xcb: track fallback damage

And only upload the parts of the image that are modified during the
fallback. I have to keep reminding myself that the goal is always to
reduce the amount of fallbacks required...

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/cairo-composite-rectangles-private.h b/src/cairo-composite-rectangles-private.h
index 8603108dd..fd7728995 100644
--- a/src/cairo-composite-rectangles-private.h
+++ b/src/cairo-composite-rectangles-private.h
@@ -147,6 +147,10 @@ cairo_private cairo_bool_t
 _cairo_composite_rectangles_can_reduce_clip (cairo_composite_rectangles_t *composite,
 					     cairo_clip_t *clip);
 
+cairo_private cairo_int_status_t
+_cairo_composite_rectangles_add_to_damage (cairo_composite_rectangles_t *composite,
+					   cairo_boxes_t *damage);
+
 cairo_private void
 _cairo_composite_rectangles_fini (cairo_composite_rectangles_t *extents);