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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* Utility code for performing CSS Box Alignment */
#include "CSSAlignUtils.h"
#include "ReflowInput.h"
#include "nsIFrame.h"
#include "nsIFrameInlines.h"
namespace mozilla {
StyleAlignFlags CSSAlignUtils::UsedAlignmentForAbsPos(nsIFrame* aFrame,
StyleAlignFlags aFlags,
LogicalAxis aLogicalAxis,
WritingMode aCBWM) {
MOZ_ASSERT(aFrame->IsAbsolutelyPositioned());
// Extract and strip the flag bits
StyleAlignFlags alignmentFlags = aFlags & StyleAlignFlags::FLAG_BITS;
aFlags &= ~StyleAlignFlags::FLAG_BITS;
if (aFlags == StyleAlignFlags::NORMAL) {
// "the 'normal' keyword behaves as 'start' on replaced
// absolutely-positioned boxes, and behaves as 'stretch' on all other
// absolutely-positioned boxes."
// https://drafts.csswg.org/css-align/#align-abspos
// https://drafts.csswg.org/css-align/#justify-abspos
aFlags = aFrame->HasReplacedSizing() ? StyleAlignFlags::START
: StyleAlignFlags::STRETCH;
} else if (aFlags == StyleAlignFlags::FLEX_START) {
aFlags = StyleAlignFlags::START;
} else if (aFlags == StyleAlignFlags::FLEX_END) {
aFlags = StyleAlignFlags::END;
} else if (aFlags == StyleAlignFlags::LEFT ||
aFlags == StyleAlignFlags::RIGHT) {
if (aLogicalAxis == LogicalAxis::Inline) {
const bool isLeft = (aFlags == StyleAlignFlags::LEFT);
aFlags = (isLeft == aCBWM.IsBidiLTR()) ? StyleAlignFlags::START
: StyleAlignFlags::END;
} else {
aFlags = StyleAlignFlags::START;
}
} else if (aFlags == StyleAlignFlags::BASELINE) {
aFlags = StyleAlignFlags::START;
} else if (aFlags == StyleAlignFlags::LAST_BASELINE) {
aFlags = StyleAlignFlags::END;
}
return (aFlags | alignmentFlags);
}
static nscoord SpaceToFill(WritingMode aWM, const LogicalSize& aSize,
nscoord aMargin, LogicalAxis aAxis,
nscoord aCBSize) {
nscoord size = aSize.Size(aAxis, aWM);
return aCBSize - (size + aMargin);
}
nscoord CSSAlignUtils::AlignJustifySelf(
const StyleAlignFlags& aAlignment, LogicalAxis aAxis,
AlignJustifyFlags aFlags, nscoord aBaselineAdjust, nscoord aCBSize,
const ReflowInput& aRI, const LogicalSize& aChildSize,
const Maybe<AnchorAlignInfo>& aAnchorInfo) {
MOZ_ASSERT(aAlignment != StyleAlignFlags::AUTO,
"auto values should have resolved already");
MOZ_ASSERT(aAlignment != StyleAlignFlags::LEFT &&
aAlignment != StyleAlignFlags::RIGHT,
"caller should map that to the corresponding START/END");
const bool isSameSide = aFlags.contains(AlignJustifyFlag::SameSide);
StyleAlignFlags alignment = aAlignment;
// Map some alignment values to 'start' / 'end'.
if (alignment == StyleAlignFlags::SELF_START) {
// align/justify-self: self-start
alignment =
MOZ_LIKELY(isSameSide) ? StyleAlignFlags::START : StyleAlignFlags::END;
} else if (alignment == StyleAlignFlags::SELF_END) {
alignment =
MOZ_LIKELY(isSameSide) ? StyleAlignFlags::END : StyleAlignFlags::START;
// flex-start/flex-end are the same as start/end, in most contexts.
// (They have special behavior in flex containers, so flex containers
// should map them to some other value before calling this method.)
} else if (alignment == StyleAlignFlags::FLEX_START) {
alignment = StyleAlignFlags::START;
} else if (alignment == StyleAlignFlags::FLEX_END) {
alignment = StyleAlignFlags::END;
}
// Get the item's margin corresponding to the container's start/end side.
