Add utility methods to Theme, improve error messages and documentation

2 files changed, 450 insertions, 22 deletions

diff --git a/scene/resources/theme.cpp b/scene/resources/theme.cpp
index 0405ea98bb..2b173add38 100644
--- a/scene/resources/theme.cpp
+++ b/scene/resources/theme.cpp
@@ -141,6 +141,21 @@ Vector<String> Theme::_get_font_size_list(const String &p_node_type) const {
 	return ilret;
 }
 
+Vector<String> Theme::_get_font_size_type_list() const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_font_size_type_list(&il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
 Vector<String> Theme::_get_color_list(const String &p_node_type) const {
 	Vector<String> ilret;
 	List<StringName> il;
@@ -201,6 +216,48 @@ Vector<String> Theme::_get_constant_type_list() const {
 	return ilret;
 }
 
+Vector<String> Theme::_get_theme_item_list(DataType p_data_type, const String &p_node_type) const {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			return _get_color_list(p_node_type);
+		case DATA_TYPE_CONSTANT:
+			return _get_constant_list(p_node_type);
+		case DATA_TYPE_FONT:
+			return _get_font_list(p_node_type);
+		case DATA_TYPE_FONT_SIZE:
+			return _get_font_size_list(p_node_type);
+		case DATA_TYPE_ICON:
+			return _get_icon_list(p_node_type);
+		case DATA_TYPE_STYLEBOX:
+			return _get_stylebox_list(p_node_type);
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+
+	return Vector<String>();
+}
+
+Vector<String> Theme::_get_theme_item_type_list(DataType p_data_type) const {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			return _get_color_type_list();
+		case DATA_TYPE_CONSTANT:
+			return _get_constant_type_list();
+		case DATA_TYPE_FONT:
+			return _get_font_type_list();
+		case DATA_TYPE_FONT_SIZE:
+			return _get_font_size_type_list();
+		case DATA_TYPE_ICON:
+			return _get_icon_type_list();
+		case DATA_TYPE_STYLEBOX:
+			return _get_stylebox_type_list();
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+
+	return Vector<String>();
+}
+
 Vector<String> Theme::_get_type_list() const {
 	Vector<String> ilret;
 	List<StringName> il;
@@ -421,8 +478,6 @@ void Theme::set_default_font_size(int p_font_size) {
 }
 
 void Theme::set_icon(const StringName &p_name, const StringName &p_node_type, const Ref<Texture2D> &p_icon) {
-	//ERR_FAIL_COND(p_icon.is_null());
-
 	bool new_value = !icon_map.has(p_node_type) || !icon_map[p_node_type].has(p_name);
 
 	if (icon_map[p_node_type].has(p_name) && icon_map[p_node_type][p_name].is_valid()) {
@@ -453,9 +508,21 @@ bool Theme::has_icon(const StringName &p_name, const StringName &p_node_type) co
 	return (icon_map.has(p_node_type) && icon_map[p_node_type].has(p_name) && icon_map[p_node_type][p_name].is_valid());
 }
 
+void Theme::rename_icon(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type) {
+	ERR_FAIL_COND_MSG(!icon_map.has(p_node_type), "Cannot rename the icon '" + String(p_old_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(icon_map[p_node_type].has(p_name), "Cannot rename the icon '" + String(p_old_name) + "' because the new name '" + String(p_name) + "' already exists.");
+	ERR_FAIL_COND_MSG(!icon_map[p_node_type].has(p_old_name), "Cannot rename the icon '" + String(p_old_name) + "' because it does not exist.");
+
+	icon_map[p_node_type][p_name] = icon_map[p_node_type][p_old_name];
+	icon_map[p_node_type].erase(p_old_name);
+
+	notify_property_list_changed();
+	emit_changed();
+}
+
 void Theme::clear_icon(const StringName &p_name, const StringName &p_node_type) {
-	ERR_FAIL_COND(!icon_map.has(p_node_type));
-	ERR_FAIL_COND(!icon_map[p_node_type].has(p_name));
+	ERR_FAIL_COND_MSG(!icon_map.has(p_node_type), "Cannot clear the icon '" + String(p_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(!icon_map[p_node_type].has(p_name), "Cannot clear the icon '" + String(p_name) + "' because it does not exist.");
 
 	if (icon_map[p_node_type][p_name].is_valid()) {
 		icon_map[p_node_type][p_name]->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
@@ -481,6 +548,10 @@ void Theme::get_icon_list(StringName p_node_type, List<StringName> *p_list) cons
 	}
 }
 
