1/*
2 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
3 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
4 *           (C) 2007 David Smith (catfish.man@gmail.com)
5 * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Library General Public License for more details.
16 *
17 * You should have received a copy of the GNU Library General Public License
18 * along with this library; see the file COPYING.LIB.  If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
20 * Boston, MA 02110-1301, USA.
21 */
22
23#ifndef RenderBlock_h
24#define RenderBlock_h
25
26#include "DeprecatedPtrList.h"
27#include "GapRects.h"
28#include "RenderBox.h"
29#include "RenderLineBoxList.h"
30#include "RootInlineBox.h"
31#include <wtf/ListHashSet.h>
32
33namespace WebCore {
34
35class InlineIterator;
36class RenderInline;
37
38struct BidiRun;
39
40template <class Iterator, class Run> class BidiResolver;
41template <class Iterator> class MidpointState;
42typedef BidiResolver<InlineIterator, BidiRun> InlineBidiResolver;
43typedef MidpointState<InlineIterator> LineMidpointState;
44
45enum CaretType { CursorCaret, DragCaret };
46
47class RenderBlock : public RenderBox {
48public:
49    RenderBlock(Node*);
50    virtual ~RenderBlock();
51
52    const RenderObjectChildList* children() const { return &m_children; }
53    RenderObjectChildList* children() { return &m_children; }
54
55    virtual void destroy();
56
57    // These two functions are overridden for inline-block.
58    virtual int lineHeight(bool firstLine, bool isRootLineBox = false) const;
59    virtual int baselinePosition(bool firstLine, bool isRootLineBox = false) const;
60
61    RenderLineBoxList* lineBoxes() { return &m_lineBoxes; }
62    const RenderLineBoxList* lineBoxes() const { return &m_lineBoxes; }
63
64    InlineFlowBox* firstLineBox() const { return m_lineBoxes.firstLineBox(); }
65    InlineFlowBox* lastLineBox() const { return m_lineBoxes.lastLineBox(); }
66
67    void deleteLineBoxTree();
68
69    virtual void addChild(RenderObject* newChild, RenderObject* beforeChild = 0);
70    virtual void removeChild(RenderObject*);
71
72    virtual void layoutBlock(bool relayoutChildren);
73
74    void insertPositionedObject(RenderBox*);
75    void removePositionedObject(RenderBox*);
76    void removePositionedObjects(RenderBlock*);
77
78    void addPercentHeightDescendant(RenderBox*);
79    static void removePercentHeightDescendant(RenderBox*);
80    HashSet<RenderBox*>* percentHeightDescendants() const;
81
82    RootInlineBox* createAndAppendRootInlineBox();
83
84    bool generatesLineBoxesForInlineChild(RenderObject*, bool isLineEmpty = true, bool previousLineBrokeCleanly = true);
85
86    void markAllDescendantsWithFloatsForLayout(RenderBox* floatToRemove = 0, bool inLayout = true);
87    void markPositionedObjectsForLayout();
88
89    bool containsFloats() { return m_floatingObjects && !m_floatingObjects->isEmpty(); }
90    bool containsFloat(RenderObject*);
91
92    IntRect floatRect() const;
93
94    int lineWidth(int y, bool firstLine) const;
95
96    virtual int lowestPosition(bool includeOverflowInterior = true, bool includeSelf = true) const;
97    virtual int rightmostPosition(bool includeOverflowInterior = true, bool includeSelf = true) const;
98    virtual int leftmostPosition(bool includeOverflowInterior = true, bool includeSelf = true) const;
99
100    int rightOffset(int y, bool firstLine) const { return rightRelOffset(y, rightOffset(), firstLine); }
101    int leftOffset(int y, bool firstLine) const { return leftRelOffset(y, leftOffset(), firstLine); }
102
103    virtual VisiblePosition positionForPoint(const IntPoint&);
104
105    // Block flows subclass availableWidth to handle multi column layout (shrinking the width available to children when laying out.)
