element-timing/image-with-css-scale.html

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Element Timing: image with scaling.</title>
<head>
<style>
/* The margin of 50px allows the rect to be fully shown when the div is scaled. */
body {
  margin: 50px;
}
.my_div {
  width: 100px;
  height: 50px;
  transform: scale(2);
}
</style>
</head>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/element-timing-helpers.js"></script>
<script>
  const beforeRender = performance.now();
  async_test(function (t) {
    assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
    const observer = new PerformanceObserver(
      t.step_func_done(function(entryList) {
        assert_equals(entryList.getEntries().length, 1);
        const entry = entryList.getEntries()[0];
        const pathname = window.location.origin + '/images/black-rectangle.png';
        checkElement(entry, pathname, 'rectangle', 'rect_id', beforeRender,
            document.getElementById('rect_id'));
        checkRect(entry, [0, 200, 25, 125]);
        checkNaturalSize(entry, 100, 50);
      })
    );
    observer.observe({entryTypes: ['element']});
  }, 'Image intersectionRect is affected by scaling, but not its intrinsic size.');
</script>
<div class="my_div" id='div_id'>
  <img src="/images/black-rectangle.png" elementtiming="rectangle" id='rect_id'/>
</div>
</body>