Cross Reference: /external/libpng/

README for libpng version 1.6.10 - March 6, 2014 (shared library 16.0)
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 or
libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
or lpng*.7z or lpng*.zip if you want DOS-style line endings.

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-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-manual.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 zlib.net.

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/documents/

This code is currently being archived at libpng.sf.net in the
[DOWNLOAD] area, and at ftp://ftp.simplesystems.org.  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
development group.

Send comments/corrections/commendations to png-mng-implement at
lists.sourceforge.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-implement list, however.

Please do not send general questions about PNG.  Send them to
png-mng-misc at lists.sf.net (subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
subscribe).  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 nineteen 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.3      =>  manual page for libpng (includes libpng-manual.txt)
      libpng-manual.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 (public)
      pngpriv.h     =>  Library function and interface declarations (private)
      pngconf.h     =>  System specific library configuration (public)
      pngstruct.h   =>  png_struct declaration (private)
      pnginfo.h     =>  png_info struct declaration (private)
      pngdebug.h    =>  debugging macros (private)
      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
      arm           =>  Contains optimized code for the ARM platform
      contrib       =>  Contributions
       examples         =>  Example programs
       gregbook         =>  source code for PNG reading and writing, from
                            Greg Roelofs' "PNG: The Definitive Guide",
                            O'Reilly, 1999
       libtests         =>  Test programs
       pngminim         =>  Minimal decoder, encoder, and progressive decoder
                            programs demonstrating use of pngusr.dfa
       pngminus         =>  Simple pnm2png and png2pnm programs
       pngsuite         =>  Test images
       tools            =>  Various tools
       visupng      =>  Contains a MSVC workspace for VisualPng
      projects      =>  Contains project files and workspaces for
                        building a DLL
       owatcom          =>  Contains a WATCOM project for building libpng
       visualc71        =>  Contains a Microsoft Visual C++ (MSVC)
                            workspace for building libpng and zlib
       vstudio          =>  Contains a Microsoft Visual C++ (MSVC)
                            workspace for building libpng and zlib
      scripts       =>  Directory containing scripts for building libpng:
                            (see scripts/README.txt for the list of scripts)

Good luck, and happy coding.

-Glenn Randers-Pehrson (current maintainer, since 1998)
 Internet: glennrp at users.sourceforge.net

-Andreas Eric Dilger (former maintainer, 1996-1997)
 Internet: adilger at enel.ucalgary.ca
 Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/

-Guy Eric Schalnat (original author and former maintainer, 1995-1996)
 (formerly of Group 42, Inc)
 Internet: gschal at infinet.com
Name	Date	Size
..	12-Mar-2015	4 KiB
aclocal.m4	12-Mar-2015	43.5 KiB
Android.mk	12-Mar-2015	3.2 KiB
ANNOUNCE	12-Mar-2015	4.5 KiB
arm/	12-Mar-2015	4 KiB
autogen.sh	12-Mar-2015	7.8 KiB
CHANGES	12-Mar-2015	240.6 KiB
CleanSpec.mk	12-Mar-2015	2.2 KiB
CMakeLists.txt	12-Mar-2015	12.8 KiB
compile	12-Mar-2015	7.2 KiB
config.guess	12-Mar-2015	44.7 KiB
config.h.in	12-Mar-2015	3 KiB
config.sub	12-Mar-2015	34.8 KiB
configure	12-Mar-2015	447.2 KiB
configure.ac	12-Mar-2015	11.5 KiB
contrib/	12-Mar-2015	4 KiB
depcomp	12-Mar-2015	23 KiB
example.c	12-Mar-2015	39.3 KiB
INSTALL	12-Mar-2015	6 KiB
install-sh	12-Mar-2015	13.7 KiB
libpng-config.in	12-Mar-2015	2.3 KiB
libpng-manual.txt	12-Mar-2015	227.3 KiB
libpng.3	12-Mar-2015	273.4 KiB
libpng.pc.in	12-Mar-2015	293
libpngpf.3	12-Mar-2015	760
LICENSE	12-Mar-2015	4.1 KiB
ltmain.sh	12-Mar-2015	276.8 KiB
Makefile.am	12-Mar-2015	12.9 KiB
Makefile.in	12-Mar-2015	87 KiB
missing	12-Mar-2015	6.7 KiB
MODULE_LICENSE_BSD_LIKE	12-Mar-2015	0
NOTICE	12-Mar-2015	4.1 KiB
png.5	12-Mar-2015	2.4 KiB
png.c	12-Mar-2015	145.9 KiB
png.h	12-Mar-2015	142.5 KiB
pngbar.jpg	12-Mar-2015	2.4 KiB
pngbar.png	12-Mar-2015	2.3 KiB
pngconf.h	12-Mar-2015	22.8 KiB
pngdebug.h	12-Mar-2015	5.2 KiB
pngerror.c	12-Mar-2015	28.4 KiB
pngget.c	12-Mar-2015	32 KiB
pnginfo.h	12-Mar-2015	12.1 KiB
pnglibconf.h	12-Mar-2015	7.1 KiB
pngmem.c	12-Mar-2015	8.1 KiB
pngnow.png	12-Mar-2015	2 KiB
pngpread.c	12-Mar-2015	35.5 KiB
pngpriv.h	12-Mar-2015	79.7 KiB
pngread.c	12-Mar-2015	139.2 KiB
pngrio.c	12-Mar-2015	4.4 KiB
pngrtran.c	12-Mar-2015	163.8 KiB
pngrutil.c	12-Mar-2015	139.5 KiB
pngset.c	12-Mar-2015	45.6 KiB
pngstruct.h	12-Mar-2015	21.4 KiB
pngtest.c	12-Mar-2015	56.8 KiB
pngtest.png	12-Mar-2015	8.5 KiB
pngtrans.c	12-Mar-2015	24.4 KiB
pngusr.dfa	12-Mar-2015	502
pngusr.h	12-Mar-2015	153
pngwio.c	12-Mar-2015	5.5 KiB
pngwrite.c	12-Mar-2015	75.8 KiB
pngwtran.c	12-Mar-2015	14.9 KiB
pngwutil.c	12-Mar-2015	86.9 KiB
projects/	12-Mar-2015	4 KiB
README	12-Mar-2015	10.2 KiB
scripts/	12-Mar-2015	4 KiB
test-driver	12-Mar-2015	4.2 KiB
test-pngtest.sh	12-Mar-2015	43
tests/	12-Mar-2015	4 KiB
TODO	12-Mar-2015	1.2 KiB
updatenotes	12-Mar-2015	247