ui/views/controls/scrollbar/base_scroll_bar_thumb.h

   1 // Copyright (c) 2011 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_THUMB_H_
   6 #define UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_THUMB_H_
   7
   8 #include "ui/gfx/geometry/size.h"
   9 #include "ui/views/controls/button/custom_button.h"
  10 #include "ui/views/controls/scrollbar/scroll_bar.h"
  11 #include "ui/views/view.h"
  12
  13 namespace gfx {
  14 class Canvas;
  15 }
  16
  17 namespace views {
  18
  19 class BaseScrollBar;
  20
  21 ///////////////////////////////////////////////////////////////////////////////
  22 //
  23 // BaseScrollBarThumb
  24 //
  25 //  A view that acts as the thumb in the scroll bar track that the user can
  26 //  drag to scroll the associated contents view within the viewport.
  27 //
  28 ///////////////////////////////////////////////////////////////////////////////
  29 class VIEWS_EXPORT BaseScrollBarThumb : public View {
  30  public:
  31   explicit BaseScrollBarThumb(BaseScrollBar* scroll_bar);
  32   ~BaseScrollBarThumb() override;
  33
  34   // Sets the size (width or height) of the thumb to the specified value.
  35   void SetSize(int size);
  36
  37   // Retrieves the size (width or height) of the thumb.
  38   int GetSize() const;
  39
  40   // Sets the position of the thumb on the x or y axis.
  41   void SetPosition(int position);
  42
  43   // Gets the position of the thumb on the x or y axis.
  44   int GetPosition() const;
  45
  46   // View overrides:
  47   gfx::Size GetPreferredSize() const override = 0;
  48
  49  protected:
  50   // View overrides:
  51   void OnPaint(gfx::Canvas* canvas) override = 0;
  52   void OnMouseEntered(const ui::MouseEvent& event) override;
  53   void OnMouseExited(const ui::MouseEvent& event) override;
  54   bool OnMousePressed(const ui::MouseEvent& event) override;
  55   bool OnMouseDragged(const ui::MouseEvent& event) override;
  56   void OnMouseReleased(const ui::MouseEvent& event) override;
  57   void OnMouseCaptureLost() override;
  58
  59   CustomButton::ButtonState GetState() const;
  60   // Update our state and schedule a repaint when the mouse moves over us.
  61   void SetState(CustomButton::ButtonState state);
  62
  63   BaseScrollBar* scroll_bar() { return scroll_bar_; }
  64
  65  private:
  66   // The BaseScrollBar that owns us.
  67   BaseScrollBar* scroll_bar_;
  68
  69   int drag_start_position_;
  70
  71   // The position of the mouse on the scroll axis relative to the top of this
  72   // View when the drag started.
  73   int mouse_offset_;
  74
  75   // The current state of the thumb button.
  76   CustomButton::ButtonState state_;
  77
  78   DISALLOW_COPY_AND_ASSIGN(BaseScrollBarThumb);
  79 };
  80
  81 }  // namespace views
  82
  83 #endif  // UI_VIEWS_CONTROLS_SCROLLBAR_BASE_SCROLL_BAR_THUMB_H_