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

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef LayoutMultiColumnSpannerPlaceholder_h
   6 #define LayoutMultiColumnSpannerPlaceholder_h
   7
   8 #include "core/layout/LayoutMultiColumnFlowThread.h"
   9
  10 namespace blink {
  11
  12 // Placeholder layoutObject for column-span:all elements. The column-span:all layoutObject itself is a
  13 // descendant of the flow thread, but due to its out-of-flow nature, we need something on the
  14 // outside to take care of its positioning and sizing. LayoutMultiColumnSpannerPlaceholder objects
  15 // are siblings of LayoutMultiColumnSet objects, i.e. direct children of the multicol container.
  16 class LayoutMultiColumnSpannerPlaceholder final : public LayoutBox {
  17 public:
  18     bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectLayoutMultiColumnSpannerPlaceholder || LayoutBox::isOfType(type); }
  19
  20     static LayoutMultiColumnSpannerPlaceholder* createAnonymous(const ComputedStyle& parentStyle, LayoutBox&);
  21
  22     LayoutMultiColumnFlowThread* flowThread() const { return toLayoutBlockFlow(parent())->multiColumnFlowThread(); }
  23
  24     LayoutBox* layoutObjectInFlowThread() const { return m_layoutObjectInFlowThread; }
  25     void markForLayoutIfObjectInFlowThreadNeedsLayout()
  26     {
  27         if (!m_layoutObjectInFlowThread->needsLayout())
  28             return;
  29         // The containing block of a spanner is the multicol container (our parent here), but the
  30         // spanner is laid out via its spanner set (us), so we need to make sure that we enter it.
  31         setChildNeedsLayout(MarkOnlyThis);
  32     }
  33
  34     void layoutObjectInFlowThreadStyleDidChange(const ComputedStyle* oldStyle);
  35     void updateMarginProperties();
  36
  37     const char* name() const override { return "LayoutMultiColumnSpannerPlaceholder"; }
  38
  39 protected:
  40     void willBeRemovedFromTree() override;
  41     bool needsPreferredWidthsRecalculation() const override;
  42     LayoutUnit minPreferredLogicalWidth() const override;
  43     LayoutUnit maxPreferredLogicalWidth() const override;
  44     void layout() override;
  45     void computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop, LogicalExtentComputedValues&) const override;
  46     void invalidateTreeIfNeeded(PaintInvalidationState&) override;
  47     void paint(const PaintInfo&, const LayoutPoint& paintOffset) override;
  48     bool nodeAtPoint(HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction) override;
  49
  50 private:
  51     LayoutMultiColumnSpannerPlaceholder(LayoutBox*);
  52
  53     LayoutBox* m_layoutObjectInFlowThread; // The actual column-span:all layoutObject inside the flow thread.
  54 };
  55
  56 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutMultiColumnSpannerPlaceholder, isLayoutMultiColumnSpannerPlaceholder());
  57
  58 } // namespace blink
  59
  60 #endif