Add ThemeDB, expose previously static Theme methods

15 files changed, 447 insertions, 253 deletions

diff --git a/scene/3d/label_3d.cpp b/scene/3d/label_3d.cpp
index 40b8af7d63..e4a7cf6ee5 100644
--- a/scene/3d/label_3d.cpp
+++ b/scene/3d/label_3d.cpp
@@ -34,6 +34,7 @@
 #include "scene/main/viewport.h"
 #include "scene/resources/theme.h"
 #include "scene/scene_string_names.h"
+#include "scene/theme/theme_db.h"
 
 void Label3D::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_horizontal_alignment", "alignment"), &Label3D::set_horizontal_alignment);
@@ -734,13 +735,13 @@ Ref<Font> Label3D::_get_font_or_default() const {
 	}
 
 	// Check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
 		List<StringName> theme_types;
-		Theme::get_project_default()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
+		ThemeDB::get_singleton()->get_project_theme()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
 
 		for (const StringName &E : theme_types) {
-			if (Theme::get_project_default()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
-				Ref<Font> f = Theme::get_project_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
+			if (ThemeDB::get_singleton()->get_project_theme()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
+				Ref<Font> f = ThemeDB::get_singleton()->get_project_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
 				if (f.is_valid()) {
 					theme_font = f;
 					theme_font->connect(CoreStringNames::get_singleton()->changed, Callable(const_cast<Label3D *>(this), "_font_changed"));
@@ -753,11 +754,11 @@ Ref<Font> Label3D::_get_font_or_default() const {
 	// Lastly, fall back on the items defined in the default Theme, if they exist.
 	{
 		List<StringName> theme_types;
-		Theme::get_default()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
+		ThemeDB::get_singleton()->get_default_theme()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
 
 		for (const StringName &E : theme_types) {
-			if (Theme::get_default()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
-				Ref<Font> f = Theme::get_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
+			if (ThemeDB::get_singleton()->get_default_theme()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
+				Ref<Font> f = ThemeDB::get_singleton()->get_default_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
 				if (f.is_valid()) {
 					theme_font = f;
 					theme_font->connect(CoreStringNames::get_singleton()->changed, Callable(const_cast<Label3D *>(this), "_font_changed"));
@@ -768,7 +769,7 @@ Ref<Font> Label3D::_get_font_or_default() const {
 	}
 
 	// If they don't exist, use any type to return the default/empty value.
-	Ref<Font> f = Theme::get_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", StringName());
+	Ref<Font> f = ThemeDB::get_singleton()->get_default_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", StringName());
 	if (f.is_valid()) {
 		theme_font = f;
 		theme_font->connect(CoreStringNames::get_singleton()->changed, Callable(const_cast<Label3D *>(this), "_font_changed"));
diff --git a/scene/SCsub b/scene/SCsub
index 92288211bb..b4b2d6dd0a 100644
--- a/scene/SCsub
+++ b/scene/SCsub
@@ -17,6 +17,7 @@ SConscript("animation/SCsub")
 SConscript("audio/SCsub")
 SConscript("resources/SCsub")
 SConscript("debugger/SCsub")
+SConscript("theme/SCsub")
 
 # Build it all as a library
 lib = env.add_library("scene", env.scene_sources)
diff --git a/scene/gui/control.cpp b/scene/gui/control.cpp
index 9b6a19c50a..6dd3d46b27 100644
--- a/scene/gui/control.cpp
+++ b/scene/gui/control.cpp
@@ -43,6 +43,7 @@
 #include "scene/main/canvas_layer.h"
 #include "scene/main/window.h"
 #include "scene/scene_string_names.h"
+#include "scene/theme/theme_db.h"
 #include "servers/rendering_server.h"
 #include "servers/text_server.h"
 
@@ -193,15 +194,15 @@ void Control::get_argument_options(const StringName &p_function, int p_idx, List
 		List<StringName> sn;
 		String pf = p_function;
 		if (pf == "add_theme_color_override" || pf == "has_theme_color" || pf == "has_theme_color_override" || pf == "get_theme_color") {
-			Theme::get_default()->get_color_list(get_class(), &sn);
+			ThemeDB::get_singleton()->get_default_theme()->get_color_list(get_class(), &sn);
 		} else if (pf == "add_theme_style_override" || pf == "has_theme_style" || pf == "has_theme_style_override" || pf == "get_theme_style") {
-			Theme::get_default()->get_stylebox_list(get_class(), &sn);
+			ThemeDB::get_singleton()->get_default_theme()->get_stylebox_list(get_class(), &sn);
 		} else if (pf == "add_theme_font_override" || pf == "has_theme_font" || pf == "has_theme_font_override" || pf == "get_theme_font") {
-			Theme::get_default()->get_font_list(get_class(), &sn);
+			ThemeDB::get_singleton()->get_default_theme()->get_font_list(get_class(), &sn);
 		} else if (pf == "add_theme_font_size_override" || pf == "has_theme_font_size" || pf == "has_theme_font_size_override" || pf == "get_theme_font_size") {
-			Theme::get_default()->get_font_size_list(get_class(), &sn);
+			ThemeDB::get_singleton()->get_default_theme()->get_font_size_list(get_class(), &sn);
 		} else if (pf == "add_theme_constant_override" || pf == "has_theme_constant" || pf == "has_theme_constant_override" || pf == "get_theme_constant") {
-			Theme::get_default()->get_constant_list(get_class(), &sn);
+			ThemeDB::get_singleton()->get_default_theme()->get_constant_list(get_class(), &sn);
 		}
 
 		sn.sort_custom<StringName::AlphCompare>();
@@ -344,7 +345,7 @@ bool Control::_get(const StringName &p_name, Variant &r_ret) const {
 }
 
 void Control::_get_property_list(List<PropertyInfo> *p_list) const {
-	Ref<Theme> theme = Theme::get_default();
+	Ref<Theme> theme = ThemeDB::get_singleton()->get_default_theme();
 
 	p_list->push_back(PropertyInfo(Variant::NIL, TTRC("Theme Overrides"), PROPERTY_HINT_NONE, "theme_override_", PROPERTY_USAGE_GROUP));
 
@@ -429,9 +430,9 @@ void Control::_validate_property(PropertyInfo &p_property) const {
 
 		// Only the default theme and the project theme are used for the list of options.
 		// This is an imposed limitation to simplify the logic needed to leverage those options.
-		Theme::get_default()->get_type_variation_list(get_class_name(), &names);
-		if (Theme::get_project_default().is_valid()) {
-			Theme::get_project_default()->get_type_variation_list(get_class_name(), &names);
+		ThemeDB::get_singleton()->get_default_theme()->get_type_variation_list(get_class_name(), &names);
+		if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
+			ThemeDB::get_singleton()->get_project_theme()->get_type_variation_list(get_class_name(), &names);
 		}
 		names.sort_custom<StringName::AlphCompare>();
 
