ui/views/controls/scrollbar/base_scroll_bar.h

   1 // Copyright (c) 2012 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 UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_H_
   6 #define UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_H_
   7
   8 #include "base/gtest_prod_util.h"
   9 #include "ui/views/animation/scroll_animator.h"
  10 #include "ui/views/context_menu_controller.h"
  11 #include "ui/views/controls/button/image_button.h"
  12 #include "ui/views/controls/menu/menu_delegate.h"
  13 #include "ui/views/controls/scrollbar/scroll_bar.h"
  14 #include "ui/views/repeat_controller.h"
  15
  16 namespace views {
  17
  18 class BaseScrollBarThumb;
  19 class MenuRunner;
  20
  21 ///////////////////////////////////////////////////////////////////////////////
  22 //
  23 // BaseScrollBar
  24 //
  25 ///////////////////////////////////////////////////////////////////////////////
  26 class VIEWS_EXPORT BaseScrollBar : public ScrollBar,
  27                                    public ScrollDelegate,
  28                                    public ContextMenuController,
  29                                    public MenuDelegate {
  30  public:
  31   BaseScrollBar(bool horizontal, BaseScrollBarThumb* thumb);
  32   ~BaseScrollBar() override;
  33
  34   // Get the bounds of the "track" area that the thumb is free to slide within.
  35   virtual gfx::Rect GetTrackBounds() const = 0;
  36
  37   // An enumeration of different amounts of incremental scroll, representing
  38   // events sent from different parts of the UI/keyboard.
  39   enum ScrollAmount {
  40     SCROLL_NONE = 0,
  41     SCROLL_START,
  42     SCROLL_END,
  43     SCROLL_PREV_LINE,
  44     SCROLL_NEXT_LINE,
  45     SCROLL_PREV_PAGE,
  46     SCROLL_NEXT_PAGE,
  47   };
  48
  49   // Scroll the contents by the specified type (see ScrollAmount above).
  50   void ScrollByAmount(ScrollAmount amount);
  51
  52   // Scroll the contents to the appropriate position given the supplied
  53   // position of the thumb (thumb track coordinates). If |scroll_to_middle| is
  54   // true, then the conversion assumes |thumb_position| is in the middle of the
  55   // thumb rather than the top.
  56   void ScrollToThumbPosition(int thumb_position, bool scroll_to_middle);
  57
  58   // Scroll the contents by the specified offset (contents coordinates).
  59   bool ScrollByContentsOffset(int contents_offset);
  60
  61   // Called when the thumb state has been changed from |old_state| to
  62   // |new_state|.
  63   void OnThumbStateChanged(CustomButton::ButtonState old_state,
  64                            CustomButton::ButtonState new_state);
  65
  66   // View overrides:
  67   gfx::Size GetPreferredSize() const override = 0;
  68   void Layout() override = 0;
  69   bool OnMousePressed(const ui::MouseEvent& event) override;
  70   void OnMouseReleased(const ui::MouseEvent& event) override;
  71   void OnMouseCaptureLost() override;
  72   void OnMouseEntered(const ui::MouseEvent& event) override;
  73   void OnMouseExited(const ui::MouseEvent& event) override;
  74   bool OnKeyPressed(const ui::KeyEvent& event) override;
  75   bool OnMouseWheel(const ui::MouseWheelEvent& event) override;
  76
  77   // ui::EventHandler overrides:
  78   void OnGestureEvent(ui::GestureEvent* event) override;
  79
  80   // ScrollBar overrides:
  81   void Update(int viewport_size,
  82               int content_size,
  83               int contents_scroll_offset) override;
  84   int GetLayoutSize() const override = 0;
  85   int GetPosition() const override;
  86
  87   // ScrollDelegate overrides:
  88   bool OnScroll(float dx, float dy) override;
  89
  90   // ContextMenuController overrides:
  91   void ShowContextMenuForView(View* source,
  92                               const gfx::Point& point,
  93                               ui::MenuSourceType source_type) override;
  94
  95   // Menu::Delegate overrides:
  96   base::string16 GetLabel(int id) const override;
  97   bool IsCommandEnabled(int id) const override;
  98   void ExecuteCommand(int id) override;
  99
 100  protected:
 101   // View overrides:
 102   void OnPaint(gfx::Canvas* canvas) override = 0;
 103
 104   BaseScrollBarThumb* GetThumb() const;
 105   CustomButton::ButtonState GetThumbTrackState() const;
 106
 107   // Wrapper functions that calls the controller. We need this since native
 108   // scrollbars wrap around a different scrollbar. When calling the controller
 109   // we need to pass in the appropriate scrollbar. For normal scrollbars it's
 110   // the |this| scrollbar, for native scrollbars it's the native scrollbar used
 111   // to create this.
