*** DO NOT LAND *** Attempt to understand Regions complexity

Source/core/rendering/RenderRegion.h

Index: Source/core/rendering/RenderRegion.h
diff --git a/Source/core/rendering/RenderRegion.h b/Source/core/rendering/RenderRegion.h
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index e47c3593a183f135789925beb51d37a9c5ec4a3b..0000000000000000000000000000000000000000
--- a/Source/core/rendering/RenderRegion.h
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-/*
- * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above
- *    copyright notice, this list of conditions and the following
- *    disclaimer.
- * 2. Redistributions in binary form must reproduce the above
- *    copyright notice, this list of conditions and the following
- *    disclaimer in the documentation and/or other materials
- *    provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY
- * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
- * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
- * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
- * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#ifndef RenderRegion_h
-#define RenderRegion_h
-
-#include "core/rendering/RenderBlockFlow.h"
-#include "core/rendering/style/StyleInheritedData.h"
-
-namespace WebCore {
-
-struct LayerFragment;
-typedef Vector<LayerFragment, 1> LayerFragments;
-class RenderBox;
-class RenderBoxRegionInfo;
-class RenderFlowThread;
-class RenderNamedFlowThread;
-
-class RenderRegion : public RenderBlockFlow {
-public:
-    explicit RenderRegion(Element*, RenderFlowThread*);
-
-    virtual bool isRenderRegion() const OVERRIDE FINAL { return true; }
-
-    bool hitTestFlowThreadContents(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction);
-
-    virtual void styleDidChange(StyleDifference, const RenderStyle* oldStyle) OVERRIDE;
-
-    void setFlowThreadPortionRect(const LayoutRect& rect) { m_flowThreadPortionRect = rect; }
-    LayoutRect flowThreadPortionRect() const { return m_flowThreadPortionRect; }
-    LayoutRect flowThreadPortionOverflowRect() const;
-
-    void attachRegion();
-    void detachRegion();
-
-    RenderNamedFlowThread* parentNamedFlowThread() const { return m_parentNamedFlowThread; }
-    RenderFlowThread* flowThread() const { return m_flowThread; }
-
-    // Valid regions do not create circular dependencies with other flows.
-    bool isValid() const { return m_isValid; }
-    void setIsValid(bool valid) { m_isValid = valid; }
-
-    bool hasCustomRegionStyle() const { return m_hasCustomRegionStyle; }
-    void setHasCustomRegionStyle(bool hasCustomRegionStyle) { m_hasCustomRegionStyle = hasCustomRegionStyle; }
-
-    RenderBoxRegionInfo* renderBoxRegionInfo(const RenderBox*) const;
-    RenderBoxRegionInfo* setRenderBoxRegionInfo(const RenderBox*, LayoutUnit logicalLeftInset, LayoutUnit logicalRightInset,
-        bool containingBlockChainIsInset);
-    PassOwnPtr<RenderBoxRegionInfo> takeRenderBoxRegionInfo(const RenderBox*);
-    void removeRenderBoxRegionInfo(const RenderBox*);
-
-    void deleteAllRenderBoxRegionInfo();
-
-    bool isFirstRegion() const;
-    bool isLastRegion() const;
-
-    void clearObjectStyleInRegion(const RenderObject*);
-
-    RegionOversetState regionOversetState() const;
-    void setRegionOversetState(RegionOversetState);
-
-    // These methods represent the width and height of a "page" and for a RenderRegion they are just the
-    // content width and content height of a region. For RenderRegionSets, however, they will be the width and
-    // height of a single column or page in the set.
-    virtual LayoutUnit pageLogicalWidth() const;
-    virtual LayoutUnit pageLogicalHeight() const;
-    virtual LayoutUnit maxPageLogicalHeight() const;
-
-    LayoutUnit logicalTopOfFlowThreadContentRect(const LayoutRect&) const;
-    LayoutUnit logicalBottomOfFlowThreadContentRect(const LayoutRect&) const;
-    LayoutUnit logicalTopForFlowThreadContent() const { return logicalTopOfFlowThreadContentRect(flowThreadPortionRect()); };
-    LayoutUnit logicalBottomForFlowThreadContent() const { return logicalBottomOfFlowThreadContentRect(flowThreadPortionRect()); };
-
-    void getRanges(Vector<RefPtr<Range> >&) const;
-
-    // This method represents the logical height of the entire flow thread portion used by the region or set.
-    // For RenderRegions it matches logicalPaginationHeight(), but for sets it is the height of all the pages
-    // or columns added together.