106    virtual int availableWidth() const;
107
108    RootInlineBox* firstRootBox() const { return static_cast<RootInlineBox*>(firstLineBox()); }
109    RootInlineBox* lastRootBox() const { return static_cast<RootInlineBox*>(lastLineBox()); }
110
111    bool containsNonZeroBidiLevel() const;
112
113    virtual void setSelectionState(SelectionState s);
114
115    GapRects selectionGapRectsForRepaint(RenderBoxModelObject* repaintContainer);
116    IntRect fillLeftSelectionGap(RenderObject* selObj, int xPos, int yPos, int height, RenderBlock* rootBlock,
117                                 int blockX, int blockY, int tx, int ty, const PaintInfo*);
118    IntRect fillRightSelectionGap(RenderObject* selObj, int xPos, int yPos, int height, RenderBlock* rootBlock,
119                                  int blockX, int blockY, int tx, int ty, const PaintInfo*);
120    IntRect fillHorizontalSelectionGap(RenderObject* selObj, int xPos, int yPos, int width, int height, const PaintInfo*);
121
122    void getHorizontalSelectionGapInfo(SelectionState, bool& leftGap, bool& rightGap);
123
124    // Helper methods for computing line counts and heights for line counts.
125    RootInlineBox* lineAtIndex(int);
126    int lineCount();
127    int heightForLineCount(int);
128    void clearTruncation();
129
130    void adjustRectForColumns(IntRect&) const;
131
132    void addContinuationWithOutline(RenderInline*);
133
134    RenderInline* inlineContinuation() const { return m_inlineContinuation; }
135    void setInlineContinuation(RenderInline* c) { m_inlineContinuation = c; }
136
137    // This function is a convenience helper for creating an anonymous block that inherits its
138    // style from this RenderBlock.
139    RenderBlock* createAnonymousBlock(bool isFlexibleBox = false) const;
140
141    static void appendRunsForObject(int start, int end, RenderObject*, InlineBidiResolver&);
142    static bool requiresLineBox(const InlineIterator&, bool isLineEmpty = true, bool previousLineBrokeCleanly = true);
143
144protected:
145    void moveChildTo(RenderObject* to, RenderObjectChildList* toChildList, RenderObject* child);
146    void moveChildTo(RenderObject* to, RenderObjectChildList* toChildList, RenderObject* beforeChild, RenderObject* child);
147    void moveAllChildrenTo(RenderObject* to, RenderObjectChildList* toChildList);
148    void moveAllChildrenTo(RenderObject* to, RenderObjectChildList* toChildList, RenderObject* beforeChild);
149
150    int maxTopPosMargin() const { return m_maxMargin ? m_maxMargin->m_topPos : MaxMargin::topPosDefault(this); }
151    int maxTopNegMargin() const { return m_maxMargin ? m_maxMargin->m_topNeg : MaxMargin::topNegDefault(this); }
152    int maxBottomPosMargin() const { return m_maxMargin ? m_maxMargin->m_bottomPos : MaxMargin::bottomPosDefault(this); }
153    int maxBottomNegMargin() const { return m_maxMargin ? m_maxMargin->m_bottomNeg : MaxMargin::bottomNegDefault(this); }
154    void setMaxTopMargins(int pos, int neg);
155    void setMaxBottomMargins(int pos, int neg);
156
157    void initMaxMarginValues()
158    {
159        if (m_maxMargin) {
160            m_maxMargin->m_topPos = MaxMargin::topPosDefault(this);
161            m_maxMargin->m_topNeg = MaxMargin::topNegDefault(this);
162            m_maxMargin->m_bottomPos = MaxMargin::bottomPosDefault(this);
163            m_maxMargin->m_bottomNeg = MaxMargin::bottomNegDefault(this);
164        }
165    }
166
167    virtual void layout();
168
169    void layoutPositionedObjects(bool relayoutChildren);
170
171    virtual void paint(PaintInfo&, int tx, int ty);
172    virtual void paintObject(PaintInfo&, int tx, int ty);
173
174    int rightRelOffset(int y, int fixedOffset, bool applyTextIndent = true, int* heightRemaining = 0) const;
175    int leftRelOffset(int y, int fixedOffset, bool applyTextIndent = true, int* heightRemaining = 0) const;
176
177    virtual bool nodeAtPoint(const HitTestRequest&, HitTestResult&, int x, int y, int tx, int ty, HitTestAction);
178
179    virtual void calcPrefWidths();
180
181    virtual int firstLineBoxBaseline() const;
182    virtual int lastLineBoxBaseline() const;
183
184    virtual void updateFirstLetter();
185
186    virtual void updateHitTestResult(HitTestResult&, const IntPoint&);
187
188    // Delay update scrollbar until finishDelayRepaint() will be
189    // called. This function is used when a flexbox is laying out its
190    // descendant. If multiple calls are made to startDelayRepaint(),
191    // finishDelayRepaint() will do nothing until finishDelayRepaint()
192    // is called the same number of times.
