From b49b05518358852452f88b123ca3b6c031a595c0 Mon Sep 17 00:00:00 2001
From: Benjamin Otte <otte@redhat.com>
Date: Sun, 28 Jan 2024 03:21:52 +0100
Subject: [PATCH] rendernode: Implement diff() for repeat nodes

If the children have an empty diff and the repeat nodes' sizes are
equal, the diff is empty.
---
 gsk/gskrendernodeimpl.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/gsk/gskrendernodeimpl.c b/gsk/gskrendernodeimpl.c
index 01c1b53716..ec91dc8f79 100644
--- a/gsk/gskrendernodeimpl.c
+++ b/gsk/gskrendernodeimpl.c
@@ -4224,6 +4224,32 @@ gsk_repeat_node_draw (GskRenderNode *node,
     }
 }
 
+static void
+gsk_repeat_node_diff (GskRenderNode  *node1,
+                      GskRenderNode  *node2,
+                      GskDiffData    *data)
+{
+  GskRepeatNode *self1 = (GskRepeatNode *) node1;
+  GskRepeatNode *self2 = (GskRepeatNode *) node2;
+
+  if (gsk_rect_equal (&node1->bounds, &node2->bounds) &&
+      gsk_rect_equal (&self1->child_bounds, &self2->child_bounds))
+    {
+      cairo_region_t *sub;
+
+      sub = cairo_region_create();
+      gsk_render_node_data_diff (self1->child, self2->child, &(GskDiffData) {sub, data->offload });
+      if (cairo_region_is_empty (sub))
+        {
+          cairo_region_destroy (sub);
+          return;
+        }
+      cairo_region_destroy (sub);
+    }
+
+  gsk_render_node_diff_impossible (node1, node2, data);
+}
+
 static void
 gsk_repeat_node_class_init (gpointer g_class,
                             gpointer class_data)
@@ -4234,6 +4260,7 @@ gsk_repeat_node_class_init (gpointer g_class,
 
   node_class->finalize = gsk_repeat_node_finalize;
   node_class->draw = gsk_repeat_node_draw;
+  node_class->diff = gsk_repeat_node_diff;
 }
 
 /**