<!DOCTYPE html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/html/canvas/resources/canvas-tests.js"></script>
<link rel="help" href="https://html.spec.whatwg.org/#offscreencontext2d-commit">
<script>

function verifyPlaceholder(placeholder, expectedR, expectedG, expectedB, expectedA, expectedClrStr)
{
    var canvas = document.createElement('canvas');
    canvas.width = canvas.height = 10;
    var ctx = canvas.getContext('2d');
    ctx.drawImage(placeholder, 0, 0);
    _assertPixel(canvas, 5,5, expectedR, expectedG, expectedB, expectedA, "5,5", expectedClrStr);
}

async_test(function(t) {
    var placeholder = document.createElement('canvas');
    placeholder.width = placeholder.height = 10;
    var offscreenCanvas = placeholder.transferControlToOffscreen();
    var ctx = offscreenCanvas.getContext('2d');
    ctx.fillStyle = "#0f0";
    ctx.fillRect(0, 0, 10, 10);
    // commit() propagation is taken care of by an async task, which means the
    // place holder contents should still be transparent black at this moment.
    verifyPlaceholder(placeholder, 0,0,0,0, "0,0,0,0");
    // Set timeout acts as a sync barrier to allow commit to propagate
    t.step_timeout(function() {
        verifyPlaceholder(placeholder, 0,255,0,255, "0,255,0,255");
        t.done();
    }, 0);
}, "Test that calling OffscreenCanvas's commit pushes its contents to its placeholder.");

test(function() {
    var offscreenCanvas = new OffscreenCanvas(10, 10);
    var ctx = offscreenCanvas.getContext('2d');
    ctx.fillStyle = "#0f0";
    ctx.fillRect(0, 0, 10, 10);
    ctx.commit();
}, "Test that calling commit on an OffscreenCanvas that is not transferred from a HTMLCanvasElement is a noop.");

</script>
