README for libpng version 1.2.40 - September 10, 2009 (shared library 12.0)+ −
See the note about version numbers near the top of png.h+ −
+ − See INSTALL for instructions on how to install libpng.+ −
+ − Libpng comes in several distribution formats. Get libpng-*.tar.gz,+ −
libpng-*.tar.lzma, or libpng-*.tar.bz2 if you want UNIX-style line+ −
endings in the text files, or lpng*.7z or lpng*.zip if you want DOS-style+ −
line endings. You can get UNIX-style line endings from the *.zip file+ −
by using "unzip -a" but there seems to be no simple way to recover+ −
UNIX-style line endings from the *.7z file. The *.tar.lzma file is+ −
recommended for *NIX users instead.+ −
+ − Version 0.89 was the first official release of libpng. Don't let the+ −
fact that it's the first release fool you. The libpng library has been in+ −
extensive use and testing since mid-1995. By late 1997 it had+ −
finally gotten to the stage where there hadn't been significant+ −
changes to the API in some time, and people have a bad feeling about+ −
libraries with versions < 1.0. Version 1.0.0 was released in+ −
March 1998.+ −
+ − ****+ −
Note that some of the changes to the png_info structure render this+ −
version of the library binary incompatible with libpng-0.89 or+ −
earlier versions if you are using a shared library. The type of the+ −
"filler" parameter for png_set_filler() has changed from png_byte to+ −
png_uint_32, which will affect shared-library applications that use+ −
this function.+ −
+ − To avoid problems with changes to the internals of png_info_struct,+ −
new APIs have been made available in 0.95 to avoid direct application+ −
access to info_ptr. These functions are the png_set_<chunk> and+ −
png_get_<chunk> functions. These functions should be used when+ −
accessing/storing the info_struct data, rather than manipulating it+ −
directly, to avoid such problems in the future.+ −
+ − It is important to note that the APIs do not make current programs+ −
that access the info struct directly incompatible with the new+ −
library. However, it is strongly suggested that new programs use+ −
the new APIs (as shown in example.c and pngtest.c), and older programs+ −
be converted to the new format, to facilitate upgrades in the future.+ −
****+ −
+ − Additions since 0.90 include the ability to compile libpng as a+ −
Windows DLL, and new APIs for accessing data in the info struct.+ −
Experimental functions include the ability to set weighting and cost+ −
factors for row filter selection, direct reads of integers from buffers+ −
on big-endian processors that support misaligned data access, faster+ −
methods of doing alpha composition, and more accurate 16->8 bit color+ −
conversion.+ −
+ − The additions since 0.89 include the ability to read from a PNG stream+ −
which has had some (or all) of the signature bytes read by the calling+ −
application. This also allows the reading of embedded PNG streams that+ −
do not have the PNG file signature. As well, it is now possible to set+ −
the library action on the detection of chunk CRC errors. It is possible+ −
to set different actions based on whether the CRC error occurred in a+ −
critical or an ancillary chunk.+ −
+ − The changes made to the library, and bugs fixed are based on discussions+ −
on the png-mng-implement mailing list+ −
and not on material submitted privately to Guy, Andreas, or Glenn. They will+ −
forward any good suggestions to the list.+ −
+ − For a detailed description on using libpng, read libpng.txt. For+ −
examples of libpng in a program, see example.c and pngtest.c. For usage+ −
information and restrictions (what little they are) on libpng, see+ −
png.h. For a description on using zlib (the compression library used by+ −
libpng) and zlib's restrictions, see zlib.h+ −
+ − I have included a general makefile, as well as several machine and+ −
compiler specific ones, but you may have to modify one for your own needs.+ −
+ − You should use zlib 1.0.4 or later to run this, but it MAY work with+ −
versions as old as zlib 0.95. Even so, there are bugs in older zlib+ −
versions which can cause the output of invalid compression streams for+ −
some images. You will definitely need zlib 1.0.4 or later if you are+ −
taking advantage of the MS-DOS "far" structure allocation for the small+ −
and medium memory models. You should also note that zlib is a+ −
compression library that is useful for more things than just PNG files.+ −
