7f76377bad
- Updates libpng to 1.6.37 (from 1.6.23) Note: Seems svn can't merge it automatic when a folder was removed and readded with same name. Easier to update libs by deleting all files - copying new ones over and then check svn stat for differences and resolve them manually. git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6171 dfc29bdd-3216-0410-991c-e03cc46cb475
184 lines
9.4 KiB
Plaintext
184 lines
9.4 KiB
Plaintext
README for libpng version 1.6.37 - April 14, 2019
|
|
=================================================
|
|
|
|
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 the 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 did not make current programs
|
|
that access the info struct directly incompatible with the new
|
|
library, through libpng-1.2.x. In libpng-1.4.x, which was meant to
|
|
be a transitional release, members of the png_struct and the
|
|
info_struct can still be accessed, but the compiler will issue a
|
|
warning about deprecated usage. Since libpng-1.5.0, direct access
|
|
to these structs is not allowed, and the definitions of the structs
|
|
reside in private pngstruct.h and pnginfo.h header files that are not
|
|
accessible to applications. 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.
|
|
|
|
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 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
|
|
https://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/pngdocs.html .
|
|
|
|
This code is currently being archived at libpng.sourceforge.io in the
|
|
[DOWNLOAD] area, and at http://libpng.download/src .
|
|
|
|
This release, based in a large way on Glenn's, Guy's and Andreas'
|
|
earlier work, was created and will be supported by myself 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).
|
|
|
|
Send general questions about the PNG specification to png-mng-misc
|
|
at lists.sourceforge.net (subscription required; visit
|
|
https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
|
|
subscribe).
|
|
|
|
Files in this distribution:
|
|
|
|
ANNOUNCE => Announcement of this version, with recent changes
|
|
AUTHORS => List of contributing authors
|
|
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
|
|
TRADEMARK => Trademark information
|
|
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
|
|
powerpc => Contains optimized code for the PowerPC platform
|
|
contrib => Contributions
|
|
arm-neon => Optimized code for ARM-NEON platform
|
|
powerpc-vsx => Optimized code for POWERPC-VSX platform
|
|
examples => Example programs
|
|
gregbook => source code for PNG reading and writing, from
|
|
Greg Roelofs' "PNG: The Definitive Guide",
|
|
O'Reilly, 1999
|
|
libtests => Test programs
|
|
mips-msa => Optimized code for MIPS-MSA platform
|
|
pngminim => Minimal decoder, encoder, and progressive decoder
|
|
programs demonstrating use of pngusr.dfa
|
|
pngminus => Simple pnm2png and png2pnm programs
|
|
pngsuite => Test images
|
|
testpngs
|
|
tools => Various tools
|
|
visupng => Contains a MSVC workspace for VisualPng
|
|
intel => Optimized code for INTEL-SSE2 platform
|
|
mips => Optimized code for MIPS platform
|
|
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!
|
|
|
|
* Cosmin Truta (current maintainer, since 2018)
|
|
* Glenn Randers-Pehrson (former maintainer, 1998-2018)
|
|
* Andreas Eric Dilger (former maintainer, 1996-1997)
|
|
* Guy Eric Schalnat (original author and former maintainer, 1995-1996)
|
|
(formerly of Group 42, Inc.)
|