@ -16,9 +16,11 @@ VIII. Configuring libpng for 16-bit platforms
@@ -16,9 +16,11 @@ VIII. Configuring libpng for 16-bit platforms
XI. Prepending a prefix to exported symbols
XII. Configuring for compiler xxx:
XIII. Removing unwanted object code
XIV. Changes to the build and configuration of libpng in libpng-1.5.x
XV. Configuring libpng for multiprocessing
XVI. Other sources of information about libpng
XIV. Enabling or disabling hardware optimizations
XV. Changes to the build and configuration of libpng in libpng-1.5.x
XVI. Setjmp/longjmp issues
XVII. Common linking failures
XVIII. Other sources of information about libpng
I. Simple installation
@ -47,7 +49,9 @@ If configure does not work on your system, or if you have a need to
@@ -47,7 +49,9 @@ If configure does not work on your system, or if you have a need to
change configure.ac or Makefile.am, and you have a reasonably
up-to-date set of tools, running ./autogen.sh in a git clone before
running ./configure may fix the problem. To be really sure that you
aren't using any of the included pre-built scripts, you can do this:
aren't using any of the included pre-built scripts, especially if you
are building from a tar distribution instead of a git distribution,
do this:
./configure --enable-maintainer-mode
make maintainer-clean
@ -75,8 +79,8 @@ Or you can use one of the "projects" in the "projects" directory.
@@ -75,8 +79,8 @@ Or you can use one of the "projects" in the "projects" directory.
Before installing libpng, you must first install zlib, if it
is not already on your system. zlib can usually be found
wherever you got libpng; otherwise go to http://zlib.net. You can place
zlib in in the same directory as libpng or in another directory.
wherever you got libpng; otherwise go to https://zlib.net/. You can
place zlib in the same directory as libpng or in another directory.
If your system already has a preinstalled zlib you will still need
to have access to the zlib.h and zconf.h include files that
If you are using one of the makefile scripts, put ZLIBLIB and ZLIBINC
in your environment and type "make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test".
in your environment and type
make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test
IV. Using cmake
@ -160,9 +166,14 @@ VII. Building with makefiles
@@ -160,9 +166,14 @@ VII. Building with makefiles
Copy the file (or files) that you need from the
scripts directory into this directory, for example
MSDOS example: copy scripts\makefile.msc makefile
MSDOS example:
copy scripts\makefile.msc makefile
copy scripts\pnglibconf.h.prebuilt pnglibconf.h
UNIX example: cp scripts/makefile.std makefile
UNIX example:
cp scripts/makefile.std makefile
cp scripts/pnglibconf.h.prebuilt pnglibconf.h
Read the makefile to see if you need to change any source or
@ -189,7 +200,7 @@ run "make install".
@@ -189,7 +200,7 @@ run "make install".
VIII. Configuring libpng for 16-bit platforms
You will want to look into zconf.h to tell zlib (and thus libpng) that
it cannot allocate more then 64K at a time. Even if you can, the memory
it cannot allocate more than 64K at a time. Even if you can, the memory
won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K.
IX. Configuring for DOS
@ -239,7 +250,7 @@ libpng are compiled. All the defines end in _SUPPORTED. If you are
@@ -239,7 +250,7 @@ libpng are compiled. All the defines end in _SUPPORTED. If you are
never going to use a capability, you can change the #define to #undef
before recompiling libpng and save yourself code and data space, or
you can turn off individual capabilities with defines that begin with
PNG_NO_.
"PNG_NO_".
In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
@ -271,7 +282,57 @@ library to fail if they call functions not available in your library.
@@ -271,7 +282,57 @@ library to fail if they call functions not available in your library.
The size of the library itself should not be an issue, because only
those sections that are actually used will be loaded into memory.
