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<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap-1/#scroll-snap-type" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
div {
position: absolute;
margin: 0px;
}
#scroller {
width: 400px;
height: 350px;
overflow: scroll;
scroll-snap-type: both mandatory;
}
#space {
width: 1000px;
height: 1000px;
}
#target {
width: 200px;
height: 200px;
left: 300px;
top: 300px;
}
</style>
<div id="scroller">
<div id="space"></div>
<div id="target"></div>
</div>
<script>
const scroller_width = scroller.clientWidth;
const scroller_height = scroller.clientHeight;
[
["horizontal-tb", 300, 500 - scroller_height],
["vertical-lr", 500 - scroller_width, 300],
["vertical-rl", scroller_width - 700, 300]
].forEach(([writing_mode, left, top]) => {
test(() => {
const target_left = getComputedStyle(target).left;
scroller.style.writingMode = writing_mode;
target.style.scrollSnapAlign = "end start";
if (writing_mode == "vertical-rl") {
target.style.left = (scroller_width - 700) + "px";
scroller.scrollTo(-500, 0);
} else {
scroller.scrollTo(0, 0);
}
assert_equals(scroller.scrollLeft, left, "aligns correctly on x");
assert_equals(scroller.scrollTop, top, "aligns correctly on y");
target.style.left = target_left;
scroller.style.writingMode = "";
}, "Snaps correctly for " + writing_mode +
" writing mode with 'scroll-snap-align: end start' alignment");
});
[
["horizontal-tb", 500 - scroller_width, 300],
["vertical-lr", 300, 500 - scroller_height],
["vertical-rl", target.clientWidth - 700, 500 - scroller_height]
].forEach(([writing_mode, left, top]) => {
test(() => {
const target_left = getComputedStyle(target).left;
scroller.style.writingMode = writing_mode;
target.style.scrollSnapAlign = "start end";
if (writing_mode == "vertical-rl") {
target.style.left = (scroller_width - 700) + "px";
scroller.scrollTo(-500, 0);
} else {
scroller.scrollTo(0, 0);
}
assert_equals(scroller.scrollLeft, left, "aligns correctly on x");
assert_equals(scroller.scrollTop, top, "aligns correctly on y");
target.style.left = target_left;
scroller.style.writingMode = "";
}, "Snaps correctly for " + writing_mode +
" writing mode with 'scroll-snap-align: start end' alignment");
});
test(() => {
const target_left = getComputedStyle(target).left;
scroller.style.direction = "rtl";
target.style.scrollSnapAlign = "end start";
target.style.left = (scroller_width - 700) + "px";
scroller.scrollTo(-500, 0);
assert_equals(scroller.scrollLeft, target.clientWidth - 700,
"aligns correctly on x");
assert_equals(scroller.scrollTop, 500 - scroller_height,
"aligns correctly on y");
target.style.left = target_left;
scroller.style.direction = "";
}, "Snaps correctly for 'direction: rtl' with 'scroll-snap-align: end start' " +
"alignment");
test(() => {
const target_left = getComputedStyle(target).left;
scroller.style.direction = "rtl";
target.style.scrollSnapAlign = "start end";
target.style.left = (scroller_width - 700) + "px";
scroller.scrollTo(-500, 0);
assert_equals(scroller.scrollLeft, scroller_width - 700,
"aligns correctly on x");
assert_equals(scroller.scrollTop, 300, "aligns correctly on y");
target.style.left = target_left;
scroller.style.direction = "";
}, "Snaps correctly for 'direction: rtl' with 'scroll-snap-align: start end' " +
"alignment");
</script>
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