[gtk+] snapshot: Only create clip nodes if we need to

[Timm Bäder <baedert src gnome org>]

commit 94184eda4214b3162eead554212443b3a0f50481
Author: Timm Bäder <mail baedert org>
Date:   Fri Dec 1 07:38:43 2017 +0100

    snapshot: Only create clip nodes if we need to
    
    Clip nodes have a clip rect and we only need to actually create a clip
    node if any child node gets clipped at all. If the clip rect conains the
    child node bounds entirely, we don't need a clip node.

 gtk/gtksnapshot.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtksnapshot.c b/gtk/gtksnapshot.c
index 4995c3d..c969fde 100644
--- a/gtk/gtksnapshot.c
+++ b/gtk/gtksnapshot.c
@@ -548,6 +548,10 @@ gtk_snapshot_collect_clip (GtkSnapshot      *snapshot,
   if (node == NULL)
     return NULL;
 
+  /* Check if the child node will even be clipped */
+  if (graphene_rect_contains_rect (&state->data.clip.bounds, &node->bounds))
+    return node;
+
   /* Its not uncommon to produce stacked clip nodes, which are trivial
      to merge, so do that here */
   if (gsk_render_node_get_node_type (node) == GSK_CLIP_NODE)