transferFromImageBitmap-TransferToImageBitmap-transferControlToOffscreen.html

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This WPT test may be referenced by the following Test IDs:
- /imagebitmap-renderingcontext/transferFromImageBitmap-TransferToImageBitmap-transferControlToOffscreen.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<meta charset="utf-8">

<title>Canvas's ImageBitmapRenderingContext test</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<link rel="help" href="https://html.spec.whatwg.org/multipage/scripting.html#the-imagebitmap-rendering-context">

<script>

var width = 10;

var height = 10;

function testCanvas(bitmapCanvas, r, g, b, a)

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

    myCanvas.width = width;

    myCanvas.height = height;

    var myCtx = myCanvas.getContext('2d');

    myCtx.drawImage(bitmapCanvas, 0, 0);

    var color = myCtx.getImageData(5, 5, 1, 1).data;

    assert_array_equals(color, [r, g, b, a]);

promise_test(function() {

    function testTransferFromImageBitmapNullability(greenImage) {

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

        bitmapCanvas.width = width;

        bitmapCanvas.height = height;

        var offscreenCanvas = bitmapCanvas.transferControlToOffscreen();

        var bitmapCtx = offscreenCanvas.getContext('bitmaprenderer');

        bitmapCtx.transferFromImageBitmap(greenImage);

        // Make sure the bitmap renderer canvas is filled correctly.

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

        var myCtx = myCanvas.getContext('bitmaprenderer');

        myCtx.transferFromImageBitmap(offscreenCanvas.transferToImageBitmap());

        testCanvas(myCanvas, 0, 255, 0, 255);

        // Test that after transfering for second time to ImageBitmap produces

        // a black bitmap of the same size

        var myCanvas2 = document.createElement('canvas');

        var myCtx2 = myCanvas2.getContext('bitmaprenderer');

        myCtx2.transferFromImageBitmap(offscreenCanvas.transferToImageBitmap());

        testCanvas(myCanvas2, 0, 0, 0, 0);

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

    greenCanvas.width = width;

    greenCanvas.height = height;

    var greenCtx = greenCanvas.getContext('2d');

    greenCtx.fillStyle = '#0f0';

    greenCtx.fillRect(0, 0, width, height);

    return Promise.all([

        createImageBitmap(greenCanvas),

    ]).then(([greenImage]) => {

        testTransferFromImageBitmapNullability(greenImage);

});

},'Test that transferToImageBitmap works and that resets the imagebitmap to black');

</script>