tor-browser

The Tor Browser
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helper_displayport_estimation.html (4261B)

      1 <!DOCTYPE html>
      2 <html id="html">
      3 <title>Test for making sure that an instant scroll update on the main-thread is reflected to displayport</title>
      4 <meta charset="utf-8">
      5 <meta name="viewport" content="width=device-width,initial-scale=1">
      6 <script src="apz_test_utils.js"></script>
      7 <script src="apz_test_native_event_utils.js"></script>
      8 <script src="/tests/SimpleTest/EventUtils.js"></script>
      9 <script src="/tests/SimpleTest/paint_listener.js"></script>
     10 <style>
     11 html {
     12  overflow: scroll;
     13  scrollbar-width: none;
     14 }
     15 </style>
     16 <body>
     17 <div style="height: 50000px"></div>
     18 </body>
     19 <script>
     20 // Displayport alignment multiplier calculation; see AsyncPanZoomController::GetDisplayportAlignmentMultiplier
     21 function GetDisplayportAlignmentMultiplier(aBaseHeight) {
     22  return Math.min(aBaseHeight / 250, 8.0);
     23 }
     24 
     25 async function test() {
     26  const resolution = await getResolution();
     27  const deviceScale = window.devicePixelRatio;
     28 
     29  // Invoke scrollToVisual to diverge the visual scroll offset from the
     30  // layout scroll offset.
     31  const utils = SpecialPowers.getDOMWindowUtils(window);
     32  utils.scrollToVisual(0, 1000,
     33                       utils.UPDATE_TYPE_MAIN_THREAD,
     34                       utils.SCROLL_MODE_INSTANT);
     35  await promiseApzFlushedRepaints();
     36 
     37  const initialVisualOffset = visualViewport.offsetTop;
     38  info(`The visualViewport.offsetTop is now ${visualViewport.offsetTop}`);
     39  ok(visualViewport.offsetTop > 0, `The visual viewport has scrolled`);
     40  info(`The visualViewport.pageTop is now ${visualViewport.pageTop}`);
     41  const initialScrollY = window.scrollY;
     42  info(`The window.scrollY is now ${window.scrollY}`);
     43  ok(window.scrollY > 0, `The layout viewport has scrolled`);
     44  is(initialScrollY + initialVisualOffset, 1000,
     45     "The visual scroll offset + the layout scroll offset should equal to 1000");
     46 
     47  // Start in a requestAnimationFrame callback so that awaiting an additional
     48  // requestAnimationFrame callback should result a paint.
     49  await promiseFrame();
     50  const currentTime = document.timeline.currentTime;
     51 
     52  // Do an instant relative scroll operation on the main-thread.
     53  // NOTE: Until the next paint this scroll position update will not be sent
     54  // to APZ.
     55  window.scrollBy(0, 1000);
     56 
     57  // Wait a frame so that a paint should have happened.
     58  await promiseFrame();
     59 
     60  // Make sure now that refresh driver's time has advanced.
     61  ok(document.timeline.currentTime > currentTime,
     62    `${document.timeline.currentTime} > ${currentTime}`);
     63 
     64  // Displayport margins calculation; see DisplayPortMargins::GetRelativeToLayoutViewport
     65  // https://searchfox.org/mozilla-central/rev/380b8fd795e7d96d8a5a3e6ec2b50a9f2b65854a/layout/base/DisplayPortUtils.cpp#85-92
     66  const margin = initialVisualOffset * resolution * deviceScale;
     67 
     68  const clientHeightInScreen = document.documentElement.clientHeight * deviceScale;
     69  const multiplier = GetDisplayportAlignmentMultiplier(clientHeightInScreen);
     70 
     71  // These calculations need to be same as the ones in GetDisplayPortFromMarginsData().
     72  // https://searchfox.org/mozilla-central/rev/380b8fd795e7d96d8a5a3e6ec2b50a9f2b65854a/layout/base/DisplayPortUtils.cpp#169
     73  const currentScrollPosition = initialScrollY + 1000;
     74  const currentScrollPositionInScreen = currentScrollPosition * resolution * deviceScale;
     75  const notAlignedDisplayportPosition = currentScrollPositionInScreen + margin;
     76  const displayportAlignment = 128 * multiplier;
     77  const alignedDisplayportPosition =
     78      displayportAlignment * Math.floor(notAlignedDisplayportPosition / displayportAlignment);
     79 
     80  let displayport = getLastContentDisplayportFor(document.documentElement.id);
     81  isfuzzy(displayport.y,
     82     (alignedDisplayportPosition - currentScrollPositionInScreen) / (resolution * deviceScale),
     83     1.0 * deviceScale, // `getLastContentDisplayportFor` returns rounded interger values.
     84                        // `document.documentElement.clientHeight` also returns rounded values.
     85     "The displayport y should be reflecting the instant scroll distance");
     86 }
     87 
     88 // Scale 2.0x to diverge the visual scroll offset from the layout scroll
     89 // offset by calling nsIDOMWindowUtils.scrollToVisual.
     90 SpecialPowers.DOMWindowUtils.setResolutionAndScaleTo(2.0);
     91 waitUntilApzStable()
     92 .then(test)
     93 .then(subtestDone, subtestFailed);
     94 </script>
     95 </html>