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

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef LayoutMultiColumnSpannerPlaceholder_h
#define LayoutMultiColumnSpannerPlaceholder_h

#include "core/layout/LayoutBlockFlow.h"

namespace blink {

// Placeholder layoutObject for column-span:all elements. The column-span:all
// layoutObject itself is a descendant of the flow thread, but due to its
// out-of-flow nature, we need something on the outside to take care of its
// positioning and sizing. LayoutMultiColumnSpannerPlaceholder objects are
// siblings of LayoutMultiColumnSet objects, i.e. direct children of the
// multicol container.
class LayoutMultiColumnSpannerPlaceholder final : public LayoutBox {
 public:
  bool isOfType(LayoutObjectType type) const override {
    return type == LayoutObjectLayoutMultiColumnSpannerPlaceholder ||
           LayoutBox::isOfType(type);
  }

  static LayoutMultiColumnSpannerPlaceholder* createAnonymous(
      const ComputedStyle& parentStyle,
      LayoutBox&);

  LayoutMultiColumnFlowThread* flowThread() const {
    return toLayoutBlockFlow(parent())->multiColumnFlowThread();
  }

  LayoutBox* layoutObjectInFlowThread() const {
    return m_layoutObjectInFlowThread;
  }
  void markForLayoutIfObjectInFlowThreadNeedsLayout() {
    if (!m_layoutObjectInFlowThread->needsLayout())
      return;
    // The containing block of a spanner is the multicol container (our parent
    // here), but the spanner is laid out via its spanner set (us), so we need
    // to make sure that we enter it.
    setChildNeedsLayout(MarkOnlyThis);
  }

  void layoutObjectInFlowThreadStyleDidChange(const ComputedStyle* oldStyle);
  void updateMarginProperties();

  const char* name() const override {
    return "LayoutMultiColumnSpannerPlaceholder";
  }

 protected:
  void insertedIntoTree() override;
  void willBeRemovedFromTree() override;
  bool needsPreferredWidthsRecalculation() const override;
  LayoutUnit minPreferredLogicalWidth() const override;
  LayoutUnit maxPreferredLogicalWidth() const override;
  void layout() override;
  void computeLogicalHeight(LayoutUnit logicalHeight,
                            LayoutUnit logicalTop,
                            LogicalExtentComputedValues&) const override;
  void invalidatePaintOfSubtreesIfNeeded(
      const PaintInvalidationState&) override;
  void paint(const PaintInfo&, const LayoutPoint& paintOffset) const override;
  bool nodeAtPoint(HitTestResult&,
                   const HitTestLocation& locationInContainer,
                   const LayoutPoint& accumulatedOffset,
                   HitTestAction) override;

 private:
  LayoutMultiColumnSpannerPlaceholder(LayoutBox*);

  // The actual column-span:all layoutObject inside the flow thread.
  LayoutBox* m_layoutObjectInFlowThread;
};

DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutMultiColumnSpannerPlaceholder,
                                isLayoutMultiColumnSpannerPlaceholder());

}  // namespace blink

#endif