Merge pull request #2239 from pearcetm/viewer-destroy-event

Viewer destroy event

src/viewer.js

@@ -756,6 +756,8 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
      * viewer = null; //important
      *
      * @function
+     * @fires OpenSeadragon.Viewer.event:before-destroy
+     * @fires OpenSeadragon.Viewer.event:destroy
      */
     destroy: function( ) {
         if ( !THIS[ this.hash ] ) {
@@ -763,6 +765,17 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
             return;
         }
 
+        /**
+         * Raised when the viewer is about to be destroyed (see {@link OpenSeadragon.Viewer#before-destroy}).
+         *
+         * @event before-destroy
+         * @memberof OpenSeadragon.Viewer
+         * @type {object}
+         * @property {OpenSeadragon.Viewer} eventSource - A reference to the Viewer which raised the event.
+         * @property {?Object} userData - Arbitrary subscriber-defined object.
+         */
+        this.raiseEvent( 'before-destroy' );
+
         this._removeUpdatePixelDensityRatioEvent();
 
         this.close();
@@ -795,7 +808,6 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
             this.navigator = null;
         }
 
-        this.removeAllHandlers();
 
         if (this.buttonGroup) {
             this.buttonGroup.destroy();
@@ -841,6 +853,19 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
 
         // clear our reference to the main element - they will need to pass it in again, creating a new viewer
         this.element = null;
+
+        /**
+         * Raised when the viewer is destroyed (see {@link OpenSeadragon.Viewer#destroy}).
+         *
+         * @event destroy
+         * @memberof OpenSeadragon.Viewer
+         * @type {object}
+         * @property {OpenSeadragon.Viewer} eventSource - A reference to the Viewer which raised the event.
+         * @property {?Object} userData - Arbitrary subscriber-defined object.
+         */
+        this.raiseEvent( 'destroy' );
+
+        this.removeAllHandlers();
     },
 
     /**

src/viewport.js

@@ -514,7 +514,7 @@ $.Viewport.prototype = {
      * @param {OpenSeadragon.Rect} bounds
      * @returns {OpenSeadragon.Rect} constrained bounds.
      */
-    _applyBoundaryConstraints: function(bounds) {
+     _applyBoundaryConstraints: function(bounds) {
         var newBounds = new $.Rect(
                 bounds.x,
                 bounds.y,