[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, 26 insertions, 0 deletions

diff --git a/boilerplate/cairo-boilerplate-win32-printing.c b/boilerplate/cairo-boilerplate-win32-printing.c
index 617b08714..691552d1d 100644
--- a/boilerplate/cairo-boilerplate-win32-printing.c
+++ b/boilerplate/cairo-boilerplate-win32-printing.c
@@ -298,6 +298,32 @@ _cairo_boilerplate_win32_printing_surface_write_to_png (cairo_surface_t *surface
     return CAIRO_STATUS_SUCCESS;
 }
 
+cairo_surface_t *
+_cairo_boilerplate_win32_printing_get_image_surface (cairo_surface_t *surface,
+						     int width,
+						     int height)
+{
+    win32_target_closure_t *ptc = cairo_surface_get_user_data (surface,
+							       &win32_closure_key);
+    char *filename;
+    cairo_status_t status;
+
+    xasprintf (&filename, "%s.png", ptc->filename);
+    status = _cairo_boilerplate_win32_printing_surface_write_to_png (surface, filename);
+    if (status)
+	return cairo_boilerplate_surface_create_in_error (status);
+
+    surface = cairo_boilerplate_get_image_surface_from_png (filename,
+							    width,
+							    height,
+							    ptc->target == NULL);
+
+    remove (filename);
+    free (filename);
+
+    return surface;
+}
+
 void
 _cairo_boilerplate_win32_printing_cleanup (void *closure)
 {