render_block.cpp

khtml在gtk上的移植版本

        // The remerge has knocked us down to containing only a single anonymous
        // box.  We can go ahead and pull the content right back up into our
        // box.
        RenderObject* anonBlock = removeChildNode(prev);
        m_childrenInline = true;
        RenderObject* o = anonBlock->firstChild();
        while (o) {
            RenderObject* no = o;
            o = no->nextSibling();
            appendChildNode(anonBlock->removeChildNode(no));
            no->setNeedsLayoutAndMinMaxRecalc();
        }
        
        // Nuke the now-empty block.
        anonBlock->detach();
    }
}

bool RenderBlock::isSelfCollapsingBlock() const
{
    // We are not self-collapsing if we
    // (a) have a non-zero height according to layout (an optimization to avoid wasting time)
    // (b) are a table,
    // (c) have border/padding,
    // (d) have a min-height
    if (m_height > 0 ||
        isTable() || (borderBottom() + paddingBottom() + borderTop() + paddingTop()) != 0 ||
        style()->minHeight().value > 0)
        return false;

    // If the height is 0 or auto, then whether or not we are a self-collapsing block depends
    // on whether we have content that is all self-collapsing or not.
    if (style()->height().isVariable() ||
        (style()->height().isFixed() && style()->height().value == 0)) {
        // If the block has inline children, see if we generated any line boxes.  If we have any
        // line boxes, then we can't be self-collapsing, since we have content.
        if (childrenInline())
            return !firstLineBox();
        
        // Whether or not we collapse is dependent on whether all our normal flow children
        // are also self-collapsing.
        for (RenderObject* child = firstChild(); child; child = child->nextSibling()) {
            if (child->isFloatingOrPositioned())
                continue;
            if (!child->isSelfCollapsingBlock())
                return false;
        }
        return true;
    }
    return false;
}

void RenderBlock::layout()
{
    // Table cells call layoutBlock directly, so don't add any logic here.  Put code into
    // layoutBlock().
    layoutBlock(false);
}

void RenderBlock::layoutBlock(bool relayoutChildren)
{
    //    kdDebug( 6040 ) << renderName() << " " << this << "::layoutBlock() start" << endl;
    //     QTime t;
    //     t.start();
    KHTMLAssert( needsLayout() );
    KHTMLAssert( minMaxKnown() );

    if (isInline() && !isInlineBlockOrInlineTable()) // Inline <form>s inside various table elements can
        return;	    		                     // cause us to come in here.  Just bail. -dwh

    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, oldFullBounds;
    bool checkForRepaint = checkForRepaintDuringLayout();
    if (checkForRepaint)
        getAbsoluteRepaintRectIncludingFloats(oldBounds, oldFullBounds);

    int oldWidth = m_width;
    
    calcWidth();
    m_overflowWidth = m_width;

    if ( oldWidth != m_width )
        relayoutChildren = true;

    //     kdDebug( 6040 ) << floatingObjects << "," << oldWidth << ","
    //                     << m_width << ","<< needsLayout() << "," << isAnonymous() << ","
    //                     << "," << isPositioned() << endl;

#ifdef DEBUG_LAYOUT
    kdDebug( 6040 ) << renderName() << "(RenderBlock) " << this << " ::layout() width=" << m_width << ", needsLayout=" << needsLayout() << endl;
    if(containingBlock() == static_cast<RenderObject *>(this))
        kdDebug( 6040 ) << renderName() << ": containingBlock == this" << endl;
#endif

    clearFloats();

    m_height = 0;
    m_overflowHeight = 0;
    m_clearStatus = CNONE;

    // We use four values, maxTopPos, maxPosNeg, maxBottomPos, and maxBottomNeg, to track
    // our current maximal positive and negative margins.  These values are used when we
    // are collapsed with adjacent blocks, so for example, if you have block A and B
    // collapsing together, then you'd take the maximal positive margin from both A and B
    // and subtract it from the maximal negative margin from both A and B to get the
    // true collapsed margin.  This algorithm is recursive, so when we finish layout()
    // our block knows its current maximal positive/negative values.
    //
    // Start out by setting our margin values to our current margins.  Table cells have
    // no margins, so we don't fill in the values for table cells.
    if (!isTableCell()) {
        initMaxMarginValues();

        m_topMarginQuirk = style()->marginTop().quirk;
        m_bottomMarginQuirk = style()->marginBottom().quirk;

        if (element() && element()->id() == ID_FORM && element()->isMalformed())
            // See if this form is malformed (i.e., unclosed). If so, don't give the form
            // a bottom margin.
            m_maxBottomPosMargin = m_maxBottomNegMargin = 0;
    }

    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();
    }
    
    //    kdDebug( 6040 ) << "childrenInline()=" << childrenInline() << endl;
    QRect repaintRect(0,0,0,0);
    if (childrenInline())
        repaintRect = layoutInlineChildren( relayoutChildren );
    else
        layoutBlockChildren( relayoutChildren );