XIV. Changes to the build and configuration of libpng in libpng-1.5.x
XIV. Enabling or disabling hardware optimizations
Certain hardware capabilities, such as the Intel SSE instructions,
are normally detected at run time. Enable them with configure options
such as one of
--enable-arm-neon=yes
--enable-mips-msa=yes
--enable-intel-sse=yes
--enable-powerpc-vsx=yes
or enable them all at once with
--enable-hardware-optimizations=yes
or, if you are not using "configure", you can use one
If you are using cmake, hardware optimizations are "on"
by default. To disable them, use
cmake . -DPNG_ARM_NEON=no -DPNG_INTEL_SSE=no \
-DPNG_MIPS_MSA=no -DPNG_POWERPC_VSX=no
or disable them all at once with
cmake . -DPNG_HARDWARE_OPTIMIZATIONS=no
XV. Changes to the build and configuration of libpng in libpng-1.5.x
Details of internal changes to the library code can be found in the CHANGES
file and in the GIT repository logs. These will be of no concern to the vast
@ -307,7 +368,7 @@ only png_longjmp_ptr, which must match the C longjmp function.) The new
@@ -307,7 +368,7 @@ only png_longjmp_ptr, which must match the C longjmp function.) The new
approach is documented in pngconf.h
Despite these changes, libpng 1.5.0 only supports the native C function
calling standard on those platforms tested so far (__cdecl on Microsoft
calling standard on those platforms tested so far ("__cdecl" on Microsoft
Windows). This is because the support requirements for alternative
calling conventions seem to no longer exist. Developers who find it
necessary to set PNG_API_RULE to 1 should advise the mailing list
@ -362,7 +423,7 @@ $PREFIX/include directory). Do not edit pnglibconf.h after you have built
@@ -362,7 +423,7 @@ $PREFIX/include directory). Do not edit pnglibconf.h after you have built
libpng, because than the settings would not accurately reflect the settings
that were used to build libpng.
XV. Configuring libpng for multiprocessing
XVI. Setjmp/longjmp issues
Libpng uses setjmp()/longjmp() for error handling. Unfortunately setjmp()
is known to be not thread-safe on some platforms and we don't know of
@ -375,28 +436,30 @@ configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
@@ -375,28 +436,30 @@ configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
in your pnglibconf.h or pngusr.h.
XVI. Other sources of information about libpng:
Starting with libpng-1.6.0, the library included a "simplified API".
This requires setjmp/longjmp, so you must either build the library
with PNG_SETJMP_SUPPORTED defined, or with PNG_SIMPLIFIED_READ_SUPPORTED
and PNG_SIMPLIFIED_WRITE_SUPPORTED undefined.
Further information can be found in the README and libpng-manual.txt
files, in the individual makefiles, in png.h, and the manual pages
libpng.3 and png.5.
XVII. Common linking failures
If your application fails to find libpng or zlib entries while linking:
Using the ./configure script -- 16 December 2002.
=================================================
Be sure "-lz" appears after "-lpng" on your linking command.
The ./configure script should work compatibly with what scripts/makefile.*
did, however there are some options you might need to add to configure
explicitly, which previously was done semi-automatically (if you didn't edit
scripts/makefile.* yourself, that is)
Be sure you have built libpng, zlib, and your application for the
libpng versions 1.0.7, July 1, 2000, through 1.2.5 - October 3, 2002, are
Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-1.0.6
with the following individuals added to the list of Contributing Authors
libpng versions 1.0.7, July 1, 2000, through 1.6.35, July 15, 2018 are
Copyright (c) 2000-2002, 2004, 2006-2018 Glenn Randers-Pehrson, are
derived from libpng-1.0.6, and are distributed according to the same
disclaimer and license as libpng-1.0.6 with the following individuals
added to the list of Contributing Authors:
Simon-Pierre Cadieux
Eric S. Raymond
Mans Rullgard
Cosmin Truta
Gilles Vollant
James Yu
Mandar Sahastrabuddhe
Google Inc.
Vadim Barkov
and with the following additions to the disclaimer:
There is no warranty against interference with your enjoyment of the
library or against infringement. There is no warranty that our
There is no warranty against interference with your enjoyment of
the library or against infringement. There is no warranty that our
efforts or the library will fulfill any of your particular purposes
or needs. This library is provided with all faults, and the entire
risk of satisfactory quality, performance, accuracy, and effort is with
the user.
risk of satisfactory quality, performance, accuracy, and effort is
with the user.
Some files in the "contrib" directory and some configure-generated
files that are distributed with libpng have other copyright owners, and
are released under other open source licenses.
libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
Copyright (c) 1998, 1999 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-0.96,
with the following individuals added to the list of Contributing Authors:
Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
libpng-0.96, and are distributed according to the same disclaimer and
license as libpng-0.96, with the following individuals added to the
list of Contributing Authors:
Tom Lane
Glenn Randers-Pehrson
Willem van Schaik
libpng versions 0.89, June 1996, through 0.96, May 1997, are
Copyright (c) 1996, 1997 Andreas Dilger
Distributed according to the same disclaimer and license as libpng-0.88,
with the following individuals added to the list of Contributing Authors:
Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
and are distributed according to the same disclaimer and license as
libpng-0.88, with the following individuals added to the list of
Contributing Authors:
John Bowler
Kevin Bracey
@ -56,8 +91,11 @@ with the following individuals added to the list of Contributing Authors:
@@ -56,8 +91,11 @@ with the following individuals added to the list of Contributing Authors:
Greg Roelofs
Tom Tanner
Some files in the "scripts" directory have other copyright owners,
but are released under this license.