193    static void startDelayUpdateScrollInfo();
194    static void finishDelayUpdateScrollInfo();
195
196    virtual void styleWillChange(StyleDifference, const RenderStyle* newStyle);
197    virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle);
198
199    virtual bool hasLineIfEmpty() const;
200    bool layoutOnlyPositionedObjects();
201
202private:
203    virtual RenderObjectChildList* virtualChildren() { return children(); }
204    virtual const RenderObjectChildList* virtualChildren() const { return children(); }
205
206    virtual const char* renderName() const;
207
208    virtual bool isRenderBlock() const { return true; }
209    virtual bool isBlockFlow() const { return (!isInline() || isReplaced()) && !isTable(); }
210    virtual bool isInlineBlockOrInlineTable() const { return isInline() && isReplaced(); }
211
212    void makeChildrenNonInline(RenderObject* insertionPoint = 0);
213    virtual void removeLeftoverAnonymousBlock(RenderBlock* child);
214
215    virtual void dirtyLinesFromChangedChild(RenderObject* child) { m_lineBoxes.dirtyLinesFromChangedChild(this, child); }
216
217    virtual bool isSelfCollapsingBlock() const;
218
219    virtual int maxTopMargin(bool positive) const { return positive ? maxTopPosMargin() : maxTopNegMargin(); }
220    virtual int maxBottomMargin(bool positive) const { return positive ? maxBottomPosMargin() : maxBottomNegMargin(); }
221
222    virtual void repaintOverhangingFloats(bool paintAllDescendants);
223
224    void layoutBlockChildren(bool relayoutChildren, int& maxFloatBottom);
225    void layoutInlineChildren(bool relayoutChildren, int& repaintTop, int& repaintBottom);
226
227    virtual void positionListMarker() { }
228
229    virtual void borderFitAdjust(int& x, int& w) const; // Shrink the box in which the border paints if border-fit is set.
230
231    virtual void updateBeforeAfterContent(PseudoId);
232
233    virtual RootInlineBox* createRootInlineBox(); // Subclassed by SVG and Ruby.
234
235    // Called to lay out the legend for a fieldset.
236    virtual RenderObject* layoutLegend(bool /*relayoutChildren*/) { return 0; }
237
238    struct FloatWithRect {
239        FloatWithRect(RenderBox* f)
240            : object(f)
241            , rect(IntRect(f->x() - f->marginLeft(), f->y() - f->marginTop(), f->width() + f->marginLeft() + f->marginRight(), f->height() + f->marginTop() + f->marginBottom()))
242            , everHadLayout(f->m_everHadLayout)
243        {
244        }
245
246        RenderBox* object;
247        IntRect rect;
248        bool everHadLayout;
249    };
250
251    // The following functions' implementations are in RenderBlockLineLayout.cpp.
