chromium/third_party/blink/web_tests/external/wpt/html/editing/dnd/canvas/003.html

<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="../resources/test-helper.js"></script>
<head>
<title>Drag and drop from iframe: dropping block element onto canvas</title>
<style type="text/css">
iframe
  {width:150px;
  height:150px;
  border-style:none;}
</style>
<script>
function paint(color)
  {var canvas = document.querySelector('canvas'),
  c = canvas.getContext('2d');
  c.fillStyle = color;
  c.beginPath();
  c.moveTo(0,0);
  c.lineTo(100,0);
  c.lineTo(100,100);
  c.lineTo(0,100);
  c.closePath();
  c.fill();}
function start(event)
  {event.dataTransfer.effectAllowed = 'copy';
  event.dataTransfer.setData('text/plain', 'green');}
</script>
</head>
<body onload="paint('gray')">
<p><iframe src="003-1.xhtml">Green box</iframe></p>
<p>Drag green box above to the gray canvas below. Canvas should turn green when you drop green box on it.</p>
<p>
  <canvas width="100" height="100" ondragenter="event.preventDefault()" ondragover="return false">Canvas</canvas>
</p>
<script>
async function test(){
  await new Promise(loaded => window.addEventListener("load", loaded));
  const iframe = document.querySelector('iframe');
  const innerDoc = iframe.contentDocument || iframe.contentWindow.document;
  const div = innerDoc.querySelector('div');
  const canvas = document.querySelector('canvas');
  function onDropCallBack(event) {
    paint(event.dataTransfer.getData('text/plain'));
    let style = window.getComputedStyle(canvas);
    let currentColor = "rgba(0, 0, 0, 0)";
    assert_equals(style.getPropertyValue("background-color"), currentColor);
    return true;
  }

  dragDropTest(iframe, canvas, onDropCallBack, 'Dragging the canvas to the bottom iframe should turn it green');
}
test();
</script>
</body>
</html>