Allow users to pass canvas: undefined

PiperOrigin-RevId: 520142520

mediapipe/tasks/web/core/task_runner_test.ts

@@ -118,9 +118,10 @@ describe('TaskRunner', () => {
 
   let fetchSpy: jasmine.Spy;
   let taskRunner: TaskRunnerFake;
-  let fetchStatus = 200;
+  let fetchStatus: number;
 
   beforeEach(() => {
+    fetchStatus = 200;
     fetchSpy = jasmine.createSpy().and.callFake(async url => {
       return {
         arrayBuffer: () => mockBytes.buffer,

mediapipe/tasks/web/vision/core/vision_task_runner.test.ts

@@ -185,6 +185,23 @@ describe('VisionTaskRunner', () => {
     }).toThrowError(/You must create a new task to reset the canvas./);
   });
 
+  it('validates that an undefined canvas leaves the graph unmodified',
+     async () => {
+       if (typeof OffscreenCanvas === 'undefined') {
+         console.log('Test is not supported under Node.');
+         return;
+       }
+
+       const visionTaskRunner = new VisionTaskRunnerFake();
+       const canvas = new OffscreenCanvas(1, 1);
+       visionTaskRunner.graphRunner.wasmModule.canvas = canvas;
+
+       await visionTaskRunner.setOptions({canvas});
+       await visionTaskRunner.setOptions({canvas: undefined});
+
+       expect(visionTaskRunner.graphRunner.wasmModule.canvas).toBe(canvas);
+     });
+
   it('sends packets to graph', async () => {
     const visionTaskRunner = new VisionTaskRunnerFake();
     await visionTaskRunner.setOptions({runningMode: 'VIDEO'});

mediapipe/tasks/web/vision/core/vision_task_runner.ts

@@ -89,7 +89,7 @@ export abstract class VisionTaskRunner extends TaskRunner {
       this.baseOptions.setUseStreamMode(useStreamMode);
     }
 
-    if ('canvas' in options) {
+    if (options.canvas !== undefined) {
       if (this.graphRunner.wasmModule.canvas !== options.canvas) {
         throw new Error('You must create a new task to reset the canvas.');
       }