Adding a Views scrollbar implementation.

views/controls/scrollbar/bitmap_scroll_bar.h

 // Copyright (c) 2011 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 VIEWS_CONTROLS_SCROLLBAR_BITMAP_SCROLL_BAR_H_
 #define VIEWS_CONTROLS_SCROLLBAR_BITMAP_SCROLL_BAR_H_
 #pragma once
 
-#include "views/context_menu_controller.h"
-#include "views/controls/button/image_button.h"
-#include "views/controls/menu/menu.h"
-#include "views/controls/scrollbar/scroll_bar.h"
-#include "views/repeat_controller.h"
+#include "views/controls/scrollbar/base_scroll_bar.h"
 
 namespace views {
 
 namespace {
 class BitmapScrollBarThumb;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 //
 // BitmapScrollBar
 //
 //  A ScrollBar subclass that implements a scroll bar rendered using bitmaps
 //  that the user provides. There are bitmaps for the up and down buttons, as
 //  well as for the thumb and track. This is intended for creating UIs that
 //  have customized, non-native appearances, like floating HUDs etc.
 //
-//  Maybe TODO(beng): (Cleanup) If we need to, we may want to factor rendering
-//                    out of this altogether and have the user supply
-//                    Background impls for each component, and just use those
-//                    to render, so that for example we get native theme
-//                    rendering.
-//
 ///////////////////////////////////////////////////////////////////////////////
-class BitmapScrollBar : public ScrollBar,
-                        public ButtonListener,
-                        public ContextMenuController,
-                        public Menu::Delegate {
+class BitmapScrollBar : public BaseScrollBar,
+                        public ButtonListener {
  public:
   BitmapScrollBar(bool horizontal, bool show_scroll_buttons);
   virtual ~BitmapScrollBar() { }
 
-  // Get the bounds of the "track" area that the thumb is free to slide within.
-  gfx::Rect GetTrackBounds() const;
-
   // A list of parts that the user may supply bitmaps for.
   enum ScrollBarPart {
     // The button used to represent scrolling up/left by 1 line.
     PREV_BUTTON = 0,
     // The button used to represent scrolling down/right by 1 line.
     // IMPORTANT: The code assumes the prev and next
     // buttons have equal width and equal height.
     NEXT_BUTTON,
     // The top/left segment of the thumb on the scrollbar.
     THUMB_START_CAP,
     // The tiled background image of the thumb.
     THUMB_MIDDLE,
     // The bottom/right segment of the thumb on the scrollbar.
     THUMB_END_CAP,
     // The grippy that is rendered in the center of the thumb.
     THUMB_GRIPPY,
     // The tiled background image of the thumb track.
     THUMB_TRACK,
     PART_COUNT
   };
 
   // Sets the bitmap to be rendered for the specified part and state.
   void SetImage(ScrollBarPart part,
                 CustomButton::ButtonState state,
                 SkBitmap* bitmap);
 
-  // An enumeration of different amounts of incremental scroll, representing
-  // events sent from different parts of the UI/keyboard.
-  enum ScrollAmount {
-    SCROLL_NONE = 0,
-    SCROLL_START,
-    SCROLL_END,
-    SCROLL_PREV_LINE,
-    SCROLL_NEXT_LINE,
-    SCROLL_PREV_PAGE,
-    SCROLL_NEXT_PAGE,
-  };
 
-  // Scroll the contents by the specified type (see ScrollAmount above).
-  void ScrollByAmount(ScrollAmount amount);
-
-  // Scroll the contents to the appropriate position given the supplied
-  // position of the thumb (thumb track coordinates). If |scroll_to_middle| is
-  // true, then the conversion assumes |thumb_position| is in the middle of the
-  // thumb rather than the top.
-  void ScrollToThumbPosition(int thumb_position, bool scroll_to_middle);
-
-  // Scroll the contents by the specified offset (contents coordinates).
-  void ScrollByContentsOffset(int contents_offset);
-
+  gfx::Rect GetTrackBounds() const;
+ protected:

[Ben Goodger (Google), 2011/08/23 16:05:15]

