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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title> CSS Scroll Snap 2 Test: scroll-start-target*</title>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap-2/#scroll-start-target">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
<style>
#space-filler {
width: 500px;
height: 500px;
border: solid 1px red;
}
#outer-container {
width: 400px;
height: 400px;
overflow: scroll;
border: solid 2px blue;
}
#inner-container {
top: 20px;
left: 20px;
width: 300px;
height: 300px;
overflow: scroll;
position: relative;
border: solid 2px black;
}
#target {
width: 100px;
height: 100px;
background-color: pink;
scroll-start-target: auto auto;
}
</style>
<div id="outer-container">
<div id="inner-container">
<div id="space-filler"></div>
<div id="target">
</div>
</div>
</div>
<script>
let outer_scroller = document.getElementById("outer-container");
let inner_scroller = document.getElementById("inner-container");
let space_filler = document.getElementById("space-filler");
let target = document.getElementById("target");
const target_height = target.getBoundingClientRect().height;
const space_filler_height = space_filler.getBoundingClientRect().height;
const total_content_height = target_height + space_filler_height;
async function resetDisplay() {
return new Promise((resolve) => {
if (getComputedStyle(outer_scroller).display == "block" &&
getComputedStyle(inner_scroller).display == "block" &&
getComputedStyle(target).display == "block") {
resolve();
} else {
outer_scroller.style.display = "block";
inner_scroller.style.display = "block";
target.style.display = "block";
requestAnimationFrame(async () => {
await resetDisplay();
resolve();
});
}
});
}
async function waitForDisplay(element, display) {
return new Promise((resolve) => {
if (getComputedStyle(element).display == display) {
resolve();
} else {
requestAnimationFrame(async () => {
await waitForDisplay(element, display);
resolve();
})
}
});
}
promise_test(async (t) => {
await resetDisplay();
let initial_expected_scroll_top =
total_content_height - inner_scroller.clientHeight;
assert_equals(inner_scroller.scrollTop, initial_expected_scroll_top,
"inner-scroller is scrolled to scroll-start-target");
let display_promise = waitForDisplay(target, "none");
target.style.display = "none";
await display_promise;
let final_expected_scroll_top = initial_expected_scroll_top - target_height;
assert_equals(inner_scroller.scrollTop, final_expected_scroll_top,
"inner scroller is clamped to updated scroll range");
}, "display:block scroll-start-target becomes display: none");
promise_test(async (t) => {
await resetDisplay();
let initial_expected_scroll_top =
total_content_height - inner_scroller.clientHeight;
assert_equals(inner_scroller.scrollTop, initial_expected_scroll_top,
"inner-scroller is scrolled to scroll-start-target");
let display_promise = waitForDisplay(target, "none");
target.style.display = "none";
await display_promise;
assert_equals(inner_scroller.scrollTop,
initial_expected_scroll_top - target_height,
"inner scroller is clamped to updated scroll range");
display_promise = waitForDisplay(target, "block");
target.style.display = "block";
await display_promise;
assert_equals(inner_scroller.scrollTop, initial_expected_scroll_top,
"inner scroller is updated as scroll-start-target reappears");
}, "display:none scroll-start-target becomes display: block");
</script>
</body>
</html>
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