helper_bug1662800.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 with a scale component</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 (7px). The bug in this case is that the

  // scrollthumb "jumps" most of the way down the scroll track because with

  // the bug, the code was incorrectly combining the transforms.

  // Given the scrollable height of 0.7*2000px and scrollframe height of 0.7*400px,

  // the scrollthumb should be approximately 0.7*80px = 56px tall. Dragging it 7px

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

  // dragged by a lot more and scroll to approximately 1300px.

  var dragFinisher = await promiseVerticalScrollbarDrag(scrollableDiv, 7, 7, 0.7);

  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();

  // Ensure the scroll position ended up roughly where we wanted it (around

  // 50px, but definitely less than 1300px).

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

waitUntilApzStable()

.then(test)

.then(subtestDone, subtestFailed);

  </script>

</head>

<body>

    <div style="width: 500px; height: 300px; transform: translate(500px, 500px) scale(0.7)">

        <div id="scrollable" style="transform: translate(-600px, -600px); overflow: scroll">

            <div style="width: 600px; height: 400px">

                <div style="width: 600px; height: 2000px; background-image: linear-gradient(red,blue)"></div>

            </div>

        </div>

    </div>

</body>

</html>