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Bug 1874242 - Centralize border/padding/content box baseline calculations. r=dshin

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I wrote this because I thought I was going to need the padding-box stuff
for bug 221154, but I ended up not needing it. However I think it's a
bit nicer, wdyt?

Differential Revision: https://phabricator.services.mozilla.com/D198306
This commit is contained in:
Emilio Cobos Álvarez
2024-01-11 22:25:18 +00:00
parent 2757782dc8
commit 17cefba02e
2 changed files with 60 additions and 60 deletions
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98
layout/base/Baseline.cpp
View File

@@ -37,61 +37,69 @@ nscoord Baseline::SynthesizeBOffsetFromMarginBox(const nsIFrame* aFrame,
return marginBoxCenter - margin.BEnd(aWM);
}
nscoord Baseline::SynthesizeBOffsetFromBorderBox(const nsIFrame* aFrame,
WritingMode aWM,
BaselineSharingGroup aGroup) {
nscoord borderBoxSize =
MOZ_UNLIKELY(aWM.IsOrthogonalTo(aFrame->GetWritingMode()))
? aFrame->ISize(aWM)
: aFrame->BSize(aWM);
if (aGroup == BaselineSharingGroup::First) {
if (MOZ_LIKELY(aWM.IsAlphabeticalBaseline())) {
// First baseline for inverted-line content is the block-start border-box
// edge, as the frame is in effect "flipped" for alignment purposes.
return MOZ_UNLIKELY(aWM.IsLineInverted()) ? 0 : borderBoxSize;
enum class BoxType { Border, Padding, Content };
template <BoxType aType>
static nscoord SynthesizeBOffsetFromInnerBox(const nsIFrame* aFrame,
WritingMode aWM,
BaselineSharingGroup aGroup) {
WritingMode wm = aFrame->GetWritingMode();
MOZ_ASSERT_IF(aType != BoxType::Border, !aWM.IsOrthogonalTo(wm));
const nscoord borderBoxSize = MOZ_UNLIKELY(aWM.IsOrthogonalTo(wm))
? aFrame->ISize(aWM)
: aFrame->BSize(aWM);
const LogicalMargin bp = ([&] {
switch (aType) {
case BoxType::Border:
return LogicalMargin(wm);
case BoxType::Padding:
return aFrame->GetLogicalUsedBorder(wm)
.ApplySkipSides(aFrame->GetLogicalSkipSides())
.ConvertTo(aWM, wm);
case BoxType::Content:
return aFrame->GetLogicalUsedBorderAndPadding(wm)
.ApplySkipSides(aFrame->GetLogicalSkipSides())
.ConvertTo(aWM, wm);
}
return borderBoxSize / 2;
MOZ_CRASH();
})();
if (MOZ_UNLIKELY(aWM.IsCentralBaseline())) {
nscoord boxBSize = borderBoxSize - bp.BStartEnd(aWM);
if (aGroup == BaselineSharingGroup::First) {
return boxBSize / 2 + bp.BStart(aWM);
}
// Return the same center position as for ::First, but as offset from end:
nscoord halfBoxBSize = (boxBSize / 2) + (boxBSize % 2);
return halfBoxBSize + bp.BEnd(aWM);
}
MOZ_ASSERT(aGroup == BaselineSharingGroup::Last);
if (MOZ_LIKELY(aWM.IsAlphabeticalBaseline())) {
// Last baseline for inverted-line content is the block-start border-box
if (aGroup == BaselineSharingGroup::First) {
// First baseline for inverted-line content is the block-start content
// edge, as the frame is in effect "flipped" for alignment purposes.
return MOZ_UNLIKELY(aWM.IsLineInverted()) ? borderBoxSize : 0;
return MOZ_UNLIKELY(aWM.IsLineInverted()) ? bp.BStart(aWM)
: borderBoxSize - bp.BEnd(aWM);
}
// Round up for central baseline offset, to be consistent with ::First.
return (borderBoxSize / 2) + (borderBoxSize % 2);
// Last baseline for inverted-line content is the block-start content edge,
// as the frame is in effect "flipped" for alignment purposes.
return MOZ_UNLIKELY(aWM.IsLineInverted()) ? borderBoxSize - bp.BStart(aWM)
: bp.BEnd(aWM);
}
nscoord Baseline::SynthesizeBOffsetFromContentBox(const nsIFrame* aFrame,
WritingMode aWM,
BaselineSharingGroup aGroup) {
WritingMode wm = aFrame->GetWritingMode();
MOZ_ASSERT(!aWM.IsOrthogonalTo(wm));
const auto bp = aFrame->GetLogicalUsedBorderAndPadding(wm)
.ApplySkipSides(aFrame->GetLogicalSkipSides())
.ConvertTo(aWM, wm);
return SynthesizeBOffsetFromInnerBox<BoxType::Content>(aFrame, aWM, aGroup);
}
if (MOZ_UNLIKELY(aWM.IsCentralBaseline())) {
nscoord contentBoxBSize = aFrame->BSize(aWM) - bp.BStartEnd(aWM);
if (aGroup == BaselineSharingGroup::First) {
return contentBoxBSize / 2 + bp.BStart(aWM);
}
// Return the same center position as for ::First, but as offset from end:
nscoord halfContentBoxBSize = (contentBoxBSize / 2) + (contentBoxBSize % 2);
return halfContentBoxBSize + bp.BEnd(aWM);
}
if (aGroup == BaselineSharingGroup::First) {
// First baseline for inverted-line content is the block-start content
// edge, as the frame is in effect "flipped" for alignment purposes.
return MOZ_UNLIKELY(aWM.IsLineInverted())
? bp.BStart(aWM)
: aFrame->BSize(aWM) - bp.BEnd(aWM);
}
// Last baseline for inverted-line content is the block-start content edge,
// as the frame is in effect "flipped" for alignment purposes.
return MOZ_UNLIKELY(aWM.IsLineInverted())
? aFrame->BSize(aWM) - bp.BStart(aWM)
: bp.BEnd(aWM);
nscoord Baseline::SynthesizeBOffsetFromPaddingBox(const nsIFrame* aFrame,
WritingMode aWM,
BaselineSharingGroup aGroup) {
return SynthesizeBOffsetFromInnerBox<BoxType::Padding>(aFrame, aWM, aGroup);
}
nscoord Baseline::SynthesizeBOffsetFromBorderBox(const nsIFrame* aFrame,
WritingMode aWM,
BaselineSharingGroup aGroup) {
return SynthesizeBOffsetFromInnerBox<BoxType::Border>(aFrame, aWM, aGroup);
}
} // namespace mozilla

