PNG decoder Files

The purpose of the OmniMark PNG decoder is to convert a PNG image to a stream of markup events. This stream of markup events can further be processed by sending it through additional filters. The PNG specification can be found at

http://www.libpng.org/pub/png/spec/1.2/PNG-Contents.html

The OmniMark PNG decoder implements Sections 3 and 4 of the specification, and consists of four modules (found in the xin/ sub-folder):

• chunks.xmd - handles Section 3.2 and 3.4,
• critical.xmd - handles Section 4.1,
• ancillary.xmd - handles Section 4.2, and
• ordering.xmd - handles Section 4.3, specifically any ordering constraints that cannot be determined by the other modules.

These are are wrapped and re-exported by a mother-module:

• ompng.xmd

The test harnesses (ancillary.xom, chunks.xom, and critical.xom) demonstrate how to use the libraries.

There is a test suite included, which was obtained from

http://www.schaik.com/pngsuite2011/pngsuite.html

The test suite can be run by going to the test/ sub-folder and running:

$ ./run-test.sh