text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   * 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 THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER 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.
   */
  
  #pragma once
  
  #include <AK/Badge.h>
  #include <AK/HashMap.h>
  #include <AK/String.h>
  #include <LibCore/CElapsedTimer.h>
  #include <LibCore/CObject.h>
  #include <LibGfx/Color.h>
  #include <LibGfx/Font.h>
  #include <LibGfx/Orientation.h>
  #include <LibGfx/Palette.h>
  #include <LibGfx/Rect.h>
  #include <LibGfx/SystemTheme.h>
  #include <LibGUI/GEvent.h>
  #include <LibGUI/GShortcut.h>
  
  #define REGISTER_GWIDGET(class_name)                          \
      extern WidgetClassRegistration registration_##class_name; \
      WidgetClassRegistration registration_##class_name(#class_name, [](Widget* parent) { return class_name::construct(parent); });
  
  namespace Gfx {
  class Bitmap;
  }
  
  namespace GUI {
  class Widget;
  }
  
  template<>
  inline bool Core::is<GUI::Widget>(const Core::Object& object)
  {
      return object.is_widget();
  }
  
  namespace GUI {
  
  class Action;
  class Layout;
  class Menu;
  class Window;
  
  enum class SizePolicy {
      Fixed,
      Fill
  };
  inline const char* to_string(SizePolicy policy)
  {
      switch (policy) {
      case SizePolicy::Fixed:
          return "SizePolicy::Fixed";
      case SizePolicy::Fill:
          return "SizePolicy::Fill";
      }
      return "SizePolicy::(Invalid)";
  }
  
  enum class HorizontalDirection {
      Left,
      Right
  };
  enum class VerticalDirection {
      Up,
      Down
  };
  
  class Widget;
  
  class WidgetClassRegistration {
      AK_MAKE_NONCOPYABLE(WidgetClassRegistration)
      AK_MAKE_NONMOVABLE(WidgetClassRegistration)
  public:
      WidgetClassRegistration(const String& class_name, Function<NonnullRefPtr<Widget>(Widget*)> factory);
      ~WidgetClassRegistration();
  
      String class_name() const { return m_class_name; }
      NonnullRefPtr<Widget> construct(Widget* parent) const { return m_factory(parent); }
  
      static void for_each(Function<void(const WidgetClassRegistration&)>);
      static const WidgetClassRegistration* find(const String& class_name);
  
  private:
      String m_class_name;
      Function<NonnullRefPtr<Widget>(Widget*)> m_factory;
  };
  
  class Widget : public Core::Object {
      C_OBJECT(Widget)
  public:
      virtual ~Widget() override;
  
      Layout* layout() { return m_layout.ptr(); }
      const Layout* layout() const { return m_layout.ptr(); }
      void set_layout(OwnPtr<Layout>&&);
  
      SizePolicy horizontal_size_policy() const { return m_horizontal_size_policy; }
      SizePolicy vertical_size_policy() const { return m_vertical_size_policy; }
      SizePolicy size_policy(Orientation orientation) { return orientation == Orientation::Horizontal ? m_horizontal_size_policy : m_vertical_size_policy; }
      void set_size_policy(SizePolicy horizontal_policy, SizePolicy vertical_policy);
      void set_size_policy(Orientation, SizePolicy);
  
      Gfx::Size preferred_size() const { return m_preferred_size; }
      void set_preferred_size(const Gfx::Size&);
      void set_preferred_size(int width, int height) { set_preferred_size({ width, height }); }
  
      bool has_tooltip() const { return !m_tooltip.is_empty(); }
      String tooltip() const { return m_tooltip; }
      void set_tooltip(const StringView& tooltip) { m_tooltip = tooltip; }
  
      bool is_enabled() const { return m_enabled; }
      void set_enabled(bool);
  
      bool updates_enabled() const { return m_updates_enabled; }
      void set_updates_enabled(bool);
  
      virtual void event(Core::Event&) override;
  
