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webkit / WebKit / d0e9359bbbbbe54170cea1569c9fb736cfa3bccd / . / Source / WebCore / rendering / RenderFlexibleBox.cpp
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/*
* Copyright (C) 2011 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "RenderFlexibleBox.h"
#include "FlexibleBoxAlgorithm.h"
#include "HitTestResult.h"
#include "LayoutRepainter.h"
#include "RenderChildIterator.h"
#include "RenderLayer.h"
#include "RenderLayoutState.h"
#include "RenderStyleConstants.h"
#include "RenderView.h"
#include "WritingMode.h"
#include <limits>
#include <wtf/IsoMallocInlines.h>
#include <wtf/MathExtras.h>
#include <wtf/SetForScope.h>
namespace WebCore {
WTF_MAKE_ISO_ALLOCATED_IMPL(RenderFlexibleBox);
struct RenderFlexibleBox::LineContext {
LineContext(LayoutUnit crossAxisOffset, LayoutUnit crossAxisExtent, LayoutUnit maxAscent, Vector<FlexItem>&& flexItems)
: crossAxisOffset(crossAxisOffset)
, crossAxisExtent(crossAxisExtent)
, maxAscent(maxAscent)
, flexItems(flexItems)
{
}
LayoutUnit crossAxisOffset;
LayoutUnit crossAxisExtent;
LayoutUnit maxAscent;
Vector<FlexItem> flexItems;
};
RenderFlexibleBox::RenderFlexibleBox(Element& element, RenderStyle&& style)
: RenderBlock(element, WTFMove(style), 0)
{
setChildrenInline(false); // All of our children must be block-level.
}
RenderFlexibleBox::RenderFlexibleBox(Document& document, RenderStyle&& style)
: RenderBlock(document, WTFMove(style), 0)
{
setChildrenInline(false); // All of our children must be block-level.
}
RenderFlexibleBox::~RenderFlexibleBox() = default;
const char* RenderFlexibleBox::renderName() const
{
return "RenderFlexibleBox";
}
void RenderFlexibleBox::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
{
auto addScrollbarWidth = [&]() {
LayoutUnit scrollbarWidth(scrollbarLogicalWidth());
maxLogicalWidth += scrollbarWidth;
minLogicalWidth += scrollbarWidth;
};
if (shouldApplySizeContainment(*this)) {
addScrollbarWidth();
return;
}
LayoutUnit childMinWidth;
LayoutUnit childMaxWidth;
bool hadExcludedChildren = computePreferredWidthsForExcludedChildren(childMinWidth, childMaxWidth);
// FIXME: We're ignoring flex-basis here and we shouldn't. We can't start
// honoring it though until the flex shorthand stops setting it to 0. See
// https://bugs.webkit.org/show_bug.cgi?id=116117 and
// https://crbug.com/240765.
size_t numItemsWithNormalLayout = 0;
for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
if (child->isOutOfFlowPositioned() || child->isExcludedFromNormalLayout())
continue;
++numItemsWithNormalLayout;
LayoutUnit margin = marginIntrinsicLogicalWidthForChild(*child);
LayoutUnit minPreferredLogicalWidth;
LayoutUnit maxPreferredLogicalWidth;
computeChildPreferredLogicalWidths(*child, minPreferredLogicalWidth, maxPreferredLogicalWidth);
minPreferredLogicalWidth += margin;
maxPreferredLogicalWidth += margin;
if (!isColumnFlow()) {
maxLogicalWidth += maxPreferredLogicalWidth;
if (isMultiline()) {
// For multiline, the min preferred width is if you put a break between
// each item.
minLogicalWidth = std::max(minLogicalWidth, minPreferredLogicalWidth);
} else
minLogicalWidth += minPreferredLogicalWidth;
} else {
minLogicalWidth = std::max(minPreferredLogicalWidth, minLogicalWidth);
maxLogicalWidth = std::max(maxPreferredLogicalWidth, maxLogicalWidth);
}
}
if (!isColumnFlow() && numItemsWithNormalLayout > 1) {
LayoutUnit inlineGapSize = (numItemsWithNormalLayout - 1) * computeGap(GapType::BetweenItems);
maxLogicalWidth += inlineGapSize;
if (!isMultiline())
minLogicalWidth += inlineGapSize;
}
maxLogicalWidth = std::max(minLogicalWidth, maxLogicalWidth);
// Due to negative margins, it is possible that we calculated a negative
// intrinsic width. Make sure that we never return a negative width.
minLogicalWidth = std::max(0_lu, minLogicalWidth);
maxLogicalWidth = std::max(0_lu, maxLogicalWidth);
if (hadExcludedChildren) {
minLogicalWidth = std::max(minLogicalWidth, childMinWidth);
maxLogicalWidth = std::max(maxLogicalWidth, childMaxWidth);
}
addScrollbarWidth();
}
#define SET_OR_CLEAR_OVERRIDING_SIZE(box, SizeType, size) \
{ \
if (size) \
box.setOverridingLogical##SizeType(*size); \
else \
box.clearOverridingLogical##SizeType(); \
}
// RAII class which defines a scope in which overriding sizes of a box are either:
// 1) replaced by other size in one axis if size is specified
// 2) cleared in both axis if size == std::nullopt
//
// In any case the previous overriding sizes are restored on destruction (in case of
// not having a previous value it's simply cleared).
class OverridingSizesScope {
public:
enum class Axis {
Inline,
Block,
Both
};
OverridingSizesScope(RenderBox& box, Axis axis, std::optional<LayoutUnit> size = std::nullopt)
: m_box(box)
, m_axis(axis)
{
ASSERT(!size || (axis != Axis::Both));
if (axis == Axis::Both || axis == Axis::Inline) {
if (box.hasOverridingLogicalWidth())
m_overridingWidth = box.overridingLogicalWidth();
SET_OR_CLEAR_OVERRIDING_SIZE(m_box, Width, size);
}
if (axis == Axis::Both || axis == Axis::Block) {
if (box.hasOverridingLogicalHeight())
m_overridingHeight = box.overridingLogicalHeight();
SET_OR_CLEAR_OVERRIDING_SIZE(m_box, Height, size);
}
}
~OverridingSizesScope()
{
if (m_axis == Axis::Inline || m_axis == Axis::Both)
SET_OR_CLEAR_OVERRIDING_SIZE(m_box, Width, m_overridingWidth);
if (m_axis == Axis::Block || m_axis == Axis::Both)
SET_OR_CLEAR_OVERRIDING_SIZE(m_box, Height, m_overridingHeight);
}
private:
RenderBox& m_box;
Axis m_axis;
std::optional<LayoutUnit> m_overridingWidth;
std::optional<LayoutUnit> m_overridingHeight;
};
void RenderFlexibleBox::computeChildIntrinsicLogicalWidths(RenderObject& childObject, LayoutUnit& minPreferredLogicalWidth, LayoutUnit& maxPreferredLogicalWidth) const
{
ASSERT(childObject.isBox());
RenderBox& child = downcast<RenderBox>(childObject);
// If the item cross size should use the definite container cross size then set the overriding size now so
// the intrinsic sizes are properly computed in the presence of aspect ratios. The only exception is when
// we are both a flex item&container, because our parent might have already set our overriding size.
if (childCrossSizeShouldUseContainerCrossSize(child) && !isFlexItem()) {
auto axis = mainAxisIsChildInlineAxis(child) ? OverridingSizesScope::Axis::Block : OverridingSizesScope::Axis::Inline;
OverridingSizesScope overridingSizeScope(child, axis, computeCrossSizeForChildUsingContainerCrossSize(child));
RenderBlock::computeChildIntrinsicLogicalWidths(childObject, minPreferredLogicalWidth, maxPreferredLogicalWidth);
return;
}
OverridingSizesScope cleanOverridingSizesScope(child, OverridingSizesScope::Axis::Both);
RenderBlock::computeChildIntrinsicLogicalWidths(childObject, minPreferredLogicalWidth, maxPreferredLogicalWidth);
}
LayoutUnit RenderFlexibleBox::baselinePosition(FontBaseline, bool, LineDirectionMode direction, LinePositionMode) const
{
auto baseline = firstLineBaseline();
if (!baseline)
return synthesizedBaselineFromBorderBox(*this, direction) + marginLogicalHeight();
return baseline.value() + (direction == HorizontalLine ? marginTop() : marginRight()).toInt();
}
std::optional<LayoutUnit> RenderFlexibleBox::firstLineBaseline() const
{
if (isWritingModeRoot() || m_numberOfInFlowChildrenOnFirstLine <= 0 || shouldApplyLayoutContainment(*this))
return std::optional<LayoutUnit>();
RenderBox* baselineChild = nullptr;
int childNumber = 0;
for (RenderBox* child = m_orderIterator.first(); child; child = m_orderIterator.next()) {
if (m_orderIterator.shouldSkipChild(*child))
continue;
if (alignmentForChild(*child) == ItemPosition::Baseline && !hasAutoMarginsInCrossAxis(*child)) {
baselineChild = child;
break;
}
if (!baselineChild)
baselineChild = child;
++childNumber;
if (childNumber == m_numberOfInFlowChildrenOnFirstLine)
break;
}
if (!baselineChild)
return std::optional<LayoutUnit>();
if (!isColumnFlow() && !mainAxisIsChildInlineAxis(*baselineChild))
return LayoutUnit { (crossAxisExtentForChild(*baselineChild) + baselineChild->logicalTop()).toInt() };
if (isColumnFlow() && mainAxisIsChildInlineAxis(*baselineChild))
return LayoutUnit { (mainAxisExtentForChild(*baselineChild) + baselineChild->logicalTop()).toInt() };
std::optional<LayoutUnit> baseline = baselineChild->firstLineBaseline();
if (!baseline) {
// FIXME: We should pass |direction| into firstLineBoxBaseline and stop bailing out if we're a writing mode root.
// This would also fix some cases where the flexbox is orthogonal to its container.
LineDirectionMode direction = isHorizontalWritingMode() ? HorizontalLine : VerticalLine;
return synthesizedBaselineFromBorderBox(*baselineChild, direction) + baselineChild->logicalTop();
}
return LayoutUnit { (baseline.value() + baselineChild->logicalTop()).toInt() };
}
std::optional<LayoutUnit> RenderFlexibleBox::inlineBlockBaseline(LineDirectionMode) const
{
return firstLineBaseline();
}
static const StyleContentAlignmentData& contentAlignmentNormalBehavior()
{
// The justify-content property applies along the main axis, but since
// flexing in the main axis is controlled by flex, stretch behaves as
// flex-start (ignoring the specified fallback alignment, if any).
// https://drafts.csswg.org/css-align/#distribution-flex
static const StyleContentAlignmentData normalBehavior = { ContentPosition::Normal, ContentDistribution::Stretch};
return normalBehavior;
}
void RenderFlexibleBox::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
{
RenderBlock::styleDidChange(diff, oldStyle);
if (!oldStyle || diff != StyleDifference::Layout)
return;
if (oldStyle->resolvedAlignItems(selfAlignmentNormalBehavior()).position() == ItemPosition::Stretch) {
// Flex items that were previously stretching need to be relayed out so we
// can compute new available cross axis space. This is only necessary for
// stretching since other alignment values don't change the size of the
// box.
for (auto& child : childrenOfType<RenderBox>(*this)) {
ItemPosition previousAlignment = child.style().resolvedAlignSelf(oldStyle, selfAlignmentNormalBehavior()).position();
if (previousAlignment == ItemPosition::Stretch && previousAlignment != child.style().resolvedAlignSelf(&style(), selfAlignmentNormalBehavior()).position())
child.setChildNeedsLayout(MarkOnlyThis);
}
}
}
bool RenderFlexibleBox::hitTestChildren(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& adjustedLocation, HitTestAction hitTestAction)
{
if (hitTestAction != HitTestForeground)
return false;
LayoutPoint scrolledOffset = hasNonVisibleOverflow() ? adjustedLocation - toLayoutSize(scrollPosition()) : adjustedLocation;
// If collecting the children in reverse order is bad for performance, this Vector could be determined at layout time.
