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Test Info: Warnings

<!DOCTYPE HTML>
<title>Prevent drawing Elements into different canvases</title>
<script src='/resources/testharness.js'></script>
<script src='/resources/testharnessreport.js'></script>
<script src="/html/canvas/resources/wait-for-canvas-paint.js"></script>
<style>
#child1, #child2 {
width: 100px;
height: 100px;
background: green;
}
</style>
<canvas id="canvas1" width="200" height="200" layoutsubtree>
<div id="child1"></div>
</canvas>
<canvas id="canvas2" width="200" height="200" layoutsubtree>
<div id="child2"></div>
</canvas>
<script>
'use strict';
promise_test(async t => {
await waitForCanvasPaint(canvas1);
const ctx2 = canvas2.getContext('2d');
assert_throws_dom('InvalidStateError', () => {
ctx2.drawElementImage(child1, 0, 0);
}, 'Drawing an Element from a different canvas must throw InvalidStateError');
assert_throws_dom('InvalidStateError', () => {
canvas2.getElementTransform(child1, new DOMMatrix());
}, 'Getting transform for an Element from a different canvas must throw InvalidStateError');
assert_throws_dom('InvalidStateError', () => {
let standaloneCtx = new OffscreenCanvas(200, 200).getContext('2d');
standaloneCtx.drawElementImage(child1, 0, 0);
}, 'Drawing an Element into a standalone OffscreenCanvas must throw InvalidStateError');
assert_throws_dom('InvalidStateError', () => {
let standalone = new OffscreenCanvas(200, 200);
standalone.getElementTransform(child1, new DOMMatrix());
}, 'Getting transform for an Element from a standalone OffscreenCanvas must throw InvalidStateError');
}, 'Prevent drawing Element into a different canvas');
</script>