rectangular-image.html (1657B)
1 <!DOCTYPE HTML> 2 <meta charset=utf-8> 3 <title>Element Timing: observe a rectangular image</title> 4 <body> 5 <style> 6 body { 7 margin: 20px; 8 } 9 </style> 10 <script src="/resources/testharness.js"></script> 11 <script src="/resources/testharnessreport.js"></script> 12 <script src="resources/element-timing-helpers.js"></script> 13 <script> 14 let beforeRender; 15 let img; 16 async_test(function (t) { 17 assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented"); 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 pathname = window.location.origin + '/images/black-rectangle.png'; 23 checkElement(entry, pathname, 'my_image', 'rectangle', beforeRender, img); 24 // Assume viewport has size at least 100, so the element is fully visible. 25 checkRect(entry, [20, 120, 20, 70]); 26 checkNaturalSize(entry, 100, 50); 27 }) 28 ); 29 observer.observe({entryTypes: ['element']}); 30 // We add the image during onload to be sure that the observer is registered 31 // in time for it to observe the element timing. 32 window.onload = () => { 33 // Add image of width equal to 100 and height equal to 50. 34 img = document.createElement('img'); 35 img.src = '/images/black-rectangle.png'; 36 img.id = 'rectangle'; 37 img.setAttribute('elementtiming', 'my_image'); 38 document.body.appendChild(img); 39 beforeRender = performance.now(); 40 }; 41 }, 'Element with rectangular image has correct rect and instrinsic size.'); 42 </script> 43 </body>