content/test/data/gpu/pixel_offscreenCanvas_ibrc_worker.html

<!DOCTYPE HTML>

<html>
<head>
<title>OffscreenCanvas transferToImageBitmap on worker thread: green and blue squares on white background.</title>
<style type="text/css">
.nomargin {
  margin: 0px auto;
}
</style>
<script id="myWorker" type="text/worker">
self.onmessage = function(msg) {
  const dst_canvas = msg.data;
  const ibrc = dst_canvas.getContext('bitmaprenderer');

  const src_canvas = new OffscreenCanvas(100, 100);
  var gl = src_canvas.getContext('webgl');
  gl.clearColor(0.0, 0.0, 1.0, 1.0);
  gl.clear(gl.COLOR_BUFFER_BIT);

  ibrc.transferFromImageBitmap(src_canvas.transferToImageBitmap());

  self.postMessage('done');
};
</script>
<script>
var g_swapsBeforeAck = 15;

function makeWorker(script) {
   var blob = new Blob([script]);
   return new Worker(URL.createObjectURL(blob));
}

function main()
{
  var worker = makeWorker(document.getElementById("myWorker").textContent);
  worker.onmessage = waitForFinish;
  const canvas = document.getElementById('canvas').transferControlToOffscreen();
  worker.postMessage(canvas, [canvas]);
}

function waitForFinish()
{
  if (g_swapsBeforeAck == 0) {
    domAutomationController.send("SUCCESS");
  } else {
    g_swapsBeforeAck--;
    document.getElementById('container').style.zIndex = g_swapsBeforeAck + 1;
    window.requestAnimationFrame(waitForFinish);
  }
}
</script>
</head>
<body onload="main()">
<div id="container" class="nomargin">
<canvas id="canvas" width="100" height="100" class="nomargin"></canvas>
</div>
</body>
</html>