content/canvas/test/reftest/webgl-resize-test.html

<!DOCTYPE html>
<html class="reftest-wait">
<head>
<meta charset="UTF-8">

<script type="text/javascript" src="webgl-utils.js"></script>
<script type="text/javascript">
/* Resize Test
 *
 * Create canvas of wrong size.
 * Clear the canvas to red.
 * Resize to correct size.
 * Clear to green.
 */

"use strict";

function render(gl) {
  gl.clearColor(1.0, 0.0, 0.0, 1.0);
  gl.clear(gl.COLOR_BUFFER_BIT);

  gl.canvas.width = 256;
  gl.canvas.height = 256;
  gl.clearColor(0.0, 1.0, 0.0, 1.0);
  gl.clear(gl.COLOR_BUFFER_BIT);

  gl.finish();
}

function renderFailure(canvas) {
  // This will also trigger RAF for us.
  var context = canvas.getContext("2d");
  context.fillText('WebGL failed.', 64, 64);
}

function runTest() {
  var canvas = document.getElementById("canvas");

  var gl = initGL(canvas);
  if (gl)
    render(gl);
  else
    renderFailure(canvas);

  waitForComposite(testComplete);
}

function testComplete() {
  document.documentElement.removeAttribute("class");
}
</script>
</head>

<body onload="rAF(runTest);">
  <canvas id="canvas" width="128" height="128" bgcolor='yellow'></canvas>
</body>

</html>