render_line.cpp

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        m_firstChild = child->nextOnLine();
    if (child == m_lastChild)
        m_lastChild = child->prevOnLine();
    if (child->nextOnLine())
        child->nextOnLine()->setPrevOnLine(child->prevOnLine());
    if (child->prevOnLine())
        child->prevOnLine()->setNextOnLine(child->nextOnLine());

    child->setParent(0);
}

void InlineFlowBox::deleteLine(RenderArena* arena)
{
    InlineBox* child = m_firstChild;
    InlineBox* next = 0;
    while (child) {
        next = child->nextOnLine();
        child->deleteLine(arena);
        child = next;
    }

    static_cast<RenderFlow*>(m_object)->removeLineBox(this);
    detach(arena);
}

void InlineFlowBox::extractLine()
{
    if (!m_extracted)
        static_cast<RenderFlow*>(m_object)->extractLineBox(this);
    for (InlineBox* child = m_firstChild; child; child = child->nextOnLine())
        child->extractLine();
}

void InlineFlowBox::attachLine()
{
    if (m_extracted)
        static_cast<RenderFlow*>(m_object)->attachLineBox(this);
    for (InlineBox* child = m_firstChild; child; child = child->nextOnLine())
        child->attachLine();
}

void InlineFlowBox::adjustPosition(int dx, int dy)
{
    InlineRunBox::adjustPosition(dx, dy);
    for (InlineBox* child = m_firstChild; child; child = child->nextOnLine())
        child->adjustPosition(dx, dy);
}

bool InlineFlowBox::onEndChain(RenderObject* endObject)
{
    if (!endObject)
        return false;

    if (endObject == object())
        return true;

    RenderObject* curr = endObject;
    RenderObject* parent = curr->parent();
    while (parent && !parent->isRenderBlock()) {
        if (parent->lastChild() != curr)
            return false;
        curr = parent;
        parent = curr->parent();
    }

    return true;
}

void InlineFlowBox::determineSpacingForFlowBoxes(bool lastLine, RenderObject* endObject)
{
    // All boxes start off open.  They will not apply any margins/border/padding on
    // any side.
    bool includeLeftEdge = false;
    bool includeRightEdge = false;

    RenderFlow* flow = static_cast<RenderFlow*>(object());

    if (!flow->firstChild())
        includeLeftEdge = includeRightEdge = true; // Empty inlines never split across lines.
    else if (parent()) { // The root inline box never has borders/margins/padding.
        bool ltr = flow->style()->direction() == LTR;

        // Check to see if all initial lines are unconstructed.  If so, then
        // we know the inline began on this line.
        if (!flow->firstLineBox()->isConstructed()) {
            if (ltr && flow->firstLineBox() == this)
                includeLeftEdge = true;
            else if (!ltr && flow->lastLineBox() == this)
                includeRightEdge = true;
        }

        // In order to determine if the inline ends on this line, we check three things:
        // (1) If we are the last line and we don't have a continuation(), then we can
        // close up.
        // (2) If the last line box for the flow has an object following it on the line (ltr,
        // reverse for rtl), then the inline has closed.
        // (3) The line may end on the inline.  If we are the last child (climbing up
        // the end object's chain), then we just closed as well.
        if (!flow->lastLineBox()->isConstructed()) {
            if (ltr) {
                if (!nextLineBox() &&
                    ((lastLine && !object()->continuation()) || nextOnLineExists()
                     || onEndChain(endObject)))
                    includeRightEdge = true;
            }
            else {
                if ((!prevLineBox() || !prevLineBox()->isConstructed()) &&
                    ((lastLine && !object()->continuation()) ||
                     prevOnLineExists() || onEndChain(endObject)))
                    includeLeftEdge = true;
            }

        }
    }

    setEdges(includeLeftEdge, includeRightEdge);

