From 767c897e7fce32650cd7252dba66da435f926e42 Mon Sep 17 00:00:00 2001
From: Robert Hickman <robhobbes@gmail.com>
Date: Fri, 16 Aug 2013 11:32:21 -0600
Subject: [PATCH] Revisions to rotate after second code review.

---
 src/drawer.js    |  4 ++++
 src/rectangle.js |  7 ++++++-
 src/viewport.js  | 26 +++++++++++++++++++++-----
 3 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/src/drawer.js b/src/drawer.js
index abc7969d..4a198e8c 100644
--- a/src/drawer.js
+++ b/src/drawer.js
@@ -403,6 +403,10 @@ $.Drawer.prototype = {
         }
 
         return loading;
+    },
+
+    canRotate: function() {
+        return USE_CANVAS;
     }
 };
 
diff --git a/src/rectangle.js b/src/rectangle.js
index 32fc20dc..a3b1c7dd 100644
--- a/src/rectangle.js
+++ b/src/rectangle.js
@@ -182,7 +182,12 @@ $.Rect.prototype = {
         }
 
         if( degrees === 0 ){
-            return this;
+            return new $.Rect(
+                this.x,
+                this.y,
+                this.width,
+                this.height
+            );
         }
 
         pivot = pivot || this.getCenter();
diff --git a/src/viewport.js b/src/viewport.js
index 074011d3..e79492e5 100644
--- a/src/viewport.js
+++ b/src/viewport.js
@@ -533,7 +533,7 @@ $.Viewport.prototype = {
      * @return {OpenSeadragon.Viewport} Chainable.
      */
     zoomBy: function( factor, refPoint, immediately ) {
-        if( typeof refPoint != 'undefined' ) {
+        if( refPoint ) {
             refPoint = refPoint.rotate(
                 -this.degrees,
                 new $.Point( this.centerSpringX.target.value, this.centerSpringY.target.value )
@@ -574,19 +574,35 @@ $.Viewport.prototype = {
      * Currently only supports 90 degree rotation.
      * Currently only works with canvas.
      * @function
-     * @name OpenSeadragon.Viewport.prototype.rotate
+     * @name OpenSeadragon.Viewport.prototype.setRotation
      * @return {OpenSeadragon.Viewport} Chainable.
      */
-    setRotation: function(degrees){
+    setRotation: function( degrees ) {
+        if( !( this.viewer && this.viewer.drawer.canRotate() ) ) {
+            return this;
+        }
+
         degrees = ( degrees + 360 ) % 360;
-        if(degrees % 90 !== 0){
+        if( degrees % 90 !== 0 ) {
             throw new Error('Currently only 0, 90, 180, and 270 degrees are supported.');
         }
         this.degrees = degrees;
-        this.viewer.drawer.update();
+        if( this.viewer ) {
+            this.viewer.drawer.update();
+        }
         return this;
     },
 
+    /**
+     * Gets the current rotation in degrees.
+     * @function
+     * @name OpenSeadragon.Viewport.prototype.setRotation
+     * @return {Number} The current rotation in degrees.
+     */
+    getRotation: function() {
+        return this.degrees;
+    },
+
     /**
      * @function
      * @return {OpenSeadragon.Viewport} Chainable.