1
README for libpng 1.0.8 - July 24, 2000 (shared library 2.1)
2
See the note about version numbers near the top of png.h
4
See INSTALL for instructions on how to install libpng.
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.
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
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
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.
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.
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
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.
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.
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
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.
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
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
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.
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.
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.
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.
108
png-implement@ccrc.wustl.edu
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.
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.
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.
130
Files in this distribution:
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
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",
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
msvc => Contains a Microsoft Visual C++ (MSVC) workspace
175
for building libpng and zlib
176
scripts => Directory containing scripts for building libpng:
177
descrip.mms => VMS makefile for MMS or MMK
178
makefile.std => Generic UNIX makefile (cc, creates static libpng.a)
179
makefile.linux => Linux/ELF makefile
180
(gcc, creates libpng.so.2.1.0.8)
181
makefile.gcmmx => Linux/ELF makefile (gcc, creates
182
libpng.so.2.1.0.8, uses assembler code
183
tuned for Intel MMX platform)
184
makefile.gcc => Generic makefile (gcc, creates static libpng.a)
185
makefile.knr => Archaic UNIX Makefile that converts files with
186
ansi2knr (Requires ansi2knr.c from
187
ftp://ftp.cs.wisc.edu/ghost)
188
makefile.dec => DEC Alpha UNIX makefile
189
makefile.hpux => HPUX (10.20 and 11.00) makefile
190
makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2 (static)
191
makefile.intel => Intel C/C++ version 4.0 and later
192
libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later
193
makefile.sgi => Silicon Graphics IRIX (cc, creates static lib)
194
makefile.sggcc => Silicon Graphics (gcc, creates libpng.so.2.1.0.8)
195
makefile.sunos => Sun makefile
196
makefile.solaris => Solaris 2.X makefile
197
(gcc, creates libpng.so.2.1.0.8)
198
makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc
199
makefile.mips => MIPS makefile
200
makefile.acorn => Acorn makefile
201
makefile.amiga => Amiga makefile
202
smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC
203
compiler (Requires SCOPTIONS, copied from
204
scripts/SCOPTIONS.ppc)
205
makefile.atari => Atari makefile
206
makefile.beos => BEOS makefile for X86
207
makefile.bor => Borland makefile (uses bcc)
208
makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode)
209
makefile.bd32 => To make a png32bd.dll with Borland C++ 4.5
210
makefile.tc3 => Turbo C 3.0 makefile
211
makefile.dj2 => DJGPP 2 makefile
212
makefile.msc => Microsoft C makefile
213
makefile.vcawin32 => makefile for Microsoft Visual C++ 5.0 and
214
later (uses assembler code tuned for Intel MMX
216
makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and
217
later (does not use assembler code)
218
makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def)
219
pngos2.def => OS/2 module definition file used by makefile.os2
220
makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model
221
makevms.com => VMS build script
222
pngdef.pas => Defines for a png32bd.dll with Borland C++ 4.5
223
SCOPTIONS.ppc => Used with smakefile.ppc
224
wince => Contains a Microsoft Visual C++ (Windows CD Toolkit)
225
workspace for building libpng and zlib on WindowsCE
227
Good luck, and happy coding.
229
-Glenn Randers-Pehrson
230
Internet: randeg@alum.rpi.edu
233
Internet: adilger@enel.ucalgary.ca
234
Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
237
(formerly of Group 42, Inc)
238
Internet: gschal@infinet.com
added
removed
gdchart0.94c/gd-1.8.3/libpng-1.0.8/README
