| Index: third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/onscroll-bouncing.html
|
| diff --git a/third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/onscroll-bouncing.html b/third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/onscroll-bouncing.html
|
| new file mode 100644
|
| index 0000000000000000000000000000000000000000..902b7cdeed2fc06a438fca783d8d0dcc8984ae29
|
| --- /dev/null
|
| +++ b/third_party/WebKit/LayoutTests/fast/layout/scroll-anchoring/onscroll-bouncing.html
|
| @@ -0,0 +1,98 @@
|
| +<!DOCTYPE html>
|
| +<script src="../../../resources/testharness.js"></script>
|
| +<script src="../../../resources/testharnessreport.js"></script>
|
| +<style>
|
| +
|
| +body { margin: 80px 0; height: 5000px; }
|
| +#a, #b { height: 200px; width: 200px; }
|
| +#c { height: 400px; }
|
| +#left, #c { display: inline-block; width: 200px; vertical-align: top; }
|
| +#a.f { position: fixed; top: 30px; left: 150px; }
|
| +#a { background-color: #fcc; }
|
| +#b { background-color: #cfc; }
|
| +#c { background-color: #ccf; }
|
| +
|
| +</style>
|
| +<div id="left">
|
| + <div id="a"></div>
|
| + <div id="b"></div>
|
| +</div><div id="c"></div>
|
| +<script>
|
| +
|
| +internals.runtimeFlags.scrollAnchoringEnabled = true;
|
| +
|
| +// The scroll handler marks #a as position: fixed when scroll offset > 300px.
|
| +// This triggers layout during which we anchor to #b, which has moved up 200px.
|
| +// After our anchoring adjustment, the scroll offset is < 300px again, so the
|
| +// scroll handler removes position: fixed from #a, triggering a second layout,
|
| +// during which #b "bounces" back to its original location.
|
| +//
|
| +// The desired behavior here is for ScrollAnchor to follow #b back the first
|
| +// time it bounces, but not follow a second bounce.
|
| +//
|
| +// There are two failure modes we are concerned about:
|
| +//
|
| +// - If ScrollAnchor doesn't follow #b back to its original position during the
|
| +// FIRST bounce, we've "trapped" the user above 300px. Every time they try to
|
| +// scroll past this point we will push them back up.
|
| +//
|
| +// - If ScrollAnchor follows #b religiously, we get stuck in an infinite cycle
|
| +// of continuous bouncing, which looks hilariously broken.
|
| +
|
| +var a = document.querySelector('#a');
|
| +var fixed = false;
|
| +onscroll = function() {
|
| + var y = scrollY;
|
| + if (fixed == (y > 300))
|
| + return;
|
| + if (y < 130) {
|
| + // Clear the scroll anchor.
|
| + scrollBy(0, 10);
|
| + scrollBy(0, -10);
|
| + }
|
| + a.className = (fixed = !fixed) ? "f" : "";
|
| +};
|
| +
|
| +var frame = () => new Promise((resolve) => { requestAnimationFrame(resolve); });
|
| +
|
| +var waitFor = function(condition, failmsg, deadline) {
|
| + if (!deadline) deadline = Date.now() + 1000;
|
| + if (condition()) return Promise.resolve();
|
| + else if (Date.now() > deadline) return Promise.reject(failmsg);
|
| + else return frame().then(() => waitFor(condition, failmsg, deadline));
|
| +};
|
| +
|
| +var waitFrames = function(n, condition, failmsg) {
|
| + var p = Promise.resolve();
|
| + var check = () => (!condition || condition() ?
|
| + Promise.resolve() : Promise.reject(failmsg));
|
| + while (n--)
|
| + p = p.then(check).then(frame);
|
| + return p.then(check);
|
| +};
|
| +
|
| +var scrollSettlesAt = function(expectedY) {
|
| + return waitFor(() => (scrollY == expectedY),
|
| + "scroll did not reach " + expectedY)
|
| + .then(() => waitFrames(3))
|
| + .then(() => waitFrames(3, () => (scrollY == expectedY),
|
| + "scroll did not stay at " + expectedY));
|
| +};
|
| +
|
| +promise_test(function() {
|
| + return Promise.resolve()
|
| +
|
| + // The 320px offset tests for the first failure mode.
|
| + .then(() => { eventSender.continuousMouseScrollBy(0, -320); })
|
| + .then(() => scrollSettlesAt(320))
|
| +
|
| + .then(() => { scrollTo(0, 0); })
|
| + .then(() => frame())
|
| +
|
| + // The 360px offset tests for the second failure mode.
|
| + .then(() => { eventSender.continuousMouseScrollBy(0, -360); })
|
| + .then(() => scrollSettlesAt(360));
|
| +
|
| +}, "Scroll anchoring with scroll event handlers");
|
| +
|
| +</script>
|
|
|
Chromium Code Reviews
Issue 1971423002:
Implement bounce suppression in ScrollAnchor. (Closed)
Base URL: https://chromium.googlesource.com/chromium/src.git@master