libpng versions 0.5, May 1995, through 0.88, January 1996, are
Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
For the purposes of this copyright and license, "Contributing Authors"
is defined as the following set of individuals:
@ -68,13 +106,14 @@ is defined as the following set of individuals:
@@ -68,13 +106,14 @@ is defined as the following set of individuals:
Paul Schmidt
Tim Wegner
The PNG Reference Library is supplied "AS IS". The Contributing Authors
and Group 42, Inc. disclaim all warranties, expressed or implied,
including, without limitation, the warranties of merchantability and of
fitness for any purpose. The Contributing Authors and Group 42, Inc.
assume no liability for direct, indirect, incidental, special, exemplary,
or consequential damages, which may result from the use of the PNG
Reference Library, even if advised of the possibility of such damage.
The PNG Reference Library is supplied "AS IS". The Contributing
Authors and Group 42, Inc. disclaim all warranties, expressed or
implied, including, without limitation, the warranties of
merchantability and of fitness for any purpose. The Contributing
Authors and Group 42, Inc. assume no liability for direct, indirect,
incidental, special, exemplary, or consequential damages, which may
result from the use of the PNG Reference Library, even if advised of
the possibility of such damage.
Permission is hereby granted to use, copy, modify, and distribute this
source code, or portions hereof, for any purpose, without fee, subject
@ -88,24 +127,8 @@ to the following restrictions:
@@ -88,24 +127,8 @@ to the following restrictions:
3. This Copyright notice may not be removed or altered from any
source or altered source distribution.
The Contributing Authors and Group 42, Inc. specifically permit, without
fee, and encourage the use of this source code as a component to
supporting the PNG file format in commercial products. If you use this
source code in a product, acknowledgment is not required but would be
appreciated.
A "png_get_copyright" function is available, for convenient use in "about"
boxes and the like:
printf("%s",png_get_copyright(NULL));
Also, the PNG logo (in PNG format, of course) is supplied in the
files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a
certification mark of the Open Source Initiative.
Glenn Randers-Pehrson
glennrp at users.sourceforge.net
December 22, 2014
The Contributing Authors and Group 42, Inc. specifically permit,
without fee, and encourage the use of this source code as a component
to supporting the PNG file format in commercial products. If you use
this source code in a product, acknowledgment is not required but would
README for libpng version 1.6.16 - December 22, 2014 (shared library 16.0)
See the note about version numbers near the top of png.h
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.
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
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
@ -23,7 +24,7 @@ earlier versions if you are using a shared library. The type of the
@@ -23,7 +24,7 @@ earlier versions if you are using a shared library. The type of the
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,
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
@ -60,94 +61,59 @@ the library action on the detection of chunk CRC errors. It is possible
@@ -60,94 +61,59 @@ 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
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.
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.
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 zlib.net.
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/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.
I am not a lawyer, but I believe that the Export Control Classification
Number (ECCN) for libpng is EAR99, which means not subject to export
controls or International Traffic in Arms Regulations (ITAR) because it
is open source, publicly available software, that does not contain any
encryption software. See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
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
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
\fBAs of libpng version \fP\fI1.5.1\fP\fB, this section is no longer \fP\fImaintained\fP\fB, now that the private function prototypes are hidden in pngpriv.h and not accessible to applications. Look in pngpriv.h for the prototypes and a short description of each \fIfunction.
\fBAs of libpng version \fP\fI1.5.1\fP\fB, this section is no longer
\fP\fImaintained\fP\fB, now that the private function prototypes are hidden in
\fP\fIpngpriv.h\fP\fB and not accessible to applications. Look in
\fP\fIpngpriv.h\fP\fB for the prototypes and a short description of each
function.
.SHDESCRIPTION
The functions previously listed here are used privately by libpng and are not
available for use by applications. They are not "exported" to applications
/* Set the action on getting a CRC error for an ancillary or critical chunk. */
@ -49,6 +60,7 @@ png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
@@ -49,6 +60,7 @@ png_set_crc_action(png_structrp png_ptr, int crit_action, int ancil_action)
casePNG_CRC_WARN_DISCARD:/* Not a valid action for critical data */
png_warning(png_ptr,
"Can't discard critical data on CRC error");
/* FALLTHROUGH */
casePNG_CRC_ERROR_QUIT:/* Error/quit */
casePNG_CRC_DEFAULT:
@ -289,9 +301,12 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,
@@ -289,9 +301,12 @@ png_set_alpha_mode_fixed(png_structrp png_ptr, int mode,