<!DOCTYPE html>
<html>
<head>
<title>drawFocusIfNeeded()</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="author" title="W3C">
<link rel="help" href="http://www.w3.org/TR/2dcontext/#dom-context-2d-drawFocusIfNeeded">
</head>
<body>
<h1>Description</h1>
<p>This test uses drawFocusIfNeeded does nothing if the element is not a descendant but comparing ImageData from before and after.</p>
<div>
<p>Before:</p>
<canvas height=100 width=100 id='original'>
<label><a href='http://www.w3.org' id='element'>Focus</a></label>
</canvas>
<p>After:</p>
<canvas height=100 width=100 id=canvas>
</canvas>
</div>
<script>
test(function() {
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
var element = document.getElementById('element');
element.focus();
context.fillStyle = 'white';
context.fillRect(0, 0, 100, 100);
context.beginPath();
context.strokeStyle = 'black';
context.rect(10, 10, 80, 80);
context.stroke();
context.save();
var refImage = context.getImageData(0, 0, 100, 100);
assert_equals(40000, refImage.data.length, "ImageData.data.length is 40000");
var original = document.getElementById('original');
var o_context = original.getContext('2d');
o_context.fillStyle = 'white';
o_context.fillRect(0, 0, 100, 100);
o_context.putImageData(refImage, 0, 0, 0, 0, 100, 100);
context.strokeStyle = 'blue';
context.rect(5, 5, 90, 90);
context.drawFocusIfNeeded(element);
var ringImage = context.getImageData(0, 0, 100, 100);
assert_equals(40000, ringImage.data.length, "ImageData.data.length is 40000");
// make sure refImage and ringImage are different
var length = 40000;
var index = length;
var identical = true;
while (--index > 0) {
if (refImage.data[index] != ringImage.data[index]) identical = false;
}
assert_true(identical, "No focus ring appears in the canvas");
}, 'drawFocusIfNeeded does not draw a focus ring if the element is not a descendant of the context.');
</script>
<div id="log"></div>
</body>
</html>