
VisualStudio instructions

libpng version 1.6.21 - January 15, 2016

Copyright (c) 2010,2013,2015 Glenn Randers-Pehrson

This code is released under the libpng license.
For conditions of distribution and use, see the disclaimer
and license in png.h

This directory  contains support for building libpng under MicroSoft
VisualStudio 2010.  It may also work under later versions of VisualStudio.
You should be familiar with VisualStudio before using this directory.

Initial preparations
====================
You must enter some information in zlib.props before attempting to build
with this 'solution'.  Please read and edit zlib.props first.  You will
probably not be familiar with the contents of zlib.props - do not worry,
it is mostly harmless.

This is all you need to do to build the 'release' and 'release library'
configurations.

Debugging
=========
The release configurations default to /Ox optimization.  Full debugging
information is produced (in the .pdb), but if you encounter a problem the
optimization may make it difficult to debug.  Simply rebuild with a lower
optimization level (e.g. /Od.)

Linking your application
========================
Normally you should link against the 'release' configuration.  This builds a
DLL for libpng with the default runtime options used by Visual Studio 2010.
In particular the runtime library is the "MultiThreaded DLL" version.
If you use Visual Studio defaults to build your application you will have no
problems.

If you don't use the Visual Studio defaults your application must still be
built with the default runtime option (/MD).  If, for some reason, it is not
then your application will crash inside libpng16.dll as soon as libpng
tries to read from a file handle you pass in.

If you do not want to use the DLL, for example for a very small application,
the 'release library' configuration may be more appropriate.  This is built
with a non-standard runtime library - the "MultiThreaded" version.  When you
build your application it must be compiled with this option (/MT), otherwise
it will not build (if you are lucky) or crash (if you are not.) See the
WARNING file that is distributed along with this readme.txt.

Stop reading here
=================
You have enough information to build a working application.

Debug versions have limited support
===================================
This solution includes limited support for debug versions of libpng.  You
do not need these unless your own solution itself uses debug builds (it is
far more effective to debug on the release builds, there is no point building
a special debug build unless you have heap corruption problems that you can't
track down.)

The debug build of libpng is minimally supported.  Support for debug builds of
zlib is also minimal.  You really don't want to do this.

WARNING
=======
Libpng 1.6.x does not use the default run-time library when building static
library builds of libpng; instead of the shared DLL runtime it uses a static
runtime.  If you need to change this make sure to change the setting on all the
relevant projects:

    libpng
    zlib
    all the test programs

The runtime library settings for each build are as follows:

               Release        Debug
    DLL         /MD            /MDd
    Library     /MT            /MTd

NOTICE that libpng 1.5.x erroneously used /MD for Debug DLL builds; if you used
the debug builds in your app and you changed your app to use /MD you will need
to change it back to /MDd for libpng 1.6.0 and later.

The Visual Studio 2010 defaults for a Win32 DLL or Static Library project are
as follows:

                     Release     Debug
    DLL               /MD         /MDd
    Static Library    /MD         /MDd

