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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /css/css-scroll-snap/snap-to-combination-of-two-elements-2.tentative.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<meta name="viewport" content="width=device-width">
<title>
Snap to points of combinations of two different elements
</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
div {
position: absolute;
margin: 0px;
}
#scroller {
height: 600px;
width: 600px;
overflow: hidden;
scroll-snap-type: both mandatory;
}
#space {
width: 2000px;
height: 2000px;
}
#left-top {
/*
* the scroll position of this `scroll-snap-align: start start` is (200, 200)
*/
left: 200px;
top: 200px;
height: 450px;
width: 450px;
background-color: rgb(255, 0, 0);
opacity: 0.5;
scroll-snap-align: start start;
}
#right-bottom {
/*
* the scroll position of this `scroll-snap-align: end end` is (50, 250),
* i.e, (`left` - scroll container's `width` + this element's `width,
`top` - scroll container's `height` + this element's `height)
*/
left: 600px;
top: 800px;
width: 50px;
height: 50px;
background-color: rgb(0, 255, 0);
opacity: 0.5;
scroll-snap-align: end end;
}
</style>
<div id="scroller">
<div id="space"></div>
<div id="left-top"></div>
<div id="right-bottom"></div>
</div>
<script>
test(t => {
// There are four combinations of snap positions defined by #top-left and
// #right-bottom elements.
// (200, 200), (50, 250), (200, 250) and (50, 200).
// But snapping to (50, 200) leaves the snap area of #right-bottom element
// outside of the snapport, thus it won't be a valid snap position.
const scroller = document.getElementById("scroller");
// The nearest valid snap position from (0, 0) is (50, 250).
assert_equals(scroller.scrollLeft, 50);
assert_equals(scroller.scrollTop, 250);
// (50, 200) is not valid, thus the nearest one from (100, 150) is (200, 200).
scroller.scrollTo(100, 150);
assert_equals(scroller.scrollLeft, 200);
assert_equals(scroller.scrollTop, 200);
scroller.scrollTo(300, 300);
assert_equals(scroller.scrollLeft, 200);
assert_equals(scroller.scrollTop, 250);
scroller.scrollTo(200, 100);
assert_equals(scroller.scrollLeft, 200);
assert_equals(scroller.scrollTop, 200);
}, 'Snap to points of combinations of two different elements');
</script>