flutter_flutter/engine/core/rendering/RenderBlockFlow.cpp

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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#include "sky/engine/config.h"
#include "sky/engine/core/rendering/RenderBlockFlow.h"

#include "sky/engine/core/frame/FrameView.h"
#include "sky/engine/core/frame/LocalFrame.h"
#include "sky/engine/core/frame/Settings.h"
#include "sky/engine/core/rendering/BidiRun.h"
#include "sky/engine/core/rendering/HitTestLocation.h"
#include "sky/engine/core/rendering/RenderLayer.h"
#include "sky/engine/core/rendering/RenderText.h"
#include "sky/engine/core/rendering/RenderView.h"
#include "sky/engine/core/rendering/line/LineWidth.h"
#include "sky/engine/platform/text/BidiTextRun.h"

namespace blink {

RenderBlockFlow::RenderBlockFlow(ContainerNode* node)
    : RenderBlock(node)
{
}

RenderBlockFlow::~RenderBlockFlow()
{
}

RenderBlockFlow* RenderBlockFlow::createAnonymous(Document* document)
{
    RenderBlockFlow* renderer = new RenderBlockFlow(0);
    renderer->setDocumentForAnonymous(document);
    return renderer;
}

void RenderBlockFlow::layout()
{
    ASSERT(needsLayout());
    ASSERT(isInlineBlock() || !isInline());

    if (simplifiedLayout())
        return;

    SubtreeLayoutScope layoutScope(*this);

    layoutBlockFlow(layoutScope);

    updateLayerTransformAfterLayout();

    clearNeedsLayout();
}

inline void RenderBlockFlow::layoutBlockFlow(SubtreeLayoutScope& layoutScope)
{
    LayoutUnit oldLeft = logicalLeft();
    bool logicalWidthChanged = updateLogicalWidthAndColumnWidth();
    bool relayoutChildren = logicalWidthChanged;

    LayoutUnit beforeEdge = borderBefore() + paddingBefore();
    LayoutUnit afterEdge = borderAfter() + paddingAfter();
    LayoutUnit previousHeight = logicalHeight();
    setLogicalHeight(beforeEdge);

    layoutChildren(relayoutChildren, layoutScope, beforeEdge, afterEdge);

    LayoutUnit oldClientAfterEdge = clientLogicalBottom();

    updateLogicalHeight();

    if (previousHeight != logicalHeight())
        relayoutChildren = true;

    layoutPositionedObjects(relayoutChildren, oldLeft != logicalLeft() ? ForcedLayoutAfterContainingBlockMoved : DefaultLayout);

    // Add overflow from children (unless we're multi-column, since in that case all our child overflow is clipped anyway).
    computeOverflow(oldClientAfterEdge);
}

void RenderBlockFlow::determineLogicalLeftPositionForChild(RenderBox* child)
{
    LayoutUnit startPosition = borderStart() + paddingStart();
    LayoutUnit totalAvailableLogicalWidth = borderAndPaddingLogicalWidth() + availableLogicalWidth();

    LayoutUnit childMarginStart = marginStartForChild(child);
    LayoutUnit newPosition = startPosition + childMarginStart;

    // If the child has an offset from the content edge to avoid floats then use that, otherwise let any negative
    // margin pull it back over the content edge or any positive margin push it out.
    if (child->style()->marginStartUsing(style()).isAuto())
        newPosition = std::max(newPosition, childMarginStart);

    child->setX(style()->isLeftToRightDirection() ? newPosition : totalAvailableLogicalWidth - newPosition - logicalWidthForChild(child));
}

void RenderBlockFlow::layoutBlockChild(RenderBox* child)
{
    child->computeAndSetBlockDirectionMargins(this);
    LayoutUnit marginBefore = marginBeforeForChild(child);
    child->setY(logicalHeight() + marginBefore);
    child->layoutIfNeeded();
    determineLogicalLeftPositionForChild(child);
    setLogicalHeight(logicalHeight() + marginBefore + logicalHeightForChild(child) + marginAfterForChild(child));
}

void RenderBlockFlow::layoutChildren(bool relayoutChildren, SubtreeLayoutScope& layoutScope, LayoutUnit beforeEdge, LayoutUnit afterEdge)
{
    dirtyForLayoutFromPercentageHeightDescendants(layoutScope);

