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Test Info:
<!DOCTYPE html>
<html lang="en" class="reftest-wait"
reftest-displayport-x="0"
reftest-displayport-y="0"
reftest-displayport-w="800"
reftest-displayport-h="1000">
<meta charset="utf-8">
<title>Scrolling shouldn't invalidate the fixed items</title>
<style>
.content {
box-sizing: border-box;
width: 200px;
height: 200px;
border: 1px solid black;
}
.fixed {
position: fixed;
top: 20px;
left: 20px;
}
.reftest-no-paint {
border-color: lime;
}
.distanceFromTop {
margin-top: 240px;
}
.clip {
width: 200px;
height: 200px;
overflow: hidden;
}
.transform {
position: relative;
will-change: transform;
}
body {
margin: 0;
padding: 20px;
height: 3000px;
}
</style>
<div class="fixed reftest-no-paint content">
<!--
This fixed layer gets its own PaintedLayer above the page.
-->
</div>
<div class="distanceFromTop clip">
<!--
This clip determines the potential pixels that can be affected by the
animated transform, *in relation to the scrolled page*. If the page
is scrolled, the clip moves relative to the fixed items, so the fixed
items need to anticipate the transform getting between them.
-->
<div class="transform content">
<!--
This is an animated transform item. It can move freely but will be
clipped by the .clip element.
-->
</div>
</div>
<div class="fixed reftest-no-paint content">
<!--
This fixed layer is above the animated transform, in z-order. The
transform is clipped in such a way that initially, the clip doesn't
intersect the fixed items, but once the page is scrolled, it does.
So this fixed item must not share a layer with the lower fixed item.
-->
</div>
<script>
function doTest() {
document.documentElement.scrollTop = 100;
document.documentElement.removeAttribute("class");
}
document.documentElement.scrollTop = 0;
document.addEventListener("MozReftestInvalidate", doTest);
// setTimeout(doTest, 500);
</script>