containertiming-img-itself.html

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<!DOCTYPE HTML>

<meta charset=utf-8>

<title>Container Timing: observe an image with containertiming attribute</title>

<body>

<style>

body {

  margin: 0;

</style>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="/container-timing/resources/container-timing-helpers.js"></script>

<script src="/element-timing/resources/element-timing-helpers.js"></script>

<script>

  let beforeRender;

  async_test(function (t) {

    assert_implements(window.PerformanceContainerTiming, "PerformanceContainerTiming is not implemented");

    const observer = new PerformanceObserver(

      t.step_func_done(function(entryList) {

        assert_equals(entryList.getEntries().length, 1);

        const entry = entryList.getEntries()[0];

        checkContainerEntry(entry, 'image_ct', 'my_id', beforeRender);

        checkRect(entry, [0, 100, 0, 100])

        checkContainerSize(entry, 10000);

})

);

    observer.observe({entryTypes: ['container']});

    // Add the image during onload to be sure that the observer is registered

    // in time.

    window.onload = () => {

      // Add image of width equal to 100 and height equal to 100.

      const img = document.createElement('img');

      img.src = '/container-timing/resources/square100.png';

      img.setAttribute('containertiming', 'image_ct');

      img.setAttribute('id', 'my_id');

      document.body.appendChild(img);

      beforeRender = performance.now();

};

  }, 'Element with containertiming attribute is observable and reports the image paint.');

</script>

</body>