offscreencanvas.transfer.to.imagebitmap.html

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This WPT test may be referenced by the following Test IDs:
- /html/canvas/offscreen/manual/the-offscreen-canvas/offscreencanvas.transfer.to.imagebitmap.html - WPT Dashboard Interop Dashboard

<!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/#dom-offscreencanvas-transfertoimagebitmap">

<script id="myWorker" type="text/worker">

self.onmessage = function(e) {

};

</script>

<script>

function makeWorker(script)

    var blob = new Blob([script]);

    return new Worker(URL.createObjectURL(blob));

test(function() {

    function testSize(contextType) {

        var offscreenCanvas = new OffscreenCanvas(100, 50);

        var ctx = offscreenCanvas.getContext(contextType);

        var image = offscreenCanvas.transferToImageBitmap();

        assert_equals(image.width, 100);

        assert_equals(image.height, 50);

    testSize('2d');

    testSize('webgl');

}, "Test that transferToImageBitmap returns an ImageBitmap with correct width and height");

test(function() {

    function testImageBitmapClr(shouldCallTwice, alphaVal) {

        var offscreenCanvas = new OffscreenCanvas(100, 50);

        var ctx = offscreenCanvas.getContext('2d', {alpha: alphaVal});

        ctx.fillStyle = "#0f0";

        ctx.fillRect(0, 0, 100, 50);

        var image = offscreenCanvas.transferToImageBitmap();

        if (shouldCallTwice)

            image = offscreenCanvas.transferToImageBitmap();

        var drawCanvas = document.createElement('canvas');

        drawCanvas.width = 100;

        drawCanvas.height = 50;

        var dCtx = drawCanvas.getContext('2d');

        dCtx.drawImage(image, 0, 0);

        if (shouldCallTwice) {

            if (alphaVal)

                _assertPixel(drawCanvas, 50,25, 0,0,0,0);

            else

                _assertPixel(drawCanvas, 50,25, 0,0,0,255);

        } else {

            _assertPixel(drawCanvas, 50,25, 0,255,0,255);

    testImageBitmapClr(false, true);

    testImageBitmapClr(true, true);

    testImageBitmapClr(true, false);

}, "Test that transferToImageBitmap returns an ImageBitmap with correct color");

test(function() {

    var offscreenCanvas = new OffscreenCanvas(100, 50);

    var ctx = offscreenCanvas.getContext('2d');

    ctx.lineWidth = 10;

    var image = offscreenCanvas.transferToImageBitmap();

    assert_equals(ctx.lineWidth, 10);

}, "Test that transferToImageBitmap won't change context's property");

test(function() {

    var offscreenCanvas = new OffscreenCanvas(100, 50);

    var ctx = offscreenCanvas.getContext('2d');

    ctx.rect(0, 0, 25, 50);

    ctx.clip();

    ctx.translate(20, 20);

    ctx.fillStyle = '#0f0';

    var image1 = offscreenCanvas.transferToImageBitmap();

    // trasnform should be preserved

    ctx.fillRect(0, 0, 10, 10);

    var image2 = offscreenCanvas.transferToImageBitmap();

    var drawCanvas = document.createElement('canvas');

    drawCanvas.width = 100;

    drawCanvas.height = 50;

    var dCtx = drawCanvas.getContext('2d');

    dCtx.drawImage(image2, 0, 0);

    // Verify that transform was carried over.

    _assertPixel(drawCanvas, 23,25, 0,255,0,255);

    // Verify that clip was carried over.

    _assertPixel(drawCanvas, 27,25, 0,0,0,0);

}, "Test that transferToImageBitmap preserves transform");

async_test(function(t) {

    var worker = makeWorker(document.getElementById("myWorker").textContent);

    var offscreenCanvas = new OffscreenCanvas(10, 10);

    worker.postMessage(offscreenCanvas, [offscreenCanvas]);

    assert_throws_dom("InvalidStateError", function() { offscreenCanvas.transferToImageBitmap(); });

    t.done();

}, "Test that call transferToImageBitmap on a detached OffscreenCanvas throws an exception");

test(function() {

    var offscreenCanvas = new OffscreenCanvas(10, 10);

    assert_throws_dom("InvalidStateError", function() { offscreenCanvas.transferToImageBitmap(); });

}, "Test that transferToImageBitmap without a context throws an exception");

</script>