252    void bidiReorderLine(InlineBidiResolver&, const InlineIterator& end, bool previousLineBrokeCleanly);
253    RootInlineBox* determineStartPosition(bool& firstLine, bool& fullLayout, bool& previousLineBrokeCleanly,
254                                          InlineBidiResolver&, Vector<FloatWithRect>& floats, unsigned& numCleanFloats);
255    RootInlineBox* determineEndPosition(RootInlineBox* startBox, InlineIterator& cleanLineStart,
256                                        BidiStatus& cleanLineBidiStatus,
257                                        int& yPos);
258    bool matchedEndLine(const InlineBidiResolver&, const InlineIterator& endLineStart, const BidiStatus& endLineStatus,
259                        RootInlineBox*& endLine, int& endYPos, int& repaintBottom, int& repaintTop);
260
261    void skipTrailingWhitespace(InlineIterator&, bool isLineEmpty, bool previousLineBrokeCleanly);
262    int skipLeadingWhitespace(InlineBidiResolver&, bool firstLine, bool isLineEmpty, bool previousLineBrokeCleanly);
263    void fitBelowFloats(int widthToFit, bool firstLine, int& availableWidth);
264    InlineIterator findNextLineBreak(InlineBidiResolver&, bool firstLine, bool& isLineEmpty, bool& previousLineBrokeCleanly, EClear* clear = 0);
265    RootInlineBox* constructLine(unsigned runCount, BidiRun* firstRun, BidiRun* lastRun, bool firstLine, bool lastLine, RenderObject* endObject);
266    InlineFlowBox* createLineBoxes(RenderObject*, bool firstLine);
267    void computeHorizontalPositionsForLine(RootInlineBox*, bool firstLine, BidiRun* firstRun, BidiRun* trailingSpaceRun, bool reachedEnd);
268    void computeVerticalPositionsForLine(RootInlineBox*, BidiRun*);
269    void deleteEllipsisLineBoxes();
270    void checkLinesForTextOverflow();
271    void addOverflowFromInlineChildren();
272    // End of functions defined in RenderBlockLineLayout.cpp.
273
274    void addOverflowFromBlockChildren();
275    void addOverflowFromFloats();
276
277    void paintFloats(PaintInfo&, int tx, int ty, bool preservePhase = false);
278    void paintContents(PaintInfo&, int tx, int ty);
279    void paintColumnContents(PaintInfo&, int tx, int ty, bool paintFloats = false);
280    void paintColumnRules(PaintInfo&, int tx, int ty);
281    void paintChildren(PaintInfo&, int tx, int ty);
282    void paintEllipsisBoxes(PaintInfo&, int tx, int ty);
283    void paintSelection(PaintInfo&, int tx, int ty);
284    void paintCaret(PaintInfo&, int tx, int ty, CaretType);
285
286    void insertFloatingObject(RenderBox*);
287    void removeFloatingObject(RenderBox*);
288
289    // Called from lineWidth, to position the floats added in the last line.
290    // Returns ture if and only if it has positioned any floats.
291    bool positionNewFloats();
292    void clearFloats();
293    int getClearDelta(RenderBox* child, int yPos);
294
295    virtual bool avoidsFloats() const;
296
297    bool hasOverhangingFloats() { return parent() && !hasColumns() && floatBottom() > height(); }
298    void addIntrudingFloats(RenderBlock* prev, int xoffset, int yoffset);
299    int addOverhangingFloats(RenderBlock* child, int xoffset, int yoffset, bool makeChildPaintOtherFloats);
300
301    int nextFloatBottomBelow(int) const;
302    int floatBottom() const;
303    inline int leftBottom();
304    inline int rightBottom();
305
306    int rightOffset() const;
307    int leftOffset() const;
308    virtual bool hitTestColumns(const HitTestRequest&, HitTestResult&, int x, int y, int tx, int ty, HitTestAction);
309    virtual bool hitTestContents(const HitTestRequest&, HitTestResult&, int x, int y, int tx, int ty, HitTestAction);
310
311    virtual bool isPointInOverflowControl(HitTestResult&, int x, int y, int tx, int ty);
312
313    void calcInlinePrefWidths();
314    void calcBlockPrefWidths();
315
316    // Obtains the nearest enclosing block (including this block) that contributes a first-line style to our inline
317    // children.
