third_party/WebKit/Source/platform/scroll/Scrollbar.h

/*
 * Copyright (C) 2004, 2006 Apple Computer, 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 COMPUTER, 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 COMPUTER, 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 Scrollbar_h
#define Scrollbar_h

#include "platform/Timer.h"
#include "platform/Widget.h"
#include "platform/graphics/paint/DisplayItem.h"
#include "platform/heap/Handle.h"
#include "platform/scroll/ScrollTypes.h"
#include "platform/scroll/ScrollbarThemeClient.h"
#include "wtf/MathExtras.h"

namespace blink {

class GraphicsContext;
class HostWindow;
class IntRect;
class PlatformGestureEvent;
class PlatformMouseEvent;
class ScrollAnimatorBase;
class ScrollableArea;
class ScrollbarTheme;

class PLATFORM_EXPORT Scrollbar : public Widget,
                                  public ScrollbarThemeClient,
                                  public DisplayItemClient {
 public:
  static Scrollbar* create(ScrollableArea* scrollableArea,
                           ScrollbarOrientation orientation,
                           ScrollbarControlSize size,
                           HostWindow* hostWindow) {
    return new Scrollbar(scrollableArea, orientation, size, hostWindow);
  }

  // Theme object ownership remains with the caller and it must outlive the
  // scrollbar.
  static Scrollbar* createForTesting(ScrollableArea* scrollableArea,
                                     ScrollbarOrientation orientation,
                                     ScrollbarControlSize size,
                                     ScrollbarTheme* theme) {
    return new Scrollbar(scrollableArea, orientation, size, nullptr, theme);
  }

  ~Scrollbar() override;

  // ScrollbarThemeClient implementation.
  int x() const override { return Widget::x(); }
  int y() const override { return Widget::y(); }
  int width() const override { return Widget::width(); }
  int height() const override { return Widget::height(); }
  IntSize size() const override { return Widget::size(); }
  IntPoint location() const override { return Widget::location(); }

  Widget* parent() const override { return Widget::parent(); }
  Widget* root() const override { return Widget::root(); }

  void setFrameRect(const IntRect&) override;
  IntRect frameRect() const override { return Widget::frameRect(); }

  ScrollbarOverlayStyle getScrollbarOverlayStyle() const override;
  void getTickmarks(Vector<IntRect>&) const override;
  bool isScrollableAreaActive() const override;

  IntPoint convertFromRootFrame(
      const IntPoint& pointInRootFrame) const override {
    return Widget::convertFromRootFrame(pointInRootFrame);
  }

  bool isCustomScrollbar() const override { return false; }
  ScrollbarOrientation orientation() const override { return m_orientation; }
  bool isLeftSideVerticalScrollbar() const override;

  int value() const override { return lroundf(m_currentPos); }
  float currentPos() const override { return m_currentPos; }
  int visibleSize() const override { return m_visibleSize; }
  int totalSize() const override { return m_totalSize; }
  int maximum() const override { return m_totalSize - m_visibleSize; }
  ScrollbarControlSize controlSize() const override { return m_controlSize; }

  ScrollbarPart pressedPart() const override { return m_pressedPart; }
  ScrollbarPart hoveredPart() const override { return m_hoveredPart; }

  void styleChanged() override {}
  void visibilityChanged() override;
  bool enabled() const override { return m_enabled; }
  void setEnabled(bool) override;

  int scrollbarThickness() const;

  // Called by the ScrollableArea when the scroll offset changes.
  // Will trigger paint invalidation if required.
  void offsetDidChange();

  void disconnectFromScrollableArea();
  ScrollableArea* getScrollableArea() const { return m_scrollableArea; }

  int pressedPos() const { return m_pressedPos; }

  virtual void setHoveredPart(ScrollbarPart);
  virtual void setPressedPart(ScrollbarPart);

  void setProportion(int visibleSize, int totalSize);
  void setPressedPos(int p) { m_pressedPos = p; }

  void paint(GraphicsContext&, const CullRect&) const final;

  bool isOverlayScrollbar() const override;
  bool shouldParticipateInHitTesting();

  bool isWindowActive() const;

  // Return if the gesture event was handled. |shouldUpdateCapture|
  // will be set to true if the handler should update the capture
  // state for this scrollbar.
  bool gestureEvent(const PlatformGestureEvent&, bool* shouldUpdateCapture);

  // These methods are used for platform scrollbars to give :hover feedback.
  // They will not get called when the mouse went down in a scrollbar, since it
  // is assumed the scrollbar will start
  // grabbing all events in that case anyway.
  void mouseMoved(const PlatformMouseEvent&);
  void mouseEntered();
  void mouseExited();

