render_flexbox.cpp

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/*
 * This file is part of the render object implementation for KHTML.
 *
 * Copyright (C) 1999 Lars Knoll ([e-mail])
 *           (C) 1999 Antti Koivisto ([e-mail])
 * Copyright (C) 2003 Apple Computer, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 */

#include "render_flexbox.h"

using namespace DOM;

namespace khtml {

class FlexBoxIterator 
OOM_MODIFIED
{
public:
    FlexBoxIterator(RenderFlexibleBox* parent) {
        box = parent;
        if (box->style()->boxOrient() == HORIZONTAL && box->style()->direction() == RTL)
            forward = box->style()->boxDirection() != BNORMAL;
        else
            forward = box->style()->boxDirection() == BNORMAL;
        lastOrdinal = 1; 
        if (!forward) {
            // No choice, since we're going backwards, we have to find out the highest ordinal up front.
            RenderObject* child = box->firstChild();
            while (child) {
                if (child->style()->boxOrdinalGroup() > lastOrdinal)
                    lastOrdinal = child->style()->boxOrdinalGroup();
                child = child->nextSibling();
            }
        }
        
        reset();
    }

    void reset() {
        current = 0;
        currentOrdinal = forward ? 0 : lastOrdinal+1;
    }

    RenderObject* first() {
        reset();
        return next();
    }
    
    RenderObject* next() {

        do { 
            if (!current) {
                if (forward) {
                    currentOrdinal++; 
                    if (currentOrdinal > lastOrdinal)
                        return 0;
                    current = box->firstChild();
                }
                else {
                    currentOrdinal--;
                    if (currentOrdinal == 0)
                        return 0;
                    current = box->lastChild();
                }
            }
            else
                current = forward ? current->nextSibling() : current->previousSibling();
            if (current && current->style()->boxOrdinalGroup() > lastOrdinal)
                lastOrdinal = current->style()->boxOrdinalGroup();
        } while (!current || current->style()->boxOrdinalGroup() != currentOrdinal ||
                 current->style()->visibility() == COLLAPSE);
        return current;
    }

private:
    RenderFlexibleBox* box;
    RenderObject* current;
    bool forward;
    unsigned int currentOrdinal;
    unsigned int lastOrdinal;
};
    
RenderFlexibleBox::RenderFlexibleBox(DOM::NodeImpl* node)
:RenderBlock(node)
{
    setChildrenInline(false); // All of our children must be block-level
    m_flexingChildren = m_stretchingChildren = false;
}

RenderFlexibleBox::~RenderFlexibleBox()
{
}

void RenderFlexibleBox::calcHorizontalMinMaxWidth()
{
    RenderObject *child = firstChild();
    while (child) {
        // positioned children don't affect the minmaxwidth
        if (child->isPositioned() || child->style()->visibility() == COLLAPSE)
        {
            child = child->nextSibling();
            continue;
        }

        int margin=0;
        //  auto margins don't affect minwidth

        Length ml = child->style()->marginLeft();
        Length mr = child->style()->marginRight();

        // Call calcWidth on the child to ensure that our margins are
        // up to date.  This method can be called before the child has actually
        // calculated its margins (which are computed inside calcWidth).
        child->calcWidth();

        if (!(ml.type==Variable) && !(mr.type==Variable))
        {
            if (!(child->style()->width().type==Variable))
            {
                if (child->style()->direction()==LTR)
                    margin = child->marginLeft();
                else
                    margin = child->marginRight();
            }
            else
                margin = child->marginLeft()+child->marginRight();

        }
        else if (!(ml.type == Variable))
            margin = child->marginLeft();
        else if (!(mr.type == Variable))
            margin = child->marginRight();

        if (margin < 0) margin = 0;

        m_minWidth += child->minWidth() + margin;
        m_maxWidth += child->maxWidth() + margin;

        child = child->nextSibling();
    }    
}

void RenderFlexibleBox::calcVerticalMinMaxWidth()
{
    RenderObject *child = firstChild();
    while(child != 0)
    {
        // Positioned children and collapsed children don't affect the min/max width
        if (child->isPositioned() || child->style()->visibility() == COLLAPSE) {
            child = child->nextSibling();
            continue;
        }

        Length ml = child->style()->marginLeft();
        Length mr = child->style()->marginRight();

        // Call calcWidth on the child to ensure that our margins are
        // up to date.  This method can be called before the child has actually
        // calculated its margins (which are computed inside calcWidth).
        if (ml.type == Percent || mr.type == Percent)
            calcWidth();

        // A margin basically has three types: fixed, percentage, and auto (variable).
        // Auto margins simply become 0 when computing min/max width.
        // Fixed margins can be added in as is.
        // Percentage margins are computed as a percentage of the width we calculated in
        // the calcWidth call above.  In this case we use the actual cached margin values on
        // the RenderObject itself.
        int margin = 0;
        if (ml.type == Fixed)
            margin += ml.value;
        else if (ml.type == Percent)
            margin += child->marginLeft();

        if (mr.type == Fixed)
            margin += mr.value;
        else if (mr.type == Percent)
            margin += child->marginRight();

        if (margin < 0) margin = 0;
        
        int w = child->minWidth() + margin;
        if(m_minWidth < w) m_minWidth = w;
        
        w = child->maxWidth() + margin;

        if(m_maxWidth < w) m_maxWidth = w;

        child = child->nextSibling();
    }    
}

void RenderFlexibleBox::calcMinMaxWidth()
{
    KHTMLAssert( !minMaxKnown() );

    m_minWidth = 0;
    m_maxWidth = 0;

    if (hasMultipleLines() || isVertical())
        calcVerticalMinMaxWidth();
    else
        calcHorizontalMinMaxWidth();

