render_flexbox.cpp

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                    childX += child->marginLeft() + (contentWidth() - (child->width() + child->marginLeft() + child->marginRight()))/2;
                    break;
                case BEND:
                    if (style()->direction() == RTL)
                        childX += child->marginLeft();
                    else
                        childX += contentWidth() - child->marginRight() - child->width();
                    break;
                default: // BSTART/BSTRETCH
                    if (style()->direction() == LTR)
                        childX += child->marginLeft();
                    else
                        childX += contentWidth() - child->marginRight() - child->width();
                    break;
            }
    
            // Place the child.
            placeChild(child, childX, m_height);
            m_height += child->height() + child->marginBottom();
    
            // See if this child has made our overflow need to grow.
            // XXXdwh Work with left overflow as well as right overflow.
            int rightChildPos = child->xPos() + kMax(child->overflowWidth(false), child->width());
            if (rightChildPos > m_overflowWidth)
                m_overflowWidth = rightChildPos;
            
            child = iterator.next();
        }

        yPos = m_height;
        m_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 (m_height < minHeight)
            m_height = minHeight;

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

        // Now we have to calc our height, so we know how much space we have remaining.
        oldHeight = m_height;
        calcHeight();
        if (oldHeight != m_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).
                    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 ? kMin(spaceAvailableThisPass, projectedFlex) : kMax(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();
                    }
                } 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->xPos(), child->yPos()+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->xPos(), child->yPos()+offset);
                child = iterator.next();
            }
        }
    }
    
    // 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)
        m_height = oldHeight;    
}

void RenderFlexibleBox::placeChild(RenderObject* child, int x, int y)
{
    int oldChildX = child->xPos();
    int oldChildY = child->yPos();

    // Place the child.
    child->setPos(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(oldChildX, oldChildY);
}

int RenderFlexibleBox::allowedChildFlex(RenderObject* 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().value != UNDEFINED &&
                child->style()->maxWidth().isFixed())
                maxW = child->style()->maxWidth().value;
            else if (child->style()->maxWidth().type == Intrinsic)
                maxW = child->maxWidth();
            else if (child->style()->maxWidth().type == MinIntrinsic)
                maxW = child->minWidth();
            int allowedGrowth = kMax(0, maxW - w);
            return allowedGrowth;
        }
        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().value != UNDEFINED &&
                child->style()->maxHeight().isFixed())
                maxH = child->style()->maxHeight().value;
            int allowedGrowth = kMax(0, maxH - h);
            return allowedGrowth;
        }
    }

    // FIXME: For now just handle fixed values.
    if (isHorizontal()) {
        int minW = child->minWidth();
        int w = child->contentWidth();
        if (child->style()->minWidth().isFixed())
            minW = child->style()->minWidth().value;
        else if (child->style()->minWidth().type == Intrinsic)
            minW = child->maxWidth();
        else if (child->style()->minWidth().type == MinIntrinsic)
            minW = child->minWidth();
            
        int allowedShrinkage = kMin(0, minW - w);
        return allowedShrinkage;
    }
    else {
        if (child->style()->minHeight().isFixed()) {
            int minH = child->style()->minHeight().value;
            int h = child->contentHeight();
            int allowedShrinkage = kMin(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 khtml