 112   virtual void ScrollToPosition(int position);
 113   virtual int GetScrollIncrement(bool is_page, bool is_positive);
 114
 115  private:
 116   FRIEND_TEST_ALL_PREFIXES(NativeScrollBarTest, ScrollBarFitsToBottom);
 117   int GetThumbSizeForTest();
 118
 119   // Changes to 'pushed' state and starts a timer to scroll repeatedly.
 120   void ProcessPressEvent(const ui::LocatedEvent& event);
 121
 122   // Sets state to |state| and stops the repeater.
 123   void SetState(CustomButton::ButtonState state);
 124
 125   // Called when the mouse is pressed down in the track area.
 126   void TrackClicked();
 127
 128   // Responsible for scrolling the contents and also updating the UI to the
 129   // current value of the Scroll Offset.
 130   void ScrollContentsToOffset();
 131
 132   // Returns the size (width or height) of the track area of the ScrollBar.
 133   int GetTrackSize() const;
 134
 135   // Calculate the position of the thumb within the track based on the
 136   // specified scroll offset of the contents.
 137   int CalculateThumbPosition(int contents_scroll_offset) const;
 138
 139   // Calculates the current value of the contents offset (contents coordinates)
 140   // based on the current thumb position (thumb track coordinates). See
 141   // |ScrollToThumbPosition| for an explanation of |scroll_to_middle|.
 142   int CalculateContentsOffset(int thumb_position,
 143                               bool scroll_to_middle) const;
 144
 145   // Called when the state of the thumb track changes (e.g. by the user
 146   // pressing the mouse button down in it).
 147   void SetThumbTrackState(CustomButton::ButtonState state);
 148
 149   BaseScrollBarThumb* thumb_;
 150
 151   // The size of the scrolled contents, in pixels.
 152   int contents_size_;
 153
 154   // The current amount the contents is offset by in the viewport.
 155   int contents_scroll_offset_;
 156
 157   // The current size of the view port, in pixels.
 158   int viewport_size_;
 159
 160   // The state of the scrollbar track. Typically, the track will highlight when
 161   // the user presses the mouse on them (during page scrolling).
 162   CustomButton::ButtonState thumb_track_state_;
 163
 164   // The last amount of incremental scroll that this scrollbar performed. This
 165   // is accessed by the callbacks for the auto-repeat up/down buttons to know
 166   // what direction to repeatedly scroll in.
 167   ScrollAmount last_scroll_amount_;
 168
 169   // An instance of a RepeatController which scrolls the scrollbar continuously
 170   // as the user presses the mouse button down on the up/down buttons or the
 171   // track.
 172   RepeatController repeater_;
 173
 174   // The position of the mouse within the scroll bar when the context menu
 175   // was invoked.
 176   int context_menu_mouse_position_;
 177
 178   scoped_ptr<MenuRunner> menu_runner_;
 179   scoped_ptr<ScrollAnimator> scroll_animator_;
 180
 181   // Difference between current position and cumulative deltas obtained from
 182   // scroll update events.
 183   // TODO(tdresser): This should be removed when raw pixel scrolling for views
 184   // is enabled. See crbug.com/329354.
 185   gfx::Vector2dF roundoff_error_;
 186
 187   DISALLOW_COPY_AND_ASSIGN(BaseScrollBar);
 188 };
 189
 190 }  // namespace views
 191
 192 #endif  // UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_H_