text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   *
   * SPDX-License-Identifier: BSD-2-Clause
   */
  
  #pragma once
  
  #include <AK/EnumBits.h>
  #include <AK/JsonObject.h>
  #include <AK/NonnullRefPtr.h>
  #include <AK/String.h>
  #include <AK/Variant.h>
  #include <LibCore/Object.h>
  #include <LibCore/Timer.h>
  #include <LibGUI/Event.h>
  #include <LibGUI/FocusPolicy.h>
  #include <LibGUI/Forward.h>
  #include <LibGUI/GML/AST.h>
  #include <LibGUI/Margins.h>
  #include <LibGfx/Color.h>
  #include <LibGfx/Forward.h>
  #include <LibGfx/Orientation.h>
  #include <LibGfx/Rect.h>
  #include <LibGfx/StandardCursor.h>
  
  namespace Core {
  namespace Registration {
  extern Core::ObjectClassRegistration registration_Widget;
  }
  }
  
  #define REGISTER_WIDGET(namespace_, class_name)                                                                                                   \
      namespace Core {                                                                                                                              \
      namespace Registration {                                                                                                                      \
      Core::ObjectClassRegistration registration_##class_name(                                                                                      \
          #namespace_ "::" #class_name, []() { return static_ptr_cast<Core::Object>(namespace_::class_name::construct()); }, &registration_Widget); \
      }                                                                                                                                             \
      }
  
  namespace GUI {
  
  enum class HorizontalDirection {
      Left,
      Right
  };
  
  enum class VerticalDirection {
      Up,
      Down
  };
  
  enum class AllowCallback {
      No,
      Yes
  };
  
  class Widget : public Core::Object {
      C_OBJECT(Widget)
  public:
      virtual ~Widget() override;
  
      Layout* layout() { return m_layout.ptr(); }
      Layout const* layout() const { return m_layout.ptr(); }
      void set_layout(NonnullRefPtr<Layout>);
  
      template<class T, class... Args>
      ErrorOr<NonnullRefPtr<T>> try_set_layout(Args&&... args)
      {
          auto layout = TRY(T::try_create(forward<Args>(args)...));
          set_layout(*layout);
          return layout;
      }
  
      template<class T, class... Args>
      inline T& set_layout(Args&&... args)
      {
          auto layout = T::construct(forward<Args>(args)...);
          set_layout(*layout);
          return layout;
      }
  
      Gfx::IntSize min_size() const { return m_min_size; }
      void set_min_size(Gfx::IntSize const&);
      void set_min_size(int width, int height) { set_min_size({ width, height }); }
  
      int min_width() const { return m_min_size.width(); }
      int min_height() const { return m_min_size.height(); }
      void set_min_width(int width) { set_min_size(width, min_height()); }
      void set_min_height(int height) { set_min_size(min_width(), height); }
  
      Gfx::IntSize max_size() const { return m_max_size; }
      void set_max_size(Gfx::IntSize const&);
      void set_max_size(int width, int height) { set_max_size({ width, height }); }
  
      int max_width() const { return m_max_size.width(); }
      int max_height() const { return m_max_size.height(); }
      void set_max_width(int width) { set_max_size(width, max_height()); }
      void set_max_height(int height) { set_max_size(max_width(), height); }
  
      void set_fixed_size(Gfx::IntSize const& size)
      {
          set_min_size(size);
          set_max_size(size);
      }
  
      void set_fixed_size(int width, int height) { set_fixed_size({ width, height }); }
  
      void set_fixed_width(int width)
      {
          set_min_width(width);
          set_max_width(width);
      }
  
      void set_fixed_height(int height)
      {
          set_min_height(height);
          set_max_height(height);
      }
  
      virtual bool is_visible_for_timer_purposes() const override;
  
      bool has_tooltip() const { return !m_tooltip.is_empty(); }
      String tooltip() const { return m_tooltip; }
      void set_tooltip(String);
  
      bool is_auto_focusable() const { return m_auto_focusable; }
      void set_auto_focusable(bool auto_focusable) { m_auto_focusable = auto_focusable; }
  
      bool is_enabled() const { return m_enabled; }
      void set_enabled(bool);
  
      bool updates_enabled() const { return m_updates_enabled; }
      void set_updates_enabled(bool);
  
