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<!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, redImage) {
var bitmapCanvas = new OffscreenCanvas(width,height);
var bitmapCtx = bitmapCanvas.getContext('bitmaprenderer');
bitmapCtx.transferFromImageBitmap(greenImage);
// Make sure the bitmap renderer canvas is filled correctly.
testCanvas(bitmapCanvas, 0, 255, 0, 255);
// Test if passing null resets the bitmap renderer canvas.
// Drawing the resetted canvas cannot change the destination canvas.
bitmapCtx.transferFromImageBitmap(null);
testCanvas(bitmapCanvas, 0, 0, 0, 0);
// Test if we can redraw the bitmap canvas correctly after reset.
bitmapCtx.transferFromImageBitmap(redImage);
testCanvas(bitmapCanvas, 255, 0, 0, 255);
}
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);
var redCanvas = document.createElement('canvas');
redCanvas.width = width;
redCanvas.height = height;
var redCtx = redCanvas.getContext('2d');
redCtx.fillStyle = '#f00';
redCtx.fillRect(0, 0, width, height);
return Promise.all([
createImageBitmap(greenCanvas),
createImageBitmap(redCanvas),
]).then(([greenImage, redImage]) => {
testTransferFromImageBitmapNullability(greenImage, redImage);
});
},'Test that transferFromImageBitmap(null) discards the previously transferred image');
</script>
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