    if(m_maxWidth < m_minWidth) m_maxWidth = m_minWidth;

    if (style()->width().isFixed() && style()->width().value > 0)
        m_minWidth = m_maxWidth = style()->width().value;
   
    if (style()->minWidth().isFixed() && style()->minWidth().value > 0) {
        m_maxWidth = kMax(m_maxWidth, style()->minWidth().value);
        m_minWidth = kMax(m_minWidth, style()->minWidth().value);
    }
    
    if (style()->maxWidth().isFixed() && style()->maxWidth().value != UNDEFINED) {
        m_maxWidth = kMin(m_maxWidth, style()->maxWidth().value);
        m_minWidth = kMin(m_minWidth, style()->maxWidth().value);
    }

    int toAdd = borderLeft() + borderRight() + paddingLeft() + paddingRight();
    m_minWidth += toAdd;
    m_maxWidth += toAdd;

    setMinMaxKnown();
}

void RenderFlexibleBox::layoutBlock(bool relayoutChildren)
{
    KHTMLAssert(needsLayout());
    KHTMLAssert(minMaxKnown());

    if (!relayoutChildren && posChildNeedsLayout() && !normalChildNeedsLayout() && !selfNeedsLayout()) {
        // All we have to is lay out our positioned objects.
        layoutPositionedObjects(relayoutChildren);
        if (hasOverflowClip())
            m_layer->updateScrollInfoAfterLayout();
        setNeedsLayout(false);
        return;
    }

    QRect oldBounds;
    bool checkForRepaint = checkForRepaintDuringLayout();
    if (checkForRepaint)
        oldBounds = getAbsoluteRepaintRect();
    
    int oldWidth = m_width;
    int oldHeight = m_height;
    
    calcWidth();
    calcHeight();
    m_overflowWidth = m_width;

    if (oldWidth != m_width || oldHeight != m_height ||
        (parent()->isFlexibleBox() && parent()->style()->boxOrient() == HORIZONTAL &&
         parent()->style()->boxAlign() == BSTRETCH))
        relayoutChildren = true;

    m_height = 0;
    m_overflowHeight = 0;
    m_flexingChildren = m_stretchingChildren = false;

    initMaxMarginValues();

    if (scrollsOverflow()) {
        // For overflow:scroll blocks, ensure we have both scrollbars in place always.
        if (style()->overflow() == OSCROLL) {
            m_layer->setHasHorizontalScrollbar(true);
            m_layer->setHasVerticalScrollbar(true);
        }

        // Move the scrollbars aside during layout.  The layer will move them back when it
        // does painting or event handling.
        m_layer->moveScrollbarsAside();
    }

    if (isHorizontal())
        layoutHorizontalBox(relayoutChildren);
    else
        layoutVerticalBox(relayoutChildren);
    
    oldHeight = m_height;
    calcHeight();
    if (oldHeight != m_height) {
        relayoutChildren = true;

        // If the block got expanded in size, then increase our overflowheight to match.
        if (m_overflowHeight > m_height)
            m_overflowHeight -= (borderBottom()+paddingBottom());
        if (m_overflowHeight < m_height)
            m_overflowHeight = m_height;
    }

    layoutPositionedObjects( relayoutChildren );

    //kdDebug() << renderName() << " layout width=" << m_width << " height=" << m_height << endl;

    if (!isFloatingOrPositioned() && m_height == 0) {
        // We are a block with no border and padding and a computed height
        // of 0.  The CSS spec states that zero-height blocks collapse their margins
        // together.
        // When blocks are self-collapsing, we just use the top margin values and set the
        // bottom margin max values to 0.  This way we don't factor in the values
        // twice when we collapse with our previous vertically adjacent and
        // following vertically adjacent blocks.
        if (m_maxBottomPosMargin > m_maxTopPosMargin)
            m_maxTopPosMargin = m_maxBottomPosMargin;
        if (m_maxBottomNegMargin > m_maxTopNegMargin)
            m_maxTopNegMargin = m_maxBottomNegMargin;
        m_maxBottomNegMargin = m_maxBottomPosMargin = 0;
    }

    // Always ensure our overflow width is at least as large as our width.
    if (m_overflowWidth < m_width)
        m_overflowWidth = m_width;

    // Update our scrollbars if we're overflow:auto/scroll/hidden now that we know if
    // we overflow or not.
    if (hasOverflowClip())
        m_layer->updateScrollInfoAfterLayout();

    // Repaint with our new bounds if they are different from our old bounds.
    if (checkForRepaint)
        repaintAfterLayoutIfNeeded(oldBounds, oldBounds);
    
    setNeedsLayout(false);
}

void RenderFlexibleBox::layoutHorizontalBox(bool relayoutChildren)
{
    int toAdd = borderBottom() + paddingBottom();
    int yPos = borderTop() + paddingTop();
    int xPos = borderLeft() + paddingLeft();
    bool heightSpecified = false;
    int oldHeight = 0;
    
    unsigned int highestFlexGroup = 0;
    unsigned int lowestFlexGroup = 0;
    bool haveFlex = false;
    int remainingSpace = 0;
    m_overflowHeight = m_height;

    // The first walk over our kids is to find out if we have any flexible children.
    FlexBoxIterator iterator(this);
    RenderObject* child = iterator.next();
    while (child) {
        // Check to see if this child flexes.
        if (!child->isPositioned() && child->style()->boxFlex() > 0.0f) {
            // We always have to lay out flexible objects again, since the flex distribution
            // may have changed, and we need to reallocate space.
            child->setOverrideSize(-1);
            if (!relayoutChildren)
                child->setChildNeedsLayout(true, false);
            haveFlex = true;