    // Expand our intrinsic height to encompass floats.
    int toAdd = borderBottom() + paddingBottom();
    if (includeScrollbarSize())
        toAdd += m_layer->horizontalScrollbarHeight();
    if ( hasOverhangingFloats() && (isInlineBlockOrInlineTable() || isFloatingOrPositioned() || hasOverflowClip() ||
                                    (parent() && parent()->isFlexibleBox())) )
        m_height = floatBottom() + toAdd;
           
    int 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 -= paddingBottom() + borderBottom();
        if (m_overflowHeight < m_height)
            m_overflowHeight = m_height;
    }

    if (isTableCell()) {
        // Table cells need to grow to accommodate both overhanging floats and
        // blocks that have overflowed content.
        // Check for an overhanging float first.
        // FIXME: This needs to look at the last flow, not the last child.
        if (lastChild() && lastChild()->hasOverhangingFloats()) {
            KHTMLAssert(lastChild()->isRenderBlock());
            m_height = lastChild()->yPos() + static_cast<RenderBlock*>(lastChild())->floatBottom();
            m_height += borderBottom() + paddingBottom();
        }

        if (m_overflowHeight > m_height && !hasOverflowClip())
            m_height = m_overflowHeight + borderBottom() + paddingBottom();
    }

    if( hasOverhangingFloats() && (isFloating() || isTableCell())) {
        m_height = floatBottom();
        m_height += borderBottom() + paddingBottom();
    }

    layoutPositionedObjects( relayoutChildren );

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

    // Always ensure our overflow width/height are at least as large as our width/height.
    if (m_overflowWidth < m_width)
        m_overflowWidth = m_width;
    if (m_overflowHeight < m_height)
        m_overflowHeight = m_height;
    
    // Update our scroll information 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.
    bool didFullRepaint = false;
    if (checkForRepaint)
        didFullRepaint = repaintAfterLayoutIfNeeded(oldBounds, oldFullBounds);
    if (!didFullRepaint && !repaintRect.isEmpty()) {
        RenderCanvas* c = canvas();
        if (c && c->view())
            c->view()->addRepaintInfo(this, repaintRect); // We need to do a partial repaint of our content.
    }
    setNeedsLayout(false);
}

void RenderBlock::layoutBlockChildren( bool relayoutChildren )
{
#ifdef DEBUG_LAYOUT
    kdDebug( 6040 ) << renderName() << " layoutBlockChildren( " << this <<" ), relayoutChildren="<< relayoutChildren << endl;
#endif

    int xPos = borderLeft() + paddingLeft();
    if( style()->direction() == RTL )
        xPos = m_width - paddingRight() - borderRight();

    int toAdd = borderBottom() + paddingBottom();
    if (includeScrollbarSize())
        toAdd += m_layer->horizontalScrollbarHeight();
    
    m_height = borderTop() + paddingTop();

    // Fieldsets need to find their legend and position it inside the border of the object.
    // The legend then gets skipped during normal layout.
    RenderObject* legend = layoutLegend(relayoutChildren);
    
    int minHeight = m_height + toAdd;
    m_overflowHeight = m_height;

    RenderObject* child = firstChild();
    RenderBlock* prevFlow = 0;
    RenderObject* prevBlock = 0;
    
    // A compact child that needs to be collapsed into the margin of the following block.
    RenderObject* compactChild = 0;
    // The block with the open margin that the compact child is going to place itself within.
    RenderObject* blockForCompactChild = 0;
    // For compact children that don't fit, we lay them out as though they are blocks.  This
    // boolean allows us to temporarily treat a compact like a block and lets us know we need
    // to turn the block back into a compact when we're done laying out.
    bool treatCompactAsBlock = false;
    
    // Whether or not we can collapse our own margins with our children.  We don't do this
    // if we had any border/padding (obviously), if we're the root or HTML elements, or if
    // we're positioned, floating, a table cell.
    // For now we only worry about the top border/padding.  We will update the variable's
    // value when it comes time to check against the bottom border/padding.
    bool canCollapseWithChildren = !isCanvas() && !isRoot() && !isPositioned() &&
        !isFloating() && !isTableCell() && !hasOverflowClip() && !isInlineBlockOrInlineTable();
    bool canCollapseTopWithChildren = canCollapseWithChildren && (m_height == 0);

    // If any height other than auto is specified in CSS, then we don't collapse our bottom
    // margins with our children's margins.  To do otherwise would be to risk odd visual
    // effects when the children overflow out of the parent block and yet still collapse
    // with it.  We also don't collapse if we had any bottom border/padding (represented by
    // |toAdd|).
    bool canCollapseBottomWithChildren = canCollapseWithChildren && (toAdd == 0) &&
        (style()->height().isVariable() && style()->height().value == 0);
    
    // Whether or not we are a quirky container, i.e., do we collapse away top and bottom
    // margins in our container.
    bool quirkContainer = isTableCell() || isBody();

    // This flag tracks whether the child should collapse with the top margins of the block.
    // It can remain set through multiple iterations as long as we keep encountering
    // self-collapsing blocks.
    bool topMarginContributor = true;

    // These flags track the previous maximal positive and negative margins.
    int prevPosMargin = canCollapseTopWithChildren ? maxTopMargin(true) : 0;
    int prevNegMargin = canCollapseTopWithChildren ? maxTopMargin(false) : 0;

    // Whether or not we encountered an element with clear set that actually had to
    // be pushed down below a float.
    bool clearOccurred = false;

    // If our last normal flow child was a self-collapsing block that cleared a float,
    // we track it in this variable.
    bool selfCollapsingBlockClearedFloat = false;
    
    bool topChildQuirk = false;
    bool bottomChildQuirk = false;
    bool determinedTopQuirk = false;

    bool strictMode = !style()->htmlHacks();

    //kdDebug() << "RenderBlock::layoutBlockChildren " << prevMargin << endl;

    //     QTime t;
    //     t.start();

    while( child != 0 )
    {
        // Sometimes an element will be shoved down away from a previous sibling, e.g., when
        // clearing to pass beyond a float.  In this case, you don't need to collapse.  This
        // boolean is updated with each iteration through our child list to reflect whether
        // that particular child should be collapsed with its previous sibling (or with the top
        // of the block).
        bool shouldCollapseChild = true;
                
        int oldTopPosMargin = m_maxTopPosMargin;