You can use zlib as a drop-in replacement for fread() and fwrite() if+ −
you are so inclined.+ −
+ − zlib should be available at the same place that libpng is, or at+ −
ftp://ftp.simplesystems.org/pub/png/src/+ −
+ − You may also want a copy of the PNG specification. It is available+ −
as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find+ −
these at http://www.libpng.org/pub/png/pngdocs.html+ −
+ − This code is currently being archived at libpng.sf.net in the+ −
[DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT)+ −
at GO GRAPHSUP. If you can't find it in any of those places,+ −
e-mail me, and I'll help you find it.+ −
+ − If you have any code changes, requests, problems, etc., please e-mail+ −
them to me. Also, I'd appreciate any make files or project files,+ −
and any modifications you needed to make to get libpng to compile,+ −
along with a #define variable to tell what compiler/system you are on.+ −
If you needed to add transformations to libpng, or wish libpng would+ −
provide the image in a different way, drop me a note (and code, if+ −
possible), so I can consider supporting the transformation.+ −
Finally, if you get any warning messages when compiling libpng+ −
(note: not zlib), and they are easy to fix, I'd appreciate the+ −
fix. Please mention "libpng" somewhere in the subject line. Thanks.+ −
+ − This release was created and will be supported by myself (of course+ −
based in a large way on Guy's and Andreas' earlier work), and the PNG group.+ −
+ − Send comments/corrections/commendations to png-mng-implement at lists.sf.net+ −
(subscription required; visit + −
https://lists.sourceforge.net/lists/listinfo/png-mng-implement+ −
to subscribe) or to glennrp at users.sourceforge.net+ −
+ − You can't reach Guy, the original libpng author, at the addresses+ −
given in previous versions of this document. He and Andreas will read mail+ −
addressed to the png-mng-implement list, however.+ −
+ − Please do not send general questions about PNG. Send them to+ −
the (png-mng-misc at lists.sourceforge.net, subscription required, visit+ −
https://lists.sourceforge.net/lists/listinfo/png-mng-implement to subscribe)+ −
On the other hand,+ −
please do not send libpng questions to that address, send them to me+ −
or to the png-mng-implement list. I'll+ −
get them in the end anyway. If you have a question about something+ −
in the PNG specification that is related to using libpng, send it+ −
to me. Send me any questions that start with "I was using libpng,+ −
and ...". If in doubt, send questions to me. I'll bounce them+ −
to others, if necessary.+ −
+ − Please do not send suggestions on how to change PNG. We have+ −
been discussing PNG for twelve years now, and it is official and+ −
finished. If you have suggestions for libpng, however, I'll+ −
gladly listen. Even if your suggestion is not used immediately,+ −
it may be used later.+ −
+ − Files in this distribution:+ −
+ − ANNOUNCE => Announcement of this version, with recent changes+ −
CHANGES => Description of changes between libpng versions+ −
KNOWNBUG => List of known bugs and deficiencies+ −
LICENSE => License to use and redistribute libpng+ −
README => This file+ −
TODO => Things not implemented in the current library+ −
Y2KINFO => Statement of Y2K compliance+ −
example.c => Example code for using libpng functions+ −
libpng-*-*-diff.txt => Diff from previous release+ −
libpng.3 => manual page for libpng (includes libpng.txt)+ −
libpng.txt => Description of libpng and its functions+ −
libpngpf.3 => manual page for libpng's private functions+ −
png.5 => manual page for the PNG format+ −
png.c => Basic interface functions common to library+ −
png.h => Library function and interface declarations+ −
pngconf.h => System specific library configuration+ −
pngerror.c => Error/warning message I/O functions+ −
pngget.c => Functions for retrieving info from struct+ −
pngmem.c => Memory handling functions+ −
pngbar.png => PNG logo, 88x31+ −
pngnow.png => PNG logo, 98x31+ −
pngpread.c => Progressive reading functions+ −
pngread.c => Read data/helper high-level functions+ −
pngrio.c => Lowest-level data read I/O functions+ −
pngrtran.c => Read data transformation functions+ −
pngrutil.c => Read data utility functions+ −
pngset.c => Functions for storing data into the info_struct+ −
pngtest.c => Library test program+ −
pngtest.png => Library test sample image+ −
pngtrans.c => Common data transformation functions+ −
pngwio.c => Lowest-level write I/O functions+ −
