| <!DOCTYPE html> |
| <title>Layout Instability: shift accompanied by body display change</title> |
| <link rel="help" href="https://wicg.github.io/layout-instability/" /> |
| <style> |
| |
| body { margin: 0; } |
| #cont { |
| background: white; |
| width: 300px; |
| height: 200px; |
| } |
| #ch { |
| background: blue; |
| position: relative; |
| width: 300px; |
| height: 100px; |
| top: 100px; |
| } |
| |
| </style> |
| <style id="s"></style> |
| <div id="cont"> |
| <div id="ch"></div> |
| </div> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <script src="resources/util.js"></script> |
| <script> |
| |
| promise_test(async () => { |
| const watcher = new ScoreWatcher; |
| await waitForAnimationFrames(2); |
| |
| document.querySelector("#s").innerHTML = ` |
| body { |
| display: flex; |
| flex-direction: column; |
| } |
| #ch { top: 0; } |
| `; |
| |
| // An element of size (300 x 100) has shifted by 100px. |
| const expectedScore = computeExpectedScore(300 * (100 + 100), 100); |
| |
| // Observer fires after the frame is painted. |
| assert_equals(watcher.score, 0); |
| await watcher.promise; |
| assert_equals(watcher.score, expectedScore); |
| }, 'Shift accompanied by body display change.'); |
| |
| </script> |
