119 lines
3.9 KiB
HTML
119 lines
3.9 KiB
HTML
<!DOCTYPE html>
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<title>
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Updating the snap alignment of a snap container's content should make the snap
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container resnap accordingly.
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</title>
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<link rel="help" href="https://drafts.csswg.org/css-scroll-snap/#re-snap" />
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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<style>
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div {
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position: absolute;
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margin: 0;
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}
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#scroller {
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height: 200px;
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width: 200px;
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overflow: hidden;
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scroll-snap-type: both mandatory;
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}
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#initial-target {
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width: 300px;
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height: 300px;
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top: 100px;
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left: 100px;
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background-color: green;
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scroll-snap-align: start;
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}
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#other-target {
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width: 300px;
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height: 300px;
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top: 300px;
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left: 300px;
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background-color: red;
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scroll-snap-align: start;
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}
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.area {
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width: 2000px;
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height: 2000px;
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}
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.snap-area {
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scroll-snap-align: start !important;
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}
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</style>
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<div id="scroller">
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<div class="area"></div>
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<div id="initial-target"></div>
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<div id="other-target"></div>
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</div>
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<script>
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const initial_target = document.getElementById("initial-target");
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const other_target = document.getElementById("other-target");
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const scroller = document.getElementById("scroller");
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function cleanup() {
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initial_target.style.setProperty("scroll-snap-align", "start");
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other_target.style.setProperty("scroll-snap-align", "start");
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initial_target.removeAttribute("class");
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}
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test(t => {
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t.add_cleanup(cleanup);
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scroller.scrollTo(0,0);
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assert_equals(scroller.scrollTop, 100);
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assert_equals(scroller.scrollLeft, 100);
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initial_target.style.setProperty("scroll-snap-align", "end");
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// scroller maintains scroll position which is still valid as the target's
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// snap area covers the snap port.
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assert_equals(scroller.scrollTop, 100);
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assert_equals(scroller.scrollLeft, 100);
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}, "Changing a large target's snap alignment shouldn't make the scroller" +
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" resnap if the scroller is already in a valid snap position.");
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// Similar to above test case except targets are too small to cover snap port,
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// so scroller must snap in response to change in scroll-snap-align.
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test(t => {
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t.add_cleanup(cleanup);
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const initial_target_height = initial_target.offsetHeight;
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const initial_target_width = initial_target.offsetWidth;
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const other_target_height = initial_target.offsetHeight;
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const other_target_width = initial_target.offsetWidth;
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t.add_cleanup(() => {
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initial_target.style.setProperty("height", `${initial_target_height}px`);
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initial_target.style.setProperty("width", `${initial_target_width}px`);
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other_target.style.setProperty("height", `${other_target_height}px`);
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other_target.style.setProperty("width", `${other_target_width}px`);
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})
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scroller.scrollTo(0,0);
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assert_equals(scroller.scrollTop, 100);
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assert_equals(scroller.scrollLeft, 100);
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initial_target.style.setProperty("height", `${scroller.clientHeight * 2/3 }px`);
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initial_target.style.setProperty("width", `${scroller.clientWidth * 2/3 }px`);
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other_target.style.setProperty("height", `${scroller.clientHeight * 2/3 }px`);
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other_target.style.setProperty("width", `${scroller.clientWidth * 2/3 }px`);
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// scroll (and snap) to top left of other target.
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scroller.scrollTo(other_target.offsetTop,
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other_target.offsetLeft);
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assert_equals(scroller.scrollTop, other_target.offsetTop);
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assert_equals(scroller.scrollLeft, other_target.offsetLeft);
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other_target.style.setProperty("scroll-snap-align", "end");
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// should be scrolled so as to align scroller's bottom-right with
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// other_target's bottom-right.
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assert_approx_equals(scroller.scrollTop,
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other_target.offsetTop + other_target.offsetHeight - scroller.clientHeight, 1.0);
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assert_approx_equals(scroller.scrollLeft,
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other_target.offsetLeft + other_target.offsetWidth - scroller.clientWidth, 1.0);
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}, "Changing the current (non-covering) target's snap alignment should make " +
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"the scroller snap according to the new alignment.");
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</script>
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