@@ -2419,22 +2420,22 @@ T Control::get_theme_item_in_types(Control *p_theme_owner, Window *p_theme_owner
 	}
 
 	// Secondly, check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
 		for (const StringName &E : p_theme_types) {
-			if (Theme::get_project_default()->has_theme_item(p_data_type, p_name, E)) {
-				return Theme::get_project_default()->get_theme_item(p_data_type, p_name, E);
+			if (ThemeDB::get_singleton()->get_project_theme()->has_theme_item(p_data_type, p_name, E)) {
+				return ThemeDB::get_singleton()->get_project_theme()->get_theme_item(p_data_type, p_name, E);
 			}
 		}
 	}
 
 	// Lastly, fall back on the items defined in the default Theme, if they exist.
 	for (const StringName &E : p_theme_types) {
-		if (Theme::get_default()->has_theme_item(p_data_type, p_name, E)) {
-			return Theme::get_default()->get_theme_item(p_data_type, p_name, E);
+		if (ThemeDB::get_singleton()->get_default_theme()->has_theme_item(p_data_type, p_name, E)) {
+			return ThemeDB::get_singleton()->get_default_theme()->get_theme_item(p_data_type, p_name, E);
 		}
 	}
 	// If they don't exist, use any type to return the default/empty value.
-	return Theme::get_default()->get_theme_item(p_data_type, p_name, p_theme_types[0]);
+	return ThemeDB::get_singleton()->get_default_theme()->get_theme_item(p_data_type, p_name, p_theme_types[0]);
 }
 
 bool Control::has_theme_item_in_types(Control *p_theme_owner, Window *p_theme_owner_window, Theme::DataType p_data_type, const StringName &p_name, List<StringName> p_theme_types) {
@@ -2475,9 +2476,9 @@ bool Control::has_theme_item_in_types(Control *p_theme_owner, Window *p_theme_ow
 	}
 
 	// Secondly, check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
 		for (const StringName &E : p_theme_types) {
-			if (Theme::get_project_default()->has_theme_item(p_data_type, p_name, E)) {
+			if (ThemeDB::get_singleton()->get_project_theme()->has_theme_item(p_data_type, p_name, E)) {
 				return true;
 			}
 		}
@@ -2485,7 +2486,7 @@ bool Control::has_theme_item_in_types(Control *p_theme_owner, Window *p_theme_ow
 
 	// Lastly, fall back on the items defined in the default Theme, if they exist.
 	for (const StringName &E : p_theme_types) {
-		if (Theme::get_default()->has_theme_item(p_data_type, p_name, E)) {
+		if (ThemeDB::get_singleton()->get_default_theme()->has_theme_item(p_data_type, p_name, E)) {
 			return true;
 		}
 	}
@@ -2494,13 +2495,13 @@ bool Control::has_theme_item_in_types(Control *p_theme_owner, Window *p_theme_ow
 
 void Control::_get_theme_type_dependencies(const StringName &p_theme_type, List<StringName> *p_list) const {
 	if (p_theme_type == StringName() || p_theme_type == get_class_name() || p_theme_type == data.theme_type_variation) {
-		if (Theme::get_project_default().is_valid() && Theme::get_project_default()->get_type_variation_base(data.theme_type_variation) != StringName()) {
-			Theme::get_project_default()->get_type_dependencies(get_class_name(), data.theme_type_variation, p_list);
+		if (ThemeDB::get_singleton()->get_project_theme().is_valid() && ThemeDB::get_singleton()->get_project_theme()->get_type_variation_base(data.theme_type_variation) != StringName()) {
+			ThemeDB::get_singleton()->get_project_theme()->get_type_dependencies(get_class_name(), data.theme_type_variation, p_list);
 		} else {
-			Theme::get_default()->get_type_dependencies(get_class_name(), data.theme_type_variation, p_list);
+			ThemeDB::get_singleton()->get_default_theme()->get_type_dependencies(get_class_name(), data.theme_type_variation, p_list);
 		}
 	} else {
-		Theme::get_default()->get_type_dependencies(p_theme_type, StringName(), p_list);
+		ThemeDB::get_singleton()->get_default_theme()->get_type_dependencies(p_theme_type, StringName(), p_list);
 	}
 }
 
@@ -2851,17 +2852,17 @@ float Control::fetch_theme_default_base_scale(Control *p_theme_owner, Window *p_
 	}
 
 	// Secondly, check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
-		if (Theme::get_project_default()->has_default_base_scale()) {
-			return Theme::get_project_default()->get_default_base_scale();
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
+		if (ThemeDB::get_singleton()->get_project_theme()->has_default_base_scale()) {
+			return ThemeDB::get_singleton()->get_project_theme()->get_default_base_scale();
 		}
 	}
 
 	// Lastly, fall back on the default Theme.
-	if (Theme::get_default()->has_default_base_scale()) {
-		return Theme::get_default()->get_default_base_scale();
+	if (ThemeDB::get_singleton()->get_default_theme()->has_default_base_scale()) {
+		return ThemeDB::get_singleton()->get_default_theme()->get_default_base_scale();
 	}
-	return Theme::get_fallback_base_scale();
+	return ThemeDB::get_singleton()->get_fallback_base_scale();
 }
 
 float Control::get_theme_default_base_scale() const {
@@ -2902,17 +2903,17 @@ Ref<Font> Control::fetch_theme_default_font(Control *p_theme_owner, Window *p_th
 	}
 
 	// Secondly, check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
-		if (Theme::get_project_default()->has_default_font()) {
-			return Theme::get_project_default()->get_default_font();
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
+		if (ThemeDB::get_singleton()->get_project_theme()->has_default_font()) {
+			return ThemeDB::get_singleton()->get_project_theme()->get_default_font();
 		}
 	}
 
 	// Lastly, fall back on the default Theme.
-	if (Theme::get_default()->has_default_font()) {
-		return Theme::get_default()->get_default_font();
+	if (ThemeDB::get_singleton()->get_default_theme()->has_default_font()) {
+		return ThemeDB::get_singleton()->get_default_theme()->get_default_font();
 	}
-	return Theme::get_fallback_font();
+	return ThemeDB::get_singleton()->get_fallback_font();
 }
 
 Ref<Font> Control::get_theme_default_font() const {
@@ -2953,17 +2954,17 @@ int Control::fetch_theme_default_font_size(Control *p_theme_owner, Window *p_the
 	}
 
