content/canvas/test/test_toDataURL_parameters.html

<!DOCTYPE HTML>
<title>Canvas test: toDataURL parameters (Bug 564388)</title>
<script src="/MochiKit/MochiKit.js"></script>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" href="/tests/SimpleTest/test.css">
<body>
<p>
This test covers the JPEG quality parameter. If (when) the HTML5 spec changes the
allowed parameters for ToDataURL, new tests should go here.
</p>
<canvas id="c" width="100" height="100"><p class="fallback">FAIL (fallback content)</p></canvas>
<script>
var canvas = document.getElementById('c');
var ctx = canvas.getContext("2d");

ctx.strokeStyle = '#FF0000';
ctx.fillStyle = '#00FF00';
ctx.fillRect(0, 0, 100, 100);
ctx.beginPath();
ctx.moveTo(10, 10);
ctx.lineTo(90, 90);
ctx.stroke();

var pngData = canvas.toDataURL('image/png');
var pngQuality = canvas.toDataURL('image/png', 0.1);
is(pngQuality, pngData, "Quality is not supported for PNG images");

var data = canvas.toDataURL('image/jpeg');
if (data.match(/^data:image\/jpeg[;,]/)) {
    // Test the JPEG quality parameter
    
    var fullQuality = canvas.toDataURL('image/jpeg', 1.0);
    var lowQuality = canvas.toDataURL('image/jpeg', 0.1);
    isnot(lowQuality, fullQuality, "A low quality (0.1) should differ from high quality (1.0)");
    
    var medQuality = canvas.toDataURL('image/jpeg', 0.5);
    isnot(medQuality, fullQuality, "A medium quality (0.5) should differ from high (1.0)");
    isnot(medQuality, lowQuality, "A medium quality (0.5) should differ from low (0.5)");
    
    var tooHigh = canvas.toDataURL('image/jpeg', 2.0);
    is(tooHigh, data, "Quality above 1.0 is treated as unspecified");
    
    var tooLow = canvas.toDataURL('image/jpeg', -1.0);
    is(tooLow, data, "Quality below 0.0 is treated as unspecified");
    
    var lowQualityExtra = canvas.toDataURL('image/jpeg', 0.1, 'foo', 'bar', null);
    is(lowQualityExtra, lowQuality, "Quality applies even if extra arguments are present");
    
    var lowQualityUppercase = canvas.toDataURL('IMAGE/JPEG', 0.1);
    is(lowQualityUppercase, lowQuality, "Quality applies to image/jpeg regardless of case");
    
    var lowQualityString = canvas.toDataURL('image/jpeg', '0.1');
    isnot(lowQualityString, lowQuality, "Quality must be a number (should not be a string)");
}
</script>