Is AGG portable?

To answer my own question. Yes, AGG is tested on Windows, Linux, Sun,
SGI, and Apple (MacOS X, X11)

The website is a little out of date. Here's some info the author sent
me:

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=============================================================
AGG has been considerably modified last time and its development is
still in
process, but major design issues are stabilized now.
The good news is that there many new things were implemented, such as:

- Gradients and Gouraud Shading
- Image affine transformations
- Strokes with different types of line joins and line caps
- Dashed line generator
- Markers, such as arrowheads/arrowtails
- Fast vectorial polygon clipping to a rectangle
- Low-level clipping to multiple rectangular regions
- Alpha-Masking
- New fast anti-aliased line algorithm
- Using arbitrary images as line patterns
- Rendering in separate color channels
- Perspective and bilinear transformations of vector and image data
- General polygon clipping (and, or, xor, sub) based on Alan Murta's GPC

The library is platform independent and it's considerably redesigned.
You can find many examples, including image transformation ones in
agg2/examples. The examples are platform independent too and you
can find the building environments in the respective directories.
If you use Win32 platform with VC++ 6 or later just open
the projects, the library doesn't need any preliminary building. If you
use
Unix/Linux with X11 and gcc, first execute make in the agg2 directory
and then make in examples/X11/.

There is also a simple SVG viewer, it's in agg2/svg. You will
need Expat XML parser.

The latest snapshot of AGG is always here:
http://www.antigrain.com/agg2.zip (MS-DOS end-of-line style)
http://www.antigrain.com/agg2.tar.gz (Unix end-of-line style)
or in the CVS repository at SourceForge:
http://sourceforge.net/cvs/?group_id=42020

Also there's a lite, minimalistic version:
http://www.antigrain.com/lite/agg2_lite.zip

There is a mailing list:
http://lists.sourceforge.net/lists/listinfo/vector-agg-general
where I publish news from time to time and where some very nice people
are
discussing AGG issues. They are giving me a lot of recommendations and
new
ideas.

I'd recommend you to subscribe and take part in it. Look at the mailing
archives for details:
http://sourceforge.net/mailarchive/forum.php?forum=vector-agg-general