 	// Secondly, check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
-		if (Theme::get_project_default()->has_default_font_size()) {
-			return Theme::get_project_default()->get_default_font_size();
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
+		if (ThemeDB::get_singleton()->get_project_theme()->has_default_font_size()) {
+			return ThemeDB::get_singleton()->get_project_theme()->get_default_font_size();
 		}
 	}
 
 	// Lastly, fall back on the default Theme.
-	if (Theme::get_default()->has_default_font_size()) {
-		return Theme::get_default()->get_default_font_size();
+	if (ThemeDB::get_singleton()->get_default_theme()->has_default_font_size()) {
+		return ThemeDB::get_singleton()->get_default_theme()->get_default_font_size();
 	}
-	return Theme::get_fallback_font_size();
+	return ThemeDB::get_singleton()->get_fallback_font_size();
 }
 
 int Control::get_theme_default_font_size() const {
diff --git a/scene/main/window.cpp b/scene/main/window.cpp
index 35414da9ed..fa71040159 100644
--- a/scene/main/window.cpp
+++ b/scene/main/window.cpp
@@ -35,6 +35,7 @@
 #include "core/string/translation.h"
 #include "scene/gui/control.h"
 #include "scene/scene_string_names.h"
+#include "scene/theme/theme_db.h"
 
 void Window::set_title(const String &p_title) {
 	title = p_title;
@@ -1330,13 +1331,13 @@ StringName Window::get_theme_type_variation() const {
 
 void Window::_get_theme_type_dependencies(const StringName &p_theme_type, List<StringName> *p_list) const {
 	if (p_theme_type == StringName() || p_theme_type == get_class_name() || p_theme_type == theme_type_variation) {
-		if (Theme::get_project_default().is_valid() && Theme::get_project_default()->get_type_variation_base(theme_type_variation) != StringName()) {
-			Theme::get_project_default()->get_type_dependencies(get_class_name(), theme_type_variation, p_list);
+		if (ThemeDB::get_singleton()->get_project_theme().is_valid() && ThemeDB::get_singleton()->get_project_theme()->get_type_variation_base(theme_type_variation) != StringName()) {
+			ThemeDB::get_singleton()->get_project_theme()->get_type_dependencies(get_class_name(), theme_type_variation, p_list);
 		} else {
-			Theme::get_default()->get_type_dependencies(get_class_name(), theme_type_variation, p_list);
+			ThemeDB::get_singleton()->get_default_theme()->get_type_dependencies(get_class_name(), theme_type_variation, p_list);
 		}
 	} else {
-		Theme::get_default()->get_type_dependencies(p_theme_type, StringName(), p_list);
+		ThemeDB::get_singleton()->get_default_theme()->get_type_dependencies(p_theme_type, StringName(), p_list);
 	}
 }
 
@@ -1522,9 +1523,9 @@ void Window::_validate_property(PropertyInfo &p_property) const {
 
 		// Only the default theme and the project theme are used for the list of options.
 		// This is an imposed limitation to simplify the logic needed to leverage those options.
-		Theme::get_default()->get_type_variation_list(get_class_name(), &names);
-		if (Theme::get_project_default().is_valid()) {
-			Theme::get_project_default()->get_type_variation_list(get_class_name(), &names);
+		ThemeDB::get_singleton()->get_default_theme()->get_type_variation_list(get_class_name(), &names);
+		if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
+			ThemeDB::get_singleton()->get_project_theme()->get_type_variation_list(get_class_name(), &names);
 		}
 		names.sort_custom<StringName::AlphCompare>();
 
diff --git a/scene/register_scene_types.cpp b/scene/register_scene_types.cpp
index 9665873dce..6bfb1907a2 100644
--- a/scene/register_scene_types.cpp
+++ b/scene/register_scene_types.cpp
@@ -193,12 +193,14 @@
 #include "scene/resources/sky.h"
 #include "scene/resources/sky_material.h"
 #include "scene/resources/sphere_shape_3d.h"
+#include "scene/resources/style_box.h"
 #include "scene/resources/surface_tool.h"
 #include "scene/resources/syntax_highlighter.h"
 #include "scene/resources/text_file.h"
 #include "scene/resources/text_line.h"
 #include "scene/resources/text_paragraph.h"
 #include "scene/resources/texture.h"
+#include "scene/resources/theme.h"
 #include "scene/resources/tile_set.h"
 #include "scene/resources/video_stream.h"
 #include "scene/resources/visual_shader.h"
@@ -210,6 +212,7 @@
 #include "scene/resources/world_boundary_shape_2d.h"
 #include "scene/resources/world_boundary_shape_3d.h"
 #include "scene/scene_string_names.h"
+#include "scene/theme/theme_db.h"
 
 #include "scene/main/shader_globals_override.h"
 
@@ -1122,62 +1125,8 @@ void register_scene_types() {
 	SceneDebugger::initialize();
 }
 
-void initialize_theme() {
-	// Allow creating the default theme at a different scale to suit higher/lower base resolutions.
-	float default_theme_scale = GLOBAL_DEF("gui/theme/default_theme_scale", 1.0);
-	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/default_theme_scale", PropertyInfo(Variant::FLOAT, "gui/theme/default_theme_scale", PROPERTY_HINT_RANGE, "0.5,8,0.01", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
-
-	String theme_path = GLOBAL_DEF_RST("gui/theme/custom", "");
-	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/custom", PropertyInfo(Variant::STRING, "gui/theme/custom", PROPERTY_HINT_FILE, "*.tres,*.res,*.theme", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
-
-	String font_path = GLOBAL_DEF_RST("gui/theme/custom_font", "");
-	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/custom_font", PropertyInfo(Variant::STRING, "gui/theme/custom_font", PROPERTY_HINT_FILE, "*.tres,*.res", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
-
-	TextServer::FontAntialiasing font_antialiasing = (TextServer::FontAntialiasing)(int)GLOBAL_DEF_RST("gui/theme/default_font_antialiasing", 1);
-	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/default_font_antialiasing", PropertyInfo(Variant::INT, "gui/theme/default_font_antialiasing", PROPERTY_HINT_ENUM, "None,Grayscale,LCD sub-pixel", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
-
-	TextServer::Hinting font_hinting = (TextServer::Hinting)(int)GLOBAL_DEF_RST("gui/theme/default_font_hinting", TextServer::HINTING_LIGHT);
-	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/default_font_hinting", PropertyInfo(Variant::INT, "gui/theme/default_font_hinting", PROPERTY_HINT_ENUM, "None,Light,Normal", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
-
-	TextServer::SubpixelPositioning font_subpixel_positioning = (TextServer::SubpixelPositioning)(int)GLOBAL_DEF_RST("gui/theme/default_font_subpixel_positioning", TextServer::SUBPIXEL_POSITIONING_AUTO);
-	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/default_font_subpixel_positioning", PropertyInfo(Variant::INT, "gui/theme/default_font_subpixel_positioning", PROPERTY_HINT_ENUM, "Disabled,Auto,One half of a pixel,One quarter of a pixel", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
-
-	const bool font_msdf = GLOBAL_DEF_RST("gui/theme/default_font_multichannel_signed_distance_field", false);
-	const bool font_generate_mipmaps = GLOBAL_DEF_RST("gui/theme/default_font_generate_mipmaps", false);
-
-	GLOBAL_DEF_RST("gui/theme/lcd_subpixel_layout", 1);
-	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/lcd_subpixel_layout", PropertyInfo(Variant::INT, "gui/theme/lcd_subpixel_layout", PROPERTY_HINT_ENUM, "Disabled,Horizontal RGB,Horizontal BGR,Vertical RGB,Vertical BGR"));
-	ProjectSettings::get_singleton()->set_restart_if_changed("gui/theme/lcd_subpixel_layout", false);
-
-	Ref<Font> font;
-	if (!font_path.is_empty()) {
-		font = ResourceLoader::load(font_path);
-		if (!font.is_valid()) {
-			ERR_PRINT("Error loading custom font '" + font_path + "'");
-		}
-	}
-
-	// Always make the default theme to avoid invalid default font/icon/style in the given theme.
-	if (RenderingServer::get_singleton()) {
-		make_default_theme(default_theme_scale, font, font_subpixel_positioning, font_hinting, font_antialiasing, font_msdf, font_generate_mipmaps);
-	}
-
-	if (!theme_path.is_empty()) {
-		Ref<Theme> theme = ResourceLoader::load(theme_path);
-		if (theme.is_valid()) {
-			Theme::set_project_default(theme);
-			if (font.is_valid()) {
-				Theme::set_fallback_font(font);
-			}
-		} else {
-			ERR_PRINT("Error loading custom theme '" + theme_path + "'");
-		}
-	}
-}
-
 void unregister_scene_types() {
 	SceneDebugger::deinitialize();
-	clear_default_theme();
 