318    virtual RenderBlock* firstLineBlock() const;
319    bool inRootBlockContext() const;
320
321    virtual IntRect rectWithOutlineForRepaint(RenderBoxModelObject* repaintContainer, int outlineWidth);
322    virtual RenderStyle* outlineStyleForRepaint() const;
323
324    virtual RenderObject* hoverAncestor() const;
325    virtual void updateDragState(bool dragOn);
326    virtual void childBecameNonInline(RenderObject* child);
327
328    virtual IntRect selectionRectForRepaint(RenderBoxModelObject* repaintContainer, bool /*clipToVisibleContent*/)
329    {
330        return selectionGapRectsForRepaint(repaintContainer);
331    }
332    virtual bool shouldPaintSelectionGaps() const;
333    bool isSelectionRoot() const;
334    GapRects fillSelectionGaps(RenderBlock* rootBlock, int blockX, int blockY, int tx, int ty,
335                               int& lastTop, int& lastLeft, int& lastRight, const PaintInfo* = 0);
336    GapRects fillInlineSelectionGaps(RenderBlock* rootBlock, int blockX, int blockY, int tx, int ty,
337                                     int& lastTop, int& lastLeft, int& lastRight, const PaintInfo*);
338    GapRects fillBlockSelectionGaps(RenderBlock* rootBlock, int blockX, int blockY, int tx, int ty,
339                                    int& lastTop, int& lastLeft, int& lastRight, const PaintInfo*);
340    IntRect fillVerticalSelectionGap(int lastTop, int lastLeft, int lastRight, int bottomY, RenderBlock* rootBlock,
341                                     int blockX, int blockY, const PaintInfo*);
342    int leftSelectionOffset(RenderBlock* rootBlock, int y);
343    int rightSelectionOffset(RenderBlock* rootBlock, int y);
344
345    virtual void absoluteRects(Vector<IntRect>&, int tx, int ty);
346    virtual void absoluteQuads(Vector<FloatQuad>&);
347
348    int desiredColumnWidth() const;
349    unsigned desiredColumnCount() const;
350#if PLATFORM(ANDROID)
351public:
352#endif
353    Vector<IntRect>* columnRects() const;
354#if PLATFORM(ANDROID)
355private:
356#endif
357    void setDesiredColumnCountAndWidth(int count, int width);
358#if PLATFORM(ANDROID)
359public:
360#endif
361    int columnGap() const;
362#if PLATFORM(ANDROID)
363private:
364#endif
365
366    void paintContinuationOutlines(PaintInfo&, int tx, int ty);
367
368    virtual IntRect localCaretRect(InlineBox*, int caretOffset, int* extraWidthToEndOfLine = 0);
369
370    virtual void addFocusRingRects(Vector<IntRect>&, int tx, int ty);
371
372    void adjustPointToColumnContents(IntPoint&) const;
373    void adjustForBorderFit(int x, int& left, int& right) const; // Helper function for borderFitAdjust
374
375    void markLinesDirtyInVerticalRange(int top, int bottom, RootInlineBox* highest = 0);
376
377    void newLine(EClear);
378
379    Position positionForBox(InlineBox*, bool start = true) const;
380    Position positionForRenderer(RenderObject*, bool start = true) const;
381    VisiblePosition positionForPointWithInlineChildren(const IntPoint&);
382
383    // Adjust tx and ty from painting offsets to the local coords of this renderer
384    void offsetForContents(int& tx, int& ty) const;
385
386    void calcColumnWidth();
387    int layoutColumns(int endOfContent = -1, int requestedColumnHeight = -1);
388
389    bool expandsToEncloseOverhangingFloats() const;
390
391    void updateScrollInfoAfterLayout();
392
393    struct FloatingObject : Noncopyable {
394        enum Type {
395            FloatLeft,
396            FloatRight
397        };
398
399        FloatingObject(Type type)
400            : m_renderer(0)
401            , m_top(0)
402            , m_bottom(0)
403            , m_left(0)
404            , m_width(0)
405            , m_type(type)
406            , m_shouldPaint(true)
407            , m_isDescendant(false)
408        {
409        }
410
411        Type type() { return static_cast<Type>(m_type); }
412
413        RenderBox* m_renderer;
414        int m_top;
415        int m_bottom;
416        int m_left;
417        int m_width;
418        unsigned m_type : 1; // Type (left or right aligned)
419        bool m_shouldPaint : 1;
420        bool m_isDescendant : 1;
421    };
422
423    class MarginInfo {
424        // Collapsing flags for whether we can collapse our margins with our children's margins.
