forked from mirrors/gecko-dev
1c40fa8a53
See link in the comment. We were checking both offsets, but blink only checks one. In this case, the page has a table with `overflow-x: auto` and `overflow-y: hidden`. They implement a custom virtual scrolling on the vertical axis, and scroll-anchoring interacts poorly with it. Adapt zero-scroll-offset.html to test for this. Differential Revision: https://phabricator.services.mozilla.com/D217201
56 lines
1.9 KiB
HTML
56 lines
1.9 KiB
HTML
<!DOCTYPE html>
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<head>
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<title>Test that scroll anchoring is suppressed when scroll offset is zero in the block axis, even if the inline axis scroll offset isn't.</title>
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<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@mozilla.com">
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<link rel="author" title="Mozilla" href="https://mozilla.org">
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<link rel="help" href="https://drafts.csswg.org/css-scroll-anchoring/">
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<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1905426">
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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</head>
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<style>
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#header {
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height: 100px;
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border: 1px solid black;
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overflow-anchor: none;
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}
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#content {
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height: 200vh;
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width: 200vw;
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}
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</style>
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<div id="header"></div>
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<div id="content">abc</div>
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<script>
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window.addEventListener("scroll", function() {
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if (document.scrollingElement.scrollTop > 0) {
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// On the first scroll event, shrink the header. Scroll anchoring anchors to
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// content, but the header shrinks by more than the scroll offset so the
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// resulting scroll position is zero.
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step_timeout(function() {
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document.querySelector("#header").style.height = "50px";
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}, 0);
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} else {
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// On the second scroll event, grow the header. Since the scroll offset is
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// zero, scroll anchoring should be suppressed. Otherwise, scroll anchoring
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// would anchor to content and the resulting scroll position would be 50px.
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step_timeout(function() {
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document.querySelector("#header").style.height = "100px";
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}, 0);
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}
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});
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async_test(function(t) {
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// Scroll down a bit to trigger the scroll event listener.
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window.scrollTo(10, 10);
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window.requestAnimationFrame(function() {
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window.requestAnimationFrame(function() {
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window.requestAnimationFrame(t.step_func_done(() => {
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assert_equals(document.scrollingElement.scrollTop, 0);
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}));
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});
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});
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}, "Scroll anchoring suppressed when scroll offset is zero.");
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</script>
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