NL before

   // View overrides:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
   virtual void Layout() OVERRIDE;
-  virtual bool OnMousePressed(const MouseEvent& event) OVERRIDE;
-  virtual void OnMouseReleased(const MouseEvent& event) OVERRIDE;
-  virtual void OnMouseCaptureLost() OVERRIDE;
-  virtual bool OnKeyPressed(const KeyEvent& event) OVERRIDE;
-  virtual bool OnMouseWheel(const MouseWheelEvent& event) OVERRIDE;
+  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+
+  // ScrollBar overrides:
+  virtual int GetLayoutSize() const OVERRIDE;
 
   // BaseButton::ButtonListener overrides:
   virtual void ButtonPressed(Button* sender,
                              const views::Event& event) OVERRIDE;
 
-  // ScrollBar overrides:
-  virtual void Update(int viewport_size,
-                      int content_size,
-                      int contents_scroll_offset) OVERRIDE;
-  virtual int GetLayoutSize() const OVERRIDE;
-  virtual int GetPosition() const OVERRIDE;
-
-  // ContextMenuController overrides.
-  virtual void ShowContextMenuForView(View* source,
-                                      const gfx::Point& p,
-                                      bool is_mouse_gesture) OVERRIDE;
-
-  // Menu::Delegate overrides:
-  virtual std::wstring GetLabel(int id) const OVERRIDE;
-  virtual bool IsCommandEnabled(int id) const OVERRIDE;
-  virtual void ExecuteCommand(int id) OVERRIDE;
-
- protected:
-  // View overrides:
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
-
  private:
-  // Called when the mouse is pressed down in the track area.
-  void TrackClicked();
-
-  // Responsible for scrolling the contents and also updating the UI to the
-  // current value of the Scroll Offset.
-  void ScrollContentsToOffset();
-
-  // Returns the size (width or height) of the track area of the ScrollBar.
-  int GetTrackSize() const;
-
-  // Calculate the position of the thumb within the track based on the
-  // specified scroll offset of the contents.
-  int CalculateThumbPosition(int contents_scroll_offset) const;
-
-  // Calculates the current value of the contents offset (contents coordinates)
-  // based on the current thumb position (thumb track coordinates). See
-  // |ScrollToThumbPosition| for an explanation of |scroll_to_middle|.
-  int CalculateContentsOffset(int thumb_position,
-                              bool scroll_to_middle) const;
-
-  // Called when the state of the thumb track changes (e.g. by the user
-  // pressing the mouse button down in it).
-  void SetThumbTrackState(CustomButton::ButtonState state);
+  // Up/Down/Left/Right buttons.
+  ImageButton* prev_button_;
+  ImageButton* next_button_;
 
   // The thumb needs to be able to access the part images.
   friend BitmapScrollBarThumb;
   SkBitmap* images_[PART_COUNT][CustomButton::BS_COUNT];
 
-  // The size of the scrolled contents, in pixels.
-  int contents_size_;
-
-  // The current amount the contents is offset by in the viewport.
-  int contents_scroll_offset_;
-
-  // Up/Down/Left/Right buttons and the Thumb.
-  ImageButton* prev_button_;
-  ImageButton* next_button_;
-  BitmapScrollBarThumb* thumb_;
-
-  // The state of the scrollbar track. Typically, the track will highlight when
-  // the user presses the mouse on them (during page scrolling).
-  CustomButton::ButtonState thumb_track_state_;
-
-  // The last amount of incremental scroll that this scrollbar performed. This
-  // is accessed by the callbacks for the auto-repeat up/down buttons to know
-  // what direction to repeatedly scroll in.
-  ScrollAmount last_scroll_amount_;
-
-  // An instance of a RepeatController which scrolls the scrollbar continuously
-  // as the user presses the mouse button down on the up/down buttons or the
-  // track.
-  RepeatController repeater_;
-
-  // The position of the mouse within the scroll bar when the context menu
-  // was invoked.
-  int context_menu_mouse_position_;
-
   // True if the scroll buttons at each end of the scroll bar should be shown.
   bool show_scroll_buttons_;
 
   DISALLOW_COPY_AND_ASSIGN(BitmapScrollBar);
 };
 
 }  // namespace views
 
 #endif  // VIEWS_CONTROLS_SCROLLBAR_BITMAP_SCROLL_BAR_H_