image: replay the recording surface directly onto the target

백현기 reported a use-case where he was recording an entire web-page
onto the recording surface, in order to facilitate panning. In this
scenario, where there may be lots of similar surfaces within the
recording we generate thousands of unused snapshot-images bloating
memory usage and impairing performance.

Under the right conditions we can replay directly onto the destination
which not only bypasses the snapshots but also skips the following
resampling.

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

1 files changed, 17 insertions, 0 deletions

diff --git a/src/cairo-clip-boxes.c b/src/cairo-clip-boxes.c
index 95ed265bf..98d1a18b0 100644
--- a/src/cairo-clip-boxes.c
+++ b/src/cairo-clip-boxes.c
@@ -560,3 +560,20 @@ _cairo_clip_to_boxes (cairo_clip_t *clip,
     return CAIRO_STATUS_SUCCESS;
 
 }
+
+cairo_clip_t *
+_cairo_clip_from_boxes (const cairo_boxes_t *boxes)
+{
+    cairo_clip_t *clip = _cairo_clip_create ();
+    if (clip == NULL)
+	return _cairo_clip_set_all_clipped (clip);
+
+    /* XXX cow-boxes? */
+    clip->boxes = _cairo_boxes_to_array (boxes, &clip->num_boxes, TRUE);
+    if (clip->boxes == NULL)
+	return _cairo_clip_set_all_clipped (clip);
+
+    _cairo_boxes_extents (boxes, &clip->extents);
+
+    return clip;
+}