      Gfx::IntRect relative_rect() const { return m_relative_rect; }
      Gfx::IntPoint relative_position() const { return m_relative_rect.location(); }
  
      Gfx::IntRect window_relative_rect() const;
      Gfx::IntRect 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(); }
  
      virtual Margins content_margins() const { return { 0 }; }
  
      Gfx::IntRect rect() const { return { 0, 0, width(), height() }; }
      Gfx::IntSize size() const { return m_relative_rect.size(); }
      Gfx::IntRect content_rect() const { return this->content_margins().applied_to(rect()); };
      Gfx::IntSize content_size() const { return this->content_rect().size(); };
  
      // Invalidate the widget (or an area thereof), causing a repaint to happen soon.
      void update();
      void update(Gfx::IntRect const&);
  
      // Repaint the widget (or an area thereof) immediately.
      void repaint();
      void repaint(Gfx::IntRect const&);
  
      bool is_focused() const;
      void set_focus(bool, FocusSource = FocusSource::Programmatic);
  
      Function<void(bool const, const FocusSource)> on_focus_change;
  
      // Returns true if this widget or one of its descendants is focused.
      bool has_focus_within() const;
  
      Widget* focus_proxy() { return m_focus_proxy; }
      Widget const* focus_proxy() const { return m_focus_proxy; }
      void set_focus_proxy(Widget*);
  
      void set_focus_policy(FocusPolicy policy);
      FocusPolicy focus_policy() const;
  
      enum class ShouldRespectGreediness {
          No = 0,
          Yes
      };
      struct HitTestResult {
          WeakPtr<Widget> widget;
          Gfx::IntPoint local_position;
      };
      HitTestResult hit_test(Gfx::IntPoint const&, ShouldRespectGreediness = ShouldRespectGreediness::Yes);
      Widget* child_at(Gfx::IntPoint const&) const;
  
      void set_relative_rect(Gfx::IntRect const&);
      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(Gfx::IntPoint const& point) { set_relative_rect({ point, relative_rect().size() }); }
      void move_to(int x, int y) { move_to({ x, y }); }
      void resize(Gfx::IntSize const& 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(Gfx::IntPoint const& delta) { set_relative_rect({ relative_position().translated(delta), size() }); }
  
      Gfx::ColorRole background_role() const { return m_background_role; }
      void set_background_role(Gfx::ColorRole);
  
      Gfx::ColorRole foreground_role() const { return m_foreground_role; }
      void set_foreground_role(Gfx::ColorRole);
  
      void set_autofill(bool b) { set_fill_with_background_color(b); }
  
      Window* window()
      {
          if (auto* pw = parent_widget())
              return pw->window();
          return m_window;
      }
  
      Window const* window() const
      {
          if (auto* pw = parent_widget())
              return pw->window();
          return m_window;
      }
  
      void set_window(Window*);
  
      Widget* parent_widget();
      Widget const* 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; }
  
      Gfx::Font const& font() const { return *m_font; }
  
      void set_font(Gfx::Font const*);
      void set_font(Gfx::Font const& font) { set_font(&font); }
  
      void set_font_family(String const&);
      void set_font_size(unsigned);
      void set_font_weight(unsigned);
      void set_font_fixed_width(bool);
  
      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_shortcut(Shortcut const&);
  
      template<typename Callback>
      void for_each_child_widget(Callback callback)
      {
          for_each_child([&](auto& child) {
              if (is<Widget>(child))
                  return callback(verify_cast<Widget>(child));
              return IterationDecision::Continue;
          });
      }
  
      Vector<Widget&> child_widgets() const;
  
      void do_layout();
  
      Gfx::Palette palette() const;
      void set_palette(Gfx::Palette const&);
  
      String title() const;
      void set_title(String);
  
      Margins const& grabbable_margins() const { return m_grabbable_margins; }
      void set_grabbable_margins(Margins const&);
  
      Gfx::IntRect relative_non_grabbable_rect() const;
  
      void set_accepts_emoji_input(bool b) { m_accepts_emoji_input = b; }
      bool accepts_emoji_input() const { return m_accepts_emoji_input; }
  
      void set_accepts_command_palette(bool b) { m_accepts_command_palette = b; }
      bool accepts_command_palette() const { return m_accepts_command_palette; }
  
      virtual Gfx::IntRect children_clip_rect() const;
  
