element-timing/image-with-rotation.html

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Element Timing: image with rotation.</title>
<head>
<style>
body {
  margin: 0px;
}
.my_div {
  width: 100px;
  height: 50px;
  transform: rotate(45deg);
  transform-origin: top left;
}
</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'));
        checkNaturalSize(entry, 100, 50);
        const rect = entry.intersectionRect;
        // The div rotates with respect to the origin, so part of it will be invisible.
        // The width of the visible part will be 100 / sqrt(2) and the height will be
        // 100 / sqrt(2) + 50 / sqrt(2).
        assert_equals(rect.left, 0);
        // Checking precision only to the nearest integer.
        assert_equals(Math.round(rect.right), 71);
        assert_equals(rect.top, 0);
        assert_equals(Math.round(rect.bottom), 106);
      })
    );
    observer.observe({entryTypes: ['element']});
  }, 'Image intersectionRect is affected by rotation, 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>