WindowServer+LibGUI: Add an IPC API to change the current system fonts

This patch adds a set_system_fonts() IPC API that takes the two main
font queries as parameters. We'll probably expand this with additional
queries when we figure out what they should be.

Note that changing the system fonts on a live system mostly takes
effect in newly launched programs. This is because GUI::Widget will
currently cache a pointer to the Gfx::FontDatabase::default_font()
when first constructed. This is something we'll have to fix somehow.

Also note that the settings are not yet persisted.

Userland/Libraries/LibGUI/WindowServerConnection.cpp

@@ -70,6 +70,7 @@ 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({});
 }
 
 void WindowServerConnection::paint(i32 window_id, Gfx::IntSize const& window_size, Vector<Gfx::IntRect> const& rects)

Userland/Services/WindowServer/ClientConnection.cpp

@@ -706,6 +706,27 @@ Messages::WindowServer::GetSystemThemeResponse ClientConnection::get_system_them
     return name;
 }
 
+Messages::WindowServer::SetSystemFontsResponse ClientConnection::set_system_fonts(String const& default_font_query, String const& fixed_width_font_query)
+{
+    if (!Gfx::FontDatabase::the().get_by_name(default_font_query)
+        || !Gfx::FontDatabase::the().get_by_name(fixed_width_font_query)) {
+        dbgln("Received unusable font queries: '{}' and '{}'", default_font_query, fixed_width_font_query);
+        return false;
+    }
+
+    dbgln("Updating fonts: '{}' and '{}'", default_font_query, fixed_width_font_query);
+
+    Gfx::FontDatabase::set_default_font_query(default_font_query);
+    Gfx::FontDatabase::set_fixed_width_font_query(fixed_width_font_query);
+
+    ClientConnection::for_each_client([&](auto& client) {
+        client.async_update_system_fonts(default_font_query, fixed_width_font_query);
+    });
+
+    WindowManager::the().invalidate_after_theme_or_font_change();
+    return true;
+}
+
 void ClientConnection::set_window_base_size_and_size_increment(i32 window_id, Gfx::IntSize const& base_size, Gfx::IntSize const& size_increment)
 {
     auto it = m_windows.find(window_id);

Userland/Services/WindowServer/ClientConnection.h

@@ -133,6 +133,7 @@ private:
     virtual Messages::WindowServer::StartDragResponse start_drag(String const&, HashMap<String, ByteBuffer> const&, Gfx::ShareableBitmap const&) override;
     virtual Messages::WindowServer::SetSystemThemeResponse set_system_theme(String const&, String const&) override;
     virtual Messages::WindowServer::GetSystemThemeResponse get_system_theme() override;
+    virtual Messages::WindowServer::SetSystemFontsResponse set_system_fonts(String const&, String const&) override;
     virtual void set_window_base_size_and_size_increment(i32, Gfx::IntSize const&, Gfx::IntSize const&) override;
     virtual void set_window_resize_aspect_ratio(i32, Optional<Gfx::IntSize> const&) override;
     virtual void enable_display_link() override;

Userland/Services/WindowServer/WindowManager.cpp

@@ -1543,13 +1543,8 @@ Gfx::IntRect WindowManager::dnd_rect() const
     return Gfx::IntRect(location, { width, height }).inflated(16, 8);
 }
 
-bool WindowManager::update_theme(String theme_path, String theme_name)
+void WindowManager::invalidate_after_theme_or_font_change()
 {
-    auto new_theme = Gfx::load_system_theme(theme_path);
-    if (!new_theme.is_valid())
-        return false;
-    Gfx::set_system_theme(new_theme);
-    m_palette = Gfx::PaletteImpl::create_with_anonymous_buffer(new_theme);
     Compositor::the().set_background_color(palette().desktop_background().to_string());
     HashTable<ClientConnection*> notified_clients;
     WindowFrame::reload_config();
@@ -1565,11 +1560,21 @@ bool WindowManager::update_theme(String theme_path, String theme_name)
     });
     MenuManager::the().did_change_theme();
     AppletManager::the().did_change_theme();
+    Compositor::the().invalidate_occlusions();
+    Compositor::the().invalidate_screen();
+}
+
+bool WindowManager::update_theme(String theme_path, String theme_name)
+{
+    auto new_theme = Gfx::load_system_theme(theme_path);
+    if (!new_theme.is_valid())
+        return false;
+    Gfx::set_system_theme(new_theme);
+    m_palette = Gfx::PaletteImpl::create_with_anonymous_buffer(new_theme);
     auto wm_config = Core::ConfigFile::open("/etc/WindowServer.ini");
     wm_config->write_entry("Theme", "Name", theme_name);
     wm_config->sync();
-    Compositor::the().invalidate_occlusions();
+    invalidate_after_theme_or_font_change();
-    Compositor::the().invalidate_screen();
     return true;
 }
 

Userland/Services/WindowServer/WindowManager.h

@@ -182,6 +182,7 @@ public:
     }
 
     bool update_theme(String theme_path, String theme_name);
+    void invalidate_after_theme_or_font_change();
 
     bool set_hovered_window(Window*);
     void deliver_mouse_event(Window& window, MouseEvent& event, bool process_double_click);

Userland/Services/WindowServer/WindowServer.ipc

@@ -104,6 +104,8 @@ endpoint WindowServer
     get_system_theme() => ([UTF8] String theme_name)
     refresh_system_theme() =|
 
+    set_system_fonts(String default_font_query, String fixed_width_font_query) => (bool success)
+
     set_window_base_size_and_size_increment(i32 window_id, Gfx::IntSize base_size, Gfx::IntSize size_increment) =|
     set_window_resize_aspect_ratio(i32 window_id, Optional<Gfx::IntSize> resize_aspect_ratio) =|