+void Theme::add_icon_type(const StringName &p_node_type) {
+	icon_map[p_node_type] = HashMap<StringName, Ref<Texture2D>>();
+}
+
 void Theme::get_icon_type_list(List<StringName> *p_list) const {
 	ERR_FAIL_NULL(p_list);
 
@@ -491,8 +562,6 @@ void Theme::get_icon_type_list(List<StringName> *p_list) const {
 }
 
 void Theme::set_stylebox(const StringName &p_name, const StringName &p_node_type, const Ref<StyleBox> &p_style) {
-	//ERR_FAIL_COND(p_style.is_null());
-
 	bool new_value = !style_map.has(p_node_type) || !style_map[p_node_type].has(p_name);
 
 	if (style_map[p_node_type].has(p_name) && style_map[p_node_type][p_name].is_valid()) {
@@ -523,9 +592,21 @@ bool Theme::has_stylebox(const StringName &p_name, const StringName &p_node_type
 	return (style_map.has(p_node_type) && style_map[p_node_type].has(p_name) && style_map[p_node_type][p_name].is_valid());
 }
 
+void Theme::rename_stylebox(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type) {
+	ERR_FAIL_COND_MSG(!style_map.has(p_node_type), "Cannot rename the stylebox '" + String(p_old_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(style_map[p_node_type].has(p_name), "Cannot rename the stylebox '" + String(p_old_name) + "' because the new name '" + String(p_name) + "' already exists.");
+	ERR_FAIL_COND_MSG(!style_map[p_node_type].has(p_old_name), "Cannot rename the stylebox '" + String(p_old_name) + "' because it does not exist.");
+
+	style_map[p_node_type][p_name] = style_map[p_node_type][p_old_name];
+	style_map[p_node_type].erase(p_old_name);
+
+	notify_property_list_changed();
+	emit_changed();
+}
+
 void Theme::clear_stylebox(const StringName &p_name, const StringName &p_node_type) {
-	ERR_FAIL_COND(!style_map.has(p_node_type));
-	ERR_FAIL_COND(!style_map[p_node_type].has(p_name));
+	ERR_FAIL_COND_MSG(!style_map.has(p_node_type), "Cannot clear the stylebox '" + String(p_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(!style_map[p_node_type].has(p_name), "Cannot clear the stylebox '" + String(p_name) + "' because it does not exist.");
 
 	if (style_map[p_node_type][p_name].is_valid()) {
 		style_map[p_node_type][p_name]->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
@@ -551,6 +632,10 @@ void Theme::get_stylebox_list(StringName p_node_type, List<StringName> *p_list)
 	}
 }
 
+void Theme::add_stylebox_type(const StringName &p_node_type) {
+	style_map[p_node_type] = HashMap<StringName, Ref<StyleBox>>();
+}
+
 void Theme::get_stylebox_type_list(List<StringName> *p_list) const {
 	ERR_FAIL_NULL(p_list);
 
@@ -561,8 +646,6 @@ void Theme::get_stylebox_type_list(List<StringName> *p_list) const {
 }
 
 void Theme::set_font(const StringName &p_name, const StringName &p_node_type, const Ref<Font> &p_font) {
-	//ERR_FAIL_COND(p_font.is_null());
-
 	bool new_value = !font_map.has(p_node_type) || !font_map[p_node_type].has(p_name);
 
 	if (font_map[p_node_type][p_name].is_valid()) {
@@ -595,9 +678,21 @@ bool Theme::has_font(const StringName &p_name, const StringName &p_node_type) co
 	return ((font_map.has(p_node_type) && font_map[p_node_type].has(p_name) && font_map[p_node_type][p_name].is_valid()) || default_theme_font.is_valid());
 }
 
