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<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap-1" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
div {
position: absolute;
}
.scroller-x {
overflow: scroll;
scroll-snap-type: x mandatory;
width: 500px;
height: 500px;
}
.scroller-y {
overflow: scroll;
scroll-snap-type: y mandatory;
width: 500px;
height: 500px;
}
.space {
width: 4000px;
height: 4000px;
}
.target {
scroll-snap-align: start;
}
.large-x {
width: 3000px;
height: 400px;
background-color: yellow;
}
.large-y {
width: 400px;
height: 2000px;
background-color: green;
}
.small {
height: 200px;
width: 200px;
background-color: black;
}
</style>
<div class="scroller-x" id="one-target">
<div class="space"></div>
<div class="large-x target" id="single" style="left: 200px;"></div>
</div>
<div class="scroller-x" id="x">
<div class="space"></div>
<div style="left: 200px;">
<div class="target large-x"></div>
<div class="target small" style="left: 200px"></div>
<div class="target small" style="left: 600px"></div>
<div class="target small" style="left: 1200px"></div>
</div>
</div>
<div class="scroller-y" id="y">
<div class="space"></div>
<div style="top: 200px;">
<div class="target large-y"></div>
<div class="target small" style="top: 200px"></div>
<div class="target small" style="top: 600px"></div>
<div class="target small" style="top: 1200px"></div>
<div class="target large-y" style="top: 2000px"></div>
</div>
</div>
<div class="scroller-x" id="two-axes" style="scroll-snap-type: both mandatory">
<div class="space"></div>
<div class="target large-x" style="top: 200px"></div>
</div>
<script>
var one_target_scroller = document.getElementById("one-target");
var scroller_x = document.getElementById("x");
var scroller_y = document.getElementById("y");
var two_axes_scroller = document.getElementById("two-axes");
test(() => {
one_target_scroller.scrollTo(10, 0);
assert_equals(one_target_scroller.scrollLeft, 200);
assert_equals(one_target_scroller.scrollTop, 0);
}, "Snaps to the snap position if the snap area doesn't cover the snapport on x.");
test(() => {
var right_align = 3200 - one_target_scroller.clientWidth;
one_target_scroller.scrollTo(right_align, 0);
assert_equals(one_target_scroller.scrollLeft, right_align);
assert_equals(one_target_scroller.scrollTop, 0);
}, "Snaps to the snap position if the snap area covers the snapport on x on the right border.");
// We use end alignment for this test so that we don't fall on a snap
// position when the snap area just covers the snapport on the left border.
test(() => {
document.getElementById("single").style.scrollSnapAlign = 'end';
one_target_scroller.scrollTo(200, 0);
assert_equals(one_target_scroller.scrollLeft, 200);
assert_equals(one_target_scroller.scrollTop, 0);
}, "Snaps to the snap position if the snap area covers the snapport on x on the left border.");
test(() => {
scroller_x.scrollTo(500, 0);
assert_equals(scroller_x.scrollLeft, 400);
assert_equals(scroller_x.scrollTop, 0);
}, "Snaps if the distance between the previous(400) and next(800) " +
"snap positions is smaller than snapport(500) on x.");
test(() => {
scroller_y.scrollTo(0, 500);
assert_equals(scroller_y.scrollLeft, 0);
assert_equals(scroller_y.scrollTop, 400);
}, "Snaps if the distance between the previous(400) and next(800) " +
"snap positions is smaller than snapport(500) on y.");
test(() => {
scroller_x.scrollTo(900, 0);
assert_equals(scroller_x.scrollLeft, 900);
assert_equals(scroller_x.scrollTop, 0);
}, "Snap to current scroll position which is a valid snap position, " +
"as the snap area covers snapport on x and the distance between the " +
"previous(800) and next(1400) is larger than snapport(500).");
test(() => {
scroller_y.scrollTo(0, 900);
assert_equals(scroller_y.scrollLeft, 0);
assert_equals(scroller_y.scrollTop, 900);
}, "Snap to current scroll position which is a valid snap position, " +
"as the snap area covers snapport on y and the distance between the " +
"previous(800) and next(1400) is larger than snapport(500).");
test(() => {
scroller_x.scrollTo(1500, 0);
assert_equals(scroller_x.scrollLeft, 1500);
assert_equals(scroller_x.scrollTop, 0);
}, "Snap to current scroll position which is a valid snap position, as the " +
"snap area covers snapport on x and there is no subsequent snap positions.");
test(() => {
scroller_y.scrollTo(0, 1500);
assert_equals(scroller_y.scrollLeft, 0);
assert_equals(scroller_y.scrollTop, 1500);
}, "Snap to current scroll position which is a valid snap position, as the " +
"snap area covers snapport on y and there is no subsequent snap positions.");
test(() => {
const maxScrollTop = scroller_y.scrollHeight - scroller_y.clientHeight;
// Scroll to the bottom edge which is a valid snap position that a large
// target element covers the snapport.
scroller_y.scrollTo(0, maxScrollTop);
assert_equals(scroller_y.scrollTop, maxScrollTop);
// Scroll to `the bottom edge + 1`.
scroller_y.scrollTo(0, maxScrollTop + 1);
assert_equals(scroller_y.scrollTop, maxScrollTop);
}, "Don't snap back even if scrollTo tries to scroll to positions which are " +
"outside of the scroll range and if a snap target element covers the snaport");
test(() => {
two_axes_scroller.scrollTo(10, 100);
assert_equals(two_axes_scroller.scrollLeft, 10);
assert_equals(two_axes_scroller.scrollTop, 200);
}, "Snap to current scroll position on x as the area is covering x axis." +
"However, we snap to the specified snap position on y as the area is not " +
"covering y axis.");
</script>
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