testing/web-platform/tests/largest-contentful-paint/contracted-image.html

   1 <!DOCTYPE HTML>
   2 <meta charset=utf-8>
   3 <title>Largest Contentful Paint: contracted image bounded by display size.</title>
   4 <style type="text/css">
   5   #image_id {
   6     width: 50px;
   7     height: 50px;
   8   }
   9 </style>
  10 <body>
  11 <script src="/resources/testharness.js"></script>
  12 <script src="/resources/testharnessreport.js"></script>
  13 <script src="resources/largest-contentful-paint-helpers.js"></script>
  14 <script>
  15   async_test(function (t) {
  16     assert_precondition(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented");
  17     const beforeLoad = performance.now();
  18     const observer = new PerformanceObserver(
  19       t.step_func_done(function(entryList) {
  20         assert_equals(entryList.getEntries().length, 1);
  21         const entry = entryList.getEntries()[0];
  22         const url = window.location.origin + '/images/black-rectangle.png';
  23         // black-rectangle.png is 100 x 50. It occupies 50 x 50 so size will be bounded by the displayed size.
  24         const size = 50 * 50;
  25         checkImage(entry, url, 'image_id', size, beforeLoad);
  26       })
  27     );
  28     observer.observe({type: 'largest-contentful-paint', buffered: true});
  29   }, 'Largest Contentful Paint: |size| attribute is bounded by display size.');
  30 </script>
  31 <img src='/images/black-rectangle.png' id='image_id'/>
  32 </body>