 	ResourceLoader::remove_resource_format_loader(resource_loader_texture_layered);
 	resource_loader_texture_layered.unref();
@@ -1219,3 +1168,9 @@ void unregister_scene_types() {
 	ColorPicker::finish_shaders();
 	SceneStringNames::free();
 }
+
+void register_scene_singletons() {
+	GDREGISTER_CLASS(ThemeDB);
+
+	Engine::get_singleton()->add_singleton(Engine::Singleton("ThemeDB", ThemeDB::get_singleton()));
+}
diff --git a/scene/register_scene_types.h b/scene/register_scene_types.h
index dce8713976..cb3249c5d7 100644
--- a/scene/register_scene_types.h
+++ b/scene/register_scene_types.h
@@ -33,7 +33,6 @@
 
 void register_scene_types();
 void unregister_scene_types();
-
-void initialize_theme();
+void register_scene_singletons();
 
 #endif // REGISTER_SCENE_TYPES_H
diff --git a/scene/resources/default_theme/default_theme.cpp b/scene/resources/default_theme/default_theme.cpp
index 5bfa1adfe5..410f35e597 100644
--- a/scene/resources/default_theme/default_theme.cpp
+++ b/scene/resources/default_theme/default_theme.cpp
@@ -35,6 +35,7 @@
 #include "default_theme_icons.gen.h"
 #include "scene/resources/font.h"
 #include "scene/resources/theme.h"
+#include "scene/theme/theme_db.h"
 #include "servers/text_server.h"
 
 #include "modules/modules_enabled.gen.h" // For svg.
@@ -1101,18 +1102,11 @@ void make_default_theme(float p_scale, Ref<Font> p_font, TextServer::SubpixelPos
 
 	fill_default_theme(t, default_font, bold_font, bold_italics_font, italics_font, default_icon, default_style, default_scale);
 
-	Theme::set_default(t);
-	Theme::set_fallback_base_scale(default_scale);
-	Theme::set_fallback_icon(default_icon);
-	Theme::set_fallback_style(default_style);
-	Theme::set_fallback_font(default_font);
-	Theme::set_fallback_font_size(default_font_size * default_scale);
-}
+	ThemeDB::get_singleton()->set_default_theme(t);
 
-void clear_default_theme() {
-	Theme::set_project_default(nullptr);
-	Theme::set_default(nullptr);
-	Theme::set_fallback_icon(nullptr);
-	Theme::set_fallback_style(nullptr);
-	Theme::set_fallback_font(nullptr);
+	ThemeDB::get_singleton()->set_fallback_base_scale(default_scale);
+	ThemeDB::get_singleton()->set_fallback_icon(default_icon);
+	ThemeDB::get_singleton()->set_fallback_stylebox(default_style);
+	ThemeDB::get_singleton()->set_fallback_font(default_font);
+	ThemeDB::get_singleton()->set_fallback_font_size(default_font_size * default_scale);
 }
diff --git a/scene/resources/default_theme/default_theme.h b/scene/resources/default_theme/default_theme.h
index 15be5e676f..003934ce90 100644
--- a/scene/resources/default_theme/default_theme.h
+++ b/scene/resources/default_theme/default_theme.h
@@ -37,6 +37,5 @@ const int default_font_size = 16;
 
 void fill_default_theme(Ref<Theme> &theme, const Ref<Font> &default_font, const Ref<Font> &bold_font, const Ref<Font> &bold_italics_font, const Ref<Font> &italics_font, Ref<Texture2D> &default_icon, Ref<StyleBox> &default_style, float p_scale);
 void make_default_theme(float p_scale, Ref<Font> p_font, TextServer::SubpixelPositioning p_font_subpixel = TextServer::SUBPIXEL_POSITIONING_AUTO, TextServer::Hinting p_font_hinting = TextServer::HINTING_LIGHT, TextServer::FontAntialiasing p_font_antialiased = TextServer::FONT_ANTIALIASING_GRAY, bool p_font_msdf = false, bool p_font_generate_mipmaps = false);
-void clear_default_theme();
 
 #endif // DEFAULT_THEME_H
diff --git a/scene/resources/font.cpp b/scene/resources/font.cpp
index be57d9c965..8ec5678f0a 100644
--- a/scene/resources/font.cpp
+++ b/scene/resources/font.cpp
@@ -39,6 +39,7 @@
 #include "scene/resources/text_line.h"
 #include "scene/resources/text_paragraph.h"
 #include "scene/resources/theme.h"
+#include "scene/theme/theme_db.h"
 
 /*************************************************************************/
 /*  Font                                                                 */
@@ -2552,13 +2553,13 @@ Ref<Font> FontVariation::_get_base_font_or_default() const {
 	}
 