425        bool m_canCollapseWithChildren : 1;
426        bool m_canCollapseTopWithChildren : 1;
427        bool m_canCollapseBottomWithChildren : 1;
428
429        // Whether or not we are a quirky container, i.e., do we collapse away top and bottom
430        // margins in our container.  Table cells and the body are the common examples. We
431        // also have a custom style property for Safari RSS to deal with TypePad blog articles.
432        bool m_quirkContainer : 1;
433
434        // This flag tracks whether we are still looking at child margins that can all collapse together at the beginning of a block.
435        // They may or may not collapse with the top margin of the block (|m_canCollapseTopWithChildren| tells us that), but they will
436        // always be collapsing with one another.  This variable can remain set to true through multiple iterations
437        // as long as we keep encountering self-collapsing blocks.
438        bool m_atTopOfBlock : 1;
439
440        // This flag is set when we know we're examining bottom margins and we know we're at the bottom of the block.
441        bool m_atBottomOfBlock : 1;
442
443        // These variables are used to detect quirky margins that we need to collapse away (in table cells
444        // and in the body element).
445        bool m_topQuirk : 1;
446        bool m_bottomQuirk : 1;
447        bool m_determinedTopQuirk : 1;
448
449        // These flags track the previous maximal positive and negative margins.
450        int m_posMargin;
451        int m_negMargin;
452
453    public:
454        MarginInfo(RenderBlock* b, int top, int bottom);
455
456        void setAtTopOfBlock(bool b) { m_atTopOfBlock = b; }
457        void setAtBottomOfBlock(bool b) { m_atBottomOfBlock = b; }
458        void clearMargin() { m_posMargin = m_negMargin = 0; }
459        void setTopQuirk(bool b) { m_topQuirk = b; }
460        void setBottomQuirk(bool b) { m_bottomQuirk = b; }
461        void setDeterminedTopQuirk(bool b) { m_determinedTopQuirk = b; }
462        void setPosMargin(int p) { m_posMargin = p; }
463        void setNegMargin(int n) { m_negMargin = n; }
464        void setPosMarginIfLarger(int p) { if (p > m_posMargin) m_posMargin = p; }
465        void setNegMarginIfLarger(int n) { if (n > m_negMargin) m_negMargin = n; }
466
467        void setMargin(int p, int n) { m_posMargin = p; m_negMargin = n; }
468
469        bool atTopOfBlock() const { return m_atTopOfBlock; }
470        bool canCollapseWithTop() const { return m_atTopOfBlock && m_canCollapseTopWithChildren; }
471        bool canCollapseWithBottom() const { return m_atBottomOfBlock && m_canCollapseBottomWithChildren; }
472        bool canCollapseTopWithChildren() const { return m_canCollapseTopWithChildren; }
473        bool canCollapseBottomWithChildren() const { return m_canCollapseBottomWithChildren; }
474        bool quirkContainer() const { return m_quirkContainer; }
475        bool determinedTopQuirk() const { return m_determinedTopQuirk; }
476        bool topQuirk() const { return m_topQuirk; }
477        bool bottomQuirk() const { return m_bottomQuirk; }
478        int posMargin() const { return m_posMargin; }
479        int negMargin() const { return m_negMargin; }
480        int margin() const { return m_posMargin - m_negMargin; }
481    };
482
483    void layoutBlockChild(RenderBox* child, MarginInfo&, int& previousFloatBottom, int& maxFloatBottom);