      AK::Variant<Gfx::StandardCursor, NonnullRefPtr<Gfx::Bitmap>> override_cursor() const { return m_override_cursor; }
      void set_override_cursor(AK::Variant<Gfx::StandardCursor, NonnullRefPtr<Gfx::Bitmap>>);
  
      bool load_from_gml(StringView);
      bool load_from_gml(StringView, RefPtr<Core::Object> (*unregistered_child_handler)(String const&));
  
      void set_shrink_to_fit(bool);
      bool is_shrink_to_fit() const { return m_shrink_to_fit; }
  
      bool has_pending_drop() const;
  
      // In order for others to be able to call this, it needs to be public.
      virtual bool load_from_gml_ast(NonnullRefPtr<GUI::GML::Node> ast, RefPtr<Core::Object> (*unregistered_child_handler)(String const&));
  
  protected:
      Widget();
  
      virtual void event(Core::Event&) override;
  
      // This is called after children have been painted.
      virtual void second_paint_event(PaintEvent&);
  
      virtual void custom_layout() { }
      virtual void did_change_font() { }
      virtual void did_layout() { }
      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 doubleclick_event(MouseEvent&);
      virtual void context_menu_event(ContextMenuEvent&);
      virtual void focusin_event(FocusEvent&);
      virtual void focusout_event(FocusEvent&);
      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 drag_enter_event(DragEvent&);
      virtual void drag_move_event(DragEvent&);
      virtual void drag_leave_event(Event&);
      virtual void drop_event(DropEvent&);
      virtual void theme_change_event(ThemeChangeEvent&);
      virtual void fonts_change_event(FontsChangeEvent&);
      virtual void screen_rects_change_event(ScreenRectsChangeEvent&);
      virtual void applet_area_rect_change_event(AppletAreaRectChangeEvent&);
  
      virtual void did_begin_inspection() override;
      virtual void did_end_inspection() override;
  
      void show_or_hide_tooltip();
  
  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_keydown_event(KeyEvent&);
      void handle_enter_event(Core::Event&);
      void handle_leave_event(Core::Event&);
      void focus_previous_widget(FocusSource, bool siblings_only);
      void focus_next_widget(FocusSource, bool siblings_only);
  
      // HACK: These are used as property getters for the fixed_* size property aliases.
      int dummy_fixed_width() { return 0; }
      int dummy_fixed_height() { return 0; }
      Gfx::IntSize dummy_fixed_size() { return {}; }
  
      Window* m_window { nullptr };
      RefPtr<Layout> m_layout;
  
      Gfx::IntRect m_relative_rect;
      Gfx::ColorRole m_background_role;
      Gfx::ColorRole m_foreground_role;
      NonnullRefPtr<Gfx::Font> m_font;
      String m_tooltip;
  
      Gfx::IntSize m_min_size { -1, -1 };
      Gfx::IntSize m_max_size { -1, -1 };
      Margins m_grabbable_margins;
  
      bool m_fill_with_background_color { false };
      bool m_visible { true };
      bool m_greedy_for_hits { false };
      bool m_auto_focusable { true };
      bool m_enabled { true };
      bool m_updates_enabled { true };
      bool m_accepts_emoji_input { false };
      bool m_accepts_command_palette { true };
      bool m_shrink_to_fit { false };
      bool m_default_font { true };
  
      NonnullRefPtr<Gfx::PaletteImpl> m_palette;
      String m_title { String::empty() };
  
      WeakPtr<Widget> m_focus_proxy;
      FocusPolicy m_focus_policy { FocusPolicy::NoFocus };
  
      AK::Variant<Gfx::StandardCursor, NonnullRefPtr<Gfx::Bitmap>> m_override_cursor { Gfx::StandardCursor::None };
  };
  
  inline Widget* Widget::parent_widget()
  {
      if (parent() && is<Widget>(*parent()))
          return &verify_cast<Widget>(*parent());
      return nullptr;
  }
  inline Widget const* Widget::parent_widget() const
  {
      if (parent() && is<Widget>(*parent()))
          return &verify_cast<const Widget>(*parent());
      return nullptr;
  }
  }
  
  template<>
  struct AK::Formatter<GUI::Widget> : AK::Formatter<Core::Object> {
  };
  