Vector<RenderBox*> reversedOrderIteratorForHitTesting;
for (auto* child = m_orderIterator.first(); child; child = m_orderIterator.next()) {
if (m_orderIterator.shouldSkipChild(*child))
continue;
reversedOrderIteratorForHitTesting.append(child);
}
reversedOrderIteratorForHitTesting.reverse();
for (auto* child : reversedOrderIteratorForHitTesting) {
if (child->hasSelfPaintingLayer())
continue;
auto childPoint = flipForWritingModeForChild(child, scrolledOffset);
if (child->hitTest(request, result, locationInContainer, childPoint)) {
updateHitTestResult(result, flipForWritingMode(toLayoutPoint(locationInContainer.point() - adjustedLocation)));
return true;
}
}
return false;
}
void RenderFlexibleBox::layoutBlock(bool relayoutChildren, LayoutUnit)
{
ASSERT(needsLayout());
if (!relayoutChildren && simplifiedLayout())
return;
LayoutRepainter repainter(*this, checkForRepaintDuringLayout());
resetLogicalHeightBeforeLayoutIfNeeded();
m_relaidOutChildren.clear();
bool oldInLayout = m_inLayout;
m_inLayout = true;
if (recomputeLogicalWidth())
relayoutChildren = true;
LayoutUnit previousHeight = logicalHeight();
setLogicalHeight(borderAndPaddingLogicalHeight() + scrollbarLogicalHeight());
{
LayoutStateMaintainer statePusher(*this, locationOffset(), hasTransform() || hasReflection() || style().isFlippedBlocksWritingMode());
preparePaginationBeforeBlockLayout(relayoutChildren);
m_numberOfInFlowChildrenOnFirstLine = -1;
beginUpdateScrollInfoAfterLayoutTransaction();
prepareOrderIteratorAndMargins();
// Fieldsets need to find their legend and position it inside the border of the object.
// The legend then gets skipped during normal layout. The same is true for ruby text.
// It doesn't get included in the normal layout process but is instead skipped.
layoutExcludedChildren(relayoutChildren);
ChildFrameRects oldChildRects;
appendChildFrameRects(oldChildRects);
layoutFlexItems(relayoutChildren);
endAndCommitUpdateScrollInfoAfterLayoutTransaction();
if (logicalHeight() != previousHeight)
relayoutChildren = true;
layoutPositionedObjects(relayoutChildren || isDocumentElementRenderer());
repaintChildrenDuringLayoutIfMoved(oldChildRects);
// FIXME: css3/flexbox/repaint-rtl-column.html seems to repaint more overflow than it needs to.
computeOverflow(clientLogicalRightAndBottomAfterRepositioning().height());
}
updateLayerTransform();
// We have to reset this, because changes to our ancestors' style can affect
// this value. Also, this needs to be before we call updateAfterLayout, as
// that function may re-enter this one.
m_hasDefiniteHeight = SizeDefiniteness::Unknown;
// Update our scroll information if we're overflow:auto/scroll/hidden now that we know if we overflow or not.
updateScrollInfoAfterLayout();
repainter.repaintAfterLayout();
clearNeedsLayout();
m_inLayout = oldInLayout;
}
void RenderFlexibleBox::appendChildFrameRects(ChildFrameRects& childFrameRects)
{
for (RenderBox* child = m_orderIterator.first(); child; child = m_orderIterator.next()) {
if (!child->isOutOfFlowPositioned())
childFrameRects.append(child->frameRect());
}
}
void RenderFlexibleBox::repaintChildrenDuringLayoutIfMoved(const ChildFrameRects& oldChildRects)
{
size_t childIndex = 0;
for (RenderBox* child = m_orderIterator.first(); child; child = m_orderIterator.next()) {
if (child->isOutOfFlowPositioned())
continue;
// If the child moved, we have to repaint it as well as any floating/positioned
// descendants. An exception is if we need a layout. In this case, we know we're going to
// repaint ourselves (and the child) anyway.
if (!selfNeedsLayout() && child->checkForRepaintDuringLayout())
child->repaintDuringLayoutIfMoved(oldChildRects[childIndex]);
++childIndex;
}
ASSERT(childIndex == oldChildRects.size());
}
void RenderFlexibleBox::paintChildren(PaintInfo& paintInfo, const LayoutPoint& paintOffset, PaintInfo& paintInfoForChild, bool usePrintRect)
{
for (RenderBox* child = m_orderIterator.first(); child; child = m_orderIterator.next()) {
if (!paintChild(*child, paintInfo, paintOffset, paintInfoForChild, usePrintRect, PaintAsInlineBlock))
return;
}
}
void RenderFlexibleBox::repositionLogicalHeightDependentFlexItems(Vector<LineContext>& lineContexts, LayoutUnit gapBetweenLines)
{
LayoutUnit crossAxisStartEdge = lineContexts.isEmpty() ? 0_lu : lineContexts[0].crossAxisOffset;
// If we have a single line flexbox, the line height is all the available space. For flex-direction: row,
// this means we need to use the height, so we do this after calling updateLogicalHeight.
if (!isMultiline() && !lineContexts.isEmpty())
lineContexts[0].crossAxisExtent = crossAxisContentExtent();
alignFlexLines(lineContexts, gapBetweenLines);
alignChildren(lineContexts);
if (style().flexWrap() == FlexWrap::Reverse)
flipForWrapReverse(lineContexts, crossAxisStartEdge);
// direction:rtl + flex-direction:column means the cross-axis direction is
// flipped.
flipForRightToLeftColumn(lineContexts);
}
bool RenderFlexibleBox::mainAxisIsChildInlineAxis(const RenderBox& child) const
{
return isHorizontalFlow() == child.isHorizontalWritingMode();
}
bool RenderFlexibleBox::isColumnFlow() const
{
return style().isColumnFlexDirection();
}
bool RenderFlexibleBox::isColumnOrRowReverse() const
{
return style().flexDirection() == FlexDirection::ColumnReverse || style().flexDirection() == FlexDirection::RowReverse;
}
bool RenderFlexibleBox::isHorizontalFlow() const
{
if (isHorizontalWritingMode())
return !isColumnFlow();
return isColumnFlow();
}
bool RenderFlexibleBox::isLeftToRightFlow() const
{
if (isColumnFlow())
return style().writingMode() == WritingMode::TopToBottom || style().writingMode() == WritingMode::LeftToRight;
return style().isLeftToRightDirection() ^ (style().flexDirection() == FlexDirection::RowReverse);
}
bool RenderFlexibleBox::isMultiline() const
{
return style().flexWrap() != FlexWrap::NoWrap;
}
// https://drafts.csswg.org/css-flexbox/#min-size-auto
bool RenderFlexibleBox::shouldApplyMinSizeAutoForChild(const RenderBox& child) const
{
auto minSize = mainSizeLengthForChild(MinSize, child);
// min, max and fit-content are equivalent to the automatic size for block sizes https://drafts.csswg.org/css-sizing-3/#valdef-width-min-content.
bool childBlockSizeIsEquivalentToAutomaticSize = !mainAxisIsChildInlineAxis(child) && (minSize.isMinContent() || minSize.isMaxContent() || minSize.isFitContent());
return (minSize.isAuto() || childBlockSizeIsEquivalentToAutomaticSize) && (mainAxisOverflowForChild(child) == Overflow::Visible);
}
Length RenderFlexibleBox::flexBasisForChild(const RenderBox& child) const
{
Length flexLength = child.style().flexBasis();
if (flexLength.isAuto())
flexLength = mainSizeLengthForChild(MainOrPreferredSize, child);
return flexLength;
}
LayoutUnit RenderFlexibleBox::crossAxisExtentForChild(const RenderBox& child) const
{
return isHorizontalFlow() ? child.height() : child.width();
}
LayoutUnit RenderFlexibleBox::cachedChildIntrinsicContentLogicalHeight(const RenderBox& child) const
{
if (child.isRenderReplaced())
return downcast<RenderReplaced>(child).intrinsicLogicalHeight();
if (m_intrinsicContentLogicalHeights.contains(&child))
return m_intrinsicContentLogicalHeights.get(&child);
return child.contentLogicalHeight();
}
void RenderFlexibleBox::setCachedChildIntrinsicContentLogicalHeight(const RenderBox& child, LayoutUnit height)
{
if (child.isRenderReplaced())
return; // Replaced elements know their intrinsic height already, so save space by not caching.
m_intrinsicContentLogicalHeights.set(&child, height);
}
void RenderFlexibleBox::clearCachedChildIntrinsicContentLogicalHeight(const RenderBox& child)
{
if (child.isRenderReplaced())
return; // Replaced elements know their intrinsic height already, so nothing to do.
m_intrinsicContentLogicalHeights.remove(&child);
}
LayoutUnit RenderFlexibleBox::childIntrinsicLogicalHeight(RenderBox& child) const
{
// This should only be called if the logical height is the cross size
ASSERT(mainAxisIsChildInlineAxis(child));
if (needToStretchChildLogicalHeight(child)) {
LayoutUnit childContentHeight = cachedChildIntrinsicContentLogicalHeight(child);
LayoutUnit childLogicalHeight = childContentHeight + child.scrollbarLogicalHeight() + child.borderAndPaddingLogicalHeight();
return child.constrainLogicalHeightByMinMax(childLogicalHeight, childContentHeight);
}
return child.logicalHeight();
}
LayoutUnit RenderFlexibleBox::childIntrinsicLogicalWidth(RenderBox& child)
{
// This should only be called if the logical width is the cross size
ASSERT(!mainAxisIsChildInlineAxis(child));
if (childCrossSizeIsDefinite(child, child.style().logicalWidth()))
return child.logicalWidth();
LogicalExtentComputedValues values;
{
OverridingSizesScope cleanOverridingWidthScope(child, OverridingSizesScope::Axis::Inline);
child.computeLogicalWidthInFragment(values);
}
return values.m_extent;
}
LayoutUnit RenderFlexibleBox::crossAxisIntrinsicExtentForChild(RenderBox& child)
{
return mainAxisIsChildInlineAxis(child) ? childIntrinsicLogicalHeight(child) : childIntrinsicLogicalWidth(child);
}
LayoutUnit RenderFlexibleBox::mainAxisExtentForChild(const RenderBox& child) const
{
return isHorizontalFlow() ? child.size().width() : child.size().height();
}
LayoutUnit RenderFlexibleBox::mainAxisContentExtentForChildIncludingScrollbar(const RenderBox& child) const
{
return isHorizontalFlow() ? child.contentWidth() + child.verticalScrollbarWidth() : child.contentHeight() + child.horizontalScrollbarHeight();
}
LayoutUnit RenderFlexibleBox::crossAxisExtent() const
{
return isHorizontalFlow() ? size().height() : size().width();
}
LayoutUnit RenderFlexibleBox::mainAxisExtent() const
{
return isHorizontalFlow() ? size().width() : size().height();
}
LayoutUnit RenderFlexibleBox::crossAxisContentExtent() const
{
return isHorizontalFlow() ? contentHeight() : contentWidth();
}
LayoutUnit RenderFlexibleBox::mainAxisContentExtent(LayoutUnit contentLogicalHeight)
{
if (!isColumnFlow())
return contentLogicalWidth();
LayoutUnit borderPaddingAndScrollbar = borderAndPaddingLogicalHeight() + scrollbarLogicalHeight();
LayoutUnit borderBoxLogicalHeight = contentLogicalHeight + borderPaddingAndScrollbar;
auto computedValues = computeLogicalHeight(borderBoxLogicalHeight, logicalTop());
if (computedValues.m_extent == LayoutUnit::max())
return computedValues.m_extent;
return std::max(0_lu, computedValues.m_extent - borderPaddingAndScrollbar);
}
static bool childHasAspectRatio(const RenderBox& child)
{
return child.hasIntrinsicAspectRatio() || child.style().hasAspectRatio();
}
std::optional<LayoutUnit> RenderFlexibleBox::computeMainAxisExtentForChild(RenderBox& child, SizeType sizeType, const Length& size)
{
// If we have a horizontal flow, that means the main size is the width.
// That's the logical width for horizontal writing modes, and the logical
// height in vertical writing modes. For a vertical flow, main size is the
// height, so it's the inverse. So we need the logical width if we have a
// horizontal flow and horizontal writing mode, or vertical flow and vertical
// writing mode. Otherwise we need the logical height.
if (!mainAxisIsChildInlineAxis(child)) {
// We don't have to check for "auto" here - computeContentLogicalHeight
// will just return a null Optional for that case anyway. It's safe to access
// scrollbarLogicalHeight here because ComputeNextFlexLine will have
// already forced layout on the child. We previously did a layout out the child
// if necessary (see ComputeNextFlexLine and the call to
// childHasIntrinsicMainAxisSize) so we can be sure that the two height
// calls here will return up-to-date data.
std::optional<LayoutUnit> height = child.computeContentLogicalHeight(sizeType, size, cachedChildIntrinsicContentLogicalHeight(child));
if (!height)
return height;
return height.value() + child.scrollbarLogicalHeight();
}
// computeLogicalWidth always re-computes the intrinsic widths. However, when
// our logical width is auto, we can just use our cached value. So let's do
// that here. (Compare code in RenderBlock::computePreferredLogicalWidths)
if (child.style().logicalWidth().isAuto() && !childHasAspectRatio(child)) {
if (size.isMinContent()) {
if (child.needsPreferredWidthsRecalculation())
child.setPreferredLogicalWidthsDirty(true, MarkOnlyThis);
return child.minPreferredLogicalWidth() - child.borderAndPaddingLogicalWidth();
}
if (size.isMaxContent()) {
if (child.needsPreferredWidthsRecalculation())
child.setPreferredLogicalWidthsDirty(true, MarkOnlyThis);
return child.maxPreferredLogicalWidth() - child.borderAndPaddingLogicalWidth();
}
}
// FIXME: Figure out how this should work for regions and pass in the appropriate values.