    RenderBox* next = firstChildBox();
    RenderBox* lastNormalFlowChild = 0;

    while (next) {
        RenderBox* child = next;
        next = child->nextSiblingBox();

        updateBlockChildDirtyBitsBeforeLayout(relayoutChildren, child);

        if (child->isOutOfFlowPositioned()) {
            child->containingBlock()->insertPositionedObject(child);
            continue;
        }

        // Lay out the child.
        layoutBlockChild(child);
        lastNormalFlowChild = child;
    }

    // Negative margins can cause our height to shrink below our minimal height (border/padding).
    // If this happens, ensure that the computed height is increased to the minimal height.
    setLogicalHeight(std::max(logicalHeight() + afterEdge, beforeEdge + afterEdge));
}

RootInlineBox* RenderBlockFlow::createAndAppendRootInlineBox()
{
    RootInlineBox* rootBox = createRootInlineBox();
    m_lineBoxes.appendLineBox(rootBox);

    return rootBox;
}

void RenderBlockFlow::deleteLineBoxTree()
{
    m_lineBoxes.deleteLineBoxTree();
}

void RenderBlockFlow::addChild(RenderObject* newChild, RenderObject* beforeChild)
{
    RenderBlock::addChild(newChild, beforeChild);
}

LayoutUnit RenderBlockFlow::logicalLeftSelectionOffset(RenderBlock* rootBlock, LayoutUnit position)
{
    LayoutUnit logicalLeft = logicalLeftOffsetForLine(false);
    if (logicalLeft == logicalLeftOffsetForContent())
        return RenderBlock::logicalLeftSelectionOffset(rootBlock, position);

    RenderBlock* cb = this;
    while (cb != rootBlock) {
        logicalLeft += cb->logicalLeft();
        cb = cb->containingBlock();
    }
    return logicalLeft;
}

LayoutUnit RenderBlockFlow::logicalRightSelectionOffset(RenderBlock* rootBlock, LayoutUnit position)
{
    LayoutUnit logicalRight = logicalRightOffsetForLine(false);
    if (logicalRight == logicalRightOffsetForContent())
        return RenderBlock::logicalRightSelectionOffset(rootBlock, position);

    RenderBlock* cb = this;
    while (cb != rootBlock) {
        logicalRight += cb->logicalLeft();
        cb = cb->containingBlock();
    }
    return logicalRight;
}

RootInlineBox* RenderBlockFlow::createRootInlineBox()
{
    return new RootInlineBox(*this);
}

static void updateLogicalWidthForLeftAlignedBlock(bool isLeftToRightDirection, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float availableLogicalWidth)
{
    // The direction of the block should determine what happens with wide lines.
    // In particular with RTL blocks, wide lines should still spill out to the left.
    if (isLeftToRightDirection) {
        if (totalLogicalWidth > availableLogicalWidth && trailingSpaceRun)
            trailingSpaceRun->m_box->setLogicalWidth(std::max<float>(0, trailingSpaceRun->m_box->logicalWidth() - totalLogicalWidth + availableLogicalWidth));
        return;
    }

    if (trailingSpaceRun)
        trailingSpaceRun->m_box->setLogicalWidth(0);
    else if (totalLogicalWidth > availableLogicalWidth)
        logicalLeft -= (totalLogicalWidth - availableLogicalWidth);
}

static void updateLogicalWidthForRightAlignedBlock(bool isLeftToRightDirection, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float availableLogicalWidth)
{
    // Wide lines spill out of the block based off direction.
    // So even if text-align is right, if direction is LTR, wide lines should overflow out of the right
    // side of the block.
    if (isLeftToRightDirection) {
        if (trailingSpaceRun) {
            totalLogicalWidth -= trailingSpaceRun->m_box->logicalWidth();
            trailingSpaceRun->m_box->setLogicalWidth(0);
        }
        if (totalLogicalWidth < availableLogicalWidth)
            logicalLeft += availableLogicalWidth - totalLogicalWidth;
        return;
    }

