fix: fixes canvas resources release (useful for getting rid of the canvas memory leaks on iOS)

src/Canvas.ts

@@ -23,6 +23,7 @@ function getDevicePixelRatio() {
         1;
     return devicePixelRatio / backingStoreRatio;
   })();
+  Util.releaseCanvas(canvas);
   return _pixelRatio;
 }
 

src/Layer.ts

@@ -468,6 +468,11 @@ export class Layer extends Container<Group | Shape> {
     }
   }
 
+  destroy(): this {
+    Util.releaseCanvas(this.getNativeCanvasElement(), this.getCanvas()._canvas);
+    return super.destroy();
+  }
+
   hitGraphEnabled: GetSet<boolean, this>;
 
   clearBeforeDraw: GetSet<boolean, this>;

src/Stage.ts

@@ -278,6 +278,9 @@ export class Stage extends Container<Layer> {
     if (index > -1) {
       stages.splice(index, 1);
     }
+
+    Util.releaseCanvas(this.bufferCanvas._canvas, this.bufferHitCanvas._canvas)
+
     return this;
   }
   /**

src/Util.ts

@@ -957,4 +957,10 @@ export const Util = {
       return evt.changedTouches[0].identifier;
     }
   },
+  releaseCanvas(...canvases: HTMLCanvasElement[]) {
+    canvases.forEach(c => {
+      c.width = 0;
+      c.height = 0;
+    })
+  }
 };

src/filters/Kaleidoscope.ts

@@ -197,7 +197,7 @@ export const Kaleidoscope: Filter = function (imageData) {
   var scratchData = tempCanvas
     .getContext('2d')
     .getImageData(0, 0, xSize, ySize);
-
+  Util.releaseCanvas(tempCanvas);
   // Convert thhe original to polar coordinates
   ToPolar(imageData, scratchData, {
     polarCenterX: xSize / 2,

src/shapes/TextPath.ts

@@ -533,6 +533,10 @@ export class TextPath extends Shape<TextPathConfig> {
       height: maxY - minY + fontSize,
     };
   }
+  destroy(): this {
+    Util.releaseCanvas(this.dummyCanvas);
+    return super.destroy();
+  }
 
   fontFamily: GetSet<string, this>;
   fontSize: GetSet<number, this>;