renderblock.h

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    virtual void childBecameNonInline(RenderObject* child);

    virtual void setSelectionState(SelectionState s);

    virtual IntRect selectionRectForRepaint(RenderBoxModelObject* repaintContainer, bool /*clipToVisibleContent*/)
    {
        return selectionGapRectsForRepaint(repaintContainer);
    }
    GapRects selectionGapRectsForRepaint(RenderBoxModelObject* repaintContainer);
    virtual bool shouldPaintSelectionGaps() const;
    bool isSelectionRoot() const;
    GapRects fillSelectionGaps(RenderBlock* rootBlock, int blockX, int blockY, int tx, int ty,
                               int& lastTop, int& lastLeft, int& lastRight, const PaintInfo* = 0);
    GapRects fillInlineSelectionGaps(RenderBlock* rootBlock, int blockX, int blockY, int tx, int ty,
                                     int& lastTop, int& lastLeft, int& lastRight, const PaintInfo*);
    GapRects fillBlockSelectionGaps(RenderBlock* rootBlock, int blockX, int blockY, int tx, int ty,
                                    int& lastTop, int& lastLeft, int& lastRight, const PaintInfo*);
    IntRect fillVerticalSelectionGap(int lastTop, int lastLeft, int lastRight, int bottomY, RenderBlock* rootBlock,
                                     int blockX, int blockY, const PaintInfo*);
    IntRect fillLeftSelectionGap(RenderObject* selObj, int xPos, int yPos, int height, RenderBlock* rootBlock, 
                                 int blockX, int blockY, int tx, int ty, const PaintInfo*);
    IntRect fillRightSelectionGap(RenderObject* selObj, int xPos, int yPos, int height, RenderBlock* rootBlock,
                                  int blockX, int blockY, int tx, int ty, const PaintInfo*);
    IntRect fillHorizontalSelectionGap(RenderObject* selObj, int xPos, int yPos, int width, int height, const PaintInfo*);

    void getHorizontalSelectionGapInfo(SelectionState, bool& leftGap, bool& rightGap);
    int leftSelectionOffset(RenderBlock* rootBlock, int y);
    int rightSelectionOffset(RenderBlock* rootBlock, int y);

    virtual void absoluteRects(Vector<IntRect>&, int tx, int ty, bool topLevel = true);
    virtual void absoluteQuads(Vector<FloatQuad>&, bool topLevel = true);

    // Helper methods for computing line counts and heights for line counts.
    RootInlineBox* lineAtIndex(int);
    int lineCount();
    int heightForLineCount(int);
    void clearTruncation();

    int desiredColumnWidth() const;
    unsigned desiredColumnCount() const;
    Vector<IntRect>* columnRects() const;
    void setDesiredColumnCountAndWidth(int count, int width);
    int columnGap() const;
    
    void adjustRectForColumns(IntRect&) const;

    void addContinuationWithOutline(RenderInline*);
    void paintContinuationOutlines(PaintInfo&, int tx, int ty);

    RenderInline* inlineContinuation() const { return m_inlineContinuation; }
    void setInlineContinuation(RenderInline* c) { m_inlineContinuation = c; }

    virtual IntRect localCaretRect(InlineBox*, int caretOffset, int* extraWidthToEndOfLine = 0);

    virtual void addFocusRingRects(GraphicsContext*, int tx, int ty);

    // This function is a convenience helper for creating an anonymous block that inherits its
    // style from this RenderBlock.
    RenderBlock* createAnonymousBlock() const;

private:
    void adjustPointToColumnContents(IntPoint&) const;
    void adjustForBorderFit(int x, int& left, int& right) const; // Helper function for borderFitAdjust

    void markLinesDirtyInVerticalRange(int top, int bottom);

protected:
    virtual void styleWillChange(StyleDifference, const RenderStyle* newStyle);
    virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle);

    void newLine(EClear);
    virtual bool hasLineIfEmpty() const;
    bool layoutOnlyPositionedObjects();

    virtual RootInlineBox* createRootBox(); // Subclassed by SVG.
    
