<!DOCTYPE html>
<html>
<head>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/dom/events/scrolling/scroll_support.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<script src="resources/common.js"></script>
</head>
<body>
<style>
.placeholder {
top: 0px;
left: 0px;
position: absolute;
width: 10px;
height: 10px;
background-color: black;
scroll-snap-align: start;
}
.space {
position: absolute;
height: 300vh;
width: 300vw;
top: 100px;
left: 100px;
}
.scroller {
overflow: scroll;
scroll-snap-type: both mandatory;
width: 550px;
height: 550px;
border: solid 1px black;
position: relative;
resize: both;
}
.box {
background-color: green;
height: 200px;
width: 200px;
scroll-snap-align: start;
position: absolute;
border: solid 1px white;
}
.row {
top: 100px;
}
.col {
left: 100px;
}
/* Place boxes 0 through 4 on a horizontal row. */
#box0 {
left: 300px;
}
#box1 {
left: 500px;
}
#box2 {
left: 700px;
}
#box3 {
left: 900px;
}
#box4 {
left: 1100px;
}
/* Place boxes 5 through 9 in a vertical column. */
#box5 {
top: 300px;
}
#box6 {
top: 500px;
}
#box7 {
top: 700px;
}
#box8 {
top: 900px;
}
#box9 {
top: 1100px;
}
</style>
<div id="scroller" class="scroller">
<!-- This placeholder is a snap target at the top-left of the
scroller. It gives the scroller an opportunity to scroll to the
snap targets, forcing the UA to run the snap point selection
algorithm. Each test case ensures the snap point selection algorithm is
invoked by:
- first resetting the scroller's scroll position to snap to the
placeholder,
- then configuring the tree-order and layout of the snap
targets as necessary,
- then scrolling to the snap areas and,
- finally, verifying that the correct snap area was selected.
Without the scroll from the placeholder to the snap targets, the UA would
be correct to simply make the scroller follow the previously selected snap
target (i.e. when there was no snap area aligned in both axes) even after
the layout changes made by the test. -->
<div class="placeholder"></div>
<div id="box0" class="row box">Box 0</div>
<div id="box1" class="row box">Box 1</div>
<div id="box2" class="row box">Box 2</div>
<div id="box3" class="row box">Box 3</div>
<div id="box4" class="row box">Box 4</div>
<div id="box5" class="col box">Box 5</div>
<div id="box6" class="col box">Box 6</div>
<div id="box7" class="col box">Box 7</div>
<div id="box8" class="col box">Box 8</div>
<div id="box9" class="col box">Box 9</div>
<div class="space" id="space">
</div>
<script>
window.onload = async () => {
const scroller = document.getElementById("scroller");
const boxes = document.querySelectorAll(".box");
const box = (n) => {
return boxes[n];
}
async function test(n) {
return promise_test(async (t) => {
await waitForScrollReset(t, scroller);
await waitForCompositorCommit();
const target = document.getElementById(`box${n}`);
assert_equals(scroller.scrollLeft, 0, "scrollLeft is reset");
assert_equals(scroller.scrollTop, 0, "scrollTop is reset");
// Make target the last in tree-order.
scroller.removeChild(target);
scroller.appendChild(target);
const old_style = getComputedStyle(target);
const old_top = old_style.top;
const old_left = old_style.left;
// Make target snap-aligned in both axes.
t.add_cleanup(async () => {
target.style.top = old_top;
target.style.left = old_left;
});
target.style.left = "100px";
target.style.top = "100px";
await runScrollSnapSelectionVerificationTest(t, scroller,
/*aligned_elements_x=*/[box(5), box(6), box(7), box(8), box(9)],
/*aligned_elements_y=*/[box(0), box(1), box(2), box(3), box(4)],
/*axis=*/"both",
/*expected_target_x*/target,
/*expected_target_y*/target);
}, `box${n} is common to both axes and is the snap target despite ` +
`being last in tree order.`);
}
await test(0);
await test(1);
await test(2);
await test(3);
await test(4);
await test(5);
await test(6);
await test(7);
await test(8);
await test(9);
}
</script>
</body>
<html>
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