[test] Avoid redundant writes/reads of test surfaces via png.

As Behdad suggested, we can dramatically speed up the test suite by
short-circuiting the write to a png file, only to then immediately read it
back in. So for the raster based surfaces, we avoid the round-trip through
libpng by implementing a new boilerplate method to directly extract the image
buffer from the test result. A secondary speedup is achieved by caching the
most recent reference image.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/imagediff.c b/test/imagediff.c
index c170c8e5b..640424265 100644
--- a/test/imagediff.c
+++ b/test/imagediff.c
@@ -54,7 +54,7 @@ main (int argc, char *argv[])
 	ax = ay = bx = by = 0;
     }
 
-    status = image_diff (NULL, argv[1], argv[2], NULL, ax, ay, bx, by, &result);
+    status = png_diff (NULL, argv[1], argv[2], NULL, ax, ay, bx, by, &result);
 
     if (status) {
 	fprintf (stderr, "Error comparing images: %s\n",