22
layout/base/Baseline.h
View File

@@ -61,23 +61,15 @@ class Baseline {
static nscoord SynthesizeBOffsetFromBorderBox(const nsIFrame* aFrame,
WritingMode aWM,
BaselineSharingGroup);
/**
* Synthesize a first(last) inline-axis baseline in aWM based on aFrame's
* content-box.
*
* An alphabetical baseline is at the end edge of aFrame's content-box with
* respect to aWM's block-axis, and a central baseline is halfway between the
* start and end edges. (aWM tells which baseline to use.)
* https://drafts.csswg.org/css-align-3/#synthesize-baseline
*
* @note This works only when aFrame's writing-mode is parallel to aWM.
* @param aWM the writing-mode of the alignment context.
* @return an offset from aFrame's border-box start(end) edge in aWM's
* block-axis for a first(last) baseline, respectively.
* As above, but using the content box.
*/
static nscoord SynthesizeBOffsetFromContentBox(const nsIFrame* aFrame,
WritingMode aWM,
static nscoord SynthesizeBOffsetFromContentBox(const nsIFrame*, WritingMode,
BaselineSharingGroup);
/**
* As above, but using the padding box.
*/
static nscoord SynthesizeBOffsetFromPaddingBox(const nsIFrame*, WritingMode,
BaselineSharingGroup);
};