content/canvas/test/test_mozGetAsFile.html

<!DOCTYPE HTML>
<title>Canvas test: mozGetAsFile</title>
<script src="/MochiKit/MochiKit.js"></script>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" href="/tests/SimpleTest/test.css">
<body>
<canvas id="c" width="100" height="50"><p class="fallback">FAIL (fallback content)</p></canvas>
<script>

function compareAsync(file, canvas, type)
{
  SimpleTest.waitForExplicitFinish();

  var reader = new FileReader();
  reader.onload = 
    function(e) {
      is(e.target.result, canvas.toDataURL(type),
 "<canvas>.mozGetAsFile().getAsDataURL() should equal <canvas>.toDataURL()");
      SimpleTest.finish();
    };
  reader.readAsDataURL(file);
}

SimpleTest.waitForExplicitFinish();
addLoadEvent(function () {

var canvas = document.getElementById('c');
var ctx = canvas.getContext('2d');

ctx.drawImage(document.getElementById('yellow75.png'), 0, 0);

var pngfile = canvas.mozGetAsFile("foo.png");
is(pngfile.type, "image/png", "Default type for mozGetAsFile should be PNG");
compareAsync(pngfile, canvas, "image/png");
is(pngfile.name, "foo.png", "File name should be what we passed in");

var jpegfile = canvas.mozGetAsFile("bar.jpg", "image/jpeg");
is(jpegfile.type, "image/jpeg",
   "When a valid type is specified that should be returned");
compareAsync(jpegfile, canvas, "image/jpeg");
is(jpegfile.name, "bar.jpg", "File name should be what we passed in");

SimpleTest.finish();

});
</script>
<img src="image_yellow75.png" id="yellow75.png" class="resource">