struct.
42 Experimental functions include the ability to set weighting and cost
43 factors for row filter selection, direct reads of integers from buffers
44 on big-endian processors that support misaligned data access, faster
45 methods of doing alpha composition, and more accurate 16->8 bit color
46 conversion.
47
48 The additions since 0.89 include the ability to read from a PNG stream
49 which has had some (or all) of the signature bytes read by the calling
50 application. This also allows the reading of embedded PNG streams that
51 do not have the PNG file signature. As well, it is now possible to set
52 the library action on the detection of chunk CRC errors. It is possible
53 to set different actions based on whether the CRC error occurred in a
54 critical or an ancillary chunk.
55
56 The changes made to the library, and bugs fixed are based on discussions
57 on the PNG implementation mailing list <png-implement@ccrc.wustl.edu>
58 and not on material submitted privately to Guy, Andreas, or Glenn. They will
59 forward any good suggestions to the list.
60
61 For a detailed description on using libpng, read libpng.txt. For
62 examples of libpng in a program, see example.c and pngtest.c. For usage
63 information and restrictions (what little they are) on libpng, see
64 png.h. For a description on using zlib (the compression library used by
65 libpng) and zlib's restrictions, see zlib.h
66
67 I have included a general makefile, as well as several machine and
68 compiler specific ones, but you may have to modify one for your own needs.
69
70 You should use zlib 1.0.4 or later to run this, but it MAY work with
71 versions as old as zlib 0.95. Even so, there are bugs in older zlib
72 versions which can cause the output of invalid compression streams for
73 some images. You will definitely need zlib 1.0.4 or later if you are
74 taking advantage of the MS-DOS "far" structure allocation for the small
75 and medium memory models. You should also note that zlib is a
76 compression library that is useful for more things than just PNG files.
77 You can use zlib as a drop-in replacement for fread() and fwrite() if
78 you are so inclined.
79
80 zlib should be available at the same place that libpng is.
81 If not, it should be at ftp.uu.net in /graphics/png
82 Eventually, it will be at ftp.uu.net in /pub/archiving/zip/zlib
83
84 You may also want a copy of the PNG specification. It is available
85 as an RFC and a W3C Recommendation. Failing
86 these resources you can try ftp.uu.net in the /graphics/png directory.
87
88 This code is currently being archived at ftp.uu.net in the
89 /graphics/png directory, and on CompuServe, Lib 20 (PNG SUPPORT)
90 at GO GRAPHSUP. If you can't find it in any of those places,
91 e-mail me, and I'll help you find it.
92
93 If you have any code changes, requests, problems, etc., please e-mail
94 them to me. Also, I'd appreciate any make files or project files,
95 and any modifications you needed to make to get libpng to compile,
96 along with a #define variable to tell what compiler/system you are on.
97 If you needed to add transformations to libpng, or wish libpng would
98 provide the image in a different way, drop me a note (and code, if
99 possible), so I can consider supporting the transformation.
100 Finally, if you get any warning messages when compiling libpng
101 (note: not zlib), and they are easy to fix, I'd appreciate the
102 fix. Please mention "libpng" somewhere in the subject line. Thanks.
103
104 This release was created and will be supported by myself (of course
105 based in a large way on Guy's and Andreas' earlier work), and the PNG group.
106
107 randeg@alum.rpi.edu
108 png-implement@ccrc.wustl.edu
109
110 You can't reach Guy, the original libpng author, at the addresses
111 given in previous versions of this document. He and Andreas will read mail
112 addressed to the png-implement list, however.
113
114 Please do not send general questions about PNG. Send them to
115 the address in the specification (png-group@w3.org). At the same
116 time, please do not send libpng questions to that address, send them to me
117 or to png-implement@ccrc.wustl.edu. I'll
118 get them in the end anyway. If you have a question about something
119 in the PNG specification that is related to using libpng, send it
120 to me. Send me any questions that start with "I was using libpng,
121 and ...". If in doubt, send questions to me. I'll bounce them
122 to others, if necessary.
123
124 Please do not send suggestions on how to change PNG. We have
125 been discussing PNG for three years now, and it is official and
126 finished. If you have suggestions for libpng, however, I'll
127 gladly listen. Even if your suggestion is not used for version
128 1.0, it may be used later.
129
130 Files in this distribution:
131
132 ANNOUNCE => Announcement of this version, with recent changes
133 CHANGES => Description of changes between libpng versions
134 KNOWNBUG => List of known bugs and deficiencies
135 LICENSE => License to use and redistribute libpng
136 README => This file
137 TODO => Things not implemented in the current library
138 Y2KINFO => Statement of Y2K compliance
139 example.c => Example code for using libpng functions
140 libpng.3 => manual page for libpng (includes libpng.txt)
