On Unix/Linux and similar systems, you can simply type

    ./configure [--prefix=/path]

    make check

    make install

and ignore the rest of this document.

If configure does not work on your system and you have a reasonably

up-to-date set of tools, running ./autogen.sh before running ./configure

may fix the problem.  You can also run the individual commands in

autogen.sh with the --force option, if supported by your version of

the tools.  If you run 'libtoolize --force', though, this will replace

the distributed, patched, version of ltmain.sh with an unpatched version

and your shared library builds may fail to produce libraries with the

correct version numbers.

Instead, you can use one of the custom-built makefiles in the

"scripts" directory

    cp scripts/makefile.system makefile

    make test

    make install

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.  zlib can be placed in another directory,

at the same level as libpng.

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

correspond to the version of zlib that's installed.

You can rename the directories that you downloaded (they

Your directory structure should look like this:

   ..       (the parent directory)

      libpng  (this directory)

          INSTALL (this file)

          README

          *.h

          *.c

          contrib

             gregbook

             pngminus

             pngsuite

             visupng

          projects

             visualc6 (msvc)

          scripts

             makefile.*

          pngtest.png

          etc.

      zlib

          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

endings) and zip (DOS style line endings) formats.

If you are building libpng with MSVC, you can enter the

then come back here and run "configure" or choose the appropriate

makefile.sys in the scripts directory.

Copy the file (or files) that you need from the

scripts directory into this directory, for example

   MSDOS example: copy scripts\makefile.msc makefile

   UNIX example:    cp scripts/makefile.std makefile

Read the makefile to see if you need to change any source or

target directories to match your preferences.

Then read pngconf.h to see if you want to make any configuration

changes.

Then just run "make" which will create the libpng library in

this directory and "make test" which will run a quick test that reads

the "pngtest.png" file and writes a "pngout.png" file that should be

identical to it.  Look for "9782 zero samples" in the output of the

test.  For more confidence, you can run another test by typing

"pngtest pngnow.png" and looking for "289 zero samples" in the output.

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".

If you encounter a compiler error message complaining about the

lines

      __png.h__ already includes setjmp.h;

      __dont__ include it again.;

which is hazardous because the two modules might not include exactly

the same setjmp.h.  If you are sure that you know what you are doing

and that they are exactly the same, then you can comment out or

delete the two lines.  Better yet, use the cexcept interface

instead, as demonstrated in contrib/visupng of the libpng distribution.

Further information can be found in the README and libpng.txt

files, in the individual makefiles, in png.h, and the manual pages

libpng.3 and png.5.