RenderFragmentContainer* fragment = nullptr;
return child.computeLogicalWidthInFragmentUsing(sizeType, size, contentLogicalWidth(), *this, fragment) - child.borderAndPaddingLogicalWidth();
}
WritingMode RenderFlexibleBox::transformedWritingMode() const
{
WritingMode mode = style().writingMode();
if (!isColumnFlow())
return mode;
switch (mode) {
case WritingMode::TopToBottom:
case WritingMode::BottomToTop:
return style().isLeftToRightDirection() ? WritingMode::LeftToRight : WritingMode::RightToLeft;
case WritingMode::LeftToRight:
case WritingMode::RightToLeft:
return style().isLeftToRightDirection() ? WritingMode::TopToBottom : WritingMode::BottomToTop;
}
ASSERT_NOT_REACHED();
return WritingMode::TopToBottom;
}
LayoutUnit RenderFlexibleBox::flowAwareBorderStart() const
{
if (isHorizontalFlow())
return isLeftToRightFlow() ? borderLeft() : borderRight();
return isLeftToRightFlow() ? borderTop() : borderBottom();
}
LayoutUnit RenderFlexibleBox::flowAwareBorderEnd() const
{
if (isHorizontalFlow())
return isLeftToRightFlow() ? borderRight() : borderLeft();
return isLeftToRightFlow() ? borderBottom() : borderTop();
}
LayoutUnit RenderFlexibleBox::flowAwareBorderBefore() const
{
switch (transformedWritingMode()) {
case WritingMode::TopToBottom:
return borderTop();
case WritingMode::BottomToTop:
return borderBottom();
case WritingMode::LeftToRight:
return borderLeft();
case WritingMode::RightToLeft:
return borderRight();
}
ASSERT_NOT_REACHED();
return borderTop();
}
LayoutUnit RenderFlexibleBox::flowAwareBorderAfter() const
{
switch (transformedWritingMode()) {
case WritingMode::TopToBottom:
return borderBottom();
case WritingMode::BottomToTop:
return borderTop();
case WritingMode::LeftToRight:
return borderRight();
case WritingMode::RightToLeft:
return borderLeft();
}
ASSERT_NOT_REACHED();
return borderTop();
}
LayoutUnit RenderFlexibleBox::flowAwarePaddingStart() const
{
if (isHorizontalFlow())
return isLeftToRightFlow() ? paddingLeft() : paddingRight();
return isLeftToRightFlow() ? paddingTop() : paddingBottom();
}
LayoutUnit RenderFlexibleBox::flowAwarePaddingEnd() const
{
if (isHorizontalFlow())
return isLeftToRightFlow() ? paddingRight() : paddingLeft();
return isLeftToRightFlow() ? paddingBottom() : paddingTop();
}
LayoutUnit RenderFlexibleBox::flowAwarePaddingBefore() const
{
switch (transformedWritingMode()) {
case WritingMode::TopToBottom:
return paddingTop();
case WritingMode::BottomToTop:
return paddingBottom();
case WritingMode::LeftToRight:
return paddingLeft();
case WritingMode::RightToLeft:
return paddingRight();
}
ASSERT_NOT_REACHED();
return paddingTop();
}
LayoutUnit RenderFlexibleBox::flowAwarePaddingAfter() const
{
switch (transformedWritingMode()) {
case WritingMode::TopToBottom:
return paddingBottom();
case WritingMode::BottomToTop:
return paddingTop();
case WritingMode::LeftToRight:
return paddingRight();
case WritingMode::RightToLeft:
return paddingLeft();
}
ASSERT_NOT_REACHED();
return paddingTop();
}
LayoutUnit RenderFlexibleBox::flowAwareMarginStartForChild(const RenderBox& child) const
{
if (isHorizontalFlow())
return isLeftToRightFlow() ? child.marginLeft() : child.marginRight();
return isLeftToRightFlow() ? child.marginTop() : child.marginBottom();
}
LayoutUnit RenderFlexibleBox::flowAwareMarginEndForChild(const RenderBox& child) const
{
if (isHorizontalFlow())
return isLeftToRightFlow() ? child.marginRight() : child.marginLeft();
return isLeftToRightFlow() ? child.marginBottom() : child.marginTop();
}
LayoutUnit RenderFlexibleBox::flowAwareMarginBeforeForChild(const RenderBox& child) const
{
switch (transformedWritingMode()) {
case WritingMode::TopToBottom:
return child.marginTop();
case WritingMode::BottomToTop:
return child.marginBottom();
case WritingMode::LeftToRight:
return child.marginLeft();
case WritingMode::RightToLeft:
return child.marginRight();
}
ASSERT_NOT_REACHED();
return marginTop();
}
LayoutUnit RenderFlexibleBox::crossAxisMarginExtentForChild(const RenderBox& child) const
{
if (!child.needsLayout())
return isHorizontalFlow() ? child.verticalMarginExtent() : child.horizontalMarginExtent();
LayoutUnit marginStart;
LayoutUnit marginEnd;
if (isHorizontalFlow())
child.computeBlockDirectionMargins(*this, marginStart, marginEnd);
else
child.computeInlineDirectionMargins(*this, child.containingBlockLogicalWidthForContentInFragment(nullptr), child.logicalWidth(), marginStart, marginEnd);
return marginStart + marginEnd;
}
LayoutUnit RenderFlexibleBox::crossAxisScrollbarExtent() const
{
return isHorizontalFlow() ? horizontalScrollbarHeight() : verticalScrollbarWidth();
}
LayoutPoint RenderFlexibleBox::flowAwareLocationForChild(const RenderBox& child) const
{
return isHorizontalFlow() ? child.location() : child.location().transposedPoint();
}
Length RenderFlexibleBox::crossSizeLengthForChild(SizeType sizeType, const RenderBox& child) const
{
switch (sizeType) {
case MinSize:
return isHorizontalFlow() ? child.style().minHeight() : child.style().minWidth();
case MainOrPreferredSize:
return isHorizontalFlow() ? child.style().height() : child.style().width();
case MaxSize:
return isHorizontalFlow() ? child.style().maxHeight() : child.style().maxWidth();
}
ASSERT_NOT_REACHED();
return { };
}
Length RenderFlexibleBox::mainSizeLengthForChild(SizeType sizeType, const RenderBox& child) const
{
switch (sizeType) {
case MinSize:
return isHorizontalFlow() ? child.style().minWidth() : child.style().minHeight();
case MainOrPreferredSize:
return isHorizontalFlow() ? child.style().width() : child.style().height();
case MaxSize:
return isHorizontalFlow() ? child.style().maxWidth() : child.style().maxHeight();
}
ASSERT_NOT_REACHED();
return { };
}
// FIXME: computeMainSizeFromAspectRatioUsing may need to return an std::optional<LayoutUnit> in the future
// rather than returning indefinite sizes as 0/-1.
LayoutUnit RenderFlexibleBox::computeMainSizeFromAspectRatioUsing(const RenderBox& child, Length crossSizeLength) const
{
ASSERT(childHasAspectRatio(child));
auto adjustForBoxSizing = [this] (const RenderBox& box, Length length) -> LayoutUnit {
ASSERT(length.isFixed());
auto value = LayoutUnit(length.value());
// We need to substract the border and padding extent from the cross axis.
// Furthermore, the sizing calculations that floor the content box size at zero when applying box-sizing are also ignored.
// https://drafts.csswg.org/css-flexbox/#algo-main-item.
if (box.style().boxSizing() == BoxSizing::BorderBox)
value -= isHorizontalFlow() ? box.verticalBorderAndPaddingExtent() : box.horizontalBorderAndPaddingExtent();
return value;
};
std::optional<LayoutUnit> crossSize;
if (crossSizeLength.isFixed())
crossSize = adjustForBoxSizing(child, crossSizeLength);
else if (crossSizeLength.isAuto())
crossSize = computeCrossSizeForChildUsingContainerCrossSize(child);
else {
ASSERT(crossSizeLength.isPercentOrCalculated());
crossSize = mainAxisIsChildInlineAxis(child) ? child.computePercentageLogicalHeight(crossSizeLength) : adjustBorderBoxLogicalWidthForBoxSizing(valueForLength(crossSizeLength, contentWidth()), crossSizeLength.type());
if (!crossSize)
return 0_lu;
}
const LayoutSize& childIntrinsicSize = child.intrinsicSize();
double ratio;
if (child.style().aspectRatioType() == AspectRatioType::Ratio || (child.style().aspectRatioType() == AspectRatioType::AutoAndRatio && childIntrinsicSize.isEmpty()))
ratio = child.style().aspectRatioWidth() / child.style().aspectRatioHeight();
else {
ASSERT(childIntrinsicSize.height());
ratio = childIntrinsicSize.width().toFloat() / childIntrinsicSize.height().toFloat();
}
if (isHorizontalFlow())
return LayoutUnit(crossSize.value() * ratio);
return LayoutUnit(crossSize.value() / ratio);
}
void RenderFlexibleBox::setFlowAwareLocationForChild(RenderBox& child, const LayoutPoint& location)
{
if (isHorizontalFlow())
child.setLocation(location);
else
child.setLocation(location.transposedPoint());
}
bool RenderFlexibleBox::canComputePercentageFlexBasis(const RenderBox& child, const Length& flexBasis, UpdatePercentageHeightDescendants updateDescendants)
{
if (!isColumnFlow() || m_hasDefiniteHeight == SizeDefiniteness::Definite)
return true;
if (m_hasDefiniteHeight == SizeDefiniteness::Indefinite)
return false;
bool definite = child.computePercentageLogicalHeight(flexBasis, updateDescendants).has_value();
if (m_inLayout && (isHorizontalWritingMode() == child.isHorizontalWritingMode())) {
// We can reach this code even while we're not laying ourselves out, such
// as from mainSizeForPercentageResolution.
m_hasDefiniteHeight = definite ? SizeDefiniteness::Definite : SizeDefiniteness::Indefinite;
}
return definite;
}
bool RenderFlexibleBox::childMainSizeIsDefinite(const RenderBox& child, const Length& flexBasis)
{
if (flexBasis.isAuto() || flexBasis.isContent())
return false;
if (isColumnFlow() && (flexBasis.isIntrinsic() || flexBasis.type() == LengthType::Intrinsic))
return false;
if (flexBasis.isPercentOrCalculated())
return canComputePercentageFlexBasis(child, flexBasis, UpdatePercentageHeightDescendants::No);
return true;
}
bool RenderFlexibleBox::childHasComputableAspectRatio(const RenderBox& child) const
{
if (!childHasAspectRatio(child))
return false;
return child.intrinsicSize().height() || child.style().hasAspectRatio();
}
bool RenderFlexibleBox::childHasComputableAspectRatioAndCrossSizeIsConsideredDefinite(const RenderBox& child)
{
return childHasComputableAspectRatio(child)
&& (childCrossSizeIsDefinite(child, crossSizeLengthForChild(MainOrPreferredSize, child)) || childCrossSizeShouldUseContainerCrossSize(child));
}
bool RenderFlexibleBox::childCrossSizeShouldUseContainerCrossSize(const RenderBox& child) const
{
// 9.8 https://drafts.csswg.org/css-flexbox/#definite-sizes
// 1. If a single-line flex container has a definite cross size, the automatic preferred outer cross size of any
// stretched flex items is the flex container's inner cross size (clamped to the flex item's min and max cross size)
// and is considered definite.
if (!isMultiline() && alignmentForChild(child) == ItemPosition::Stretch && !hasAutoMarginsInCrossAxis(child) && crossSizeLengthForChild(MainOrPreferredSize, child).isAuto()) {
// This must be kept in sync with computeMainSizeFromAspectRatioUsing().
