From 0bd17ed2e462578fee592a242b6d70c005d9e819 Mon Sep 17 00:00:00 2001
From: nick_m <mainsbridge@gmail.com>
Date: Thu, 19 Jun 2014 00:06:32 +1000
Subject: [PATCH] Canvas tweaks.        * Only queue a draw for changed items
 that are set visible and in-window.

---
 libs/canvas/canvas.cc | 25 +++++++++++++++++++------
 libs/canvas/item.cc   | 12 ++++++++----
 2 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/libs/canvas/canvas.cc b/libs/canvas/canvas.cc
index 3d4f9e0c5d..c13386408b 100644
--- a/libs/canvas/canvas.cc
+++ b/libs/canvas/canvas.cc
@@ -170,7 +170,9 @@ Canvas::item_shown_or_hidden (Item* item)
 {
 	boost::optional<Rect> bbox = item->bounding_box ();
 	if (bbox) {
-		queue_draw_item_area (item, bbox.get ());
+		if (item->item_to_window (*bbox).intersection (visible_area ())) {
+			queue_draw_item_area (item, bbox.get ());
+		}
 	}
 }
 
@@ -183,7 +185,9 @@ Canvas::item_visual_property_changed (Item* item)
 {
 	boost::optional<Rect> bbox = item->bounding_box ();
 	if (bbox) {
-		queue_draw_item_area (item, bbox.get ());
+		if (item->item_to_window (*bbox).intersection (visible_area ())) {
+			queue_draw_item_area (item, bbox.get ());
+		}
 	}
 }
 
@@ -195,15 +199,24 @@ Canvas::item_visual_property_changed (Item* item)
 void
 Canvas::item_changed (Item* item, boost::optional<Rect> pre_change_bounding_box)
 {
+	
+	Rect window_bbox = visible_area ();
+
 	if (pre_change_bounding_box) {
-		/* request a redraw of the item's old bounding box */
-		queue_draw_item_area (item, pre_change_bounding_box.get ());
+
+		if (item->item_to_window (*pre_change_bounding_box).intersection (window_bbox)) {
+			/* request a redraw of the item's old bounding box */
+			queue_draw_item_area (item, pre_change_bounding_box.get ());
+		}
 	}
 
 	boost::optional<Rect> post_change_bounding_box = item->bounding_box ();
 	if (post_change_bounding_box) {
-		/* request a redraw of the item's new bounding box */
-		queue_draw_item_area (item, post_change_bounding_box.get ());
+		
+		if (item->item_to_window (*post_change_bounding_box).intersection (window_bbox)) {
+			/* request a redraw of the item's new bounding box */
+			queue_draw_item_area (item, post_change_bounding_box.get ());
+		}
 	}
 }
 
diff --git a/libs/canvas/item.cc b/libs/canvas/item.cc
index ce15782b9e..90bf0972f0 100644
--- a/libs/canvas/item.cc
+++ b/libs/canvas/item.cc
@@ -545,10 +545,12 @@ Item::begin_change ()
 void
 Item::end_change ()
 {
-	_canvas->item_changed (this, _pre_change_bounding_box);
+	if (_visible) {
+		_canvas->item_changed (this, _pre_change_bounding_box);
 	
-	if (_parent) {
-		_parent->child_changed ();
+		if (_parent) {
+			_parent->child_changed ();
+		}
 	}
 }
 
@@ -560,7 +562,9 @@ Item::begin_visual_change ()
 void
 Item::end_visual_change ()
 {
-	_canvas->item_visual_property_changed (this);
+	if (_visible) {
+		_canvas->item_visual_property_changed (this);
+	}
 }
 
 void