    // Recur into our children.
    for (InlineBox* currChild = firstChild(); currChild; currChild = currChild->nextOnLine()) {
        if (currChild->isInlineFlowBox()) {
            InlineFlowBox* currFlow = static_cast<InlineFlowBox*>(currChild);
            currFlow->determineSpacingForFlowBoxes(lastLine, endObject);
        }
    }
}

int InlineFlowBox::placeBoxesHorizontally(int x, int& leftPosition, int& rightPosition)
{
    // Set our x position.
    setXPos(x);
    leftPosition = kMin(x, leftPosition);

    int startX = x;
    x += borderLeft() + paddingLeft();

    for (InlineBox* curr = firstChild(); curr; curr = curr->nextOnLine()) {
        if (curr->object()->isText()) {
            InlineTextBox* text = static_cast<InlineTextBox*>(curr);
            text->setXPos(x);
            leftPosition = kMin(x, leftPosition);
            rightPosition = kMax(x + text->width(), rightPosition);
            x += text->width();
        }
        else {
            if (curr->object()->isPositioned()) {
                if (curr->object()->parent()->style()->direction() == LTR)
                    curr->setXPos(x);
                else
                    // Our offset that we cache needs to be from the edge of the right border box and
                    // not the left border box.  We have to subtract |x| from the width of the block
                    // (which can be obtained from the root line box).
                    curr->setXPos(root()->object()->width()-x);
                continue; // The positioned object has no effect on the width.
            }
            if (curr->object()->isInlineFlow()) {
                InlineFlowBox* flow = static_cast<InlineFlowBox*>(curr);
                if (curr->object()->isCompact()) {
                    int ignoredX = x;
                    flow->placeBoxesHorizontally(ignoredX, leftPosition, rightPosition);
                }
                else {
                    x += flow->marginLeft();
                    x = flow->placeBoxesHorizontally(x, leftPosition, rightPosition);
                    x += flow->marginRight();
                }
            }
            else if (!curr->object()->isCompact()) {
                x += curr->object()->marginLeft();
                curr->setXPos(x);
                leftPosition = kMin(x, leftPosition);
                rightPosition = kMax(x + curr->width(), rightPosition);
                x += curr->width() + curr->object()->marginRight();
            }
        }
    }

    x += borderRight() + paddingRight();
    setWidth(x-startX);
    rightPosition = kMax(xPos() + width(), rightPosition);

    return x;
}

void InlineFlowBox::verticallyAlignBoxes(int& heightOfBlock)
{
    int maxPositionTop = 0;
    int maxPositionBottom = 0;
    int maxAscent = 0;
    int maxDescent = 0;

    // Figure out if we're in strict mode.  Note that we can't simply use !style()->htmlHacks(),
    // because that would match almost strict mode as well.
    RenderObject* curr = object();
    while (curr && !curr->element())
        curr = curr->container();
    bool strictMode = (curr && curr->document()->inStrictMode());

    computeLogicalBoxHeights(maxPositionTop, maxPositionBottom, maxAscent, maxDescent, strictMode);

    if (maxAscent + maxDescent < kMax(maxPositionTop, maxPositionBottom))
        adjustMaxAscentAndDescent(maxAscent, maxDescent, maxPositionTop, maxPositionBottom);

    int maxHeight = maxAscent + maxDescent;
    int topPosition = heightOfBlock;
    int bottomPosition = heightOfBlock;
    placeBoxesVertically(heightOfBlock, maxHeight, maxAscent, strictMode, topPosition, bottomPosition);

    setVerticalOverflowPositions(topPosition, bottomPosition);

    // Shrink boxes with no text children in quirks and almost strict mode.
    if (!strictMode)
        shrinkBoxesWithNoTextChildren(topPosition, bottomPosition);

    heightOfBlock += maxHeight;
}

void InlineFlowBox::adjustMaxAscentAndDescent(int& maxAscent, int& maxDescent,
                                              int maxPositionTop, int maxPositionBottom)
{
    for (InlineBox* curr = firstChild(); curr; curr = curr->nextOnLine()) {
        // The computed lineheight needs to be extended for the
        // positioned elements
        if (curr->object()->isPositioned())
            continue; // Positioned placeholders don't affect calculations.
        if (curr->yPos() == PositionTop || curr->yPos() == PositionBottom) {
            if (curr->yPos() == PositionTop) {
                if (maxAscent + maxDescent < curr->height())
                    maxDescent = curr->height() - maxAscent;
            }
            else {
                if (maxAscent + maxDescent < curr->height())
                    maxAscent = curr->height() - maxDescent;
            }

