Merge pull request #715 from LarissaSmith/master

Added autoRefigureSizes flag for disabling calls to _figureSizes …

src/world.js

@@ -52,8 +52,14 @@ $.World = function( options ) {
     this.viewer = options.viewer;
     this._items = [];
     this._needsDraw = false;
+    this._autoRefigureSizes = true;
+    this._needsSizesFigured = false;
     this._delegatedFigureSizes = function(event) {
-        _this._figureSizes();
+        if (_this._autoRefigureSizes) {
+            _this._figureSizes();
+        } else {
+            _this._needsSizesFigured = true;
+        }
     };
 
     this._figureSizes();
@@ -275,6 +281,21 @@ $.extend( $.World.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.W
         return this._contentFactor;
     },
 
+    /**
+     * As a performance optimization, setting this flag to false allows the bounds-change event handler
+     * on tiledImages to skip calculations on the world bounds. If a lot of images are going to be positioned in
+     * rapid succession, this is a good idea. When finished, setAutoRefigureSizes should be called with true
+     * or the system may behave oddly.
+     * @param {Boolean} [value] The value to which to set the flag.
+     */
+    setAutoRefigureSizes: function(value) {
+        this._autoRefigureSizes = value;
+        if (value & this._needsSizesFigured) {
+            this._figureSizes();
+            this._needsSizesFigured = false;
+        }
+    },
+
     /**
      * Arranges all of the TiledImages with the specified settings.
      * @param {Object} options - Specifies how to arrange.
@@ -304,6 +325,8 @@ $.extend( $.World.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.W
         var x = 0;
         var y = 0;
         var item, box, width, height, position;
+
+        this.setAutoRefigureSizes(false);
         for (var i = 0; i < this._items.length; i++) {
             if (i && (i % wrap) === 0) {
                 if (layout === 'horizontal') {
@@ -336,6 +359,7 @@ $.extend( $.World.prototype, $.EventSource.prototype, /** @lends OpenSeadragon.W
                 y += increment;
             }
         }
+        this.setAutoRefigureSizes(true);
     },
 
     // private