| <!DOCTYPE html> |
| <title>Layout Instability: no layout shift if translate change counters location change</title> |
| <link rel="help" href="https://wicg.github.io/layout-instability/" /> |
| <style> |
| body { margin: 0; } |
| #transformed { position: relative; translate: 20px 0; width: 100px; height: 100px; background: blue; } |
| #child { width: 400px; height: 400px; } |
| </style> |
| <div id="transformed"> |
| <div id="child"></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; |
| |
| // Wait for the initial render to complete. |
| await waitForAnimationFrames(2); |
| |
| // Modify the transform and the location at the same time, and the values |
| // cancel each other visually, for which no shift should be reported. |
| transformed.style.translate = '0 100px'; |
| transformed.style.top = '-100px'; |
| transformed.style.left = '20px'; |
| // Change size of child, for which no shift should be reported, either. |
| child.style.width = '300px'; |
| |
| await waitForAnimationFrames(2); |
| // No shift should be reported. |
| assert_equals(watcher.score, 0); |
| }, 'no layout shift if translate change counters location change'); |
| |
| </script> |