            if (maxAscent + maxDescent >= kMax(maxPositionTop, maxPositionBottom))
                break;
        }

        if (curr->isInlineFlowBox())
            static_cast<InlineFlowBox*>(curr)->adjustMaxAscentAndDescent(maxAscent, maxDescent, maxPositionTop, maxPositionBottom);
    }
}

void InlineFlowBox::computeLogicalBoxHeights(int& maxPositionTop, int& maxPositionBottom,
                                             int& maxAscent, int& maxDescent, bool strictMode)
{
    if (isRootInlineBox()) {
        // Examine our root box.
        setHeight(object()->lineHeight(m_firstLine, true));
        bool isTableCell = object()->isTableCell();
        if (isTableCell) {
            RenderTableCell* tableCell = static_cast<RenderTableCell*>(object());
            setBaseline(tableCell->RenderBlock::baselinePosition(m_firstLine, true));
        }
        else
            setBaseline(object()->baselinePosition(m_firstLine, true));
        if (hasTextChildren() || strictMode) {
            int ascent = baseline();
            int descent = height() - ascent;
            if (maxAscent < ascent)
                maxAscent = ascent;
            if (maxDescent < descent)
                maxDescent = descent;
        }
    }

    for (InlineBox* curr = firstChild(); curr; curr = curr->nextOnLine()) {
        if (curr->object()->isPositioned())
            continue; // Positioned placeholders don't affect calculations.

        curr->setHeight(curr->object()->lineHeight(m_firstLine));
        curr->setBaseline(curr->object()->baselinePosition(m_firstLine));
        curr->setYPos(curr->object()->verticalPositionHint(m_firstLine));
        if (curr->yPos() == PositionTop) {
            if (maxPositionTop < curr->height())
                maxPositionTop = curr->height();
        }
        else if (curr->yPos() == PositionBottom) {
            if (maxPositionBottom < curr->height())
                maxPositionBottom = curr->height();
        }
        else if (curr->hasTextChildren() || strictMode) {
            int ascent = curr->baseline() - curr->yPos();
            int descent = curr->height() - ascent;
            if (maxAscent < ascent)
                maxAscent = ascent;
            if (maxDescent < descent)
                maxDescent = descent;
        }

        if (curr->isInlineFlowBox())
            static_cast<InlineFlowBox*>(curr)->computeLogicalBoxHeights(maxPositionTop, maxPositionBottom, maxAscent, maxDescent, strictMode);
    }
}

void InlineFlowBox::placeBoxesVertically(int y, int maxHeight, int maxAscent, bool strictMode,
                                         int& topPosition, int& bottomPosition)
{
    if (isRootInlineBox())
        setYPos(y + maxAscent - baseline());// Place our root box.

    for (InlineBox* curr = firstChild(); curr; curr = curr->nextOnLine()) {
        if (curr->object()->isPositioned())
            continue; // Positioned placeholders don't affect calculations.

        // Adjust boxes to use their real box y/height and not the logical height (as dictated by
        // line-height).
        if (curr->isInlineFlowBox())
            static_cast<InlineFlowBox*>(curr)->placeBoxesVertically(y, maxHeight, maxAscent, strictMode,
                                                                    topPosition, bottomPosition);

        bool childAffectsTopBottomPos = true;
        if (curr->yPos() == PositionTop)
            curr->setYPos(y);
        else if (curr->yPos() == PositionBottom)
            curr->setYPos(y + maxHeight - curr->height());
        else {
            if (!curr->hasTextChildren() && !strictMode)
                childAffectsTopBottomPos = false;
            curr->setYPos(curr->yPos() + y + maxAscent - curr->baseline());
        }

        int newY = curr->yPos();
        int newHeight = curr->height();
        int newBaseline = curr->baseline();
        if (curr->isText() || curr->isInlineFlowBox()) {
            const QFontMetrics &fm = curr->object()->fontMetrics( m_firstLine );
            newBaseline = fm.ascent();
            newY += curr->baseline() - newBaseline;
            newHeight = newBaseline+fm.descent();