<!DOCTYPE HTML>
<html>
<head>
<title>WebGL in OffscreenCanvas</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" href="/tests/SimpleTest/test.css">
</head>
<body>
<canvas id="c" width="64" height="64"></canvas>
<script>

SimpleTest.waitForExplicitFinish();

function runTest() {

  var htmlCanvas = document.getElementById("c");
  var worker = new SharedWorker("offscreencanvas.js");

  ok(htmlCanvas, "Should have HTML canvas element");
  ok(worker, "Web worker successfully created");

  ok(htmlCanvas.transferControlToOffscreen, "HTMLCanvasElement has transferControlToOffscreen function");

  var offscreenCanvas = htmlCanvas.transferControlToOffscreen();
  ok(offscreenCanvas, "Expected transferControlToOffscreen to succeed");

  worker.port.start();

  // We don't support transferring OffscreenCanvas via shared worker.
  SimpleTest.doesThrow(
    function() {
      worker.port.postMessage({test: 'webgl', canvas: offscreenCanvas}, [offscreenCanvas]);
    },
    "OffscreenCanvas cannot transfer to shared worker"
  );

  SimpleTest.finish();
}

SpecialPowers.pushPrefEnv({'set': [
  ['gfx.offscreencanvas.enabled', true],
  ['webgl.force-enabled', true],
]}, runTest);

</script>
</body>
</html>
