pointerdown-becomes-scroll.html (1866B)
1 <!DOCTYPE html> 2 <title>Layout Instability: shift in pointerdown becoming scroll</title> 3 <link rel="help" href="https://wicg.github.io/layout-instability/" /> 4 <style> 5 6 body { margin: 0; height: 2000px; } 7 #box { 8 left: 0px; 9 top: 0px; 10 width: 400px; 11 height: 500px; 12 background: yellow; 13 position: relative; 14 } 15 16 </style> 17 <div id="box"></div> 18 <script src="/resources/testharness.js"></script> 19 <script src="/resources/testharnessreport.js"></script> 20 <script src="/resources/testdriver.js"></script> 21 <script src="/resources/testdriver-actions.js"></script> 22 <script src="/resources/testdriver-vendor.js"></script> 23 <script src="resources/util.js"></script> 24 <script> 25 26 const box = document.querySelector("#box"); 27 box.addEventListener("pointerdown", (e) => { 28 // Generate a layout shift before we know what type of input this pointer 29 // event sequence will become. 30 box.style.top = "100px"; 31 e.preventDefault(); 32 }); 33 34 generateScrollSequence = () => new test_driver.Actions() 35 .addPointer("tp1", "touch") 36 .pointerMove(0, 100, {sourceName: "tp1"}) 37 .pointerDown({sourceName: "tp1"}) 38 .pointerMove(0, 0, {sourceName: "tp1"}) 39 .pause(100) 40 .pointerUp({sourceName: "tp1"}) 41 .pause(100); 42 43 promise_test(async () => { 44 const watcher = new ScoreWatcher; 45 46 // Wait for the initial render to complete. 47 await waitForAnimationFrames(2); 48 49 // Send pointer events for a touch scroll. 50 await generateScrollSequence().send(); 51 52 // The box is 400 x 500 and moves by 100px. 53 const expectedScore = computeExpectedScore(400 * (500 + 100), 100); 54 55 // Both scores should increase (scroll doesn't count as input for the purpose 56 // of the LayoutShift.hadRecentInput bit). 57 assert_equals(watcher.score, expectedScore); 58 assert_equals(watcher.scoreWithInputExclusion, expectedScore); 59 60 }, "Shift in pointerdown reported when it becomes a scroll."); 61 62 </script>