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Commit a57cdd05 authored by David Shin's avatar David Shin
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Bug 1800907 - Do not `UnionRect` empty rects in `OverflowAreas::Union*`. r=jwatt 

Previously, when current overflow area has one axis at zero size, calling
`OverflowAreas::Union*` with a rect with both axes at zero would overwrite
the axis with non-zero size.

Differential Revision: https://phabricator.services.mozilla.com/D162245
parent 0515d6a0
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layout/generic/ReflowOutput.cpp
+ 24
− 3
View file @ a57cdd05
......@@ -11,6 +11,19 @@
namespace mozilla {
static bool IsValidOverflowRect(const nsRect& aRect) {
// `IsEmpty` in the context of `nsRect` means "width OR height is zero."
// However, in the context of overflow, the rect having one axis as zero is
// NOT considered empty.
if (MOZ_LIKELY(!aRect.IsEmpty())) {
return true;
}
// Be defensive and consider rects with any negative size as invalid.
return !aRect.IsEqualEdges(nsRect()) && aRect.Width() >= 0 &&
aRect.Height() >= 0;
}
/* static */
nsRect OverflowAreas::GetOverflowClipRect(const nsRect& aRectToClip,
const nsRect& aBounds,
......@@ -40,12 +53,20 @@ void OverflowAreas::ApplyOverflowClippingOnRect(nsRect& aOverflowRect,
}
void OverflowAreas::UnionWith(const OverflowAreas& aOther) {
InkOverflow().UnionRect(InkOverflow(), aOther.InkOverflow());
ScrollableOverflow().UnionRect(ScrollableOverflow(),
aOther.ScrollableOverflow());
if (IsValidOverflowRect(aOther.InkOverflow())) {
InkOverflow().UnionRect(InkOverflow(), aOther.InkOverflow());
}
if (IsValidOverflowRect(aOther.ScrollableOverflow())) {
ScrollableOverflow().UnionRect(ScrollableOverflow(),
aOther.ScrollableOverflow());
}
}
void OverflowAreas::UnionAllWith(const nsRect& aRect) {
if (!IsValidOverflowRect(aRect)) {
// Same as `UnionWith()` - avoid losing information.
return;
}
InkOverflow().UnionRect(InkOverflow(), aRect);
ScrollableOverflow().UnionRect(ScrollableOverflow(), aRect);
}
......
testing/web-platform/tests/css/css-overflow/scrollable-overflow-zero-one-axis.html 0 → 100644
+ 59
− 0
View file @ a57cdd05
<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Overflow: Scroll Length Calculated Correctly When One Axis Has Zero Length</title>
<link rel="author" title="David Shin" href="mailto:dshin@mozilla.com">
<link rel="author" title="Mozilla" href="http://www.mozilla.org/">
<link rel="help" href="https://drafts.csswg.org/css-overflow-3/#scrollable">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1800907">
<style>
.scroll {
overflow: scroll;
}
.zero-h {
width: 100px;
height: 0px;
}
.zero-w {
width: 0;
height: 100px;
}
.flex-row {
display: flex;
}
.flex-col {
display: flex;
flex-direction: column;
}
.grid {
display: grid;
}
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/check-layout-th.js"></script>
<body onload="checkLayout('.scroll')">
<div class="scroll zero-h" data-expected-scroll-height="100">
<div class="zero-w"></div>
</div>
<div class="scroll zero-w" data-expected-scroll-width="100">
<div class="zero-h"></div>
</div>
<div class="scroll zero-h flex-row" data-expected-scroll-height="100">
<div class="zero-w"></div>
</div>
<div class="scroll zero-w flex-col" data-expected-scroll-width="100">
<div class="zero-h"></div>
</div>
<div class="scroll zero-h grid" data-expected-scroll-height="100">
<div class="zero-w"></div>
</div>
<div class="scroll zero-w grid" data-expected-scroll-width="100">
<div class="zero-h"></div>
</div>
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