TweakPNG:  A low-level PNG image file manipulation utility
Version 1.2.1
Copyright (c) 1999-2004 Jason Summers  <jason1@pobox.com>

==================== License ====================

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA


A copy of the GNU General Public License is included in the file 
COPYING.txt.


========================================================


The following files should be included in the source distribution:

chunk.cpp
COPYING.txt
drag1.cur
drag2.cur
icon_1.ico
readme.txt    (this file)
resource.h
tweakpng.cpp
tweakpng.dsp  (VC6 project file)
tweakpng.dsw  (VC6 workspace file)
tweakpng.h
tweakpng.rc
viewer.cpp


To get the latest version of TweakPNG, visit the TweakPNG home page at 
<http://pobox.com/~jason1/tweakpng/>.

The source code should be compatible with Microsoft Visual C++ version 5 
and higher. It might also work in other modern C++ packages.

Basically, to compile TweakPNG, you need to include the following files in 
your project:

tweakpng.cpp
chunk.cpp
viewer.cpp
tweakpng.rc
tweakpng.h
icon_1.ico
drag1.cur
drag2.cur

Make sure you include the following potentially nondefault libraries:

comdlg32.lib
comctl32.lib


There are three configurations available:


1. With image viewing support

All features will be available. Requires pngdib (v3.0.0 or higher), libpng 
(version 1.2.2 or higher recommended), and zlib (version 1.1.4 or higher 
recommended).

This is the default configuration.

 pngdib: <http://pobox.com/~jason1/pngdib/>
 libpng: <http://www.libpng.org/pub/png/>
 zlib: <http://www.info-zip.org/pub/infozip/zlib/>

2. With compression support (but no image viewing support)

Requires zlib, but not libpng. The image viewer tool will be unavailable. 
You will be able to edit compressed text chunks.

- comment out the 
#define TWPNG_SUPPORT_VIEWER
line in tweakpng.h


3. With no image viewing or compression support

Does not require any third-party libraries. The image viewer will be 
unavailable, and you won't be able to view or edit compressed text chunks.

- comment out the 
#define TWPNG_SUPPORT_VIEWER
#define TWPNG_USE_ZLIB
lines in tweakpng.h



NOTE

The source code is not written very well. It is nearly undocumented, and 
the functions are disorganized and in essentially random order. The code 
is really in plain C; it only uses a couple of C++ classes for 
convenience. It pretty much ignores all the programming concepts of C++. 
And C for that matter. Possibly it will be improved in future versions. 
But probably not.

