renderflexiblebox.cpp

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            m_overflowWidth = max(child->x() + child->overflowWidth(false), m_overflowWidth);
            m_overflowLeft = min(child->x() + child->overflowLeft(false), m_overflowLeft);
            
            child = iterator.next();
        }

        yPos = height();
        
        if (!iterator.first() && hasLineIfEmpty())
            setHeight(height() + lineHeight(true, true));
    
        setHeight(height() + toAdd);

        // 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.
        if (height() < minHeight)
            setHeight(minHeight);

        // Always make sure our overflowheight is at least our height.
        if (m_overflowHeight < height())
            m_overflowHeight = height();

        // Now we have to calc our height, so we know how much space we have remaining.
        oldHeight = height();
        calcHeight();
        if (oldHeight != height())
            heightSpecified = true;

        remainingSpace = borderTop() + paddingTop() + contentHeight() - yPos;
        
        if (m_flexingChildren)
            haveFlex = false; // We're done.
        else if (haveFlex) {
            // We have some flexible objects.  See if we need to grow/shrink them at all.
            if (!remainingSpace)
                break;

            // Allocate the remaining space among the flexible objects.  If we are trying to
            // grow, then we go from the lowest flex group to the highest flex group.  For shrinking,
            // we go from the highest flex group to the lowest group.
            bool expanding = remainingSpace > 0;
            unsigned int start = expanding ? lowestFlexGroup : highestFlexGroup;
            unsigned int end = expanding? highestFlexGroup : lowestFlexGroup;
            for (unsigned int i = start; i <= end && remainingSpace; i++) {
                // Always start off by assuming the group can get all the remaining space.
                int groupRemainingSpace = remainingSpace;
                do {
                    // Flexing consists of multiple passes, since we have to change ratios every time an object hits its max/min-width
                    // For a given pass, we always start off by computing the totalFlex of all objects that can grow/shrink at all, and
                    // computing the allowed growth before an object hits its min/max width (and thus
                    // forces a totalFlex recomputation).
                    int groupRemainingSpaceAtBeginning = groupRemainingSpace;
                    float totalFlex = 0.0f;
                    child = iterator.first();
                    while (child) {
                        if (allowedChildFlex(child, expanding, i))
                            totalFlex += child->style()->boxFlex();
                        child = iterator.next();
                    }
                    child = iterator.first();
                    int spaceAvailableThisPass = groupRemainingSpace;
                    while (child) {
                        int allowedFlex = allowedChildFlex(child, expanding, i);
                        if (allowedFlex) {
                            int projectedFlex = (allowedFlex == INT_MAX) ? allowedFlex : (int)(allowedFlex * (totalFlex / child->style()->boxFlex()));
                            spaceAvailableThisPass = expanding ? min(spaceAvailableThisPass, projectedFlex) : max(spaceAvailableThisPass, projectedFlex);
                        }
                        child = iterator.next();
                    }

                    // The flex groups may not have any flexible objects this time around. 
                    if (!spaceAvailableThisPass || totalFlex == 0.0f) {
                        // If we just couldn't grow/shrink any more, then it's time to transition to the next flex group.
                        groupRemainingSpace = 0;
                        continue;
                    }
            
                    // Now distribute the space to objects.
                    child = iterator.first();
                    while (child && spaceAvailableThisPass && totalFlex) {
                        if (allowedChildFlex(child, expanding, i)) {
                            int spaceAdd = (int)(spaceAvailableThisPass * (child->style()->boxFlex()/totalFlex));
                            if (spaceAdd) {
                                child->setOverrideSize(child->overrideHeight() + spaceAdd);
                                m_flexingChildren = true;
                                relayoutChildren = true;
                            }

                            spaceAvailableThisPass -= spaceAdd;
                            remainingSpace -= spaceAdd;
                            groupRemainingSpace -= spaceAdd;
                            
                            totalFlex -= child->style()->boxFlex();
                        }
                        child = iterator.next();
                    }
                    if (groupRemainingSpace == groupRemainingSpaceAtBeginning) {
                        // this is not advancing, avoid getting stuck by distributing the remaining pixels
                        child = iterator.first();
                        int spaceAdd = groupRemainingSpace > 0 ? 1 : -1;
                        while (child && groupRemainingSpace) {
                            if (allowedChildFlex(child, expanding, i)) {
                                child->setOverrideSize(child->overrideHeight() + spaceAdd);
                                m_flexingChildren = true;
                                relayoutChildren = true;
                                remainingSpace -= spaceAdd;
                                groupRemainingSpace -= spaceAdd;
                            }
                            child = iterator.next();
                        }
                    }
                } while (groupRemainingSpace);
            }

            // We didn't find any children that could grow.
            if (haveFlex && !m_flexingChildren)
                haveFlex = false;
        }        
    } while (haveFlex);

    if (style()->boxPack() != BSTART && remainingSpace > 0) {
        // Children must be repositioned.
        int offset = 0;
        if (style()->boxPack() == BJUSTIFY) {
            // Determine the total number of children.
            int totalChildren = 0;
            child = iterator.first();
            while (child) {
                if (child->isPositioned()) {
                    child = iterator.next();
                    continue;
                }
                totalChildren++;
                child = iterator.next();
            }
            
