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<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Skip re-snapping during pan gesture</title>
<script src="apz_test_utils.js"></script>
<script src="apz_test_native_event_utils.js"></script>
<script src="/tests/SimpleTest/paint_listener.js"></script>
<style>
body {
margin: 0;
}
div {
position: absolute;
}
#scroller {
width: 100%;
height: 500px;
overflow-y: scroll;
scroll-snap-type: y mandatory;
}
.child {
width: 100%;
height: 100px;
background-color: blue;
scroll-snap-align: start;
}
</style>
</head>
<body>
<div id="scroller">
<div class="child" style="top: 0px;"></div>
<div id="spacer" style="width: 100%; height: 2000px;"></div>
</div>
<script type="application/javascript">
async function test() {
is(scroller.scrollTop, 0, "The initial snap point is at 0px");
let scrollEventPromise = waitForScrollEvent(scroller);
// Start a pan gesture downward.
await promiseNativePanGestureEventAndWaitForObserver(
scroller,
100,
100,
0,
-10,
1 /* kCGScrollPhaseBegan */);
await scrollEventPromise;
ok(scroller.scrollTop > 0, "The pan-start should scroll");
// Expand the scrollable region during the panning.
spacer.style.height = "2200px";
isnot(scroller.scrollTop, 0, "Do not re-snap to the original 0px");
let previousScrollPosition = scroller.scrollTop;
scrollEventPromise = waitForScrollEvent(scroller);
// Finish the pan gesture now.
await promiseNativePanGestureEventAndWaitForObserver(
scroller,
100,
100,
0,
0 /* 0 velocity to avoid further scrolling by this event */,
4 /* kCGScrollPhaseEnd */);
await scrollEventPromise;
// Make sure the new scroll positions have reached to the main-thread.
await promiseApzFlushedRepaints();
// There's no good way to tell whether the snapping has finished, has
// reached to the snap destination, so we just check whether the current
// scroll position is a bit scrolled back toward the snap destination.
ok(scroller.scrollTop < previousScrollPosition,
"The pan-end should trigger snapping toward 0px");
}
if (getPlatform() == "mac") {
waitUntilApzStable()
.then(test)
.then(subtestDone, subtestFailed);
} else {
ok(true, "Skipping test because this test works only on mac");
subtestDone();
}
</script>
</body>
</html>