-    virtual LayoutUnit logicalHeightOfAllFlowThreadContent() const;
-
-    bool hasAutoLogicalHeight() const { return m_hasAutoLogicalHeight; }
-
-    const LayoutUnit& computedAutoHeight() const
-    {
-        ASSERT(hasComputedAutoHeight());
-        return m_computedAutoHeight;
-    }
-
-    void setComputedAutoHeight(LayoutUnit computedAutoHeight)
-    {
-        ASSERT(computedAutoHeight >= 0);
-        m_computedAutoHeight = computedAutoHeight;
-    }
-
-    void clearComputedAutoHeight()
-    {
-        m_computedAutoHeight = -1;
-    }
-
-    bool hasComputedAutoHeight() const { return (m_computedAutoHeight >= 0); }
-
-    // The top of the nearest page inside the region. For RenderRegions, this is just the logical top of the
-    // flow thread portion we contain. For sets, we have to figure out the top of the nearest column or
-    // page.
-    virtual LayoutUnit pageLogicalTopForOffset(LayoutUnit offset) const;
-
-    virtual void expandToEncompassFlowThreadContentsIfNeeded() { };
-
-    // Whether or not this region is a set.
-    virtual bool isRenderRegionSet() const { return false; }
-
-    virtual void repaintFlowThreadContent(const LayoutRect& repaintRect) const;
-
-    virtual void collectLayerFragments(LayerFragments&, const LayoutRect&, const LayoutRect&) { }
-
-    virtual bool canHaveChildren() const OVERRIDE FINAL { return false; }
-    virtual bool canHaveGeneratedChildren() const OVERRIDE FINAL { return true; }
-
-    bool isElementBasedRegion() const;
-
-    Node* nodeForRegion() const;
-    Node* generatingNodeForRegion() const;
-
-    virtual const char* renderName() const OVERRIDE { return "RenderRegion"; }
-
-protected:
-    void setRegionObjectsRegionStyle();
-    void restoreRegionObjectsOriginalStyle();
-
-    virtual void computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const OVERRIDE FINAL;
-
-    LayoutRect overflowRectForFlowThreadPortion(const LayoutRect& flowThreadPortionRect, bool isFirstPortion, bool isLastPortion) const;
-    void repaintFlowThreadContentRectangle(const LayoutRect& repaintRect, const LayoutRect& flowThreadPortionRect,
-        const LayoutRect& flowThreadPortionOverflowRect, const LayoutPoint& regionLocation) const;
-
-    virtual bool shouldHaveAutoLogicalHeight() const;
-
-private:
-    virtual void insertedIntoTree() OVERRIDE FINAL;
-    virtual void willBeRemovedFromTree() OVERRIDE FINAL;
-
-    virtual void layoutBlock(bool relayoutChildren) OVERRIDE FINAL;
-    virtual bool supportsPartialLayout() const OVERRIDE FINAL { return false; }
-    virtual void paintObject(PaintInfo&, const LayoutPoint&) OVERRIDE;
-
-    virtual void updateLogicalHeight() OVERRIDE FINAL;
-
-    virtual void installFlowThread();
-
-    PassRefPtr<RenderStyle> computeStyleInRegion(const RenderObject*);
-    void computeChildrenStyleInRegion(const RenderObject*);
-    void setObjectStyleInRegion(RenderObject*, PassRefPtr<RenderStyle>, bool objectRegionStyleCached);
-
-    void checkRegionStyle();
-    void updateRegionHasAutoLogicalHeightFlag();
-
-    void incrementAutoLogicalHeightCount();
-    void decrementAutoLogicalHeightCount();
-
-    Element* element() const;
-
-protected:
-    RenderFlowThread* m_flowThread;
-
-private:
-    // If this RenderRegion is displayed as part of another named flow,
-    // we need to create a dependency tree, so that layout of the
-    // regions is always done before the regions themselves.
-    RenderNamedFlowThread* m_parentNamedFlowThread;
-    LayoutRect m_flowThreadPortionRect;
-
-    // This map holds unique information about a block that is split across regions.
-    // A RenderBoxRegionInfo* tells us about any layout information for a RenderBox that
-    // is unique to the region. For now it just holds logical width information for RenderBlocks, but eventually
-    // it will also hold a custom style for any box (for region styling).
-    typedef HashMap<const RenderBox*, OwnPtr<RenderBoxRegionInfo> > RenderBoxRegionInfoMap;
-    RenderBoxRegionInfoMap m_renderBoxRegionInfo;
-
-    struct ObjectRegionStyleInfo {
-        // Used to store the original style of the object in region
-        // so that the original style is properly restored after paint.
-        // Also used to store computed style of the object in region between
-        // region paintings, so that the style in region is computed only
-        // when necessary.
-        RefPtr<RenderStyle> style;
-        // True if the computed style in region is cached.
-        bool cached;
-    };
-    typedef HashMap<const RenderObject*, ObjectRegionStyleInfo > RenderObjectRegionStyleMap;
-    RenderObjectRegionStyleMap m_renderObjectRegionStyle;
-
-    LayoutUnit m_computedAutoHeight;
-
-    bool m_isValid : 1;
-    bool m_hasCustomRegionStyle : 1;
-    bool m_hasAutoLogicalHeight : 1;
-};
-
-DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderRegion, isRenderRegion());
-
-} // namespace WebCore
-
-#endif // RenderRegion_h