  // Used by some platform scrollbars to know when they've been released from
  // capture.
  void mouseUp(const PlatformMouseEvent&);
  void mouseDown(const PlatformMouseEvent&);

  ScrollbarTheme& theme() const { return m_theme; }

  IntRect convertToContainingWidget(const IntRect&) const override;
  IntRect convertFromContainingWidget(const IntRect&) const override;

  IntPoint convertToContainingWidget(const IntPoint&) const override;
  IntPoint convertFromContainingWidget(const IntPoint&) const override;

  void moveThumb(int pos, bool draggingDocument = false);

  float elasticOverscroll() const override { return m_elasticOverscroll; }
  void setElasticOverscroll(float elasticOverscroll) override {
    m_elasticOverscroll = elasticOverscroll;
  }

  // Use setNeedsPaintInvalidation to cause the scrollbar (or parts thereof)
  // to repaint.
  bool trackNeedsRepaint() const { return m_trackNeedsRepaint; }
  void clearTrackNeedsRepaint() { m_trackNeedsRepaint = false; }
  bool thumbNeedsRepaint() const { return m_thumbNeedsRepaint; }
  void clearThumbNeedsRepaint() { m_thumbNeedsRepaint = false; }

  bool overlapsResizer() const { return m_overlapsResizer; }
  void setOverlapsResizer(bool overlapsResizer) {
    m_overlapsResizer = overlapsResizer;
  }

  // DisplayItemClient methods.
  String debugName() const final {
    return m_orientation == HorizontalScrollbar ? "HorizontalScrollbar"
                                                : "VerticalScrollbar";
  }
  LayoutRect visualRect() const override;

  // Marks the scrollbar as needing to be redrawn.
  //
  // If invalid parts are provided, then those parts will also be repainted.
  // Otherwise, the ScrollableArea may redraw using cached renderings of
  // individual parts. For instance, if the scrollbar is composited, the thumb
  // may be cached in a GPU texture (and is only guaranteed to be repainted if
  // ThumbPart is invalidated).
  //
  // Even if no parts are invalidated, the scrollbar may need to be redrawn
  // if, for instance, the thumb moves without changing the appearance of any
  // part.
  void setNeedsPaintInvalidation(ScrollbarPart invalidParts);

  // Promptly unregister from the theme manager + run finalizers of derived
  // Scrollbars.
  EAGERLY_FINALIZE();
  DECLARE_EAGER_FINALIZATION_OPERATOR_NEW();
  DECLARE_VIRTUAL_TRACE();

 protected:
  Scrollbar(ScrollableArea*,
            ScrollbarOrientation,
            ScrollbarControlSize,
            HostWindow* = 0,
            ScrollbarTheme* = 0);

  void autoscrollTimerFired(TimerBase*);
  void startTimerIfNeeded(double delay);
  void stopTimerIfNeeded();
  void autoscrollPressedPart(double delay);
  ScrollDirectionPhysical pressedPartScrollDirectionPhysical();
  ScrollGranularity pressedPartScrollGranularity();

  Member<ScrollableArea> m_scrollableArea;
  ScrollbarOrientation m_orientation;
  ScrollbarControlSize m_controlSize;
  ScrollbarTheme& m_theme;
  Member<HostWindow> m_hostWindow;

  int m_visibleSize;
  int m_totalSize;
  float m_currentPos;
  float m_dragOrigin;

  ScrollbarPart m_hoveredPart;
  ScrollbarPart m_pressedPart;
  int m_pressedPos;
  float m_scrollPos;
  bool m_draggingDocument;
  int m_documentDragPos;

  bool m_enabled;

  Timer<Scrollbar> m_scrollTimer;
  bool m_overlapsResizer;

  float m_elasticOverscroll;

 private:
  bool isScrollbar() const override { return true; }

  void invalidate() override { setNeedsPaintInvalidation(AllParts); }
  void invalidateRect(const IntRect&) override {
    setNeedsPaintInvalidation(AllParts);
  }

  float scrollableAreaCurrentPos() const;
  float scrollableAreaTargetPos() const;
  bool thumbWillBeUnderMouse() const;

  bool m_trackNeedsRepaint;
  bool m_thumbNeedsRepaint;
};

DEFINE_TYPE_CASTS(Scrollbar,
                  Widget,
                  widget,
                  widget->isScrollbar(),
                  widget.isScrollbar());

}  // namespace blink

#endif  // Scrollbar_h