- Add freeupCanvasMemory method on Viewer.destroy method.

src/imagetilesource.js

@@ -195,6 +195,18 @@
             }
             return context;
         },
+        /**
+         * Free up canvas memory
+         * (iOS 12 or higher on 2GB RAM device has only 224MB canvas memory,
+         * and Safari keeps canvas until its height and width will be set to 0).
+         * @function
+         */
+        freeupCanvasMemory: function () {
+            for (var i = 0; i < this.levels.length; i++) {
+                this.levels[i].context2D.canvas.height = 0;
+                this.levels[i].context2D.canvas.width = 0;
+            }
+        },
 
         // private
         //

src/viewer.js

@@ -742,6 +742,10 @@ $.extend( $.Viewer.prototype, $.EventSource.prototype, $.ControlDock.prototype,
             return;
         }
 
+        if (this.source.freeupCanvasMemory) {
+            this.source.freeupCanvasMemory();
+        }
+
         this.close();
 
         this.clearOverlays();