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Big change to the test infrastructure and supporting internals. The goal now is to test both a COLOR_ALPHA and a COLOR content for each surface backend, (since the semantics are different and we probably need to support both in each backend.
The PS/PDF backends don't allow a content to be passed in right now, so they fail against the rgb24 tests, but the trivial addition to the constructors will allow them to pass all tests with both content values.
And new constructors (currently internal only) to create an image surface with a cairo_content_t rather than a cairo_format_t.
Add a cairo_content_t argument to the constructor.
Add a cairo_content_t to the constructor and use this content value when constructing intermediate image surfaces in acquire_source, show_page, copy_page, and snapshot.
Add image flattening by compositing over white, as is done in cairo-ps-surface.c.
Track changes to cairo-paginates-surface which now requires a cairo_content_t value (no change to public PS/PDF constructors yet).
Track change in meta-surface and paginated-surface interfaces by now accepting a cairo_content_t rather than a cairo_format_t.
Ignore new output files (argb32 from pdf and ps as well as rgb24 from test-fallback, test-meta, and test-paginated).
Add new utility for flattening PNG images in order to generate the -argbf-ref.png images.
Add image_diff_flattened for comparing flattened output from PS and PDF backend with ARGB reference images by first blending the reference images over white.
Get rid of conditional, format-specific background-color initialization before running tests. Now uses ARGB(0,0,0,0) in all cases. Switch from specifying tests with a format value to specifying tests with a content value. Add support for a 'fake' COLOR_ALPHA_FLATTENED content for testing the PS and PDF output against a flattened version of the argb32 reference images (first blended over white).
Track change in cairo_ps_surface_create (now requires cairo_content_t value).
Adjust tests that draw in default (black) to first paint white so that the results are visible.
Adjust ARGB32 reference images for new white background for changed tests.
Adjust RGB24 reference images for new black background due to changed initialization (and the tests themselves being unchanged).