| <!DOCTYPE HTML> |
| <meta charset=utf-8> |
| <title>Largest Contentful Paint: repeated image.</title> |
| <style> |
| #image_id { |
| width: 10px; |
| height: 10px; |
| } |
| </style> |
| <body> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <script> |
| async_test(function (t) { |
| if (!window.LargestContentfulPaint) { |
| assert_unreached("LargestContentfulPaint is not implemented"); |
| } |
| const beforeFirstLoad = performance.now(); |
| let firstCallback = true; |
| const path = window.location.origin + '/images/black-rectangle.png'; |
| let beforeSecondLoad; |
| const observer = new PerformanceObserver( |
| t.step_func(entryList => { |
| assert_equals(entryList.getEntries().length, 1); |
| const entry = entryList.getEntries()[0]; |
| assert_equals(entry.entryType, 'largest-contentful-paint'); |
| assert_equals(entry.startTime, entry.renderTime, 'startTime should equal renderTime'); |
| assert_equals(entry.duration, 0); |
| assert_equals(entry.url, path); |
| assert_less_than(entry.renderTime, performance.now(), |
| 'Image render time should be before the observer callback is executed.') |
| if (firstCallback) { |
| assert_equals(entry.id, 'image_id'); |
| assert_greater_than(entry.renderTime, entry.loadTime, |
| 'The first image render time should occur after its load time.'); |
| assert_greater_than(entry.loadTime, beforeFirstLoad, |
| 'The first image load timestamp should occur after script starts running.'); |
| // Image is shrunk to be 10 x 10. |
| assert_equals(entry.size, 100); |
| const img = document.createElement('img'); |
| img.src = '/images/black-rectangle.png'; |
| beforeSecondLoad = performance.now(); |
| document.getElementById('image_div').appendChild(img); |
| firstCallback = false; |
| return; |
| } |
| // The second image is added at its natural size: 100 x 50. |
| assert_equals(entry.size, 5000); |
| assert_greater_than(entry.loadTime, beforeSecondLoad, |
| 'The second image load time should occur after adding it to the document body.'); |
| assert_greater_than(entry.renderTime, entry.loadTime, |
| 'The second image render time should occur after its load time.'); |
| t.done(); |
| }) |
| ); |
| observer.observe({type: 'largest-contentful-paint', buffered: true}); |
| }, 'Repeated image produces different timestamps.'); |
| </script> |
| <img src='/images/black-rectangle.png' id='image_id'/> |
| <div id='image_div'></div> |
| </body> |
