third_party/WebKit/Source/core/layout/LayoutFlowThread.h

/*
 * 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 LayoutFlowThread_h
#define LayoutFlowThread_h

#include "core/CoreExport.h"
#include "core/layout/LayoutBlockFlow.h"
#include "wtf/ListHashSet.h"

namespace blink {

class LayoutMultiColumnSet;

typedef ListHashSet<LayoutMultiColumnSet*> LayoutMultiColumnSetList;

// Layout state for multicol. To be stored when laying out a block child, so
// that we can roll back to the initial state if we need to re-lay out said
// block child.
class MultiColumnLayoutState {
  friend class LayoutMultiColumnFlowThread;

 public:
  MultiColumnLayoutState() : m_columnSet(nullptr) {}

 private:
  explicit MultiColumnLayoutState(LayoutMultiColumnSet* columnSet)
      : m_columnSet(columnSet) {}
  LayoutMultiColumnSet* columnSet() const { return m_columnSet; }

  LayoutMultiColumnSet* m_columnSet;
};

// LayoutFlowThread is used to collect all the layout objects that participate
// in a flow thread. It will also help in doing the layout. However, it will not
// layout directly to screen. Instead, LayoutMultiColumnSet objects will
// redirect their paint and nodeAtPoint methods to this object. Each
// LayoutMultiColumnSet will actually be a viewPort of the LayoutFlowThread.
class CORE_EXPORT LayoutFlowThread : public LayoutBlockFlow {
 public:
  LayoutFlowThread();
  ~LayoutFlowThread() override {}

  bool isLayoutFlowThread() const final { return true; }
  virtual bool isLayoutMultiColumnFlowThread() const { return false; }
  virtual bool isLayoutPagedFlowThread() const { return false; }

  static LayoutFlowThread* locateFlowThreadContainingBlockOf(
      const LayoutObject&);

  void layout() override;

  // Always create a Layer for the LayoutFlowThread so that we
  // can easily avoid drawing the children directly.
  PaintLayerType layerTypeRequired() const final { return NormalPaintLayer; }

  virtual void flowThreadDescendantWasInserted(LayoutObject*) {}
  virtual void flowThreadDescendantWillBeRemoved(LayoutObject*) {}
  virtual void flowThreadDescendantStyleWillChange(
      LayoutBox*,
      StyleDifference,
      const ComputedStyle& newStyle) {}
  virtual void flowThreadDescendantStyleDidChange(
      LayoutBox*,
      StyleDifference,
      const ComputedStyle& oldStyle) {}

  void absoluteQuadsForDescendant(const LayoutBox& descendant,
                                  Vector<FloatQuad>&);

  bool nodeAtPoint(HitTestResult&,
                   const HitTestLocation& locationInContainer,
                   const LayoutPoint& accumulatedOffset,
                   HitTestAction) final;

  virtual void addColumnSetToThread(LayoutMultiColumnSet*) = 0;
  virtual void removeColumnSetFromThread(LayoutMultiColumnSet*);

  void computeLogicalHeight(LayoutUnit logicalHeight,
                            LayoutUnit logicalTop,
                            LogicalExtentComputedValues&) const override;

  bool hasColumnSets() const { return m_multiColumnSetList.size(); }

  void validateColumnSets();
  void invalidateColumnSets() { m_columnSetsInvalidated = true; }
  bool hasValidColumnSetInfo() const {
    return !m_columnSetsInvalidated && !m_multiColumnSetList.isEmpty();
  }

  bool mapToVisualRectInAncestorSpace(
      const LayoutBoxModelObject* ancestor,
      LayoutRect&,
      VisualRectFlags = DefaultVisualRectFlags) const override;

  LayoutUnit pageLogicalHeightForOffset(LayoutUnit);
  LayoutUnit pageRemainingLogicalHeightForOffset(LayoutUnit, PageBoundaryRule);

  virtual void contentWasLaidOut(
      LayoutUnit logicalBottomInFlowThreadAfterPagination) = 0;
  virtual bool canSkipLayout(const LayoutBox&) const = 0;

  virtual MultiColumnLayoutState multiColumnLayoutState() const = 0;
  virtual void restoreMultiColumnLayoutState(const MultiColumnLayoutState&) = 0;

  // Find and return the next logical top after |flowThreadOffset| that can fit
  // unbreakable content as tall as |contentLogicalHeight|. |flowThreadOffset|
  // is expected to be at the exact top of a column that's known to not have
  // enough space for |contentLogicalHeight|. This method is called when the
  // current column is too short to fit the content, in the hope that there
  // exists one that's tall enough further ahead. If no such column can be
  // found, |flowThreadOffset| will be returned.
  LayoutUnit nextLogicalTopForUnbreakableContent(
      LayoutUnit flowThreadOffset,
      LayoutUnit contentLogicalHeight) const;

  virtual bool isPageLogicalHeightKnown() const { return true; }
  virtual bool mayHaveNonUniformPageLogicalHeight() const = 0;
  bool pageLogicalSizeChanged() const { return m_pageLogicalSizeChanged; }

  // Return the visual bounding box based on the supplied flow-thread bounding
  // box. Both rectangles are completely physical in terms of writing mode.
  LayoutRect fragmentsBoundingBox(const LayoutRect& layerBoundingBox) const;

  // Convert a logical position in the flow thread coordinate space to a logical
  // position in the containing coordinate space.
  void flowThreadToContainingCoordinateSpace(LayoutUnit& blockPosition,
                                             LayoutUnit& inlinePosition) const;

  virtual LayoutPoint flowThreadPointToVisualPoint(
      const LayoutPoint& flowThreadPoint) const = 0;
  virtual LayoutPoint visualPointToFlowThreadPoint(
      const LayoutPoint& visualPoint) const = 0;

  virtual LayoutMultiColumnSet* columnSetAtBlockOffset(
      LayoutUnit,
      PageBoundaryRule) const = 0;

  virtual const char* name() const = 0;

 protected:
  void generateColumnSetIntervalTree();

  LayoutMultiColumnSetList m_multiColumnSetList;

  typedef PODInterval<LayoutUnit, LayoutMultiColumnSet*> MultiColumnSetInterval;
  typedef PODIntervalTree<LayoutUnit, LayoutMultiColumnSet*>
      MultiColumnSetIntervalTree;

  class MultiColumnSetSearchAdapter {
   public:
    MultiColumnSetSearchAdapter(LayoutUnit offset)
        : m_offset(offset), m_result(nullptr) {}

    const LayoutUnit& lowValue() const { return m_offset; }
    const LayoutUnit& highValue() const { return m_offset; }
    void collectIfNeeded(const MultiColumnSetInterval&);

    LayoutMultiColumnSet* result() const { return m_result; }

   private:
    LayoutUnit m_offset;
    LayoutMultiColumnSet* m_result;
  };

  MultiColumnSetIntervalTree m_multiColumnSetIntervalTree;

  bool m_columnSetsInvalidated : 1;
  bool m_pageLogicalSizeChanged : 1;
};

DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutFlowThread, isLayoutFlowThread());

// These structures are used by PODIntervalTree for debugging.
#ifndef NDEBUG
template <>
struct ValueToString<LayoutMultiColumnSet*> {
  static String toString(const LayoutMultiColumnSet* value) {
    return String::format("%p", value);
  }
};
#endif

}  // namespace blink

#endif  // LayoutFlowThread_h