 	// Check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
 		List<StringName> theme_types;
-		Theme::get_project_default()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
+		ThemeDB::get_singleton()->get_project_theme()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
 
 		for (const StringName &E : theme_types) {
-			if (Theme::get_project_default()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
-				Ref<Font> f = Theme::get_project_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
+			if (ThemeDB::get_singleton()->get_project_theme()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
+				Ref<Font> f = ThemeDB::get_singleton()->get_project_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
 				if (f.is_valid()) {
 					theme_font = f;
 					theme_font->connect(CoreStringNames::get_singleton()->changed, callable_mp(reinterpret_cast<Font *>(const_cast<FontVariation *>(this)), &Font::_invalidate_rids), CONNECT_REFERENCE_COUNTED);
@@ -2569,13 +2570,13 @@ Ref<Font> FontVariation::_get_base_font_or_default() const {
 	}
 
 	// Lastly, fall back on the items defined in the default Theme, if they exist.
-	if (Theme::get_default().is_valid()) {
+	if (ThemeDB::get_singleton()->get_default_theme().is_valid()) {
 		List<StringName> theme_types;
-		Theme::get_default()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
+		ThemeDB::get_singleton()->get_default_theme()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
 
 		for (const StringName &E : theme_types) {
-			if (Theme::get_default()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
-				Ref<Font> f = Theme::get_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
+			if (ThemeDB::get_singleton()->get_default_theme()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
+				Ref<Font> f = ThemeDB::get_singleton()->get_default_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
 				if (f.is_valid()) {
 					theme_font = f;
 					theme_font->connect(CoreStringNames::get_singleton()->changed, callable_mp(reinterpret_cast<Font *>(const_cast<FontVariation *>(this)), &Font::_invalidate_rids), CONNECT_REFERENCE_COUNTED);
@@ -2585,7 +2586,7 @@ Ref<Font> FontVariation::_get_base_font_or_default() const {
 		}
 
 		// If they don't exist, use any type to return the default/empty value.
-		Ref<Font> f = Theme::get_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", StringName());
+		Ref<Font> f = ThemeDB::get_singleton()->get_default_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", StringName());
 		if (f.is_valid()) {
 			theme_font = f;
 			theme_font->connect(CoreStringNames::get_singleton()->changed, callable_mp(reinterpret_cast<Font *>(const_cast<FontVariation *>(this)), &Font::_invalidate_rids), CONNECT_REFERENCE_COUNTED);
@@ -2859,13 +2860,13 @@ Ref<Font> SystemFont::_get_base_font_or_default() const {
 	}
 
 	// Check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
 		List<StringName> theme_types;
-		Theme::get_project_default()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
+		ThemeDB::get_singleton()->get_project_theme()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
 
 		for (const StringName &E : theme_types) {
-			if (Theme::get_project_default()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
-				Ref<Font> f = Theme::get_project_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
+			if (ThemeDB::get_singleton()->get_project_theme()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
+				Ref<Font> f = ThemeDB::get_singleton()->get_project_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
 				if (f.is_valid()) {
 					theme_font = f;
 					theme_font->connect(CoreStringNames::get_singleton()->changed, callable_mp(reinterpret_cast<Font *>(const_cast<SystemFont *>(this)), &Font::_invalidate_rids), CONNECT_REFERENCE_COUNTED);
@@ -2876,13 +2877,13 @@ Ref<Font> SystemFont::_get_base_font_or_default() const {
 	}
 
 	// Lastly, fall back on the items defined in the default Theme, if they exist.
-	if (Theme::get_default().is_valid()) {
+	if (ThemeDB::get_singleton()->get_default_theme().is_valid()) {
 		List<StringName> theme_types;
-		Theme::get_default()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
+		ThemeDB::get_singleton()->get_default_theme()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
 
 		for (const StringName &E : theme_types) {
-			if (Theme::get_default()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
-				Ref<Font> f = Theme::get_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
+			if (ThemeDB::get_singleton()->get_default_theme()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
+				Ref<Font> f = ThemeDB::get_singleton()->get_default_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
 				if (f.is_valid()) {
 					theme_font = f;
 					theme_font->connect(CoreStringNames::get_singleton()->changed, callable_mp(reinterpret_cast<Font *>(const_cast<SystemFont *>(this)), &Font::_invalidate_rids), CONNECT_REFERENCE_COUNTED);
@@ -2892,7 +2893,7 @@ Ref<Font> SystemFont::_get_base_font_or_default() const {
 		}
 
 		// If they don't exist, use any type to return the default/empty value.
-		Ref<Font> f = Theme::get_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", StringName());
+		Ref<Font> f = ThemeDB::get_singleton()->get_default_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", StringName());
 		if (f.is_valid()) {
 			theme_font = f;
 			theme_font->connect(CoreStringNames::get_singleton()->changed, callable_mp(reinterpret_cast<Font *>(const_cast<SystemFont *>(this)), &Font::_invalidate_rids), CONNECT_REFERENCE_COUNTED);
diff --git a/scene/resources/primitive_meshes.cpp b/scene/resources/primitive_meshes.cpp
index e993936350..fc5cf2a028 100644
--- a/scene/resources/primitive_meshes.cpp
+++ b/scene/resources/primitive_meshes.cpp
@@ -32,6 +32,7 @@
 
 #include "core/core_string_names.h"
 #include "scene/resources/theme.h"
+#include "scene/theme/theme_db.h"
 #include "servers/rendering_server.h"
 #include "thirdparty/misc/clipper.hpp"
 #include "thirdparty/misc/polypartition.h"
@@ -2984,13 +2985,13 @@ Ref<Font> TextMesh::_get_font_or_default() const {
 	}
 
 	// Check the project-defined Theme resource.
-	if (Theme::get_project_default().is_valid()) {
+	if (ThemeDB::get_singleton()->get_project_theme().is_valid()) {
 		List<StringName> theme_types;
-		Theme::get_project_default()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
+		ThemeDB::get_singleton()->get_project_theme()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
 
 		for (const StringName &E : theme_types) {
-			if (Theme::get_project_default()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
-				return Theme::get_project_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
+			if (ThemeDB::get_singleton()->get_project_theme()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
+				return ThemeDB::get_singleton()->get_project_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
 			}
 		}
 	}
@@ -2998,17 +2999,17 @@ Ref<Font> TextMesh::_get_font_or_default() const {
 	// Lastly, fall back on the items defined in the default Theme, if they exist.
 	{
 		List<StringName> theme_types;
-		Theme::get_default()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
+		ThemeDB::get_singleton()->get_default_theme()->get_type_dependencies(get_class_name(), StringName(), &theme_types);
 
 		for (const StringName &E : theme_types) {
-			if (Theme::get_default()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
-				return Theme::get_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
+			if (ThemeDB::get_singleton()->get_default_theme()->has_theme_item(Theme::DATA_TYPE_FONT, "font", E)) {
+				return ThemeDB::get_singleton()->get_default_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", E);
 			}
 		}
 	}
 