pngwrite.c => High-level write functions+ −
pngwtran.c => Write data transformations+ −
pngwutil.c => Write utility functions+ −
contrib => Contributions+ −
gregbook => source code for PNG reading and writing, from+ −
Greg Roelofs' "PNG: The Definitive Guide",+ −
O'Reilly, 1999+ −
msvctest => Builds and runs pngtest using a MSVC workspace+ −
pngminus => Simple pnm2png and png2pnm programs+ −
pngsuite => Test images+ −
visupng => Contains a MSVC workspace for VisualPng+ −
projects => Contains project files and workspaces for building DLL+ −
beos => Contains a Beos workspace for building libpng+ −
c5builder => Contains a Borland workspace for building libpng+ −
and zlib+ −
visualc6 => Contains a Microsoft Visual C++ (MSVC) workspace+ −
for building libpng and zlib+ −
netware.txt => Contains instructions for downloading a set of+ −
project files for building libpng and zlib on+ −
Netware.+ −
wince.txt => Contains instructions for downloading a Microsoft+ −
Visual C++ (Windows CD Toolkit) workspace for+ −
building libpng and zlib on WindowsCE+ −
scripts => Directory containing scripts for building libpng:+ −
descrip.mms => VMS makefile for MMS or MMK+ −
makefile.std => Generic UNIX makefile (cc, creates static libpng.a)+ −
makefile.elf => Linux/ELF makefile symbol versioning,+ −
gcc, creates libpng12.so.0.1.2.40)+ −
makefile.linux => Linux/ELF makefile+ −
(gcc, creates libpng12.so.0.1.2.40)+ −
makefile.gcmmx => Linux/ELF makefile+ −
(gcc, creates libpng12.so.0.1.2.40,+ −
uses assembler code tuned for Intel MMX platform)+ −
makefile.gcc => Generic makefile (gcc, creates static libpng.a)+ −
makefile.knr => Archaic UNIX Makefile that converts files with+ −
ansi2knr (Requires ansi2knr.c from+ −
ftp://ftp.cs.wisc.edu/ghost)+ −
makefile.aix => AIX makefile+ −
makefile.cygwin => Cygwin/gcc makefile+ −
makefile.darwin => Darwin makefile+ −
makefile.dec => DEC Alpha UNIX makefile+ −
makefile.freebsd => FreeBSD makefile+ −
makefile.hpgcc => HPUX makefile using gcc+ −
makefile.hpux => HPUX (10.20 and 11.00) makefile+ −
makefile.hp64 => HPUX (10.20 and 11.00) makefile, 64 bit+ −
makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2 (static)+ −
makefile.intel => Intel C/C++ version 4.0 and later+ −
libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later+ −
makefile.netbsd => NetBSD/cc makefile, PNGGCCRD, makes libpng.so.+ −
makefile.ne12bsd => NetBSD/cc makefile, PNGGCCRD, makes libpng12.so+ −
makefile.openbsd => OpenBSD makefile+ −
makefile.sgi => Silicon Graphics IRIX (cc, creates static lib)+ −
makefile.sggcc => Silicon Graphics+ −
(gcc, creates libpng12.so.0.1.2.40)+ −
makefile.sunos => Sun makefile+ −
makefile.solaris => Solaris 2.X makefile+ −
(gcc, creates libpng12.so.0.1.2.40)+ −
makefile.so9 => Solaris 9 makefile+ −
(gcc, creates libpng12.so.0.1.2.40)+ −
makefile.32sunu => Sun Ultra 32-bit makefile+ −
makefile.64sunu => Sun Ultra 64-bit makefile+ −
makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc+ −
makefile.mips => MIPS makefile+ −
makefile.acorn => Acorn makefile+ −
makefile.amiga => Amiga makefile+ −
smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC+ −
compiler (Requires SCOPTIONS, copied from+ −
scripts/SCOPTIONS.ppc)+ −
makefile.atari => Atari makefile+ −
makefile.beos => BEOS makefile for X86+ −
makefile.bor => Borland makefile (uses bcc)+ −
makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode)+ −
makefile.tc3 => Turbo C 3.0 makefile+ −
makefile.dj2 => DJGPP 2 makefile+ −
makefile.msc => Microsoft C makefile+ −
makefile.vcawin32=> makefile for Microsoft Visual C++ 5.0 and+ −
later (uses assembler code tuned for Intel MMX+ −
platform)+ −
makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and+ −
later (does not use assembler code)+ −
makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def)+ −
pngos2.def => OS/2 module definition file used by makefile.os2+ −
makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model+ −
makevms.com => VMS build script+ −
SCOPTIONS.ppc => Used with smakefile.ppc+ −
+ − Good luck, and happy coding.+ −
+ − -Glenn Randers-Pehrson (current maintainer)+ −
Internet: glennrp at users.sourceforge.net+ −
+ − -Andreas Eric Dilger (former maintainer, 1996-1997)+ −
Internet: adilger at enel.ucalgary.ca+ −
Web: http://members.shaw.ca/adilger/+ −
+ − -Guy Eric Schalnat (original author and former maintainer, 1995-1996)+ −
(formerly of Group 42, Inc)+ −
Internet: gschal at infinet.com+ −