274300 2024-05-16 23:54:00 -0700 render not work in offscreencanvas in some case 2024-05-16 23:59:33 -0700 1 1 1 Unclassified WebKit Canvas Safari 17 Mac (Apple Silicon) macOS 14 RESOLVED DUPLICATE 274301 P2 Normal --- 1 iskyler1993 webkit-unassigned dino oldest_to_newest 2035960 0 iskyler1993 2024-05-16 23:54:00 -0700 we have found a case that rendering in offscreencanvas not work on both mac safari and iOS safari (17.4.1) Use Cases: 1. create work0, pass the offscreencanvas to it 2. work0 post the offscreencanvas back to main thread 3. main thread create worker1 and pass the offscreencanvas to it 4. use raf in worker1 and we found that if we make the handler in step 3(named SpawnThread) to execute in setTimeout, rendering would be ok not sure if it's a bug, but the case work on chrome the sample code below test.html ``` <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8" /> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <title>Document</title> </head> <body> <canvas id="canvas"></canvas> </body> <script type="text/javascript"> var canvas = document.getElementById("canvas"); var Module = (window.Module = {}); var workerJs = "./test.worker.js"; var worker0 = new Worker(workerJs); function spawnThread(data) { var worker = new Worker(workerJs); worker.postMessage({ type: "load", }); worker.postMessage( { type: "run1", canvas: data.canvas, }, [data.canvas] ); } worker0.onmessage = function (event) { if (event.data.type === "loaded") { console.log("main thread receive worker0 loaded"); } else if (event.data.type === "spawnThread") { console.log("spawnThread"); // setTimeout(spawnThread, 0, event.data); spawnThread(event.data); } }; worker0.postMessage({ type: "load", }); var offscreencanvas = canvas.transferControlToOffscreen(); worker0.postMessage( { type: "run0", canvas: offscreencanvas, }, [offscreencanvas] ); </script> </html> ``` test.worker.js ``` var gl; var initGL = function (data) { var canvas = data.canvas; gl = canvas.getContext("webgl"); if (!gl) { console.error("Failed to get the rendering context for WebGL"); return; } }; var r = 0.01; var renderLoop = function () { console.log("start renderLoop"); function renderFunc() { if (r > 1) { r = 0.01; } r += 0.01; gl.clearColor(r, 0, 0, 1); gl.clear(gl.COLOR_BUFFER_BIT); requestAnimationFrame(renderFunc); } requestAnimationFrame(renderFunc); }; self.onmessage = function (event) { if (event.data.type === "load") { console.log("worker onload"); } else if (event.data.type === "run0") { console.log("worker on run0"); postMessage( { type: "spawnThread", canvas: event.data.canvas, }, [event.data.canvas] ); } else if (event.data.type === "run1") { console.log("worker on run1"); initGL(event.data); renderLoop(); } }; ``` 2035962 1 iskyler1993 2024-05-16 23:59:33 -0700 *** This bug has been marked as a duplicate of bug 274301 ***