 	// If they don't exist, use any type to return the default/empty value.
-	return Theme::get_default()->get_theme_item(Theme::DATA_TYPE_FONT, "font", StringName());
+	return ThemeDB::get_singleton()->get_default_theme()->get_theme_item(Theme::DATA_TYPE_FONT, "font", StringName());
 }
 
 void TextMesh::set_font_size(int p_size) {
diff --git a/scene/resources/theme.cpp b/scene/resources/theme.cpp
index 3f6eec8497..3321392821 100644
--- a/scene/resources/theme.cpp
+++ b/scene/resources/theme.cpp
@@ -31,17 +31,7 @@
 #include "theme.h"
 
 #include "core/string/print_string.h"
-
-// Universal Theme resources used when no other theme has the item.
-Ref<Theme> Theme::default_theme;
-Ref<Theme> Theme::project_default_theme;
-
-// Universal default values, final fallback for every theme.
-float Theme::fallback_base_scale = 1.0;
-Ref<Texture2D> Theme::fallback_icon;
-Ref<StyleBox> Theme::fallback_style;
-Ref<Font> Theme::fallback_font;
-int Theme::fallback_font_size = 16;
+#include "scene/theme/theme_db.h"
 
 // Dynamic properties.
 bool Theme::_set(const StringName &p_name, const Variant &p_value) {
@@ -185,64 +175,7 @@ void Theme::_get_property_list(List<PropertyInfo> *p_list) const {
 	}
 }
 
-// Universal fallback Theme resources.
-Ref<Theme> Theme::get_default() {
-	return default_theme;
-}
-
-void Theme::set_default(const Ref<Theme> &p_default) {
-	default_theme = p_default;
-}
-
-Ref<Theme> Theme::get_project_default() {
-	return project_default_theme;
-}
-
-void Theme::set_project_default(const Ref<Theme> &p_project_default) {
-	project_default_theme = p_project_default;
-}
-
-// Universal fallback values for theme item types.
-void Theme::set_fallback_base_scale(float p_base_scale) {
-	fallback_base_scale = p_base_scale;
-}
-
-void Theme::set_fallback_icon(const Ref<Texture2D> &p_icon) {
-	fallback_icon = p_icon;
-}
-
-void Theme::set_fallback_style(const Ref<StyleBox> &p_style) {
-	fallback_style = p_style;
-}
-
-void Theme::set_fallback_font(const Ref<Font> &p_font) {
-	fallback_font = p_font;
-}
-
-void Theme::set_fallback_font_size(int p_font_size) {
-	fallback_font_size = p_font_size;
-}
-
-float Theme::get_fallback_base_scale() {
-	return fallback_base_scale;
-}
-
-Ref<Texture2D> Theme::get_fallback_icon() {
-	return fallback_icon;
-}
-
-Ref<StyleBox> Theme::get_fallback_style() {
-	return fallback_style;
-}
-
-Ref<Font> Theme::get_fallback_font() {
-	return fallback_font;
-}
-
-int Theme::get_fallback_font_size() {
-	return fallback_font_size;
-}
-
+// Static helpers.
 bool Theme::is_valid_type_name(const String &p_name) {
 	for (int i = 0; i < p_name.length(); i++) {
 		if (!is_ascii_identifier_char(p_name[i])) {
@@ -351,7 +284,7 @@ Ref<Texture2D> Theme::get_icon(const StringName &p_name, const StringName &p_the
 	if (icon_map.has(p_theme_type) && icon_map[p_theme_type].has(p_name) && icon_map[p_theme_type][p_name].is_valid()) {
 		return icon_map[p_theme_type][p_name];
 	} else {
-		return fallback_icon;
+		return ThemeDB::get_singleton()->get_fallback_icon();
 	}
 }
 
@@ -461,7 +394,7 @@ Ref<StyleBox> Theme::get_stylebox(const StringName &p_name, const StringName &p_
 	if (style_map.has(p_theme_type) && style_map[p_theme_type].has(p_name) && style_map[p_theme_type][p_name].is_valid()) {
 		return style_map[p_theme_type][p_name];
 	} else {
-		return fallback_style;
+		return ThemeDB::get_singleton()->get_fallback_stylebox();
 	}
 }
 
@@ -573,7 +506,7 @@ Ref<Font> Theme::get_font(const StringName &p_name, const StringName &p_theme_ty
 	} else if (has_default_font()) {
 		return default_font;
 	} else {
-		return fallback_font;
+		return ThemeDB::get_singleton()->get_fallback_font();
 	}
 }
 
@@ -676,7 +609,7 @@ int Theme::get_font_size(const StringName &p_name, const StringName &p_theme_typ
 	} else if (has_default_font_size()) {
 		return default_font_size;
 	} else {
-		return fallback_font_size;
+		return ThemeDB::get_singleton()->get_fallback_font_size();
 	}
 }
 
diff --git a/scene/resources/theme.h b/scene/resources/theme.h
index a2aca5e61f..ed1dc7c938 100644
--- a/scene/resources/theme.h
+++ b/scene/resources/theme.h
@@ -102,17 +102,6 @@ protected:
 	bool _get(const StringName &p_name, Variant &r_ret) const;
 	void _get_property_list(List<PropertyInfo> *p_list) const;
 
-	// Universal Theme resources used when no other theme has the item.
-	static Ref<Theme> default_theme;
-	static Ref<Theme> project_default_theme;
-
-	// Universal default values, final fallback for every theme.
-	static float fallback_base_scale;
-	static Ref<Texture2D> fallback_icon;
-	static Ref<StyleBox> fallback_style;
-	static Ref<Font> fallback_font;
-	static int fallback_font_size;
-
 	// Default values configurable for each individual theme.
 	float default_base_scale = 0.0;
 	Ref<Font> default_font;
@@ -126,24 +115,6 @@ protected:
 	virtual void reset_state() override;
 
 public:
-	static Ref<Theme> get_default();
-	static void set_default(const Ref<Theme> &p_default);
-
-	static Ref<Theme> get_project_default();
-	static void set_project_default(const Ref<Theme> &p_project_default);
-
-	static void set_fallback_base_scale(float p_base_scale);
-	static void set_fallback_icon(const Ref<Texture2D> &p_icon);
-	static void set_fallback_style(const Ref<StyleBox> &p_style);
-	static void set_fallback_font(const Ref<Font> &p_font);
-	static void set_fallback_font_size(int p_font_size);
-
-	static float get_fallback_base_scale();
-	static Ref<Texture2D> get_fallback_icon();
-	static Ref<StyleBox> get_fallback_style();
-	static Ref<Font> get_fallback_font();
-	static int get_fallback_font_size();
-
 	static bool is_valid_type_name(const String &p_name);
 	static bool is_valid_item_name(const String &p_name);
 