// FIXME: so far we're only considered fixed sizes but we should extend it to other definite sizes.
auto& crossSize = isHorizontalFlow() ? style().height() : style().width();
return crossSize.isFixed();
}
return false;
}
bool RenderFlexibleBox::childCrossSizeIsDefinite(const RenderBox& child, const Length& length)
{
if (length.isAuto())
return false;
if (length.isPercentOrCalculated()) {
if (!mainAxisIsChildInlineAxis(child) || m_hasDefiniteHeight == SizeDefiniteness::Definite)
return true;
if (m_hasDefiniteHeight == SizeDefiniteness::Indefinite)
return false;
bool definite = bool(child.computePercentageLogicalHeight(length));
m_hasDefiniteHeight = definite ? SizeDefiniteness::Definite : SizeDefiniteness::Indefinite;
return definite;
}
// FIXME: Eventually we should support other types of sizes here.
// Requires updating computeMainSizeFromAspectRatioUsing.
return length.isFixed();
}
void RenderFlexibleBox::cacheChildMainSize(const RenderBox& child)
{
ASSERT(!child.needsLayout());
LayoutUnit mainSize;
if (mainAxisIsChildInlineAxis(child))
mainSize = child.maxPreferredLogicalWidth();
else {
auto flexBasis = flexBasisForChild(child);
if (flexBasis.isPercentOrCalculated() && !childMainSizeIsDefinite(child, flexBasis))
mainSize = cachedChildIntrinsicContentLogicalHeight(child) + child.borderAndPaddingLogicalHeight() + child.scrollbarLogicalHeight();
else
mainSize = child.logicalHeight();
}
m_intrinsicSizeAlongMainAxis.set(&child, mainSize);
m_relaidOutChildren.add(&child);
}
void RenderFlexibleBox::clearCachedMainSizeForChild(const RenderBox& child)
{
m_intrinsicSizeAlongMainAxis.remove(&child);
}
// This is a RAII class that is used to temporarily set the flex basis as the child size in the main axis.
class ScopedFlexBasisAsChildMainSize {
public:
ScopedFlexBasisAsChildMainSize(RenderBox& child, Length flexBasis, bool mainAxisIsInlineAxis)
: m_child(child)
, m_mainAxisIsInlineAxis(mainAxisIsInlineAxis)
{
if (m_mainAxisIsInlineAxis)
m_child.setOverridingLogicalWidthLength(flexBasis);
else
m_child.setOverridingLogicalHeightLength(flexBasis);
}
~ScopedFlexBasisAsChildMainSize()
{
if (m_mainAxisIsInlineAxis)
m_child.clearOverridingLogicalWidthLength();
else
m_child.clearOverridingLogicalHeightLength();
}
private:
RenderBox& m_child;
bool m_mainAxisIsInlineAxis;
};
// https://drafts.csswg.org/css-flexbox/#algo-main-item
LayoutUnit RenderFlexibleBox::computeFlexBaseSizeForChild(RenderBox& child, LayoutUnit mainAxisBorderAndPadding, bool relayoutChildren)
{
Length flexBasis = flexBasisForChild(child);
ScopedFlexBasisAsChildMainSize scoped(child, flexBasis.isContent() ? Length(LengthType::MaxContent) : flexBasis, mainAxisIsChildInlineAxis(child));
maybeCacheChildMainIntrinsicSize(child, relayoutChildren);
// 9.2.3 A.
if (childMainSizeIsDefinite(child, flexBasis))
return std::max(0_lu, computeMainAxisExtentForChild(child, MainOrPreferredSize, flexBasis).value());
// 9.2.3 B.
if (childHasComputableAspectRatioAndCrossSizeIsConsideredDefinite(child)) {
const Length& crossSizeLength = crossSizeLengthForChild(MainOrPreferredSize, child);
return adjustChildSizeForAspectRatioCrossAxisMinAndMax(child, computeMainSizeFromAspectRatioUsing(child, crossSizeLength));
}
// FIXME: 9.2.3 C.
// FIXME: 9.2.3 D.
// 9.2.3 E.
LayoutUnit mainAxisExtent;
if (!mainAxisIsChildInlineAxis(child)) {
ASSERT(!child.needsLayout());
ASSERT(m_intrinsicSizeAlongMainAxis.contains(&child));
mainAxisExtent = m_intrinsicSizeAlongMainAxis.get(&child);
} else {
// We don't need to add scrollbarLogicalWidth here because the preferred
// width includes the scrollbar, even for overflow: auto.
mainAxisExtent = child.maxPreferredLogicalWidth();
}
return mainAxisExtent - mainAxisBorderAndPadding;
}
void RenderFlexibleBox::layoutFlexItems(bool relayoutChildren)
{
Vector<LineContext> lineContexts;
LayoutUnit sumFlexBaseSize;
double totalFlexGrow;
double totalFlexShrink;
double totalWeightedFlexShrink;
LayoutUnit sumHypotheticalMainSize;
// Set up our master list of flex items. All of the rest of the algorithm
// should work off this list of a subset.
// TODO(cbiesinger): That second part is not yet true.
Vector<FlexItem> allItems;
m_orderIterator.first();
for (RenderBox* child = m_orderIterator.currentChild(); child; child = m_orderIterator.next()) {
if (m_orderIterator.shouldSkipChild(*child)) {
// Out-of-flow children are not flex items, so we skip them here.
if (child->isOutOfFlowPositioned())
prepareChildForPositionedLayout(*child);
continue;
}
allItems.append(constructFlexItem(*child, relayoutChildren));
// constructFlexItem() might set the override containing block height so any value cached for definiteness might be incorrect.
m_hasDefiniteHeight = SizeDefiniteness::Unknown;
}
const LayoutUnit lineBreakLength = mainAxisContentExtent(LayoutUnit::max());
LayoutUnit gapBetweenItems = computeGap(GapType::BetweenItems);
LayoutUnit gapBetweenLines = computeGap(GapType::BetweenLines);
FlexLayoutAlgorithm flexAlgorithm(style(), lineBreakLength, allItems, gapBetweenItems, gapBetweenLines);
LayoutUnit crossAxisOffset = flowAwareBorderBefore() + flowAwarePaddingBefore();
Vector<FlexItem> lineItems;
size_t nextIndex = 0;
size_t numLines = 0;
while (flexAlgorithm.computeNextFlexLine(nextIndex, lineItems, sumFlexBaseSize, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink, sumHypotheticalMainSize)) {
++numLines;
LayoutUnit containerMainInnerSize = mainAxisContentExtent(sumHypotheticalMainSize);
// availableFreeSpace is the initial amount of free space in this flexbox.
// remainingFreeSpace starts out at the same value but as we place and lay
// out flex items we subtract from it. Note that both values can be
// negative.
LayoutUnit remainingFreeSpace = containerMainInnerSize - sumFlexBaseSize;
FlexSign flexSign = (sumHypotheticalMainSize < containerMainInnerSize) ? PositiveFlexibility : NegativeFlexibility;
freezeInflexibleItems(flexSign, lineItems, remainingFreeSpace, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink);
// The initial free space gets calculated after freezing inflexible items.
// https://drafts.csswg.org/css-flexbox/#resolve-flexible-lengths step 3
const LayoutUnit initialFreeSpace = remainingFreeSpace;
while (!resolveFlexibleLengths(flexSign, lineItems, initialFreeSpace, remainingFreeSpace, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink)) {
ASSERT(totalFlexGrow >= 0);
ASSERT(totalWeightedFlexShrink >= 0);
}
// Recalculate the remaining free space. The adjustment for flex factors
// between 0..1 means we can't just use remainingFreeSpace here.
remainingFreeSpace = containerMainInnerSize;
for (size_t i = 0; i < lineItems.size(); ++i) {
FlexItem& flexItem = lineItems[i];
ASSERT(!flexItem.box.isOutOfFlowPositioned());
remainingFreeSpace -= flexItem.flexedMarginBoxSize();
}
remainingFreeSpace -= (lineItems.size() - 1) * gapBetweenItems;
// This will std::move lineItems into a newly-created LineContext.
layoutAndPlaceChildren(crossAxisOffset, lineItems, remainingFreeSpace, relayoutChildren, lineContexts, gapBetweenItems);
}
if (hasLineIfEmpty()) {
// Even if computeNextFlexLine returns true, the flexbox might not have
// a line because all our children might be out of flow positioned.
// Instead of just checking if we have a line, make sure the flexbox
// has at least a line's worth of height to cover this case.
LayoutUnit minHeight = borderAndPaddingLogicalHeight() + lineHeight(true, isHorizontalWritingMode() ? HorizontalLine : VerticalLine, PositionOfInteriorLineBoxes) + scrollbarLogicalHeight();
if (size().height() < minHeight)
setLogicalHeight(minHeight);
}
if (!isColumnFlow() && numLines > 1)
setLogicalHeight(logicalHeight() + computeGap(GapType::BetweenLines) * (numLines - 1));
updateLogicalHeight();
repositionLogicalHeightDependentFlexItems(lineContexts, gapBetweenLines);
}
LayoutUnit RenderFlexibleBox::autoMarginOffsetInMainAxis(const Vector<FlexItem>& children, LayoutUnit& availableFreeSpace)
{
if (availableFreeSpace <= 0_lu)
return 0_lu;
int numberOfAutoMargins = 0;
bool isHorizontal = isHorizontalFlow();
for (size_t i = 0; i < children.size(); ++i) {
const auto& child = children[i].box;
ASSERT(!child.isOutOfFlowPositioned());
if (isHorizontal) {
if (child.style().marginLeft().isAuto())
++numberOfAutoMargins;
if (child.style().marginRight().isAuto())
++numberOfAutoMargins;
} else {
if (child.style().marginTop().isAuto())
++numberOfAutoMargins;
if (child.style().marginBottom().isAuto())
++numberOfAutoMargins;
}
}
if (!numberOfAutoMargins)
return 0_lu;
LayoutUnit sizeOfAutoMargin = availableFreeSpace / numberOfAutoMargins;
availableFreeSpace = 0_lu;
return sizeOfAutoMargin;
}
void RenderFlexibleBox::updateAutoMarginsInMainAxis(RenderBox& child, LayoutUnit autoMarginOffset)
{
ASSERT(autoMarginOffset >= 0_lu);
if (isHorizontalFlow()) {
if (child.style().marginLeft().isAuto())
child.setMarginLeft(autoMarginOffset);
if (child.style().marginRight().isAuto())
child.setMarginRight(autoMarginOffset);
} else {
if (child.style().marginTop().isAuto())
child.setMarginTop(autoMarginOffset);
if (child.style().marginBottom().isAuto())
child.setMarginBottom(autoMarginOffset);
}
}
bool RenderFlexibleBox::hasAutoMarginsInCrossAxis(const RenderBox& child) const
{
if (isHorizontalFlow())
return child.style().marginTop().isAuto() || child.style().marginBottom().isAuto();
return child.style().marginLeft().isAuto() || child.style().marginRight().isAuto();
}
LayoutUnit RenderFlexibleBox::availableAlignmentSpaceForChild(LayoutUnit lineCrossAxisExtent, const RenderBox& child)
{
ASSERT(!child.isOutOfFlowPositioned());
LayoutUnit childCrossExtent = crossAxisMarginExtentForChild(child) + crossAxisExtentForChild(child);
return lineCrossAxisExtent - childCrossExtent;
}
bool RenderFlexibleBox::updateAutoMarginsInCrossAxis(RenderBox& child, LayoutUnit availableAlignmentSpace)
{
ASSERT(!child.isOutOfFlowPositioned());
ASSERT(availableAlignmentSpace >= 0_lu);
bool isHorizontal = isHorizontalFlow();
Length topOrLeft = isHorizontal ? child.style().marginTop() : child.style().marginLeft();
Length bottomOrRight = isHorizontal ? child.style().marginBottom() : child.style().marginRight();
if (topOrLeft.isAuto() && bottomOrRight.isAuto()) {
adjustAlignmentForChild(child, availableAlignmentSpace / 2);
if (isHorizontal) {
child.setMarginTop(availableAlignmentSpace / 2);
child.setMarginBottom(availableAlignmentSpace / 2);
} else {
child.setMarginLeft(availableAlignmentSpace / 2);
child.setMarginRight(availableAlignmentSpace / 2);
}
return true;
}
bool shouldAdjustTopOrLeft = true;
if (isColumnFlow() && !child.style().isLeftToRightDirection()) {
// For column flows, only make this adjustment if topOrLeft corresponds to
// the "before" margin, so that flipForRightToLeftColumn will do the right
// thing.
shouldAdjustTopOrLeft = false;
}
if (!isColumnFlow() && child.style().isFlippedBlocksWritingMode()) {
// If we are a flipped writing mode, we need to adjust the opposite side.
