LibGUI: Add FontsChanged event and deliver it to windows and widgets

Author: https://github.com/luk1337
Commit: https://github.com/SerenityOS/serenity/commit/b40d7715128
Pull-request: https://github.com/SerenityOS/serenity/pull/8676

Userland/Libraries/LibGUI/Event.h

@@ -52,6 +52,7 @@ public:
         DragMove,
         Drop,
         ThemeChange,
+        FontsChange,
         ScreenRectsChange,
         ActionEnter,
         ActionLeave,
@@ -425,6 +426,14 @@ public:
     }
 };
 
+class FontsChangeEvent final : public Event {
+public:
+    FontsChangeEvent()
+        : Event(Type::FontsChange)
+    {
+    }
+};
+
 class ScreenRectsChangeEvent final : public Event {
 public:
     explicit ScreenRectsChangeEvent(const Vector<Gfx::IntRect, 4>& rects, size_t main_screen_index)

Userland/Libraries/LibGUI/Forward.h

@@ -70,6 +70,7 @@ struct TextDocumentSpan;
 class TextDocumentUndoCommand;
 class TextEditor;
 class ThemeChangeEvent;
+class FontsChangeEvent;
 class Toolbar;
 class ToolbarContainer;
 class TreeView;

Userland/Libraries/LibGUI/Widget.cpp

@@ -295,6 +295,8 @@ void Widget::event(Core::Event& event)
         return drop_event(static_cast<DropEvent&>(event));
     case Event::ThemeChange:
         return theme_change_event(static_cast<ThemeChangeEvent&>(event));
+    case Event::FontsChange:
+        return fonts_change_event(static_cast<FontsChangeEvent&>(event));
     case Event::Enter:
         return handle_enter_event(event);
     case Event::Leave:
@@ -558,6 +560,10 @@ void Widget::theme_change_event(ThemeChangeEvent&)
 {
 }
 
+void Widget::fonts_change_event(FontsChangeEvent&)
+{
+}
+
 void Widget::screen_rects_change_event(ScreenRectsChangeEvent&)
 {
 }

Userland/Libraries/LibGUI/Widget.h

@@ -314,6 +314,7 @@ protected:
     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 did_begin_inspection() override;

Userland/Libraries/LibGUI/Window.cpp

@@ -511,6 +511,21 @@ void Window::handle_theme_change_event(ThemeChangeEvent& event)
     dispatch_theme_change(*m_main_widget.ptr(), dispatch_theme_change);
 }
 
+void Window::handle_fonts_change_event(FontsChangeEvent& event)
+{
+    if (!m_main_widget)
+        return;
+    auto dispatch_fonts_change = [&](auto& widget, auto recursive) {
+        widget.dispatch_event(event, this);
+        widget.for_each_child_widget([&](auto& widget) -> IterationDecision {
+            widget.dispatch_event(event, this);
+            recursive(widget, recursive);
+            return IterationDecision::Continue;
+        });
+    };
+    dispatch_fonts_change(*m_main_widget.ptr(), dispatch_fonts_change);
+}
+
 void Window::handle_screen_rects_change_event(ScreenRectsChangeEvent& event)
 {
     if (!m_main_widget)
@@ -594,6 +609,9 @@ void Window::event(Core::Event& event)
     if (event.type() == Event::ThemeChange)
         return handle_theme_change_event(static_cast<ThemeChangeEvent&>(event));
 
+    if (event.type() == Event::FontsChange)
+        return handle_fonts_change_event(static_cast<FontsChangeEvent&>(event));
+
     if (event.type() == Event::ScreenRectsChange)
         return handle_screen_rects_change_event(static_cast<ScreenRectsChangeEvent&>(event));
 

Userland/Libraries/LibGUI/Window.h

@@ -220,6 +220,7 @@ private:
     void handle_became_active_or_inactive_event(Core::Event&);
     void handle_close_request();
     void handle_theme_change_event(ThemeChangeEvent&);
+    void handle_fonts_change_event(FontsChangeEvent&);
     void handle_screen_rects_change_event(ScreenRectsChangeEvent&);
     void handle_drag_move_event(DragEvent&);
     void handle_left_event();

Userland/Libraries/LibGUI/WindowServerConnection.cpp

@@ -72,6 +72,9 @@ void WindowServerConnection::update_system_fonts(const String& default_font_quer
     Gfx::FontDatabase::set_default_font_query(default_font_query);
     Gfx::FontDatabase::set_fixed_width_font_query(fixed_width_font_query);
     Window::update_all_windows({});
+    Window::for_each_window({}, [](auto& window) {
+        Core::EventLoop::current().post_event(window, make<FontsChangeEvent>());
+    });
 }
 
 void WindowServerConnection::paint(i32 window_id, Gfx::IntSize const& window_size, Vector<Gfx::IntRect> const& rects)