private:
    Position positionForBox(InlineBox*, bool start = true) const;
    Position positionForRenderer(RenderObject*, bool start = true) const;

    // Adjust tx and ty from painting offsets to the local coords of this renderer
    void offsetForContents(int& tx, int& ty) const;

    void calcColumnWidth();
    int layoutColumns(int endOfContent = -1);

    bool expandsToEncloseOverhangingFloats() const;

protected:
    struct FloatingObject {
        enum Type {
            FloatLeft,
            FloatRight
        };

        FloatingObject(Type type)
            : m_renderer(0)
            , m_top(0)
            , m_bottom(0)
            , m_left(0)
            , m_width(0)
            , m_type(type)
            , m_shouldPaint(true)
            , m_isDescendant(false)
        {
        }

        Type type() { return static_cast<Type>(m_type); }

        RenderBox* m_renderer;
        int m_top;
        int m_bottom;
        int m_left;
        int m_width;
        unsigned m_type : 1; // Type (left or right aligned)
        bool m_shouldPaint : 1;
        bool m_isDescendant : 1;
    };

    class MarginInfo {
        // Collapsing flags for whether we can collapse our margins with our children's margins.
        bool m_canCollapseWithChildren : 1;
        bool m_canCollapseTopWithChildren : 1;
        bool m_canCollapseBottomWithChildren : 1;

        // Whether or not we are a quirky container, i.e., do we collapse away top and bottom
        // margins in our container.  Table cells and the body are the common examples. We
        // also have a custom style property for Safari RSS to deal with TypePad blog articles.
        bool m_quirkContainer : 1;

        // This flag tracks whether we are still looking at child margins that can all collapse together at the beginning of a block.  
        // They may or may not collapse with the top margin of the block (|m_canCollapseTopWithChildren| tells us that), but they will
        // always be collapsing with one another.  This variable can remain set to true through multiple iterations 
        // as long as we keep encountering self-collapsing blocks.
        bool m_atTopOfBlock : 1;

        // This flag is set when we know we're examining bottom margins and we know we're at the bottom of the block.
        bool m_atBottomOfBlock : 1;

        // If our last normal flow child was a self-collapsing block that cleared a float,
        // we track it in this variable.
        bool m_selfCollapsingBlockClearedFloat : 1;

        // These variables are used to detect quirky margins that we need to collapse away (in table cells
        // and in the body element).
        bool m_topQuirk : 1;
        bool m_bottomQuirk : 1;
        bool m_determinedTopQuirk : 1;

        // These flags track the previous maximal positive and negative margins.
        int m_posMargin;
        int m_negMargin;

    public:
        MarginInfo(RenderBlock* b, int top, int bottom);

        void setAtTopOfBlock(bool b) { m_atTopOfBlock = b; }
        void setAtBottomOfBlock(bool b) { m_atBottomOfBlock = b; }
        void clearMargin() { m_posMargin = m_negMargin = 0; }
        void setSelfCollapsingBlockClearedFloat(bool b) { m_selfCollapsingBlockClearedFloat = b; }
        void setTopQuirk(bool b) { m_topQuirk = b; }
        void setBottomQuirk(bool b) { m_bottomQuirk = b; }
        void setDeterminedTopQuirk(bool b) { m_determinedTopQuirk = b; }
        void setPosMargin(int p) { m_posMargin = p; }
        void setNegMargin(int n) { m_negMargin = n; }
        void setPosMarginIfLarger(int p) { if (p > m_posMargin) m_posMargin = p; }
        void setNegMarginIfLarger(int n) { if (n > m_negMargin) m_negMargin = n; }

        void setMargin(int p, int n) { m_posMargin = p; m_negMargin = n; }

        bool atTopOfBlock() const { return m_atTopOfBlock; }
        bool canCollapseWithTop() const { return m_atTopOfBlock && m_canCollapseTopWithChildren; }
        bool canCollapseWithBottom() const { return m_atBottomOfBlock && m_canCollapseBottomWithChildren; }
        bool canCollapseTopWithChildren() const { return m_canCollapseTopWithChildren; }
        bool canCollapseBottomWithChildren() const { return m_canCollapseBottomWithChildren; }
        bool selfCollapsingBlockClearedFloat() const { return m_selfCollapsingBlockClearedFloat; }
        bool quirkContainer() const { return m_quirkContainer; }
        bool determinedTopQuirk() const { return m_determinedTopQuirk; }
        bool topQuirk() const { return m_topQuirk; }
        bool bottomQuirk() const { return m_bottomQuirk; }
        int posMargin() const { return m_posMargin; }
        int negMargin() const { return m_negMargin; }
        int margin() const { return m_posMargin - m_negMargin; }
    };