// This is only needed for row flows because this only affects the
// block-direction axis.
shouldAdjustTopOrLeft = false;
}
if (topOrLeft.isAuto()) {
if (shouldAdjustTopOrLeft)
adjustAlignmentForChild(child, availableAlignmentSpace);
if (isHorizontal)
child.setMarginTop(availableAlignmentSpace);
else
child.setMarginLeft(availableAlignmentSpace);
return true;
}
if (bottomOrRight.isAuto()) {
if (!shouldAdjustTopOrLeft)
adjustAlignmentForChild(child, availableAlignmentSpace);
if (isHorizontal)
child.setMarginBottom(availableAlignmentSpace);
else
child.setMarginRight(availableAlignmentSpace);
return true;
}
return false;
}
LayoutUnit RenderFlexibleBox::marginBoxAscentForChild(const RenderBox& child)
{
LayoutUnit ascent = child.firstLineBaseline().value_or(crossAxisExtentForChild(child));
return ascent + flowAwareMarginBeforeForChild(child);
}
LayoutUnit RenderFlexibleBox::computeChildMarginValue(Length margin)
{
// When resolving the margins, we use the content size for resolving percent and calc (for percents in calc expressions) margins.
// Fortunately, percent margins are always computed with respect to the block's width, even for margin-top and margin-bottom.
LayoutUnit availableSize = contentLogicalWidth();
return minimumValueForLength(margin, availableSize);
}
void RenderFlexibleBox::prepareOrderIteratorAndMargins()
{
OrderIteratorPopulator populator(m_orderIterator);
for (RenderBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
if (!populator.collectChild(*child))
continue;
// Before running the flex algorithm, 'auto' has a margin of 0.
// Also, if we're not auto sizing, we don't do a layout that computes the start/end margins.
if (isHorizontalFlow()) {
child->setMarginLeft(computeChildMarginValue(child->style().marginLeft()));
child->setMarginRight(computeChildMarginValue(child->style().marginRight()));
} else {
child->setMarginTop(computeChildMarginValue(child->style().marginTop()));
child->setMarginBottom(computeChildMarginValue(child->style().marginBottom()));
}
}
}
std::pair<LayoutUnit, LayoutUnit> RenderFlexibleBox::computeFlexItemMinMaxSizes(RenderBox& child)
{
Length max = mainSizeLengthForChild(MaxSize, child);
std::optional<LayoutUnit> maxExtent = std::nullopt;
if (max.isSpecifiedOrIntrinsic())
maxExtent = computeMainAxisExtentForChild(child, MaxSize, max);
Length min = mainSizeLengthForChild(MinSize, child);
// Intrinsic sizes in child's block axis are handled by the min-size:auto code path.
if (min.isSpecified() || (min.isIntrinsic() && mainAxisIsChildInlineAxis(child)))
return { computeMainAxisExtentForChild(child, MinSize, min).value_or(0_lu), maxExtent.value_or(LayoutUnit::max()) };
if (shouldApplyMinSizeAutoForChild(child)) {
// FIXME: If the min value is expected to be valid here, we need to come up with a non optional version of computeMainAxisExtentForChild and
// ensure it's valid through the virtual calls of computeIntrinsicLogicalContentHeightUsing.
LayoutUnit contentSize;
Length childCrossSizeLength = crossSizeLengthForChild(MainOrPreferredSize, child);
if (child.isRenderReplaced() && childHasComputableAspectRatio(child) && childCrossSizeIsDefinite(child, childCrossSizeLength))
contentSize = computeMainSizeFromAspectRatioUsing(child, childCrossSizeLength);
else
contentSize = computeMainAxisExtentForChild(child, MinSize, Length(LengthType::MinContent)).value_or(0);
if (child.hasIntrinsicAspectRatio() && child.intrinsicSize().height())
contentSize = adjustChildSizeForAspectRatioCrossAxisMinAndMax(child, contentSize);
ASSERT(contentSize >= 0);
contentSize = std::min(contentSize, maxExtent.value_or(contentSize));
Length mainSize = mainSizeLengthForChild(MainOrPreferredSize, child);
if (childMainSizeIsDefinite(child, mainSize)) {
LayoutUnit resolvedMainSize = computeMainAxisExtentForChild(child, MainOrPreferredSize, mainSize).value_or(0);
ASSERT(resolvedMainSize >= 0);
LayoutUnit specifiedSize = std::min(resolvedMainSize, maxExtent.value_or(resolvedMainSize));
return { std::min(specifiedSize, contentSize), maxExtent.value_or(LayoutUnit::max()) };
}
if (child.isRenderReplaced() && childHasComputableAspectRatioAndCrossSizeIsConsideredDefinite(child)) {
LayoutUnit transferredSize = computeMainSizeFromAspectRatioUsing(child, childCrossSizeLength);
transferredSize = adjustChildSizeForAspectRatioCrossAxisMinAndMax(child, transferredSize);
return { std::min(transferredSize, contentSize), maxExtent.value_or(LayoutUnit::max()) };
}
return { contentSize, maxExtent.value_or(LayoutUnit::max()) };
}
return { 0_lu, maxExtent.value_or(LayoutUnit::max()) };
}
bool RenderFlexibleBox::useChildOverridingCrossSizeForPercentageResolution(const RenderBox& child)
{
ASSERT(mainAxisIsChildInlineAxis(child));
if (alignmentForChild(child) != ItemPosition::Stretch)
return false;
return child.hasOverridingLogicalHeight();
}
// This method is only called whenever a descendant of a flex item wants to resolve a percentage in its
// block axis (logical height). The key here is that percentages should be generally resolved before the
// flex item is flexed, meaning that they shouldn't be recomputed once the flex item has been flexed. There
// are some exceptions though that are implemented here, like the case of fully inflexible items with
// definite flex-basis, or whenever the flex container has a definite main size. See
// https://drafts.csswg.org/css-flexbox/#definite-sizes for additional details.
bool RenderFlexibleBox::useChildOverridingMainSizeForPercentageResolution(const RenderBox& child)
{
ASSERT(!mainAxisIsChildInlineAxis(child));
// The main size of a fully inflexible item with a definite flex basis is, by definition, definite.
if (child.style().flexGrow() == 0.0 && child.style().flexShrink() == 0.0 && childMainSizeIsDefinite(child, flexBasisForChild(child)))
return child.hasOverridingLogicalHeight();
// This function implements section 9.8. Definite and Indefinite Sizes, case 2) of the flexbox spec.
// If the flex container has a definite main size the flex item post-flexing main size is also treated
// as definite. We make up a percentage to check whether we have a definite size.
if (!canComputePercentageFlexBasis(child, Length(0, LengthType::Percent), UpdatePercentageHeightDescendants::Yes))
return false;
return child.hasOverridingLogicalHeight();
}
bool RenderFlexibleBox::useChildOverridingLogicalHeightForPercentageResolution(const RenderBox& child)
{
if (mainAxisIsChildInlineAxis(child))
return useChildOverridingCrossSizeForPercentageResolution(child);
return useChildOverridingMainSizeForPercentageResolution(child);
}
LayoutUnit RenderFlexibleBox::adjustChildSizeForAspectRatioCrossAxisMinAndMax(const RenderBox& child, LayoutUnit childSize)
{
Length crossMin = crossSizeLengthForChild(MinSize, child);
Length crossMax = crossSizeLengthForChild(MaxSize, child);
if (childCrossSizeIsDefinite(child, crossMax)) {
LayoutUnit maxValue = computeMainSizeFromAspectRatioUsing(child, crossMax);
childSize = std::min(maxValue, childSize);
}
if (childCrossSizeIsDefinite(child, crossMin)) {
LayoutUnit minValue = computeMainSizeFromAspectRatioUsing(child, crossMin);
childSize = std::max(minValue, childSize);
}
return childSize;
}
void RenderFlexibleBox::maybeCacheChildMainIntrinsicSize(RenderBox& child, bool relayoutChildren)
{
if (!childHasIntrinsicMainAxisSize(child))
return;
// If this condition is true, then computeMainAxisExtentForChild will call
// child.intrinsicContentLogicalHeight() and child.scrollbarLogicalHeight(),
// so if the child has intrinsic min/max/preferred size, run layout on it now to make sure
// its logical height and scroll bars are up to date.
updateBlockChildDirtyBitsBeforeLayout(relayoutChildren, child);
// Don't resolve percentages in children. This is especially important for the min-height calculation,
// where we want percentages to be treated as auto. For flex-basis itself, this is not a problem because
// by definition we have an indefinite flex basis here and thus percentages should not resolve.
if (child.needsLayout() || !m_intrinsicSizeAlongMainAxis.contains(&child)) {
if (isHorizontalWritingMode() == child.isHorizontalWritingMode())
child.setOverridingContainingBlockContentLogicalHeight(std::nullopt);
else
child.setOverridingContainingBlockContentLogicalWidth(std::nullopt);
child.setChildNeedsLayout(MarkOnlyThis);
child.layoutIfNeeded();
cacheChildMainSize(child);
child.clearOverridingContainingBlockContentSize();
}
}
FlexItem RenderFlexibleBox::constructFlexItem(RenderBox& child, bool relayoutChildren)
{
auto childHadLayout = child.everHadLayout();
child.clearOverridingContentSize();
LayoutUnit borderAndPadding = isHorizontalFlow() ? child.horizontalBorderAndPaddingExtent() : child.verticalBorderAndPaddingExtent();
LayoutUnit childInnerFlexBaseSize = computeFlexBaseSizeForChild(child, borderAndPadding, relayoutChildren);
LayoutUnit margin = isHorizontalFlow() ? child.horizontalMarginExtent() : child.verticalMarginExtent();
return FlexItem(child, childInnerFlexBaseSize, borderAndPadding, margin, computeFlexItemMinMaxSizes(child), childHadLayout);
}
void RenderFlexibleBox::freezeViolations(Vector<FlexItem*>& violations, LayoutUnit& availableFreeSpace, double& totalFlexGrow, double& totalFlexShrink, double& totalWeightedFlexShrink)
{
for (size_t i = 0; i < violations.size(); ++i) {
ASSERT(!violations[i]->frozen);
const auto& child = violations[i]->box;
LayoutUnit childSize = violations[i]->flexedContentSize;
availableFreeSpace -= childSize - violations[i]->flexBaseContentSize;
totalFlexGrow -= child.style().flexGrow();
totalFlexShrink -= child.style().flexShrink();
totalWeightedFlexShrink -= child.style().flexShrink() * violations[i]->flexBaseContentSize;
// totalWeightedFlexShrink can be negative when we exceed the precision of
// a double when we initially calcuate totalWeightedFlexShrink. We then
// subtract each child's weighted flex shrink with full precision, now
// leading to a negative result. See
// css3/flexbox/large-flex-shrink-assert.html
totalWeightedFlexShrink = std::max(totalWeightedFlexShrink, 0.0);
violations[i]->frozen = true;
}
}
void RenderFlexibleBox::freezeInflexibleItems(FlexSign flexSign, Vector<FlexItem>& children, LayoutUnit& remainingFreeSpace, double& totalFlexGrow, double& totalFlexShrink, double& totalWeightedFlexShrink)
{
// Per https://drafts.csswg.org/css-flexbox/#resolve-flexible-lengths step 2,
// we freeze all items with a flex factor of 0 as well as those with a min/max
// size violation.
