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