helper_bug1490393.html

Enable keyboard shortcuts

<!DOCTYPE HTML>

<html>

<head>

  <meta charset="utf-8">

  <meta name="viewport" content="width=device-width; initial-scale=1.0">

  <title>Dragging the mouse on a scrollbar for a scrollframe inside nested transforms</title>

  <script type="application/javascript" src="apz_test_native_event_utils.js"></script>

  <script type="application/javascript" src="apz_test_utils.js"></script>

  <script src="/tests/SimpleTest/paint_listener.js"></script>

  <script type="text/javascript">

async function test() {

  var scrollableDiv = document.getElementById("scrollable");

  let scrollPromise = new Promise(resolve => {

    scrollableDiv.addEventListener("scroll", resolve, {once: true});

});

  // Scroll down a small amount (10px). The bug in this case is that the

  // scrollthumb "jumps" by an additional 40 pixels (height of the "gap" div)

  // and the scrollframe scrolls by a corresponding amount. So after doing this

  // drag we check the scroll position to make sure it hasn't scrolled by

  // too much.

  // Given the scrollable height of 2000px and scrollframe height of 400px,

  // the scrollthumb should be approximately 80px tall, and dragging it 10px

  // should scroll approximately 50 pixels. If the bug manifests, it will get

  // dragged 50px and scroll approximately 250px.

  var dragFinisher = await promiseVerticalScrollbarDrag(scrollableDiv, 10, 10);

  if (!dragFinisher) {

    ok(true, "No scrollbar, can't do this test");

    return;

  // the events above might be stuck in APZ input queue for a bit until the

  // layer is activated, so we wait here until the scroll event listener is

  // triggered.

  await scrollPromise;

  await dragFinisher();

  // Flush everything just to be safe

  await promiseOnlyApzControllerFlushed();

  // In this case we just want to make sure the scroll position moved from 0

  // which indicates the thumb dragging worked properly.

  ok(scrollableDiv.scrollTop < 100, "Scrollbar drag resulted in a scroll position of " + scrollableDiv.scrollTop);

waitUntilApzStable()

.then(test)

.then(subtestDone, subtestFailed);

  </script>

</head>

<body>

    <div id="gap" style="min-height: 40px"></div>

    <div style="height: 400px; transform: translateZ(0)">

        <div style="height: 100%; opacity: 0.9; will-change: opacity">

            <div id="scrollable" style="height: 100%; overflow-y: auto; transform: translateZ(0)">

                <div style="min-height: 2000px">Yay text</div>

            </div>

        </div>

    </div>

</body>

</html>