Changelog for #2239

Viewer destroy event

changelog.txt

@@ -11,6 +11,7 @@ OPENSEADRAGON CHANGELOG
 * You can now provide an element for the navigator (as an alternative to an ID) (#1303 @cameronbaney, #2166 #2175 @joedf)
 * Now supporting IIIF "id" and "identifier" in addition to "@id" (#2173 @ahankinson)
 * We now delegate tile fetching and caching to the TileSource, to allow for custom tile formats (#2148 @Aiosa)
+* The viewer now emits before-destroy and destroy events (#2239 @pearcetm)
 * Improved documentation (#2211 @shyamkumaryadav)
 * Fixed: Cropping tiled images with polygons was broken (#2183 @altert)
 * Fixed: Disabling buttons only changed their appearance, but they were still clickable (#2187 @pearcetm)

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();
     },
 
     /**