      // This is called after children have been painted.
      virtual void second_paint_event(PaintEvent&);
  
      Gfx::Rect relative_rect() const { return m_relative_rect; }
      Gfx::Point relative_position() const { return m_relative_rect.location(); }
  
      Gfx::Rect window_relative_rect() const;
      Gfx::Rect screen_relative_rect() const;
  
      int x() const { return m_relative_rect.x(); }
      int y() const { return m_relative_rect.y(); }
      int width() const { return m_relative_rect.width(); }
      int height() const { return m_relative_rect.height(); }
      int length(Orientation orientation) const { return orientation == Orientation::Vertical ? height() : width(); }
  
      Gfx::Rect rect() const { return { 0, 0, width(), height() }; }
      Gfx::Size size() const { return m_relative_rect.size(); }
  
      void update();
      void update(const Gfx::Rect&);
  
      virtual bool accepts_focus() const { return false; }
  
      bool is_focused() const;
      void set_focus(bool);
  
      enum class ShouldRespectGreediness { No = 0,
          Yes };
      struct HitTestResult {
          Widget* widget { nullptr };
          Gfx::Point local_position;
      };
      HitTestResult hit_test(const Gfx::Point&, ShouldRespectGreediness = ShouldRespectGreediness::Yes);
      Widget* child_at(const Gfx::Point&) const;
  
      void set_relative_rect(const Gfx::Rect&);
      void set_relative_rect(int x, int y, int width, int height) { set_relative_rect({ x, y, width, height }); }
  
      void set_x(int x) { set_relative_rect(x, y(), width(), height()); }
      void set_y(int y) { set_relative_rect(x(), y, width(), height()); }
      void set_width(int width) { set_relative_rect(x(), y(), width, height()); }
      void set_height(int height) { set_relative_rect(x(), y(), width(), height); }
  
      void move_to(const Gfx::Point& point) { set_relative_rect({ point, relative_rect().size() }); }
      void move_to(int x, int y) { move_to({ x, y }); }
      void resize(const Gfx::Size& size) { set_relative_rect({ relative_rect().location(), size }); }
      void resize(int width, int height) { resize({ width, height }); }
  
      void move_by(int x, int y) { move_by({ x, y }); }
      void move_by(const Gfx::Point& delta) { set_relative_rect({ relative_position().translated(delta), size() }); }
  
      ColorRole background_role() const { return m_background_role; }
      void set_background_role(ColorRole role) { m_background_role = role; }
  
      ColorRole foreground_role() const { return m_foreground_role; }
      void set_foreground_role(ColorRole role) { m_foreground_role = role; }
  
      Color background_color() const { return m_background_color; }
      Color foreground_color() const { return m_foreground_color; }
  
      void set_background_color(Color color) { m_background_color = color; }
      void set_foreground_color(Color color) { m_foreground_color = color; }
  
      void set_backcolor(const StringView&);
      void set_forecolor(const StringView&);
  
      void set_autofill(bool b) { set_fill_with_background_color(b); }
  
      Window* window()
      {
          if (auto* pw = parent_widget())
              return pw->window();
          return m_window;
      }
  
      const Window* window() const
      {
          if (auto* pw = parent_widget())
              return pw->window();
          return m_window;
      }
  
      void set_window(Window*);
  
      Widget* parent_widget();
      const Widget* parent_widget() const;
  
      void set_fill_with_background_color(bool b) { m_fill_with_background_color = b; }
      bool fill_with_background_color() const { return m_fill_with_background_color; }
  
      const Gfx::Font& font() const { return *m_font; }
      void set_font(const Gfx::Font*);
      void set_font(const Gfx::Font& font) { set_font(&font); }
  
      void set_global_cursor_tracking(bool);
      bool global_cursor_tracking() const;
  
      void notify_layout_changed(Badge<Layout>);
      void invalidate_layout();
  
      bool is_visible() const { return m_visible; }
      void set_visible(bool);
  
      bool spans_entire_window_horizontally() const;
  
      bool is_greedy_for_hits() const { return m_greedy_for_hits; }
      void set_greedy_for_hits(bool b) { m_greedy_for_hits = b; }
  
      void move_to_front();
      void move_to_back();
  
      bool is_frontmost() const;
      bool is_backmost() const;
  