Vector<FlexItem*> newInflexibleItems;
for (size_t i = 0; i < children.size(); ++i) {
FlexItem& flexItem = children[i];
const auto& child = flexItem.box;
ASSERT(!flexItem.box.isOutOfFlowPositioned());
ASSERT(!flexItem.frozen);
float flexFactor = (flexSign == PositiveFlexibility) ? child.style().flexGrow() : child.style().flexShrink();
if (!flexFactor || (flexSign == PositiveFlexibility && flexItem.flexBaseContentSize > flexItem.hypotheticalMainContentSize) || (flexSign == NegativeFlexibility && flexItem.flexBaseContentSize < flexItem.hypotheticalMainContentSize)) {
flexItem.flexedContentSize = flexItem.hypotheticalMainContentSize;
newInflexibleItems.append(&flexItem);
}
}
freezeViolations(newInflexibleItems, remainingFreeSpace, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink);
}
// Returns true if we successfully ran the algorithm and sized the flex items.
bool RenderFlexibleBox::resolveFlexibleLengths(FlexSign flexSign, Vector<FlexItem>& children, LayoutUnit initialFreeSpace, LayoutUnit& remainingFreeSpace, double& totalFlexGrow, double& totalFlexShrink, double& totalWeightedFlexShrink)
{
LayoutUnit totalViolation;
LayoutUnit usedFreeSpace;
Vector<FlexItem*> minViolations;
Vector<FlexItem*> maxViolations;
double sumFlexFactors = (flexSign == PositiveFlexibility) ? totalFlexGrow : totalFlexShrink;
if (sumFlexFactors > 0 && sumFlexFactors < 1) {
LayoutUnit fractional(initialFreeSpace * sumFlexFactors);
if (fractional.abs() < remainingFreeSpace.abs())
remainingFreeSpace = fractional;
}
for (size_t i = 0; i < children.size(); ++i) {
FlexItem& flexItem = children[i];
auto& child = flexItem.box;
// This check also covers out-of-flow children.
if (flexItem.frozen)
continue;
LayoutUnit childSize = flexItem.flexBaseContentSize;
double extraSpace = 0;
if (remainingFreeSpace > 0 && totalFlexGrow > 0 && flexSign == PositiveFlexibility && std::isfinite(totalFlexGrow))
extraSpace = remainingFreeSpace * child.style().flexGrow() / totalFlexGrow;
else if (remainingFreeSpace < 0 && totalWeightedFlexShrink > 0 && flexSign == NegativeFlexibility && std::isfinite(totalWeightedFlexShrink) && child.style().flexShrink())
extraSpace = remainingFreeSpace * child.style().flexShrink() * flexItem.flexBaseContentSize / totalWeightedFlexShrink;
if (std::isfinite(extraSpace))
childSize += LayoutUnit::fromFloatRound(extraSpace);
LayoutUnit adjustedChildSize = flexItem.constrainSizeByMinMax(childSize);
ASSERT(adjustedChildSize >= 0);
flexItem.flexedContentSize = adjustedChildSize;
usedFreeSpace += adjustedChildSize - flexItem.flexBaseContentSize;
LayoutUnit violation = adjustedChildSize - childSize;
if (violation > 0)
minViolations.append(&flexItem);
else if (violation < 0)
maxViolations.append(&flexItem);
totalViolation += violation;
}
if (totalViolation)
freezeViolations(totalViolation < 0 ? maxViolations : minViolations, remainingFreeSpace, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink);
else
remainingFreeSpace -= usedFreeSpace;
return !totalViolation;
}
static LayoutUnit initialJustifyContentOffset(const RenderStyle& style, LayoutUnit availableFreeSpace, unsigned numberOfChildren, bool isReversed)
{
ContentPosition justifyContent = style.resolvedJustifyContentPosition(contentAlignmentNormalBehavior());
ContentDistribution justifyContentDistribution = style.resolvedJustifyContentDistribution(contentAlignmentNormalBehavior());
// First of all resolve Left and Right so we could convert it to their equivalent properties handled bellow.
// If the property's axis is not parallel with either left<->right axis, this value behaves as start. Currently,
// the only case where the property's axis is not parallel with either left<->right axis is in a column flexbox.
// https: //www.w3.org/TR/css-align-3/#valdef-justify-content-left
if ((justifyContent == ContentPosition::Left || justifyContent == ContentPosition::Right) && style.isColumnFlexDirection() && style.isHorizontalWritingMode())
justifyContent = ContentPosition::Start;
if (justifyContent == ContentPosition::Left) {
if (style.isColumnFlexDirection() && style.isFlippedBlocksWritingMode())
justifyContent = ContentPosition::End;
else
justifyContent = style.isLeftToRightDirection() ? ContentPosition::Start : ContentPosition::End;
}
if (justifyContent == ContentPosition::Right) {
if (style.isColumnFlexDirection() && !style.isFlippedLinesWritingMode())
justifyContent = ContentPosition::Start;
else
justifyContent = style.isLeftToRightDirection() ? ContentPosition::End : ContentPosition::Start;
}
ASSERT(justifyContent != ContentPosition::Left);
ASSERT(justifyContent != ContentPosition::Right);
if (justifyContent == ContentPosition::FlexEnd
|| (justifyContent == ContentPosition::End && !isReversed)
|| (justifyContent == ContentPosition::Start && isReversed))
return availableFreeSpace;
if (justifyContent == ContentPosition::Center)
return availableFreeSpace / 2;
if (justifyContentDistribution == ContentDistribution::SpaceAround) {
if (availableFreeSpace > 0 && numberOfChildren)
return availableFreeSpace / (2 * numberOfChildren);
else
return availableFreeSpace / 2;
}
if (justifyContentDistribution == ContentDistribution::SpaceEvenly) {
if (availableFreeSpace > 0 && numberOfChildren)
return availableFreeSpace / (numberOfChildren + 1);
// Fallback to 'center'
return availableFreeSpace / 2;
}
return 0;
}
static LayoutUnit justifyContentSpaceBetweenChildren(LayoutUnit availableFreeSpace, ContentDistribution justifyContentDistribution, unsigned numberOfChildren)
{
if (availableFreeSpace > 0 && numberOfChildren > 1) {
if (justifyContentDistribution == ContentDistribution::SpaceBetween)
return availableFreeSpace / (numberOfChildren - 1);
if (justifyContentDistribution == ContentDistribution::SpaceAround)
return availableFreeSpace / numberOfChildren;
if (justifyContentDistribution == ContentDistribution::SpaceEvenly)
return availableFreeSpace / (numberOfChildren + 1);
}
return 0;
}
static LayoutUnit alignmentOffset(LayoutUnit availableFreeSpace, ItemPosition position, LayoutUnit ascent, LayoutUnit maxAscent, bool isWrapReverse)
{
switch (position) {
case ItemPosition::Legacy:
case ItemPosition::Auto:
case ItemPosition::Normal:
ASSERT_NOT_REACHED();
break;
case ItemPosition::Start:
case ItemPosition::End:
case ItemPosition::SelfStart:
case ItemPosition::SelfEnd:
case ItemPosition::Left:
case ItemPosition::Right:
ASSERT_NOT_REACHED("%u alignmentForChild should have transformed this position value to something we handle below.", static_cast<uint8_t>(position));
break;
case ItemPosition::Stretch:
// Actual stretching must be handled by the caller. Since wrap-reverse
// flips cross start and cross end, stretch children should be aligned
// with the cross end. This matters because applyStretchAlignment
// doesn't always stretch or stretch fully (explicit cross size given, or
// stretching constrained by max-height/max-width). For flex-start and
// flex-end this is handled by alignmentForChild().
if (isWrapReverse)
return availableFreeSpace;
break;
case ItemPosition::FlexStart:
break;
case ItemPosition::FlexEnd:
return availableFreeSpace;
case ItemPosition::Center:
return availableFreeSpace / 2;
case ItemPosition::Baseline:
// FIXME: If we get here in columns, we want the use the descent, except
// we currently can't get the ascent/descent of orthogonal children.
// https://bugs.webkit.org/show_bug.cgi?id=98076
return maxAscent - ascent;
case ItemPosition::LastBaseline:
// FIXME: Implement last baseline.
break;
}
return 0;
}
void RenderFlexibleBox::setOverridingMainSizeForChild(RenderBox& child, LayoutUnit childPreferredSize)
{
if (mainAxisIsChildInlineAxis(child))
child.setOverridingLogicalWidth(childPreferredSize + child.borderAndPaddingLogicalWidth());
else
child.setOverridingLogicalHeight(childPreferredSize + child.borderAndPaddingLogicalHeight());
}
LayoutUnit RenderFlexibleBox::staticMainAxisPositionForPositionedChild(const RenderBox& child)
{
const LayoutUnit availableSpace = mainAxisContentExtent(contentLogicalHeight()) - mainAxisExtentForChild(child);
auto isReverse = isColumnOrRowReverse();
LayoutUnit offset = initialJustifyContentOffset(style(), availableSpace, 1, isReverse);
if (isReverse)
offset = availableSpace - offset;
return offset;
}
LayoutUnit RenderFlexibleBox::staticCrossAxisPositionForPositionedChild(const RenderBox& child)
{
LayoutUnit availableSpace = crossAxisContentExtent() - crossAxisExtentForChild(child);
return alignmentOffset(availableSpace, alignmentForChild(child), 0_lu, 0_lu, style().flexWrap() == FlexWrap::Reverse);
}
LayoutUnit RenderFlexibleBox::staticInlinePositionForPositionedChild(const RenderBox& child)
{
return startOffsetForContent() + (isColumnFlow() ? staticCrossAxisPositionForPositionedChild(child) : staticMainAxisPositionForPositionedChild(child));
}
LayoutUnit RenderFlexibleBox::staticBlockPositionForPositionedChild(const RenderBox& child)
{
return borderAndPaddingBefore() + (isColumnFlow() ? staticMainAxisPositionForPositionedChild(child) : staticCrossAxisPositionForPositionedChild(child));
}
bool RenderFlexibleBox::setStaticPositionForPositionedLayout(const RenderBox& child)
{
bool positionChanged = false;
auto* childLayer = child.layer();
if (child.style().hasStaticInlinePosition(style().isHorizontalWritingMode())) {
LayoutUnit inlinePosition = staticInlinePositionForPositionedChild(child);
if (childLayer->staticInlinePosition() != inlinePosition) {
childLayer->setStaticInlinePosition(inlinePosition);
positionChanged = true;
}
}
if (child.style().hasStaticBlockPosition(style().isHorizontalWritingMode())) {
LayoutUnit blockPosition = staticBlockPositionForPositionedChild(child);
if (childLayer->staticBlockPosition() != blockPosition) {
childLayer->setStaticBlockPosition(blockPosition);
positionChanged = true;
}
}
return positionChanged;
}
// This refers to https://drafts.csswg.org/css-flexbox-1/#definite-sizes, section 1).
LayoutUnit RenderFlexibleBox::computeCrossSizeForChildUsingContainerCrossSize(const RenderBox& child) const
{
// Keep this sync'ed with childCrossSizeShouldUseContainerCrossSize().
auto definiteSizeValue = [&] {
// Let's compute the definite size value for the flex item (value that we can resolve without running layout).
auto isHorizontal = isHorizontalFlow();
auto size = isHorizontal ? style().height() : style().width();
ASSERT(size.isFixed());
auto definiteValue = LayoutUnit { size.value() };
auto maximumSize = isHorizontal ? style().maxHeight() : style().maxWidth();
if (maximumSize.isFixed())
definiteValue = std::min(definiteValue, LayoutUnit { maximumSize.value() });
auto minimumSize = isHorizontal ? style().minHeight() : style().minWidth();
if (minimumSize.isFixed())
definiteValue = std::max(definiteValue, LayoutUnit { minimumSize.value() });
return definiteValue;
};
return std::max(0_lu, definiteSizeValue() - crossAxisMarginExtentForChild(child));
}
void RenderFlexibleBox::prepareChildForPositionedLayout(RenderBox& child)
{
ASSERT(child.isOutOfFlowPositioned());
child.containingBlock()->insertPositionedObject(child);
auto* childLayer = child.layer();
LayoutUnit staticInlinePosition = flowAwareBorderStart() + flowAwarePaddingStart();
if (childLayer->staticInlinePosition() != staticInlinePosition) {
childLayer->setStaticInlinePosition(staticInlinePosition);
if (child.style().hasStaticInlinePosition(style().isHorizontalWritingMode()))
child.setChildNeedsLayout(MarkOnlyThis);
}
LayoutUnit staticBlockPosition = flowAwareBorderBefore() + flowAwarePaddingBefore();
if (childLayer->staticBlockPosition() != staticBlockPosition) {
childLayer->setStaticBlockPosition(staticBlockPosition);
if (child.style().hasStaticBlockPosition(style().isHorizontalWritingMode()))
child.setChildNeedsLayout(MarkOnlyThis);
}
}
ItemPosition RenderFlexibleBox::alignmentForChild(const RenderBox& child) const
{
ItemPosition align = child.style().resolvedAlignSelf(&style(), selfAlignmentNormalBehavior()).position();
ASSERT(align != ItemPosition::Auto && align != ItemPosition::Normal);
// Left and Right are only for justify-*.
