Quelle  test_drawDiscardedImage.html   Sprache: HTML

<!DOCTYPE HTML>
<html>
<!--
https://bugzilla.mozilla.org/show_bug.cgi?id=731419
-->
<head>
  <title>Test for Bug 731419 - Draw an ostensibly discarded image to a canvas</title>
  <script src="/tests/SimpleTest/SimpleTest.js"></script>
  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
</head>

<body>

<!--
  Load an image in an iframe, then draw that image to a canvas.  Then set the
  iframe to display:none (after bug 731419, this causes the image's decoded
  data to be discarded) and draw the image to a canvas again.  We should draw
  the same image data both times.
-->

<script>

SimpleTest.waitForExplicitFinish();

var data1;

function drawImage()
{
  var canvas = document.getElementById('canvas');
  var ctx = canvas.getContext('2d');
  var iframeDoc = document.getElementById('iframe').contentDocument;

  ctx.clearRect(0, 0, canvas.height, canvas.width);
  ctx.drawImage(iframeDoc.getElementById('image'), 0, 0);
  return canvas.toDataURL();
}

function iframeLoad()
{
  data1 = drawImage();
  document.getElementById('iframe').style.display = 'none';

  // Spin the event loop a few times to give the image in the display:none
  // iframe a chance to be discarded.
  SimpleTest.executeSoon(function() {
    SimpleTest.executeSoon(function() {
      SimpleTest.executeSoon(function() {
        step2();
      });
    });
  });
}

function step2()
{
  is(drawImage(), data1, "Same image before and after iframe display:none");
  SimpleTest.finish();
}

</script>

<canvas id='canvas'></canvas>

<iframe id='iframe' onload='iframeLoad()' srcdoc='<img id="image"
src="data:image/png;base64,
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</body>
</html>