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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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"
namespace mozilla {
static nscoord
SpaceToFill(WritingMode aWM, const LogicalSize& aSize, nscoord aMargin,
LogicalAxis aAxis, nscoord aCBSize)
{
nscoord size = aAxis == eLogicalAxisBlock ? aSize.BSize(aWM)
: aSize.ISize(aWM);
return aCBSize - (size + aMargin);
}
nscoord
CSSAlignUtils::AlignJustifySelf(uint8_t aAlignment, LogicalAxis aAxis,
AlignJustifyFlags aFlags,
nscoord aBaselineAdjust, nscoord aCBSize,
const ReflowInput& aRI,
const LogicalSize& aChildSize)
{
MOZ_ASSERT(aAlignment != NS_STYLE_ALIGN_AUTO,
"auto values should have resolved already");
MOZ_ASSERT(aAlignment != NS_STYLE_ALIGN_LEFT &&
aAlignment != NS_STYLE_ALIGN_RIGHT,
"caller should map that to the corresponding START/END");
// Promote aFlags to convenience bools:
const bool isOverflowSafe = !!(aFlags & AlignJustifyFlags::eOverflowSafe);
const bool isSameSide = !!(aFlags & AlignJustifyFlags::eSameSide);
// Map some alignment values to 'start' / 'end'.
switch (aAlignment) {
case NS_STYLE_ALIGN_SELF_START: // align/justify-self: self-start
aAlignment = MOZ_LIKELY(isSameSide) ? NS_STYLE_ALIGN_START
: NS_STYLE_ALIGN_END;
break;
case NS_STYLE_ALIGN_SELF_END: // align/justify-self: self-end
aAlignment = MOZ_LIKELY(isSameSide) ? NS_STYLE_ALIGN_END
: NS_STYLE_ALIGN_START;
break;
// 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.)
case NS_STYLE_ALIGN_FLEX_START:
aAlignment = NS_STYLE_ALIGN_START;
break;
case NS_STYLE_ALIGN_FLEX_END:
aAlignment = NS_STYLE_ALIGN_END;
break;
}
// XXX try to condense this code a bit by adding the necessary convenience
// methods? (bug 1209710)
// Get the item's margin corresponding to the container's start/end side.
const LogicalMargin margin = aRI.ComputedLogicalMargin();
WritingMode wm = aRI.GetWritingMode();
nscoord marginStart, marginEnd;
if (aAxis == eLogicalAxisBlock) {
if (MOZ_LIKELY(isSameSide)) {
marginStart = margin.BStart(wm);
marginEnd = margin.BEnd(wm);
} else {
marginStart = margin.BEnd(wm);
marginEnd = margin.BStart(wm);
}
} else {
if (MOZ_LIKELY(isSameSide)) {
marginStart = margin.IStart(wm);
marginEnd = margin.IEnd(wm);
} else {
marginStart = margin.IEnd(wm);
marginEnd = margin.IStart(wm);
}
}
const auto& styleMargin = aRI.mStyleMargin->mMargin;
bool hasAutoMarginStart;
bool hasAutoMarginEnd;
if (aFlags & AlignJustifyFlags::eIgnoreAutoMargins) {
// (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 == eLogicalAxisBlock) {
hasAutoMarginStart = styleMargin.GetBStartUnit(wm) == eStyleUnit_Auto;
hasAutoMarginEnd = styleMargin.GetBEndUnit(wm) == eStyleUnit_Auto;
} else { /* aAxis == eLogicalAxisInline */
hasAutoMarginStart = styleMargin.GetIStartUnit(wm) == eStyleUnit_Auto;
hasAutoMarginEnd = styleMargin.GetIEndUnit(wm) == eStyleUnit_Auto;
}
// 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(isOverflowSafe) && aAlignment != NS_STYLE_ALIGN_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"
aAlignment = NS_STYLE_ALIGN_START;
} else if (hasAutoMarginEnd) {
aAlignment = hasAutoMarginStart ? NS_STYLE_ALIGN_CENTER
: (isSameSide ? NS_STYLE_ALIGN_START
: NS_STYLE_ALIGN_END);
} else if (hasAutoMarginStart) {
aAlignment = isSameSide ? NS_STYLE_ALIGN_END : NS_STYLE_ALIGN_START;
}
}
// Determine the offset for the child frame (its border-box) which will
// achieve the requested alignment.
nscoord offset = 0;
switch (aAlignment) {
case NS_STYLE_ALIGN_BASELINE:
case NS_STYLE_ALIGN_LAST_BASELINE:
if (MOZ_LIKELY(isSameSide == (aAlignment == NS_STYLE_ALIGN_BASELINE))) {
offset = marginStart + aBaselineAdjust;
} else {
nscoord size = aAxis == eLogicalAxisBlock ? aChildSize.BSize(wm)
: aChildSize.ISize(wm);
offset = aCBSize - (size + marginEnd) - aBaselineAdjust;
}
break;
case NS_STYLE_ALIGN_STRETCH:
[[fallthrough]]; // ComputeSize() deals with it
case NS_STYLE_ALIGN_START:
offset = marginStart;
break;
case NS_STYLE_ALIGN_END: {
nscoord size = aAxis == eLogicalAxisBlock ? aChildSize.BSize(wm)
: aChildSize.ISize(wm);
offset = aCBSize - (size + marginEnd);
break;
}
case NS_STYLE_ALIGN_CENTER: {
nscoord size = aAxis == eLogicalAxisBlock ? aChildSize.BSize(wm)
: aChildSize.ISize(wm);
offset = (aCBSize - size + marginStart - marginEnd) / 2;
break;
}
default:
MOZ_ASSERT_UNREACHABLE("unknown align-/justify-self value");
}
return offset;
}
} // namespace mozilla
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