rendercheck is a program to test a Render extension implementation against separate calculations of expected output. Tests currently include: - Destination coordinates correctness - Source coordinates correctness - Transformed (FilterNearest) source coordinates correctness. - Composite with and without mask (with/without component alpha), with 1x1 repeating Pictures and 10x10 Pictures. - Linear gradients - Repeating sources/masks at POT and non-POT sizes - Some regression tests for bugs from freedesktop.org bugzilla.