| <!DOCTYPE HTML> |
| <meta charset=utf-8> |
| <title>Largest Contentful Paint: largest text is reported.</title> |
| |
| <body> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <style type="text/css"> |
| #text2 { |
| position: absolute; |
| width: auto; |
| white-space: nowrap; |
| } |
| |
| </style> |
| <!-- These are some text and some tiny images. We care about the largest text. --> |
| <img id='green1' /> |
| <div id='text1'></div> |
| <div id='text2'></div> |
| <img id='green2' /> |
| <script> |
| const load_image = async (id, url) => { |
| await new Promise(resolve => { |
| const image = document.getElementById(id); |
| image.addEventListener('load', resolve); |
| image.src = url; |
| }); |
| } |
| |
| const load_text = (id, text) => { |
| let div = document.getElementById(id); |
| div.innerHTML = text; |
| } |
| |
| promise_test(async (t) => { |
| assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented"); |
| let beforeRender = performance.now(); |
| |
| // Load images and add texts. |
| await load_image('green1', '/images/green-1x1.png'); |
| |
| load_text('text1', 'This is some text.'); |
| |
| load_text('text2', 'This is more text so it will be the Largest Contentful Paint!'); |
| |
| await load_image('green2', '/images/green-2x2.png'); |
| |
| await new Promise(resolve => { |
| new PerformanceObserver( |
| (entryList, observer) => { |
| entryList.getEntries().forEach(entry => { |
| // The tiny images or text1 could be reported as LCP if it is rendered before text2. |
| if (entry.id !== 'text2') |
| return; |
| |
| assert_equals(entry.entryType, 'largest-contentful-paint', |
| 'The entry entryType should be largest-contentful-paint.'); |
| |
| assert_greater_than_equal(entry.renderTime, beforeRender, |
| 'The entry renderTime should be greater than or equal to the beforeRender.'); |
| |
| assert_greater_than_equal(performance.now(), entry.renderTime, |
| 'The performance.now() timestamp should be greater than or equal to the entry renderTime.'); |
| |
| assert_approx_equals(entry.startTime, entry.renderTime, 0.001, |
| 'The entry startTime should be equal to renderTime to the precision of 1 millisecond.'); |
| |
| assert_equals(entry.duration, 0, 'The entry duration should be 0.'); |
| |
| const div = document.getElementById('text2'); |
| |
| // The div styling makes it approximate the text size. |
| assert_greater_than_equal(entry.size, (div.clientHeight - 5) * (div.clientWidth - 5), |
| 'Reported LCP size should not be significantly smaller than the text2 div.'); |
| |
| assert_less_than_equal(entry.size, (div.clientHeight + 1) * (div.clientWidth + 1), |
| 'Reported LCP size should not be larger than the text2 div.'); |
| |
| assert_equals(entry.loadTime, 0, 'The entry loadTime should be 0.'); |
| |
| assert_equals(entry.url, '', 'The entry url should be empty.'); |
| |
| assert_equals(entry.element, div, 'The entry element should be test2 div.'); |
| |
| observer.disconnect(); |
| |
| resolve(); |
| }) |
| }).observe({ type: 'largest-contentful-paint', buffered: true }); |
| }); |
| }, 'Largest Contentful Paint: largest text is reported.'); |
| </script> |
| </body> |