1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
|
<!DOCTYPE html>
<meta name="viewport" content="width=device-width">
<title>
Snap to points of combinations of two different elements
</title>
<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;
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>
|
