element-timing/image-not-fully-visible.html

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Element Timing: intersectionRect when image overflows</title>
<body>
<style>
body {
  margin: 200px 100px;
}
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/element-timing-helpers.js"></script>
<script>
  let beforeRender;
  let img;
  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 + '/element-timing/resources/square20.png';
        checkElement(entry, pathname, 'not_fully_visible', '', beforeRender, img);
        // Image will not be fully visible. It should start from the top left part
        // of the document, excluding the margin, and then overflow.
        checkRect(entry,
          [100, document.documentElement.clientWidth, 200, document.documentElement.clientHeight]);
        checkNaturalSize(entry, 20, 20);
      })
    );
    observer.observe({entryTypes: ['element']});
    // We add the image during onload to be sure that the observer is registered
    // in time for it to observe the element timing.
    window.onload = () => {
      // Add an image setting width and height equal to viewport.
      img = document.createElement('img');
      img.src = 'resources/square20.png';
      img.setAttribute('elementtiming', 'not_fully_visible');
      img.width = document.documentElement.clientWidth;
      img.height = document.documentElement.clientHeight;
      document.body.appendChild(img);
      beforeRender = performance.now();
    };
  }, 'The intersectionRect of an img element overflowing is computed correctly');
</script>

</body>