484    void adjustPositionedBlock(RenderBox* child, const MarginInfo&);
485    void adjustFloatingBlock(const MarginInfo&);
486    bool handleSpecialChild(RenderBox* child, const MarginInfo&);
487    bool handleFloatingChild(RenderBox* child, const MarginInfo&);
488    bool handlePositionedChild(RenderBox* child, const MarginInfo&);
489    bool handleRunInChild(RenderBox* child);
490    int collapseMargins(RenderBox* child, MarginInfo&);
491    int clearFloatsIfNeeded(RenderBox* child, MarginInfo&, int oldTopPosMargin, int oldTopNegMargin, int yPos);
492    int estimateVerticalPosition(RenderBox* child, const MarginInfo&);
493    void determineHorizontalPosition(RenderBox* child);
494    void handleBottomOfBlock(int top, int bottom, MarginInfo&);
495    void setCollapsedBottomMargin(const MarginInfo&);
496    // End helper functions and structs used by layoutBlockChildren.
497
498    typedef ListHashSet<RenderBox*>::const_iterator Iterator;
499    DeprecatedPtrList<FloatingObject>* m_floatingObjects;
500    ListHashSet<RenderBox*>* m_positionedObjects;
501
502    // An inline can be split with blocks occurring in between the inline content.
503    // When this occurs we need a pointer to our next object.  We can basically be
504    // split into a sequence of inlines and blocks.  The continuation will either be
505    // an anonymous block (that houses other blocks) or it will be an inline flow.
506    RenderInline* m_inlineContinuation;
507
508    // Allocated only when some of these fields have non-default values
509    struct MaxMargin : Noncopyable {
510        MaxMargin(const RenderBlock* o)
511            : m_topPos(topPosDefault(o))
512            , m_topNeg(topNegDefault(o))
513            , m_bottomPos(bottomPosDefault(o))
514            , m_bottomNeg(bottomNegDefault(o))
515        {
516        }
517
518        static int topPosDefault(const RenderBlock* o) { return o->marginTop() > 0 ? o->marginTop() : 0; }
519        static int topNegDefault(const RenderBlock* o) { return o->marginTop() < 0 ? -o->marginTop() : 0; }
520        static int bottomPosDefault(const RenderBlock* o) { return o->marginBottom() > 0 ? o->marginBottom() : 0; }
521        static int bottomNegDefault(const RenderBlock* o) { return o->marginBottom() < 0 ? -o->marginBottom() : 0; }
522
523        int m_topPos;
524        int m_topNeg;
525        int m_bottomPos;
526        int m_bottomNeg;
527     };
528
529    MaxMargin* m_maxMargin;
530
531    RenderObjectChildList m_children;
532    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>.
533
534    mutable int m_lineHeight;
535
536    // RenderRubyBase objects need to be able to split and merge, moving their children around
537    // (calling moveChildTo, moveAllChildrenTo, and makeChildrenNonInline).
538    friend class RenderRubyBase;
539};
540
541inline RenderBlock* toRenderBlock(RenderObject* object)
542{
543    ASSERT(!object || object->isRenderBlock());
544    return static_cast<RenderBlock*>(object);
545}
546
547inline const RenderBlock* toRenderBlock(const RenderObject* object)
548{
549    ASSERT(!object || object->isRenderBlock());
550    return static_cast<const RenderBlock*>(object);
551}
552
553// This will catch anyone doing an unnecessary cast.
554void toRenderBlock(const RenderBlock*);
555
556} // namespace WebCore
557
558#endif // RenderBlock_h
559