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

/*
 * Copyright (C) 2008 Apple Inc. 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 APPLE INC. ``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 APPLE INC. OR
 * CONTRIBUTORS 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 LayoutScrollbarPart_h
#define LayoutScrollbarPart_h

#include "core/layout/LayoutBlock.h"
#include "platform/scroll/ScrollTypes.h"

namespace blink {

class LayoutScrollbar;
class ScrollableArea;

class LayoutScrollbarPart final : public LayoutBlock {
 public:
  static LayoutScrollbarPart* createAnonymous(Document*,
                                              ScrollableArea*,
                                              LayoutScrollbar* = nullptr,
                                              ScrollbarPart = NoPart);
  ~LayoutScrollbarPart() override;

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

  PaintLayerType layerTypeRequired() const override { return NoPaintLayer; }

  void layout() override;

  // Scrollbar parts needs to be rendered at device pixel boundaries.
  LayoutRectOutsets marginBoxOutsets() const override {
    ASSERT(isIntegerValue(LayoutBlock::marginBoxOutsets().top()));
    return LayoutBlock::marginBoxOutsets();
  }
  LayoutUnit marginTop() const override {
    ASSERT(isIntegerValue(LayoutBlock::marginTop()));
    return LayoutBlock::marginTop();
  }
  LayoutUnit marginBottom() const override {
    ASSERT(isIntegerValue(LayoutBlock::marginBottom()));
    return LayoutBlock::marginBottom();
  }
  LayoutUnit marginLeft() const override {
    ASSERT(isIntegerValue(LayoutBlock::marginLeft()));
    return LayoutBlock::marginLeft();
  }
  LayoutUnit marginRight() const override {
    ASSERT(isIntegerValue(LayoutBlock::marginRight()));
    return LayoutBlock::marginRight();
  }

  bool isOfType(LayoutObjectType type) const override {
    return type == LayoutObjectLayoutScrollbarPart ||
           LayoutBlock::isOfType(type);
  }
  LayoutObject* layoutObjectOwningScrollbar() const;

  // Must call setStyleWithWritingModeOfParent() instead.
  void setStyle(PassRefPtr<ComputedStyle>) = delete;

  LayoutRect visualRect() const override;

 protected:
  void styleWillChange(StyleDifference, const ComputedStyle& newStyle) override;
  void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
  void imageChanged(WrappedImagePtr, const IntRect* = nullptr) override;

 private:
  LayoutScrollbarPart(ScrollableArea*, LayoutScrollbar*, ScrollbarPart);

  void computePreferredLogicalWidths() override;

  // Have all padding getters return 0. The important point here is to avoid
  // resolving percents against the containing block, since scroll bar corners
  // don't always have one (so it would crash). Scroll bar corners are not
  // actually laid out, and they don't have child content, so what we return
  // here doesn't really matter.
  LayoutUnit paddingTop() const override { return LayoutUnit(); }
  LayoutUnit paddingBottom() const override { return LayoutUnit(); }
  LayoutUnit paddingLeft() const override { return LayoutUnit(); }
  LayoutUnit paddingRight() const override { return LayoutUnit(); }
  LayoutUnit paddingBefore() const override { return LayoutUnit(); }
  LayoutUnit paddingAfter() const override { return LayoutUnit(); }
  LayoutUnit paddingStart() const override { return LayoutUnit(); }
  LayoutUnit paddingEnd() const override { return LayoutUnit(); }

  void layoutHorizontalPart();
  void layoutVerticalPart();

  void computeScrollbarWidth();
  void computeScrollbarHeight();

  void setNeedsPaintInvalidation();

  bool allowsOverflowClip() const override { return false; }

  UntracedMember<ScrollableArea> m_scrollableArea;
  UntracedMember<LayoutScrollbar> m_scrollbar;
  ScrollbarPart m_part;
};

DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutScrollbarPart, isLayoutScrollbarPart());

}  // namespace blink

#endif  // LayoutScrollbarPart_h