diff --git a/scene/theme/SCsub b/scene/theme/SCsub
new file mode 100644
index 0000000000..fc61250247
--- /dev/null
+++ b/scene/theme/SCsub
@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+
+Import("env")
+
+env.add_source_files(env.scene_sources, "*.cpp")
diff --git a/scene/theme/theme_db.cpp b/scene/theme/theme_db.cpp
new file mode 100644
index 0000000000..d6e892cd93
--- /dev/null
+++ b/scene/theme/theme_db.cpp
@@ -0,0 +1,237 @@
+/*************************************************************************/
+/*  theme_db.cpp                                                         */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "theme_db.h"
+
+#include "core/config/project_settings.h"
+#include "core/io/resource_loader.h"
+#include "scene/resources/default_theme/default_theme.h"
+#include "scene/resources/font.h"
+#include "scene/resources/style_box.h"
+#include "scene/resources/texture.h"
+#include "scene/resources/theme.h"
+#include "servers/text_server.h"
+
+// Default engine theme creation and configuration.
+void ThemeDB::initialize_theme() {
+	// Allow creating the default theme at a different scale to suit higher/lower base resolutions.
+	float default_theme_scale = GLOBAL_DEF("gui/theme/default_theme_scale", 1.0);
+	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/default_theme_scale", PropertyInfo(Variant::FLOAT, "gui/theme/default_theme_scale", PROPERTY_HINT_RANGE, "0.5,8,0.01", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
+
+	String theme_path = GLOBAL_DEF_RST("gui/theme/custom", "");
+	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/custom", PropertyInfo(Variant::STRING, "gui/theme/custom", PROPERTY_HINT_FILE, "*.tres,*.res,*.theme", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
+
+	String font_path = GLOBAL_DEF_RST("gui/theme/custom_font", "");
+	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/custom_font", PropertyInfo(Variant::STRING, "gui/theme/custom_font", PROPERTY_HINT_FILE, "*.tres,*.res", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
+
+	TextServer::FontAntialiasing font_antialiasing = (TextServer::FontAntialiasing)(int)GLOBAL_DEF_RST("gui/theme/default_font_antialiasing", 1);
+	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/default_font_antialiasing", PropertyInfo(Variant::INT, "gui/theme/default_font_antialiasing", PROPERTY_HINT_ENUM, "None,Grayscale,LCD sub-pixel", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
+
+	TextServer::Hinting font_hinting = (TextServer::Hinting)(int)GLOBAL_DEF_RST("gui/theme/default_font_hinting", TextServer::HINTING_LIGHT);
+	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/default_font_hinting", PropertyInfo(Variant::INT, "gui/theme/default_font_hinting", PROPERTY_HINT_ENUM, "None,Light,Normal", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
+
+	TextServer::SubpixelPositioning font_subpixel_positioning = (TextServer::SubpixelPositioning)(int)GLOBAL_DEF_RST("gui/theme/default_font_subpixel_positioning", TextServer::SUBPIXEL_POSITIONING_AUTO);
+	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/default_font_subpixel_positioning", PropertyInfo(Variant::INT, "gui/theme/default_font_subpixel_positioning", PROPERTY_HINT_ENUM, "Disabled,Auto,One half of a pixel,One quarter of a pixel", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED));
+
+	const bool font_msdf = GLOBAL_DEF_RST("gui/theme/default_font_multichannel_signed_distance_field", false);
+	const bool font_generate_mipmaps = GLOBAL_DEF_RST("gui/theme/default_font_generate_mipmaps", false);
+
+	GLOBAL_DEF_RST("gui/theme/lcd_subpixel_layout", 1);
+	ProjectSettings::get_singleton()->set_custom_property_info("gui/theme/lcd_subpixel_layout", PropertyInfo(Variant::INT, "gui/theme/lcd_subpixel_layout", PROPERTY_HINT_ENUM, "Disabled,Horizontal RGB,Horizontal BGR,Vertical RGB,Vertical BGR"));
+	ProjectSettings::get_singleton()->set_restart_if_changed("gui/theme/lcd_subpixel_layout", false);
+
+	Ref<Font> font;
+	if (!font_path.is_empty()) {
+		font = ResourceLoader::load(font_path);
+		if (!font.is_valid()) {
+			ERR_PRINT("Error loading custom font '" + font_path + "'");
+		}
+	}
+
+	// Always make the default theme to avoid invalid default font/icon/style in the given theme.
+	if (RenderingServer::get_singleton()) {
+		make_default_theme(default_theme_scale, font, font_subpixel_positioning, font_hinting, font_antialiasing, font_msdf, font_generate_mipmaps);
+	}
+
+	if (!theme_path.is_empty()) {
+		Ref<Theme> theme = ResourceLoader::load(theme_path);
+		if (theme.is_valid()) {
+			set_project_theme(theme);
+			if (font.is_valid()) {
+				set_fallback_font(font);
+			}
+		} else {
+			ERR_PRINT("Error loading custom theme '" + theme_path + "'");
+		}
+	}
+}
+
+void ThemeDB::initialize_theme_noproject() {
+	if (RenderingServer::get_singleton()) {
+		make_default_theme(1.0, Ref<Font>());
+	}
+}
+
+// Universal fallback Theme resources.
+
+void ThemeDB::set_default_theme(const Ref<Theme> &p_default) {
+	default_theme = p_default;
+}
+
+Ref<Theme> ThemeDB::get_default_theme() {
+	return default_theme;
+}
+
+void ThemeDB::set_project_theme(const Ref<Theme> &p_project_default) {
+	project_theme = p_project_default;
+}
+
+Ref<Theme> ThemeDB::get_project_theme() {
+	return project_theme;
+}
+
+// Universal fallback values for theme item types.
+
+void ThemeDB::set_fallback_base_scale(float p_base_scale) {
+	if (fallback_base_scale == p_base_scale) {
+		return;
+	}
+
+	fallback_base_scale = p_base_scale;
+	emit_signal(SNAME("fallback_changed"));
+}
+
+float ThemeDB::get_fallback_base_scale() {
+	return fallback_base_scale;
+}
+
+void ThemeDB::set_fallback_font(const Ref<Font> &p_font) {
+	if (fallback_font == p_font) {
+		return;
