README
*.h, *.c => libpng source files
CMakeLists.txt => "cmake" script
+ ci
+ ci_*.sh
configuration files:
configure.ac, configure, Makefile.am, Makefile.in,
autogen.sh, config.guess, ltmain.sh, missing, libpng.pc.in,
libpng-config.in, aclocal.m4, config.h.in, config.sub,
- depcomp, install-sh, mkinstalldirs, test-pngtest.sh
+ depcomp, install-sh, mkinstalldirs, test-pngtest.sh, etc.
contrib
arm-neon, conftest, examples, gregbook, libtests, pngminim,
pngminus, pngsuite, tools, visupng
projects
- cbuilder5, owatcom, visualc71, vstudio, xcode
+ owatcom, visualc71, vstudio
scripts
makefile.*
*.def (module definition files)
pngtest.png
etc.
zlib
- README, *.h, *.c contrib, etc.
+ README, *.h, *.c, contrib, etc.
If the line endings in the files look funny, you may wish to get the other
distribution of libpng. It is available in both tar.gz (UNIX style line
VI. Building with project files
-If you are building libpng with MSVC, you can enter the
-libpng projects\visualc71 or vstudio directory and follow the instructions
-in README.txt.
+If you are building libpng with Microsoft Visual Studio, you can enter
+the directory projects\visualc71 or projects\vstudio and follow the
+instructions in README.txt.
-Otherwise enter the zlib directory and follow the instructions in zlib/README,
-then come back here and run "configure" or choose the appropriate
-makefile.sys in the scripts directory.
+Otherwise, enter the zlib directory and follow the instructions in
+zlib/README, then come back here and run "configure" or choose the
+appropriate makefile in the scripts directory.
VII. Building with makefiles
Copy the file (or files) that you need from the
scripts directory into this directory, for example
-MSDOS example:
+UNIX example:
- copy scripts\makefile.msc makefile
- copy scripts\pnglibconf.h.prebuilt pnglibconf.h
+ cp scripts/makefile.std Makefile
+ make
-UNIX example:
+Windows example:
- cp scripts/makefile.std makefile
- cp scripts/pnglibconf.h.prebuilt pnglibconf.h
+ nmake -f scripts\makefile.vcwin32
Read the makefile to see if you need to change any source or
target directories to match your preferences.
Also, you can run "pngtest -m contrib/pngsuite/*.png" and compare
your output with the result shown in contrib/pngsuite/README.
-Most of the makefiles will allow you to run "make install" to
-put the library in its final resting place (if you want to
-do that, run "make install" in the zlib directory first if necessary).
-Some also allow you to run "make test-installed" after you have
-run "make install".
-
-VIII. Configuring libpng for 16-bit platforms
+Most of the makefiles used to allow you to run "make install" to put
+the library in its final resting place, but that feature is no longer
+supported. The only tested and supported manners to install libpng are
+the conventional build and install procedures driven by the configure
+script or by the CMake file.
-You will want to look into zconf.h to tell zlib (and thus libpng) that
-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.
+VIII. Configuring for DOS and other 16-bit platforms
-IX. Configuring for DOS
+Officially, the support for 16-bit platforms has been removed.
For DOS users who only have access to the lower 640K, you will
have to limit zlib's memory usage via a png_set_compression_mem_level()
call. See zlib.h or zconf.h in the zlib library for more information.
-X. Configuring for Medium Model
+You may be or may not be in luck if you target the "large" memory model,
+but all the smaller models ("small", "compact" and "medium") are known
+to be unworkable. For DOS users who have access beyond the lower 640K,
+a "flat" 32-bit DOS model (such as DJGPP) is strongly recommended.
-Libpng's support for medium model has been tested on most of the popular
-compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
-defined, and FAR gets defined to far in pngconf.h, and you should be
-all set. Everything in the library (except for zlib's structure) is
-expecting far data. You must use the typedefs with the p or pp on
-the end for pointers (or at least look at them and be careful). Make
-note that the rows of data are defined as png_bytepp, which is
-an "unsigned char far * far *".
+For DOS users who only have access to the lower 640K, you will have to
+limit zlib's memory usage via a png_set_compression_mem_level() call.
+You will also have to look into zconf.h to tell zlib (and thus libpng)
+that it cannot allocate more than 64K at a time. Even if you can, the
+memory won't be accessible. Therefore, you should limit zlib and libpng
+to 64K by defining MAXSEG_64K.
-XI. Prepending a prefix to exported symbols
+IX. Prepending a prefix to exported symbols
Starting with libpng-1.6.0, you can configure libpng (when using the
"configure" script) to prefix all exported symbols by means of the
transparent to applications; their function calls get transformed by
the macros to use the modified names.
-XII. Configuring for compiler xxx:
+X. Configuring for compiler xxx:
All includes for libpng are in pngconf.h. If you need to add, change
or delete an include, this is the place to do it.
files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
that previously appeared in the public headers.
-XIII. Removing unwanted object code
+XI. Removing unwanted object code
There are a bunch of #define's in pngconf.h that control what parts of
libpng are compiled. All the defines end in _SUPPORTED. If you are
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. Enabling or disabling hardware optimizations
+XII. 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
cmake . -DPNG_HARDWARE_OPTIMIZATIONS=no
-XV. Changes to the build and configuration of libpng in libpng-1.5.x
+XIII. 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
libpng, because than the settings would not accurately reflect the settings
that were used to build libpng.
-XVI. Setjmp/longjmp issues
+XIV. 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
with PNG_SETJMP_SUPPORTED defined, or with PNG_SIMPLIFIED_READ_SUPPORTED
and PNG_SIMPLIFIED_WRITE_SUPPORTED undefined.
-XVII. Common linking failures
+XV. Common linking failures
If your application fails to find libpng or zlib entries while linking:
If you are using the vstudio project, observe the WARNING in
project/vstudio/README.txt.
-XVIII. Other sources of information about libpng:
+XVI. Other sources of information about libpng:
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.
+Copyright (c) 2022 Cosmin Truta
Copyright (c) 1998-2002,2006-2016 Glenn Randers-Pehrson
This document is released under the libpng license.
For conditions of distribution and use, see the disclaimer
projects / platform / upstream / libpng.git / blobdiff