      Action* action_for_key_event(const KeyEvent&);
  
      template<typename Callback>
      void for_each_child_widget(Callback callback)
      {
          for_each_child([&](auto& child) {
              if (Core::is<Widget>(child))
                  return callback(Core::to<Widget>(child));
              return IterationDecision::Continue;
          });
      }
  
      Vector<Widget*> child_widgets() const;
  
      virtual bool is_radio_button() const { return false; }
      virtual bool is_abstract_button() const { return false; }
  
      virtual void save_to(AK::JsonObject&) override;
  
      void do_layout();
  
      Palette palette() const { return Palette(*m_palette); }
      void set_palette(const Palette&);
  
  protected:
      explicit Widget(Widget* parent = nullptr);
  
      virtual void custom_layout() {}
      virtual void did_change_font() {}
      virtual void paint_event(PaintEvent&);
      virtual void resize_event(ResizeEvent&);
      virtual void show_event(ShowEvent&);
      virtual void hide_event(HideEvent&);
      virtual void keydown_event(KeyEvent&);
      virtual void keyup_event(KeyEvent&);
      virtual void mousemove_event(MouseEvent&);
      virtual void mousedown_event(MouseEvent&);
      virtual void mouseup_event(MouseEvent&);
      virtual void mousewheel_event(MouseEvent&);
      virtual void click_event(MouseEvent&);
      virtual void doubleclick_event(MouseEvent&);
      virtual void context_menu_event(ContextMenuEvent&);
      virtual void focusin_event(Core::Event&);
      virtual void focusout_event(Core::Event&);
      virtual void enter_event(Core::Event&);
      virtual void leave_event(Core::Event&);
      virtual void child_event(Core::ChildEvent&) override;
      virtual void change_event(Event&);
      virtual void drop_event(DropEvent&);
  
  private:
      void handle_paint_event(PaintEvent&);
      void handle_resize_event(ResizeEvent&);
      void handle_mousedown_event(MouseEvent&);
      void handle_mousedoubleclick_event(MouseEvent&);
      void handle_mouseup_event(MouseEvent&);
      void handle_enter_event(Core::Event&);
      void handle_leave_event(Core::Event&);
      void focus_previous_widget();
      void focus_next_widget();
  
      Window* m_window { nullptr };
      OwnPtr<Layout> m_layout;
  
      Gfx::Rect m_relative_rect;
      ColorRole m_background_role { ColorRole::Window };
      ColorRole m_foreground_role { ColorRole::WindowText };
      Color m_background_color;
      Color m_foreground_color;
      NonnullRefPtr<Gfx::Font> m_font;
      String m_tooltip;
  
      SizePolicy m_horizontal_size_policy { SizePolicy::Fill };
      SizePolicy m_vertical_size_policy { SizePolicy::Fill };
      Gfx::Size m_preferred_size;
  
      bool m_fill_with_background_color { false };
      bool m_visible { true };
      bool m_greedy_for_hits { false };
      bool m_enabled { true };
      bool m_updates_enabled { true };
  
      NonnullRefPtr<Gfx::PaletteImpl> m_palette;
  };
  
  inline Widget* Widget::parent_widget()
  {
      if (parent() && Core::is<Widget>(*parent()))
          return &Core::to<Widget>(*parent());
      return nullptr;
  }
  inline const Widget* Widget::parent_widget() const
  {
      if (parent() && Core::is<Widget>(*parent()))
          return &Core::to<const Widget>(*parent());
      return nullptr;
  }
  }
  