+	}
+
+	fallback_font = p_font;
+	emit_signal(SNAME("fallback_changed"));
+}
+
+Ref<Font> ThemeDB::get_fallback_font() {
+	return fallback_font;
+}
+
+void ThemeDB::set_fallback_font_size(int p_font_size) {
+	if (fallback_font_size == p_font_size) {
+		return;
+	}
+
+	fallback_font_size = p_font_size;
+	emit_signal(SNAME("fallback_changed"));
+}
+
+int ThemeDB::get_fallback_font_size() {
+	return fallback_font_size;
+}
+
+void ThemeDB::set_fallback_icon(const Ref<Texture2D> &p_icon) {
+	if (fallback_icon == p_icon) {
+		return;
+	}
+
+	fallback_icon = p_icon;
+	emit_signal(SNAME("fallback_changed"));
+}
+
+Ref<Texture2D> ThemeDB::get_fallback_icon() {
+	return fallback_icon;
+}
+
+void ThemeDB::set_fallback_stylebox(const Ref<StyleBox> &p_stylebox) {
+	if (fallback_stylebox == p_stylebox) {
+		return;
+	}
+
+	fallback_stylebox = p_stylebox;
+	emit_signal(SNAME("fallback_changed"));
+}
+
+Ref<StyleBox> ThemeDB::get_fallback_stylebox() {
+	return fallback_stylebox;
+}
+
+// Object methods.
+void ThemeDB::_bind_methods() {
+	ClassDB::bind_method(D_METHOD("get_default_theme"), &ThemeDB::get_default_theme);
+	ClassDB::bind_method(D_METHOD("get_project_theme"), &ThemeDB::get_project_theme);
+
+	ClassDB::bind_method(D_METHOD("set_fallback_base_scale", "base_scale"), &ThemeDB::set_fallback_base_scale);
+	ClassDB::bind_method(D_METHOD("get_fallback_base_scale"), &ThemeDB::get_fallback_base_scale);
+	ClassDB::bind_method(D_METHOD("set_fallback_font", "font"), &ThemeDB::set_fallback_font);
+	ClassDB::bind_method(D_METHOD("get_fallback_font"), &ThemeDB::get_fallback_font);
+	ClassDB::bind_method(D_METHOD("set_fallback_font_size", "font_size"), &ThemeDB::set_fallback_font_size);
+	ClassDB::bind_method(D_METHOD("get_fallback_font_size"), &ThemeDB::get_fallback_font_size);
+	ClassDB::bind_method(D_METHOD("set_fallback_icon", "icon"), &ThemeDB::set_fallback_icon);
+	ClassDB::bind_method(D_METHOD("get_fallback_icon"), &ThemeDB::get_fallback_icon);
+	ClassDB::bind_method(D_METHOD("set_fallback_stylebox", "stylebox"), &ThemeDB::set_fallback_stylebox);
+	ClassDB::bind_method(D_METHOD("get_fallback_stylebox"), &ThemeDB::get_fallback_stylebox);
+
+	ADD_GROUP("Fallback values", "fallback_");
+	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "fallback_base_scale", PROPERTY_HINT_RANGE, "0.0,2.0,0.01,or_greater"), "set_fallback_base_scale", "get_fallback_base_scale");
+	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "fallback_font", PROPERTY_HINT_RESOURCE_TYPE, "Font", PROPERTY_USAGE_NONE), "set_fallback_font", "get_fallback_font");
+	ADD_PROPERTY(PropertyInfo(Variant::INT, "fallback_font_size", PROPERTY_HINT_RANGE, "0,256,1,or_greater,suffix:px"), "set_fallback_font_size", "get_fallback_font_size");
+	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "fallback_icon", PROPERTY_HINT_RESOURCE_TYPE, "Texture2D", PROPERTY_USAGE_NONE), "set_fallback_icon", "get_fallback_icon");
+	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "fallback_stylebox", PROPERTY_HINT_RESOURCE_TYPE, "StyleBox", PROPERTY_USAGE_NONE), "set_fallback_stylebox", "get_fallback_stylebox");
+
+	ADD_SIGNAL(MethodInfo("fallback_changed"));
+}
+
+// Memory management, reference, and initialization
+ThemeDB *ThemeDB::singleton = nullptr;
+
+ThemeDB *ThemeDB::get_singleton() {
+	return singleton;
+}
+
+ThemeDB::ThemeDB() {
+	singleton = this;
+
+	// Universal default values, final fallback for every theme.
+	fallback_base_scale = 1.0;
+	fallback_font_size = 16;
+}
+
+ThemeDB::~ThemeDB() {
+	default_theme.unref();
+	project_theme.unref();
+
+	fallback_font.unref();
+	fallback_icon.unref();
+	fallback_stylebox.unref();
+
+	singleton = nullptr;
+}
diff --git a/scene/theme/theme_db.h b/scene/theme/theme_db.h
new file mode 100644
index 0000000000..aace33d82c
--- /dev/null
+++ b/scene/theme/theme_db.h
@@ -0,0 +1,95 @@
+/*************************************************************************/
+/*  theme_db.h                                                           */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2022 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2022 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef THEME_DB_H
+#define THEME_DB_H
+
+#include "core/object/class_db.h"
+#include "core/object/ref_counted.h"
+
+class Font;
+class StyleBox;
+class Texture2D;
+class Theme;
+
+class ThemeDB : public Object {
+	GDCLASS(ThemeDB, Object);
+
+	static ThemeDB *singleton;
+
+	// Universal Theme resources used when no other theme has the item.
+	Ref<Theme> default_theme;
+	Ref<Theme> project_theme;
+
+	// Universal default values, final fallback for every theme.
+	float fallback_base_scale;
+	Ref<Font> fallback_font;
+	int fallback_font_size;
+	Ref<Texture2D> fallback_icon;
+	Ref<StyleBox> fallback_stylebox;
+
+protected:
+	static void _bind_methods();
+
+public:
+	void initialize_theme();
+	void initialize_theme_noproject();
+
+	// Universal Theme resources
+
+	void set_default_theme(const Ref<Theme> &p_default);
+	Ref<Theme> get_default_theme();
+
+	void set_project_theme(const Ref<Theme> &p_project_default);
+	Ref<Theme> get_project_theme();
+
+	// Universal default values.
+
+	void set_fallback_base_scale(float p_base_scale);
+	float get_fallback_base_scale();
+
+	void set_fallback_font(const Ref<Font> &p_font);
+	Ref<Font> get_fallback_font();
+
+	void set_fallback_font_size(int p_font_size);
+	int get_fallback_font_size();
+
+	void set_fallback_icon(const Ref<Texture2D> &p_icon);
+	Ref<Texture2D> get_fallback_icon();
+
+	void set_fallback_stylebox(const Ref<StyleBox> &p_stylebox);
+	Ref<StyleBox> get_fallback_stylebox();
+
+	static ThemeDB *get_singleton();
+	ThemeDB();
+	~ThemeDB();
+};
+
+#endif // THEME_DB_H