WritingMode wm = aRI.GetWritingMode();
// If we're handling the margin box, it's already included in the incoming
// size.
const LogicalMargin margin =
aFlags.contains(AlignJustifyFlag::AligningMarginBox)
? LogicalMargin(wm)
: aRI.ComputedLogicalMargin(wm);
const auto startSide = MakeLogicalSide(
aAxis, MOZ_LIKELY(isSameSide) ? LogicalEdge::Start : LogicalEdge::End);
const nscoord marginStart = margin.Side(startSide, wm);
const auto endSide = GetOppositeSide(startSide);
const nscoord marginEnd = margin.Side(endSide, wm);
bool hasAutoMarginStart;
bool hasAutoMarginEnd;
const auto* styleMargin = aRI.mStyleMargin;
const auto anchorResolutionParams = AnchorPosResolutionParams::From(&aRI);
if (aFlags.contains(AlignJustifyFlag::IgnoreAutoMargins) ||
aFlags.contains(AlignJustifyFlag::AligningMarginBox)) {
// (Note: ReflowInput will have treated "auto" margins as 0, so we
// don't need to do anything special to avoid expanding them.)
hasAutoMarginStart = hasAutoMarginEnd = false;
} else if (aAxis == LogicalAxis::Block) {
hasAutoMarginStart =
styleMargin->GetMargin(LogicalSide::BStart, wm, anchorResolutionParams)
->IsAuto();
hasAutoMarginEnd =
styleMargin->GetMargin(LogicalSide::BEnd, wm, anchorResolutionParams)
->IsAuto();
} else { /* aAxis == LogicalAxis::Inline */
hasAutoMarginStart =
styleMargin->GetMargin(LogicalSide::IStart, wm, anchorResolutionParams)
->IsAuto();
hasAutoMarginEnd =
styleMargin->GetMargin(LogicalSide::IEnd, wm, anchorResolutionParams)
->IsAuto();
}
// https://drafts.csswg.org/css-align-3/#overflow-values
// This implements <overflow-position> = 'safe'.
// And auto-margins: https://drafts.csswg.org/css-grid/#auto-margins
if ((MOZ_UNLIKELY(aFlags.contains(AlignJustifyFlag::OverflowSafe)) &&
alignment != StyleAlignFlags::START) ||
hasAutoMarginStart || hasAutoMarginEnd) {
nscoord space =
SpaceToFill(wm, aChildSize, marginStart + marginEnd, aAxis, aCBSize);
// XXX we might want to include == 0 here as an optimization -
// I need to see what the baseline/last baseline code looks like first.
if (space < 0) {
// "Overflowing elements ignore their auto margins and overflow
// in the end directions"
alignment = StyleAlignFlags::START;
} else if (hasAutoMarginEnd) {
alignment = hasAutoMarginStart ? StyleAlignFlags::CENTER
: (isSameSide ? StyleAlignFlags::START
: StyleAlignFlags::END);
} else if (hasAutoMarginStart) {
alignment = isSameSide ? StyleAlignFlags::END : StyleAlignFlags::START;
}
}
// Determine the offset for the child frame (its border-box) which will
// achieve the requested alignment.
nscoord offset = 0;
if (alignment == StyleAlignFlags::BASELINE ||
alignment == StyleAlignFlags::LAST_BASELINE) {
const bool isFirstBaselineSharingGroup =
!aFlags.contains(AlignJustifyFlag::LastBaselineSharingGroup);
if (MOZ_LIKELY(isFirstBaselineSharingGroup)) {
offset = marginStart + aBaselineAdjust;
} else {
nscoord size = aChildSize.Size(aAxis, wm);
offset = aCBSize - (size + marginEnd) - aBaselineAdjust;
}
} else if (alignment == StyleAlignFlags::STRETCH ||
alignment == StyleAlignFlags::START) {
// ComputeSize() deals with stretch
offset = marginStart;
} else if (alignment == StyleAlignFlags::END) {
nscoord size = aChildSize.Size(aAxis, wm);
offset = aCBSize - (size + marginEnd);
} else if (alignment == StyleAlignFlags::ANCHOR_CENTER && aAnchorInfo) {
const nscoord anchorSize = aAnchorInfo->mAnchorSize;
const nscoord anchorStart = aAnchorInfo->mAnchorStart;
const nscoord size = aChildSize.Size(aAxis, wm);
// Offset relative to the anchors center, accounting for margins
offset = anchorStart + (anchorSize - size + marginStart - marginEnd) / 2;
} else {
// ANCHOR_CENTER with no Anchor is treated like CENTER.
MOZ_ASSERT(alignment == StyleAlignFlags::CENTER ||
alignment == StyleAlignFlags::ANCHOR_CENTER,
"unknown align-/justify-self value");
nscoord size = aChildSize.Size(aAxis, wm);
offset = (aCBSize - size + marginStart - marginEnd) / 2;
}
return offset;
}
} // namespace mozilla
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