141 libpng.txt => Description of libpng and its functions
142 libpngpf.3 => manual page for libpng's private functions
143 png.5 => manual page for the PNG format
144 png.c => Basic interface functions common to library
145 png.h => Library function and interface declarations
146 pngconf.h => System specific library configuration
147 pngasmrd.h => Header file for assembler-coded functions
148 pngerror.c => Error/warning message I/O functions
149 pngget.c => Functions for retrieving info from struct
150 pngmem.c => Memory handling functions
151 pngbar.png => PNG logo, 88x31
152 pngnow.png => PNG logo, 98x31
153 pngpread.c => Progressive reading functions
154 pngread.c => Read data/helper high-level functions
155 pngrio.c => Lowest-level data read I/O functions
156 pngrtran.c => Read data transformation functions
157 pngrutil.c => Read data utility functions
158 pngset.c => Functions for storing data into the info_struct
159 pngtest.c => Library test program
160 pngtest.png => Library test sample image
161 pngtrans.c => Common data transformation functions
162 pngwio.c => Lowest-level write I/O functions
163 pngwrite.c => High-level write functions
164 pngwtran.c => Write data transformations
165 pngwutil.c => Write utility functions
166 contrib => Contributions
167 gregbook => source code for PNG reading and writing, from
168 Greg Roelofs' "PNG: The Definitive Guide",
169 O'Reilly, 1999
170 msvctest => Builds and runs pngtest using a MSVC workspace
171 pngminus => Simple pnm2png and png2pnm programs
172 pngsuite => Test images
173 visupng => Contains a MSVC workspace for VisualPng
174 projects => Contains project files and workspaces for building DLL
175 beos => Contains a Beos workspace for building libpng
176 borland => Contains a Borland workspace for building libpng
177 and zlib
178 msvc => Contains a Microsoft Visual C++ (MSVC) workspace
179 for building libpng and zlib
180 netware.txt => Contains instructions for downloading a set of
181 project files for building libpng and zlib on
182 Netware.
183 wince.txt => Contains instructions for downloading a Microsoft
184 Visual C++ (Windows CD Toolkit) workspace for
185 building libpng and zlib on WindowsCE
186 scripts => Directory containing scripts for building libpng:
187 descrip.mms => VMS makefile for MMS or MMK
188 makefile.std => Generic UNIX makefile (cc, creates static libpng.a)
189 makefile.linux => Linux/ELF makefile
190 (gcc, creates libpng12.so.0.1.2.5rc3)
191 makefile.gcmmx => Linux/ELF makefile (gcc, creates
192 libpng12.so.0.1.2.5rc3, uses assembler code
193 tuned for Intel MMX platform)
194 makefile.gcc => Generic makefile (gcc, creates static libpng.a)
195 makefile.knr => Archaic UNIX Makefile that converts files with
196 ansi2knr (Requires ansi2knr.c from
197 ftp://ftp.cs.wisc.edu/ghost)
198 makefile.aix => AIX makefile
199 makefile.cygwin => Cygwin/gcc makefile
200 makefile.darwin => Darwin makefile
201 makefile.dec => DEC Alpha UNIX makefile
202 makefile.freebsd => FreeBSD makefile
203 makefile.hpgcc => HPUX makefile using gcc
204 makefile.hpux => HPUX (10.20 and 11.00) makefile
205 makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2 (static)
206 makefile.intel => Intel C/C++ version 4.0 and later
207 libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later
208 makefile.macosx => MACOS X Makefile
209 makefile.netbsd => NetBSD/cc makefile, PNGGCCRD, makes libpng.so.
210 makefile.ne0bsd => NetBSD/cc makefile, PNGGCCRD, makes libpng0.so
211 makefile.openbsd => OpenBSD makefile
212 makefile.sgi => Silicon Graphics IRIX (cc, creates static lib)
213 makefile.sggcc => Silicon Graphics (gcc, creates libpng12.so.0.1.2.5rc3)
214 makefile.sunos => Sun makefile
215 makefile.solaris => Solaris 2.X makefile
216 (gcc, creates libpng12.so.0.1.2.5rc3)
217 makefile.so9 => Solaris 9 makefile
218 (gcc, creates libpng12.so.0.1.2.5rc3)
219 makefile.32sunu => Sun Ultra 32-bit makefile
220 makefile.64sunu => Sun Ultra 64-bit makefile
221 makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc
222 makefile.mips => MIPS makefile
223 makefile.acorn => Acorn makefile
224 makefile.amiga => Amiga makefile
225 smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC
226 compiler (Requires SCOPTIONS, copied from
227 scripts/SCOPTIONS.ppc)
228 makefile.atari => Atari makefile
229 makefile.beos => BEOS makefile for X86
230 makefile.bor => Borland makefile (uses bcc)
231 makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode)
232 makefile.bd32 => To make a png32bd.dll with Borland C++ 4.5
233 makefile.tc3 => Turbo C 3.0 makefile
234 makefile.dj2 => DJGPP 2 makefile
235 makefile.msc => Microsoft C makefile
236 makefile.vcawin32 => makefile for Microsoft Visual C++ 5.0 and
237 later (uses assembler code tuned for Intel MMX
238 platform)
239 makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and
240 later (does not use assembler code)
241 makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def)
242 pngos2.def => OS/2 module definition file used by makefile.os2
243 makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model
244 makevms.com => VMS build script
245 pngdef.pas => Defines for a png32bd.dll with Borland C++ 4.5
246 SCOPTIONS.ppc => Used with smakefile.ppc
247 mangle => Directory containing scripts to build libpng12m.so:
248 mangle.in => Function-decoration macros added to png.h by the
249 makefiles.
250 makefile.linux => Linux/ELF makefile
251 (gcc, creates libpng12m.so.0.1.2.5rc3)
252 makefile.gcmmx => Linux/ELF makefile (gcc, creates
253 libpng12.so.0m.1.2.5rc3, uses assembler code
254 tuned for Intel MMX platform)
255 makefile.sgi => Silicon Graphics (cc, creates libpng12m.so)
256 makefile.sggcc => Silicon Graphics (gcc, creates libpng12m.so)
257
258 Good luck, and happy coding.
259
260 -Glenn Randers-Pehrson
261 Internet: randeg@alum.rpi.edu
262
263 -Andreas Eric Dilger
264 Internet: adilger@enel.ucalgary.ca
265 Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
266
267 -Guy Eric Schalnat
268 (formerly of Group 42, Inc)
269 Internet: gschal@infinet.com