ASSERT(align != ItemPosition::Left && align != ItemPosition::Right);
if (align == ItemPosition::Baseline && !mainAxisIsChildInlineAxis(child))
align = ItemPosition::FlexStart;
// We can safely return here because start/end are not affected by a reversed flex-wrap because the
// alignment container is the flex line, and in a wrap reversed flex container the start and end within
// a flex line are still the same. Contrary to this flex-start/flex-end depend on the flex container
// start/end edges which are flipped in the case of wrap-reverse.
if (align == ItemPosition::Start)
return ItemPosition::FlexStart;
if (align == ItemPosition::End)
return ItemPosition::FlexEnd;
if (align == ItemPosition::SelfStart || align == ItemPosition::SelfEnd) {
// self-start corresponds to flex-start (and self-end to flex-end) in the majority of the cases
// for orthogonal layouts except when the container is flipped blocks writing mode (vrl/hbt) and
// the child is ltr or the other way around. For example:
// 1) htb ltr child inside a vrl container: self-start corresponds to flex-end
// 2) htb rtl child inside a vlr container: self-end corresponds to flex-start
bool isOrthogonal = style().isHorizontalWritingMode() != child.style().isHorizontalWritingMode();
if (isOrthogonal && (style().isFlippedBlocksWritingMode() == child.style().isLeftToRightDirection()))
return align == ItemPosition::SelfStart ? ItemPosition::FlexEnd : ItemPosition::FlexStart;
if (!isOrthogonal) {
if (style().isFlippedLinesWritingMode() != child.style().isFlippedLinesWritingMode())
return align == ItemPosition::SelfStart ? ItemPosition::FlexEnd : ItemPosition::FlexStart;
if (style().isLeftToRightDirection() != child.style().isLeftToRightDirection())
return align == ItemPosition::SelfStart ? ItemPosition::FlexEnd : ItemPosition::FlexStart;
}
return align == ItemPosition::SelfStart ? ItemPosition::FlexStart : ItemPosition::FlexEnd;
}
if (style().flexWrap() == FlexWrap::Reverse) {
if (align == ItemPosition::FlexStart)
align = ItemPosition::FlexEnd;
else if (align == ItemPosition::FlexEnd)
align = ItemPosition::FlexStart;
}
return align;
}
void RenderFlexibleBox::resetAutoMarginsAndLogicalTopInCrossAxis(RenderBox& child)
{
if (hasAutoMarginsInCrossAxis(child)) {
child.updateLogicalHeight();
if (isHorizontalFlow()) {
if (child.style().marginTop().isAuto())
child.setMarginTop(0_lu);
if (child.style().marginBottom().isAuto())
child.setMarginBottom(0_lu);
} else {
if (child.style().marginLeft().isAuto())
child.setMarginLeft(0_lu);
if (child.style().marginRight().isAuto())
child.setMarginRight(0_lu);
}
}
}
bool RenderFlexibleBox::needToStretchChildLogicalHeight(const RenderBox& child) const
{
// This function is a little bit magical. It relies on the fact that blocks
// intrinsically "stretch" themselves in their inline axis, i.e. a <div> has
// an implicit width: 100%. So the child will automatically stretch if our
// cross axis is the child's inline axis. That's the case if:
// - We are horizontal and the child is in vertical writing mode
// - We are vertical and the child is in horizontal writing mode
// Otherwise, we need to stretch if the cross axis size is auto.
if (alignmentForChild(child) != ItemPosition::Stretch)
return false;
if (isHorizontalFlow() != child.style().isHorizontalWritingMode())
return false;
// Aspect ratio is properly handled by RenderReplaced during layout.
if (child.isRenderReplaced() && childHasAspectRatio(child))
return false;
return child.style().logicalHeight().isAuto();
}
bool RenderFlexibleBox::childHasIntrinsicMainAxisSize(const RenderBox& child)
{
if (mainAxisIsChildInlineAxis(child))
return false;
Length childFlexBasis = flexBasisForChild(child);
Length childMinSize = mainSizeLengthForChild(MinSize, child);
Length childMaxSize = mainSizeLengthForChild(MaxSize, child);
// FIXME: we must run childMainSizeIsDefinite() because it might end up calling computePercentageLogicalHeight()
// which has some side effects like calling addPercentHeightDescendant() for example so it is not possible to skip
// the call for example by moving it to the end of the conditional expression. This is error-prone and we should
// refactor computePercentageLogicalHeight() at some point so that it only computes stuff without those side effects.
if (!childMainSizeIsDefinite(child, childFlexBasis) || childMinSize.isIntrinsic() || childMaxSize.isIntrinsic())
return true;
if (shouldApplyMinSizeAutoForChild(child))
return true;
return false;
}
Overflow RenderFlexibleBox::mainAxisOverflowForChild(const RenderBox& child) const
{
if (isHorizontalFlow())
return child.effectiveOverflowX();
return child.effectiveOverflowY();
}
Overflow RenderFlexibleBox::crossAxisOverflowForChild(const RenderBox& child) const
{
if (isHorizontalFlow())
return child.effectiveOverflowY();
return child.effectiveOverflowX();
}
bool RenderFlexibleBox::childHasPercentHeightDescendants(const RenderBox& renderer) const
{
// FIXME: This function can be removed soon after webkit.org/b/204318 is fixed. Evaluate whether the
// skipContainingBlockForPercentHeightCalculation() check below should be moved to the caller in that case.
if (!is<RenderBlock>(renderer))
return false;
auto& renderBlock = downcast<RenderBlock>(renderer);
// FlexibleBoxImpl's like RenderButton might wrap their children in anonymous blocks. Those anonymous blocks are
// skipped for percentage height calculations in RenderBox::computePercentageLogicalHeight() and thus
// addPercentHeightDescendant() is never called for them. This means that this method would always wrongly
// return false for a child of a <button> with a percentage height.
if (hasPercentHeightDescendants() && skipContainingBlockForPercentHeightCalculation(renderer, isHorizontalWritingMode() != renderer.isHorizontalWritingMode())) {
auto& descendants = *percentHeightDescendants();
for (auto* descendant : descendants) {
if (renderBlock.isContainingBlockAncestorFor(*descendant))
return true;
}
}
if (!renderBlock.hasPercentHeightDescendants())
return false;
auto* percentHeightDescendants = renderBlock.percentHeightDescendants();
if (!percentHeightDescendants)
return false;
for (auto it = percentHeightDescendants->begin(), end = percentHeightDescendants->end(); it != end; ++it) {
bool hasOutOfFlowAncestor = false;
for (auto* ancestor = (*it)->containingBlock(); ancestor && ancestor != &renderBlock; ancestor = ancestor->containingBlock()) {
if (ancestor->isOutOfFlowPositioned()) {
hasOutOfFlowAncestor = true;
break;
}
}
if (!hasOutOfFlowAncestor)
return true;
}
return false;
}
void RenderFlexibleBox::layoutAndPlaceChildren(LayoutUnit& crossAxisOffset, Vector<FlexItem>& children, LayoutUnit availableFreeSpace, bool relayoutChildren, Vector<LineContext>& lineContexts, LayoutUnit gapBetweenItems)
{
LayoutUnit autoMarginOffset = autoMarginOffsetInMainAxis(children, availableFreeSpace);
LayoutUnit mainAxisOffset = flowAwareBorderStart() + flowAwarePaddingStart();
mainAxisOffset += initialJustifyContentOffset(style(), availableFreeSpace, children.size(), isColumnOrRowReverse());
if (style().flexDirection() == FlexDirection::RowReverse)
mainAxisOffset += isHorizontalFlow() ? verticalScrollbarWidth() : horizontalScrollbarHeight();
LayoutUnit totalMainExtent = mainAxisExtent();
LayoutUnit maxAscent, maxDescent; // Used when align-items: baseline.
LayoutUnit maxChildCrossAxisExtent;
ContentDistribution distribution = style().resolvedJustifyContentDistribution(contentAlignmentNormalBehavior());
bool shouldFlipMainAxis = !isColumnFlow() && !isLeftToRightFlow();
for (size_t i = 0; i < children.size(); ++i) {
const auto& flexItem = children[i];
auto& child = flexItem.box;
ASSERT(!flexItem.box.isOutOfFlowPositioned());
setOverridingMainSizeForChild(child, flexItem.flexedContentSize);
// The flexed content size and the override size include the scrollbar
// width, so we need to compare to the size including the scrollbar.
// TODO(cbiesinger): Should it include the scrollbar?
if (flexItem.flexedContentSize != mainAxisContentExtentForChildIncludingScrollbar(child))
child.setChildNeedsLayout(MarkOnlyThis);
else {
// To avoid double applying margin changes in
// updateAutoMarginsInCrossAxis, we reset the margins here.
resetAutoMarginsAndLogicalTopInCrossAxis(child);
}
// We may have already forced relayout for orthogonal flowing children in
// computeInnerFlexBaseSizeForChild.
bool forceChildRelayout = relayoutChildren && !m_relaidOutChildren.contains(&child);
if (!forceChildRelayout && childHasPercentHeightDescendants(child)) {
// Have to force another relayout even though the child is sized
// correctly, because its descendants are not sized correctly yet. Our
// previous layout of the child was done without an override height set.
// So, redo it here.
forceChildRelayout = true;
}
updateBlockChildDirtyBitsBeforeLayout(forceChildRelayout, child);
if (!child.needsLayout())
child.markForPaginationRelayoutIfNeeded();
if (child.needsLayout())
m_relaidOutChildren.add(&child);
child.layoutIfNeeded();
if (!flexItem.everHadLayout && child.checkForRepaintDuringLayout()) {
child.repaint();
child.repaintOverhangingFloats(true);
}
updateAutoMarginsInMainAxis(child, autoMarginOffset);
LayoutUnit childCrossAxisMarginBoxExtent;
if (alignmentForChild(child) == ItemPosition::Baseline && !hasAutoMarginsInCrossAxis(child)) {
LayoutUnit ascent = marginBoxAscentForChild(child);
LayoutUnit descent = (crossAxisMarginExtentForChild(child) + crossAxisExtentForChild(child)) - ascent;
maxAscent = std::max(maxAscent, ascent);
maxDescent = std::max(maxDescent, descent);
// FIXME: Take scrollbar into account
childCrossAxisMarginBoxExtent = maxAscent + maxDescent;
} else
childCrossAxisMarginBoxExtent = crossAxisIntrinsicExtentForChild(child) + crossAxisMarginExtentForChild(child);
if (!isColumnFlow())
setLogicalHeight(std::max(logicalHeight(), crossAxisOffset + flowAwareBorderAfter() + flowAwarePaddingAfter() + childCrossAxisMarginBoxExtent + crossAxisScrollbarExtent()));
maxChildCrossAxisExtent = std::max(maxChildCrossAxisExtent, childCrossAxisMarginBoxExtent);
mainAxisOffset += flowAwareMarginStartForChild(child);
LayoutUnit childMainExtent = mainAxisExtentForChild(child);
// In an RTL column situation, this will apply the margin-right/margin-end
// on the left. This will be fixed later in flipForRightToLeftColumn.
LayoutPoint childLocation(shouldFlipMainAxis ? totalMainExtent - mainAxisOffset - childMainExtent : mainAxisOffset, crossAxisOffset + flowAwareMarginBeforeForChild(child));
setFlowAwareLocationForChild(child, childLocation);
mainAxisOffset += childMainExtent + flowAwareMarginEndForChild(child);
if (i != children.size() - 1) {
// The last item does not get extra space added.
mainAxisOffset += justifyContentSpaceBetweenChildren(availableFreeSpace, distribution, children.size()) + gapBetweenItems;
}
// FIXME: Deal with pagination.
}
if (isColumnFlow())
setLogicalHeight(std::max(logicalHeight(), mainAxisOffset + flowAwareBorderEnd() + flowAwarePaddingEnd() + scrollbarLogicalHeight()));
if (style().flexDirection() == FlexDirection::ColumnReverse) {
// We have to do an extra pass for column-reverse to reposition the flex
// items since the start depends on the height of the flexbox, which we
// only know after we've positioned all the flex items.
updateLogicalHeight();
layoutColumnReverse(children, crossAxisOffset, availableFreeSpace);
}
if (m_numberOfInFlowChildrenOnFirstLine == -1)
m_numberOfInFlowChildrenOnFirstLine = children.size();
lineContexts.append(LineContext(crossAxisOffset, maxChildCrossAxisExtent, maxAscent, WTFMove(children)));
crossAxisOffset += maxChildCrossAxisExtent;
}
void RenderFlexibleBox::layoutColumnReverse(const Vector<FlexItem>& children, LayoutUnit crossAxisOffset, LayoutUnit availableFreeSpace)
{
// This is similar to the logic in layoutAndPlaceChildren, except we place
// the children starting from the end of the flexbox. We also don't need to
// layout anything since we're just moving the children to a new position.
