text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   *
   * SPDX-License-Identifier: BSD-2-Clause
   */
  
  #pragma once
  
  #include <AK/Function.h>
  #include <LibGUI/AbstractSlider.h>
  
  namespace GUI {
  
  class Scrollbar : public AbstractSlider {
      C_OBJECT(Scrollbar);
  
  public:
      virtual ~Scrollbar() override;
  
      bool is_scrollable() const { return max() != min(); }
  
      bool has_scrubber() const;
  
      enum Component {
          None,
          DecrementButton,
          IncrementButton,
          Gutter,
          Scrubber,
      };
  
  protected:
      explicit Scrollbar(Gfx::Orientation = Gfx::Orientation::Vertical);
  
      virtual void paint_event(PaintEvent&) override;
      virtual void mousedown_event(MouseEvent&) override;
      virtual void mouseup_event(MouseEvent&) override;
      virtual void mousemove_event(MouseEvent&) override;
      virtual void mousewheel_event(MouseEvent&) override;
      virtual void leave_event(Core::Event&) override;
      virtual void change_event(Event&) override;
  
  private:
      int default_button_size() const { return 16; }
      int button_size() const { return length(orientation()) <= (default_button_size() * 2) ? length(orientation()) / 2 : default_button_size(); }
      int button_width() const { return orientation() == Orientation::Vertical ? width() : button_size(); }
      int button_height() const { return orientation() == Orientation::Horizontal ? height() : button_size(); }
      Gfx::IntRect decrement_button_rect() const;
      Gfx::IntRect increment_button_rect() const;
      Gfx::IntRect decrement_gutter_rect() const;
      Gfx::IntRect increment_gutter_rect() const;
      Gfx::IntRect scrubber_rect() const;
      int unclamped_scrubber_size() const;
      int visible_scrubber_size() const;
      int scrubbable_range_in_pixels() const;
      void on_automatic_scrolling_timer_fired();
      void set_automatic_scrolling_active(bool, Component);
  
      void scroll_to_position(const Gfx::IntPoint&);
      void scroll_by_page(const Gfx::IntPoint&);
  
      Component component_at_position(const Gfx::IntPoint&);
  
      int m_scrub_start_value { 0 };
      Gfx::IntPoint m_scrub_origin;
  
      Component m_hovered_component { Component::None };
      Component m_pressed_component { Component::None };
      Gfx::IntPoint m_last_mouse_position;
  
      RefPtr<Core::Timer> m_automatic_scrolling_timer;
  };
  
  }
  