From 758c9b6146783edc8b7819d4b6c258ecf4c2894e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=BCrg=20Lehni?= <juerg@scratchdisk.com>
Date: Sat, 7 Dec 2013 12:47:16 +0100
Subject: [PATCH] Improve caching of decomposed transformation values.

---
 src/item/Item.js | 57 ++++++++++++++++++++++++++++++++----------------
 1 file changed, 38 insertions(+), 19 deletions(-)

diff --git a/src/item/Item.js b/src/item/Item.js
index df1ce45b..b666232f 100644
--- a/src/item/Item.js
+++ b/src/item/Item.js
@@ -212,6 +212,7 @@ var Item = Base.extend(Callback, /** @lends Item# */{
 			// Clear cached bounds and position whenever geometry changes
 			delete this._bounds;
 			delete this._position;
+			delete this._decomposed;
 		}
 		if (parent && (flags
 				& (/*#=*/ ChangeFlag.GEOMETRY | /*#=*/ ChangeFlag.STROKE))) {
@@ -962,22 +963,8 @@ var Item = Base.extend(Callback, /** @lends Item# */{
 	 * @ignore
 	 */
 }), /** @lends Item# */{
-	/**
-	 * The current scaling of the item, as described by its {@link #matrix}.
-	 *
-	 * @type Point
-	 * @bean
-	 */
-	getScaling: function() {
-		return this._matrix.getScaling();
-	},
-
-	setScaling: function(/* scale */) {
-		var scaling = this.getScaling();
-		if (scaling != null) {
-			var scale = Point.read(arguments);
-			this.scale(scale.x / scaling.x, scale.y / scaling.y);
-		}
+	_decompose: function() {
+		return this._decomposed = this._matrix.decompose();
 	},
 
 	/**
@@ -987,12 +974,44 @@ var Item = Base.extend(Callback, /** @lends Item# */{
 	 * @bean
 	 */
 	getRotation: function() {
-		return this._matrix.getRotation();
+		var decomposed = this._decomposed || this._decompose();
+		return decomposed && decomposed.rotation;
 	},
 
 	setRotation: function(rotation) {
-		if (rotation != null)
-			this.rotate(rotation - this.getRotation());
+		var current = this.getRotation();
+		if (current != null && rotation != null) {
+			// Preseve the cached _decomposed values over rotation, and only
+			// update the rotation property on it.
+			var decomposed = this._decomposed;
+			this.rotate(rotation - current);
+			decomposed.rotation = rotation;
+			this._decomposed = decomposed;
+		}
+	},
+
+	/**
+	 * The current scaling of the item, as described by its {@link #matrix}.
+	 *
+	 * @type Point
+	 * @bean
+	 */
+	getScaling: function() {
+		var decomposed = this._decomposed || this._decompose();
+		return decomposed && decomposed.scaling;
+	},
+
+	setScaling: function(/* scaling */) {
+		var current = this.getScaling();
+		if (current != null) {
+			// Clone existing points since we're caching internally.
+			var scaling = Point.read(arguments, 0, 0, { clone: true }),
+				// See #setRotation() for preservation of _decomposed.
+				decomposed = this._decomposed;
+			this.scale(scaling.x / current.x, scaling.y / current.y);
+			decomposed.scaling = scaling;
+			this._decomposed = decomposed;
+		}
 	},
 
 	/**