    void adjustPositionedBlock(RenderBox* child, const MarginInfo&);
    void adjustFloatingBlock(const MarginInfo&);
    RenderBox* handleSpecialChild(RenderBox* child, const MarginInfo&, bool& handled);
    RenderBox* handleFloatingChild(RenderBox* child, const MarginInfo&, bool& handled);
    RenderBox* handlePositionedChild(RenderBox* child, const MarginInfo&, bool& handled);
    RenderBox* handleRunInChild(RenderBox* child, bool& handled);
    int collapseMargins(RenderBox* child, MarginInfo&);
    int clearFloatsIfNeeded(RenderBox* child, MarginInfo&, int oldTopPosMargin, int oldTopNegMargin, int yPos);
    int estimateVerticalPosition(RenderBox* child, const MarginInfo&);
    void determineHorizontalPosition(RenderBox* child);
    void handleBottomOfBlock(int top, int bottom, MarginInfo&);
    void setCollapsedBottomMargin(const MarginInfo&);
    // End helper functions and structs used by layoutBlockChildren.

private:
    typedef ListHashSet<RenderBox*>::const_iterator Iterator;
    DeprecatedPtrList<FloatingObject>* m_floatingObjects;
    ListHashSet<RenderBox*>* m_positionedObjects;

    // An inline can be split with blocks occurring in between the inline content.
    // When this occurs we need a pointer to our next object.  We can basically be
    // split into a sequence of inlines and blocks.  The continuation will either be
    // an anonymous block (that houses other blocks) or it will be an inline flow.
    RenderInline* m_inlineContinuation;

    // Allocated only when some of these fields have non-default values
    struct MaxMargin {
        MaxMargin(const RenderBlock* o) 
            : m_topPos(topPosDefault(o))
            , m_topNeg(topNegDefault(o))
            , m_bottomPos(bottomPosDefault(o))
            , m_bottomNeg(bottomNegDefault(o))
        { 
        }

        static int topPosDefault(const RenderBlock* o) { return o->marginTop() > 0 ? o->marginTop() : 0; }
        static int topNegDefault(const RenderBlock* o) { return o->marginTop() < 0 ? -o->marginTop() : 0; }
        static int bottomPosDefault(const RenderBlock* o) { return o->marginBottom() > 0 ? o->marginBottom() : 0; }
        static int bottomNegDefault(const RenderBlock* o) { return o->marginBottom() < 0 ? -o->marginBottom() : 0; }

        int m_topPos;
        int m_topNeg;
        int m_bottomPos;
        int m_bottomNeg;
     };

    MaxMargin* m_maxMargin;

protected:
    RenderObjectChildList m_children;
    RenderLineBoxList m_lineBoxes;   // All of the root line boxes created for this block flow.  For example, <div>Hello<br>world.</div> will have two total lines for the <div>.

    // How much content overflows out of our block vertically or horizontally.
    int m_overflowHeight;
    int m_overflowWidth;
    int m_overflowLeft;
    int m_overflowTop;
    
    mutable int m_lineHeight;
};

inline RenderBlock* toRenderBlock(RenderObject* o)
{ 
    ASSERT(!o || o->isRenderBlock());
    return static_cast<RenderBlock*>(o);
}

inline const RenderBlock* toRenderBlock(const RenderObject* o)
{ 
    ASSERT(!o || o->isRenderBlock());
    return static_cast<const RenderBlock*>(o);
}

// This will catch anyone doing an unnecessary cast.
void toRenderBlock(const RenderBlock* o);

} // namespace WebCore

#endif // RenderBlock_h