            // Iterate over the children and space them out according to the
            // justification level.
            if (totalChildren > 1) {
                totalChildren--;
                bool firstChild = true;
                child = iterator.first();
                while (child) {
                    if (child->isPositioned()) {
                        child = iterator.next();
                        continue;
                    }
                    
                    if (firstChild) {
                        firstChild = false;
                        child = iterator.next();
                        continue;
                    }

                    offset += remainingSpace/totalChildren;
                    remainingSpace -= (remainingSpace/totalChildren);
                    totalChildren--;
                    placeChild(child, child->x(), child->y()+offset);
                    child = iterator.next();
                }
            }
        } else {
            if (style()->boxPack() == BCENTER)
                offset += remainingSpace/2;
            else // END
                offset += remainingSpace;
            child = iterator.first();
            while (child) {
                if (child->isPositioned()) {
                    child = iterator.next();
                    continue;
                }
                placeChild(child, child->x(), child->y()+offset);
                child = iterator.next();
            }
        }
    }
    
    child = iterator.first();
    while (child && child->isPositioned()) {
        child = iterator.next();
    }
    
    if (child) {
        m_overflowTop = min(child->y() + child->overflowTop(false), m_overflowTop);

        RenderBox* lastChild = child;
        while ((child = iterator.next())) {
            if (!child->isPositioned())
                lastChild = child;
        }
        m_overflowHeight = max(lastChild->y() + lastChild->overflowHeight(false), m_overflowHeight);
    }

    // So that the calcHeight in layoutBlock() knows to relayout positioned objects because of
    // a height change, we revert our height back to the intrinsic height before returning.
    if (heightSpecified)
        setHeight(oldHeight); 
}

void RenderFlexibleBox::placeChild(RenderBox* child, int x, int y)
{
    IntRect oldRect(child->x(), child->y() , child->width(), child->height());

    // Place the child.
    child->setLocation(x, y);

    // 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(oldRect);
}

int RenderFlexibleBox::allowedChildFlex(RenderBox* child, bool expanding, unsigned int group)
{
    if (child->isPositioned() || child->style()->boxFlex() == 0.0f || child->style()->boxFlexGroup() != group)
        return 0;
                        
    if (expanding) {
        if (isHorizontal()) {
            // FIXME: For now just handle fixed values.
            int maxW = INT_MAX;
            int w = child->overrideWidth() - (child->borderLeft() + child->borderRight() + child->paddingLeft() + child->paddingRight());
            if (!child->style()->maxWidth().isUndefined() &&
                child->style()->maxWidth().isFixed())
                maxW = child->style()->maxWidth().value();
            else if (child->style()->maxWidth().type() == Intrinsic)
                maxW = child->maxPrefWidth();
            else if (child->style()->maxWidth().type() == MinIntrinsic)
                maxW = child->minPrefWidth();
            if (maxW == INT_MAX)
                return maxW;
            return max(0, maxW - w);
        } else {
            // FIXME: For now just handle fixed values.
            int maxH = INT_MAX;
            int h = child->overrideHeight() - (child->borderTop() + child->borderBottom() + child->paddingTop() + child->paddingBottom());
            if (!child->style()->maxHeight().isUndefined() &&
                child->style()->maxHeight().isFixed())
                maxH = child->style()->maxHeight().value();
            if (maxH == INT_MAX)
                return maxH;
            return max(0, maxH - h);
        }
    }

    // FIXME: For now just handle fixed values.
    if (isHorizontal()) {
        int minW = child->minPrefWidth();
        int w = child->overrideWidth() - (child->borderLeft() + child->borderRight() + child->paddingLeft() + child->paddingRight());
        if (child->style()->minWidth().isFixed())
            minW = child->style()->minWidth().value();
        else if (child->style()->minWidth().type() == Intrinsic)
            minW = child->maxPrefWidth();
        else if (child->style()->minWidth().type() == MinIntrinsic)
            minW = child->minPrefWidth();
            
        int allowedShrinkage = min(0, minW - w);
        return allowedShrinkage;
    } else {
        if (child->style()->minHeight().isFixed()) {
            int minH = child->style()->minHeight().value();
            int h = child->overrideHeight() - (child->borderLeft() + child->borderRight() + child->paddingLeft() + child->paddingRight());
            int allowedShrinkage = min(0, minH - h);
            return allowedShrinkage;
        }
    }
    
    return 0;
}

const char *RenderFlexibleBox::renderName() const
{
    if (isFloating())
        return "RenderFlexibleBox (floating)";
    if (isPositioned())
        return "RenderFlexibleBox (positioned)";
    if (isRelPositioned())
        return "RenderFlexibleBox (relative positioned)";
    return "RenderFlexibleBox";
}

} // namespace WebCore