LayoutUnit mainAxisOffset = logicalHeight() - flowAwareBorderEnd() - flowAwarePaddingEnd();
mainAxisOffset -= initialJustifyContentOffset(style(), availableFreeSpace, children.size(), isColumnOrRowReverse());
mainAxisOffset -= isHorizontalFlow() ? verticalScrollbarWidth() : horizontalScrollbarHeight();
ContentDistribution distribution = style().resolvedJustifyContentDistribution(contentAlignmentNormalBehavior());
for (size_t i = 0; i < children.size(); ++i) {
auto& child = children[i].box;
ASSERT(!child.isOutOfFlowPositioned());
mainAxisOffset -= mainAxisExtentForChild(child) + flowAwareMarginEndForChild(child);
setFlowAwareLocationForChild(child, LayoutPoint(mainAxisOffset, crossAxisOffset + flowAwareMarginBeforeForChild(child)));
mainAxisOffset -= flowAwareMarginStartForChild(child);
mainAxisOffset -= justifyContentSpaceBetweenChildren(availableFreeSpace, distribution, children.size());
}
}
static LayoutUnit initialAlignContentOffset(LayoutUnit availableFreeSpace, ContentPosition alignContent, ContentDistribution alignContentDistribution, unsigned numberOfLines, bool isReversed)
{
if (alignContent == ContentPosition::FlexEnd
|| (alignContent == ContentPosition::End && !isReversed)
|| (alignContent == ContentPosition::Start && isReversed))
return availableFreeSpace;
if (alignContent == ContentPosition::Center)
return availableFreeSpace / 2;
if (alignContentDistribution == ContentDistribution::SpaceAround) {
if (availableFreeSpace > 0 && numberOfLines)
return availableFreeSpace / (2 * numberOfLines);
if (availableFreeSpace < 0)
return availableFreeSpace / 2;
}
if (alignContentDistribution == ContentDistribution::SpaceEvenly) {
if (availableFreeSpace > 0)
return availableFreeSpace / (numberOfLines + 1);
// Fallback to 'center'
return availableFreeSpace / 2;
}
return 0_lu;
}
static LayoutUnit alignContentSpaceBetweenChildren(LayoutUnit availableFreeSpace, ContentDistribution alignContentDistribution, unsigned numberOfLines)
{
if (availableFreeSpace > 0 && numberOfLines > 1) {
if (alignContentDistribution == ContentDistribution::SpaceBetween)
return availableFreeSpace / (numberOfLines - 1);
if (alignContentDistribution == ContentDistribution::SpaceAround || alignContentDistribution == ContentDistribution::Stretch)
return availableFreeSpace / numberOfLines;
if (alignContentDistribution == ContentDistribution::SpaceEvenly)
return availableFreeSpace / (numberOfLines + 1);
}
return 0_lu;
}
void RenderFlexibleBox::alignFlexLines(Vector<LineContext>& lineContexts, LayoutUnit gapBetweenLines)
{
if (lineContexts.isEmpty() || !isMultiline())
return;
ContentPosition position = style().resolvedAlignContentPosition(contentAlignmentNormalBehavior());
ContentDistribution distribution = style().resolvedAlignContentDistribution(contentAlignmentNormalBehavior());
if (position == ContentPosition::FlexStart && !gapBetweenLines)
return;
size_t numLines = lineContexts.size();
LayoutUnit availableCrossAxisSpace = crossAxisContentExtent() - (numLines - 1) * gapBetweenLines;
for (size_t i = 0; i < numLines; ++i)
availableCrossAxisSpace -= lineContexts[i].crossAxisExtent;
LayoutUnit lineOffset = initialAlignContentOffset(availableCrossAxisSpace, position, distribution, numLines, style().flexWrap() == FlexWrap::Reverse);
for (unsigned lineNumber = 0; lineNumber < numLines; ++lineNumber) {
LineContext& lineContext = lineContexts[lineNumber];
lineContext.crossAxisOffset += lineOffset;
for (size_t childNumber = 0; childNumber < lineContext.flexItems.size(); ++childNumber) {
FlexItem& flexItem = lineContext.flexItems[childNumber];
adjustAlignmentForChild(flexItem.box, lineOffset);
}
if (distribution == ContentDistribution::Stretch && availableCrossAxisSpace > 0)
lineContexts[lineNumber].crossAxisExtent += availableCrossAxisSpace / static_cast<unsigned>(numLines);
lineOffset += alignContentSpaceBetweenChildren(availableCrossAxisSpace, distribution, numLines) + gapBetweenLines;
}
}
void RenderFlexibleBox::adjustAlignmentForChild(RenderBox& child, LayoutUnit delta)
{
ASSERT(!child.isOutOfFlowPositioned());
setFlowAwareLocationForChild(child, flowAwareLocationForChild(child) + LayoutSize(0_lu, delta));
}
void RenderFlexibleBox::alignChildren(const Vector<LineContext>& lineContexts)
{
// Keep track of the space between the baseline edge and the after edge of
// the box for each line.
Vector<LayoutUnit> minMarginAfterBaselines;
for (size_t lineNumber = 0; lineNumber < lineContexts.size(); ++lineNumber) {
const LineContext& lineContext = lineContexts[lineNumber];
LayoutUnit minMarginAfterBaseline = LayoutUnit::max();
LayoutUnit lineCrossAxisExtent = lineContext.crossAxisExtent;
LayoutUnit maxAscent = lineContext.maxAscent;
for (size_t childNumber = 0; childNumber < lineContext.flexItems.size(); ++childNumber) {
const auto& flexItem = lineContext.flexItems[childNumber];
ASSERT(!flexItem.box.isOutOfFlowPositioned());
if (updateAutoMarginsInCrossAxis(flexItem.box, std::max(0_lu, availableAlignmentSpaceForChild(lineCrossAxisExtent, flexItem.box))))
continue;
ItemPosition position = alignmentForChild(flexItem.box);
if (position == ItemPosition::Stretch)
applyStretchAlignmentToChild(flexItem.box, lineCrossAxisExtent);
LayoutUnit availableSpace = availableAlignmentSpaceForChild(lineCrossAxisExtent, flexItem.box);
LayoutUnit offset = alignmentOffset(availableSpace, position, marginBoxAscentForChild(flexItem.box), maxAscent, style().flexWrap() == FlexWrap::Reverse);
adjustAlignmentForChild(flexItem.box, offset);
if (position == ItemPosition::Baseline && style().flexWrap() == FlexWrap::Reverse)
minMarginAfterBaseline = std::min(minMarginAfterBaseline, availableAlignmentSpaceForChild(lineCrossAxisExtent, flexItem.box) - offset);
}
minMarginAfterBaselines.append(minMarginAfterBaseline);
}
if (style().flexWrap() != FlexWrap::Reverse)
return;
// wrap-reverse flips the cross axis start and end. For baseline alignment,
// this means we need to align the after edge of baseline elements with the
// after edge of the flex line.
for (size_t lineNumber = 0; lineNumber < lineContexts.size(); ++lineNumber) {
const LineContext& lineContext = lineContexts[lineNumber];
LayoutUnit minMarginAfterBaseline = minMarginAfterBaselines[lineNumber];
for (size_t childNumber = 0; childNumber < lineContext.flexItems.size(); ++childNumber) {
const auto& flexItem = lineContext.flexItems[childNumber];
if (alignmentForChild(flexItem.box) == ItemPosition::Baseline && !hasAutoMarginsInCrossAxis(flexItem.box) && minMarginAfterBaseline)
adjustAlignmentForChild(flexItem.box, minMarginAfterBaseline);
}
}
}
void RenderFlexibleBox::applyStretchAlignmentToChild(RenderBox& child, LayoutUnit lineCrossAxisExtent)
{
if (mainAxisIsChildInlineAxis(child) && child.style().logicalHeight().isAuto()) {
LayoutUnit stretchedLogicalHeight = std::max(child.borderAndPaddingLogicalHeight(),
lineCrossAxisExtent - crossAxisMarginExtentForChild(child));
ASSERT(!child.needsLayout());
LayoutUnit desiredLogicalHeight = child.constrainLogicalHeightByMinMax(stretchedLogicalHeight, cachedChildIntrinsicContentLogicalHeight(child));
// FIXME: Can avoid laying out here in some cases. See https://webkit.org/b/87905.
bool childNeedsRelayout = desiredLogicalHeight != child.logicalHeight();
if (child.isRenderBlock() && downcast<RenderBlock>(child).hasPercentHeightDescendants() && m_relaidOutChildren.contains(&child)) {
// Have to force another relayout even though the child is sized
// correctly, because its descendants are not sized correctly yet. Our
// previous layout of the child was done without an override height set.
// So, redo it here.
childNeedsRelayout = true;
}
if (childNeedsRelayout || !child.hasOverridingLogicalHeight())
child.setOverridingLogicalHeight(desiredLogicalHeight);
if (childNeedsRelayout) {
SetForScope<bool> resetChildLogicalHeight(m_shouldResetChildLogicalHeightBeforeLayout, true);
// We cache the child's intrinsic content logical height to avoid it being
// reset to the stretched height.
// FIXME: This is fragile. RenderBoxes should be smart enough to
// determine their intrinsic content logical height correctly even when
// there's an overrideHeight.
LayoutUnit childIntrinsicContentLogicalHeight = cachedChildIntrinsicContentLogicalHeight(child);
child.setChildNeedsLayout(MarkOnlyThis);
// Don't use layoutChildIfNeeded to avoid setting cross axis cached size twice.
child.layoutIfNeeded();
setCachedChildIntrinsicContentLogicalHeight(child, childIntrinsicContentLogicalHeight);
}
} else if (!mainAxisIsChildInlineAxis(child) && child.style().logicalWidth().isAuto()) {
LayoutUnit childWidth = std::max(0_lu, lineCrossAxisExtent - crossAxisMarginExtentForChild(child));
childWidth = child.constrainLogicalWidthInFragmentByMinMax(childWidth, crossAxisContentExtent(), *this, nullptr);
if (childWidth != child.logicalWidth()) {
child.setOverridingLogicalWidth(childWidth);
child.setChildNeedsLayout(MarkOnlyThis);
child.layoutIfNeeded();
}
}
}
void RenderFlexibleBox::flipForRightToLeftColumn(const Vector<LineContext>& lineContexts)
{
if (style().isLeftToRightDirection() || !isColumnFlow())
return;
LayoutUnit crossExtent = crossAxisExtent();
for (size_t lineNumber = 0; lineNumber < lineContexts.size(); ++lineNumber) {
const LineContext& lineContext = lineContexts[lineNumber];
for (size_t childNumber = 0; childNumber < lineContext.flexItems.size(); ++childNumber) {
const auto& flexItem = lineContext.flexItems[childNumber];
ASSERT(!flexItem.box.isOutOfFlowPositioned());
LayoutPoint location = flowAwareLocationForChild(flexItem.box);
// For vertical flows, setFlowAwareLocationForChild will transpose x and
// y, so using the y axis for a column cross axis extent is correct.
location.setY(crossExtent - crossAxisExtentForChild(flexItem.box) - location.y());
if (!isHorizontalWritingMode())
location.move(LayoutSize(0, -horizontalScrollbarHeight()));
setFlowAwareLocationForChild(flexItem.box, location);
}
}
}
void RenderFlexibleBox::flipForWrapReverse(const Vector<LineContext>& lineContexts, LayoutUnit crossAxisStartEdge)
{
LayoutUnit contentExtent = crossAxisContentExtent();
for (size_t lineNumber = 0; lineNumber < lineContexts.size(); ++lineNumber) {
const LineContext& lineContext = lineContexts[lineNumber];
for (size_t childNumber = 0; childNumber < lineContext.flexItems.size(); ++childNumber) {
const auto& flexItem = lineContext.flexItems[childNumber];
LayoutUnit lineCrossAxisExtent = lineContexts[lineNumber].crossAxisExtent;
LayoutUnit originalOffset = lineContexts[lineNumber].crossAxisOffset - crossAxisStartEdge;
LayoutUnit newOffset = contentExtent - originalOffset - lineCrossAxisExtent;
adjustAlignmentForChild(flexItem.box, newOffset - originalOffset);
}
}
}
bool RenderFlexibleBox::isTopLayoutOverflowAllowed() const
{
bool hasTopOverflow = RenderBlock::isTopLayoutOverflowAllowed();
if (hasTopOverflow || !style().isReverseFlexDirection())
return hasTopOverflow;
return !isHorizontalFlow();
}
bool RenderFlexibleBox::isLeftLayoutOverflowAllowed() const
{
bool hasLeftOverflow = RenderBlock::isLeftLayoutOverflowAllowed();
if (hasLeftOverflow || !style().isReverseFlexDirection())
return hasLeftOverflow;
return isHorizontalFlow();
}
LayoutUnit RenderFlexibleBox::computeGap(RenderFlexibleBox::GapType gapType) const
{
// row-gap is used for gaps between flex items in column flows or for gaps between lines in row flows.
bool usesRowGap = (gapType == GapType::BetweenItems) == isColumnFlow();
auto& gapLength = usesRowGap ? style().rowGap() : style().columnGap();
if (LIKELY(gapLength.isNormal()))
return { };
auto availableSize = usesRowGap ? availableLogicalHeightForPercentageComputation().value_or(0_lu) : contentLogicalWidth();
return minimumValueForLength(gapLength.length(), availableSize);
}
}