    if (totalLogicalWidth > availableLogicalWidth && trailingSpaceRun) {
        trailingSpaceRun->m_box->setLogicalWidth(std::max<float>(0, trailingSpaceRun->m_box->logicalWidth() - totalLogicalWidth + availableLogicalWidth));
        totalLogicalWidth -= trailingSpaceRun->m_box->logicalWidth();
    } else
        logicalLeft += availableLogicalWidth - totalLogicalWidth;
}

static void updateLogicalWidthForCenterAlignedBlock(bool isLeftToRightDirection, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float availableLogicalWidth)
{
    float trailingSpaceWidth = 0;
    if (trailingSpaceRun) {
        totalLogicalWidth -= trailingSpaceRun->m_box->logicalWidth();
        trailingSpaceWidth = std::min(trailingSpaceRun->m_box->logicalWidth(), (availableLogicalWidth - totalLogicalWidth + 1) / 2);
        trailingSpaceRun->m_box->setLogicalWidth(std::max<float>(0, trailingSpaceWidth));
    }
    if (isLeftToRightDirection)
        logicalLeft += std::max<float>((availableLogicalWidth - totalLogicalWidth) / 2, 0);
    else
        logicalLeft += totalLogicalWidth > availableLogicalWidth ? (availableLogicalWidth - totalLogicalWidth) : (availableLogicalWidth - totalLogicalWidth) / 2 - trailingSpaceWidth;
}

void RenderBlockFlow::updateLogicalWidthForAlignment(const ETextAlign& textAlign, const RootInlineBox* rootInlineBox, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float& availableLogicalWidth, unsigned expansionOpportunityCount)
{
    TextDirection direction;
    if (rootInlineBox && rootInlineBox->renderer().style()->unicodeBidi() == Plaintext)
        direction = rootInlineBox->direction();
    else
        direction = style()->direction();

    // Armed with the total width of the line (without justification),
    // we now examine our text-align property in order to determine where to position the
    // objects horizontally. The total width of the line can be increased if we end up
    // justifying text.
    switch (textAlign) {
    case LEFT:
        updateLogicalWidthForLeftAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    case RIGHT:
        updateLogicalWidthForRightAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    case CENTER:
        updateLogicalWidthForCenterAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    case JUSTIFY:
        adjustInlineDirectionLineBounds(expansionOpportunityCount, logicalLeft, availableLogicalWidth);
        if (expansionOpportunityCount) {
            if (trailingSpaceRun) {
                totalLogicalWidth -= trailingSpaceRun->m_box->logicalWidth();
                trailingSpaceRun->m_box->setLogicalWidth(0);
            }
            break;
        }
        // Fall through
    case TASTART:
        if (direction == LTR)
            updateLogicalWidthForLeftAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        else
            updateLogicalWidthForRightAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    case TAEND:
        if (direction == LTR)
            updateLogicalWidthForRightAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        else
            updateLogicalWidthForLeftAlignedBlock(style()->isLeftToRightDirection(), trailingSpaceRun, logicalLeft, totalLogicalWidth, availableLogicalWidth);
        break;
    }
}

LayoutUnit RenderBlockFlow::startAlignedOffsetForLine(bool firstLine)
{
    ETextAlign textAlign = style()->textAlign();

    if (textAlign == TASTART) // FIXME: Handle TAEND here
        return startOffsetForLine(firstLine);

    // updateLogicalWidthForAlignment() handles the direction of the block so no need to consider it here
    float totalLogicalWidth = 0;
    float logicalLeft = logicalLeftOffsetForLine(false).toFloat();
    float availableLogicalWidth = logicalRightOffsetForLine(false) - logicalLeft;
    updateLogicalWidthForAlignment(textAlign, 0, 0, logicalLeft, totalLogicalWidth, availableLogicalWidth, 0);

    if (!style()->isLeftToRightDirection())
        return logicalWidth() - logicalLeft;
    return logicalLeft;
}

} // namespace blink