WindowServer: Allow temporarily overriding the system theme

This patch adds a new api to override the current system theme with an
in memory override theme.

Userland/Services/WindowServer/ConnectionFromClient.cpp

@@ -804,6 +804,27 @@ Messages::WindowServer::GetSystemThemeResponse ConnectionFromClient::get_system_
     return name;
 }
 
+Messages::WindowServer::SetSystemThemeOverrideResponse ConnectionFromClient::set_system_theme_override(Core::AnonymousBuffer const& theme_override)
+{
+    bool success = WindowManager::the().set_theme_override(theme_override);
+    return success;
+}
+
+Messages::WindowServer::GetSystemThemeOverrideResponse ConnectionFromClient::get_system_theme_override()
+{
+    return WindowManager::the().get_theme_override();
+}
+
+void ConnectionFromClient::clear_system_theme_override()
+{
+    WindowManager::the().clear_theme_override();
+}
+
+Messages::WindowServer::IsSystemThemeOverriddenResponse ConnectionFromClient::is_system_theme_overridden()
+{
+    return WindowManager::the().is_theme_overridden();
+}
+
 void ConnectionFromClient::apply_cursor_theme(String const& name)
 {
     WindowManager::the().apply_cursor_theme(name);

Userland/Services/WindowServer/ConnectionFromClient.h

@@ -142,6 +142,10 @@ 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&, bool keep_desktop_background) override;
     virtual Messages::WindowServer::GetSystemThemeResponse get_system_theme() override;
+    virtual Messages::WindowServer::SetSystemThemeOverrideResponse set_system_theme_override(Core::AnonymousBuffer const&) override;
+    virtual Messages::WindowServer::GetSystemThemeOverrideResponse get_system_theme_override() override;
+    virtual void clear_system_theme_override() override;
+    virtual Messages::WindowServer::IsSystemThemeOverriddenResponse is_system_theme_overridden() override;
     virtual void apply_cursor_theme(String const&) override;
     virtual void set_cursor_highlight_radius(int radius) override;
     virtual Messages::WindowServer::GetCursorHighlightRadiusResponse get_cursor_highlight_radius() override;

Userland/Services/WindowServer/WindowManager.cpp

@@ -2111,6 +2111,7 @@ bool WindowManager::update_theme(String theme_path, String theme_name, bool keep
     auto new_theme = Gfx::load_system_theme(theme_path);
     if (!new_theme.is_valid())
         return false;
+    m_theme_overridden = false;
     Gfx::set_system_theme(new_theme);
     m_palette = Gfx::PaletteImpl::create_with_anonymous_buffer(new_theme);
     m_config->write_entry("Theme", "Name", theme_name);
@@ -2122,6 +2123,35 @@ bool WindowManager::update_theme(String theme_path, String theme_name, bool keep
     return true;
 }
 
+bool WindowManager::set_theme_override(Core::AnonymousBuffer const& theme_override)
+{
+    if (!theme_override.is_valid())
+        return false;
+    m_theme_overridden = true;
+    Gfx::set_system_theme(theme_override);
+    m_palette = Gfx::PaletteImpl::create_with_anonymous_buffer(theme_override);
+    invalidate_after_theme_or_font_change();
+    return true;
+}
+
+Optional<Core::AnonymousBuffer> WindowManager::get_theme_override() const
+{
+    if (!m_theme_overridden)
+        return {};
+    return Gfx::current_system_theme_buffer();
+}
+
+void WindowManager::clear_theme_override()
+{
+    m_theme_overridden = false;
+    auto previous_theme_name = m_config->read_entry("Theme", "Name");
+    auto previous_theme = Gfx::load_system_theme(String::formatted("/res/themes/{}.ini", previous_theme_name));
+    VERIFY(previous_theme.is_valid());
+    Gfx::set_system_theme(previous_theme);
+    m_palette = Gfx::PaletteImpl::create_with_anonymous_buffer(previous_theme);
+    invalidate_after_theme_or_font_change();
+}
+
 void WindowManager::did_popup_a_menu(Badge<Menu>)
 {
     // Clear any ongoing input gesture

Userland/Services/WindowServer/WindowManager.h

@@ -220,6 +220,11 @@ public:
     bool update_theme(String theme_path, String theme_name, bool keep_desktop_background);
     void invalidate_after_theme_or_font_change();
 
+    bool set_theme_override(Core::AnonymousBuffer const& theme_override);
+    Optional<Core::AnonymousBuffer> get_theme_override() const;
+    void clear_theme_override();
+    bool is_theme_overridden() { return m_theme_overridden; }
+
     bool set_hovered_window(Window*);
     void deliver_mouse_event(Window&, MouseEvent const&, bool process_double_click);
 
@@ -431,6 +436,7 @@ private:
     int m_max_distance_for_double_click { 4 };
     bool m_previous_event_was_super_keydown { false };
     bool m_buttons_switched { false };
+    bool m_theme_overridden { false };
 
     WeakPtr<Window> m_hovered_window;
     WeakPtr<Window> m_highlight_window;

Userland/Services/WindowServer/WindowServer.ipc

@@ -129,6 +129,11 @@ endpoint WindowServer
     get_system_theme() => ([UTF8] String theme_name)
     refresh_system_theme() =|
 
+    set_system_theme_override(Core::AnonymousBuffer buffer) => (bool success)
+    get_system_theme_override() => (Optional<Core::AnonymousBuffer> buffer)
+    clear_system_theme_override() =|
+    is_system_theme_overridden() => (bool overridden)
+
     apply_cursor_theme(String name) =|
     get_cursor_theme() => (String name)