+void Theme::rename_font(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type) {
+	ERR_FAIL_COND_MSG(!font_map.has(p_node_type), "Cannot rename the font '" + String(p_old_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(font_map[p_node_type].has(p_name), "Cannot rename the font '" + String(p_old_name) + "' because the new name '" + String(p_name) + "' already exists.");
+	ERR_FAIL_COND_MSG(!font_map[p_node_type].has(p_old_name), "Cannot rename the font '" + String(p_old_name) + "' because it does not exist.");
+
+	font_map[p_node_type][p_name] = font_map[p_node_type][p_old_name];
+	font_map[p_node_type].erase(p_old_name);
+
+	notify_property_list_changed();
+	emit_changed();
+}
+
 void Theme::clear_font(const StringName &p_name, const StringName &p_node_type) {
-	ERR_FAIL_COND(!font_map.has(p_node_type));
-	ERR_FAIL_COND(!font_map[p_node_type].has(p_name));
+	ERR_FAIL_COND_MSG(!font_map.has(p_node_type), "Cannot clear the font '" + String(p_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(!font_map[p_node_type].has(p_name), "Cannot clear the font '" + String(p_name) + "' because it does not exist.");
 
 	if (font_map[p_node_type][p_name].is_valid()) {
 		font_map[p_node_type][p_name]->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
@@ -622,6 +717,10 @@ void Theme::get_font_list(StringName p_node_type, List<StringName> *p_list) cons
 	}
 }
 
+void Theme::add_font_type(const StringName &p_node_type) {
+	font_map[p_node_type] = HashMap<StringName, Ref<Font>>();
+}
+
 void Theme::get_font_type_list(List<StringName> *p_list) const {
 	ERR_FAIL_NULL(p_list);
 
@@ -656,9 +755,21 @@ bool Theme::has_font_size(const StringName &p_name, const StringName &p_node_typ
 	return ((font_size_map.has(p_node_type) && font_size_map[p_node_type].has(p_name) && (font_size_map[p_node_type][p_name] > 0)) || (default_theme_font_size > 0));
 }
 
+void Theme::rename_font_size(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type) {
+	ERR_FAIL_COND_MSG(!font_size_map.has(p_node_type), "Cannot rename the font size '" + String(p_old_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(font_size_map[p_node_type].has(p_name), "Cannot rename the font size '" + String(p_old_name) + "' because the new name '" + String(p_name) + "' already exists.");
+	ERR_FAIL_COND_MSG(!font_size_map[p_node_type].has(p_old_name), "Cannot rename the font size '" + String(p_old_name) + "' because it does not exist.");
+
+	font_size_map[p_node_type][p_name] = font_size_map[p_node_type][p_old_name];
+	font_size_map[p_node_type].erase(p_old_name);
+
+	notify_property_list_changed();
+	emit_changed();
+}
+
 void Theme::clear_font_size(const StringName &p_name, const StringName &p_node_type) {
-	ERR_FAIL_COND(!font_size_map.has(p_node_type));
-	ERR_FAIL_COND(!font_size_map[p_node_type].has(p_name));
+	ERR_FAIL_COND_MSG(!font_size_map.has(p_node_type), "Cannot clear the font size '" + String(p_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(!font_size_map[p_node_type].has(p_name), "Cannot clear the font size '" + String(p_name) + "' because it does not exist.");
 
 	font_size_map[p_node_type].erase(p_name);
 	notify_property_list_changed();
@@ -679,6 +790,19 @@ void Theme::get_font_size_list(StringName p_node_type, List<StringName> *p_list)
 	}
 }
 
+void Theme::add_font_size_type(const StringName &p_node_type) {
+	font_size_map[p_node_type] = HashMap<StringName, int>();
+}
+
+void Theme::get_font_size_type_list(List<StringName> *p_list) const {
+	ERR_FAIL_NULL(p_list);
+
+	const StringName *key = nullptr;
+	while ((key = font_size_map.next(key))) {
+		p_list->push_back(*key);
+	}
+}
+
 void Theme::set_color(const StringName &p_name, const StringName &p_node_type, const Color &p_color) {
 	bool new_value = !color_map.has(p_node_type) || !color_map[p_node_type].has(p_name);
 
@@ -702,9 +826,21 @@ bool Theme::has_color(const StringName &p_name, const StringName &p_node_type) c
 	return (color_map.has(p_node_type) && color_map[p_node_type].has(p_name));
 }
 
+void Theme::rename_color(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type) {
+	ERR_FAIL_COND_MSG(!color_map.has(p_node_type), "Cannot rename the color '" + String(p_old_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(color_map[p_node_type].has(p_name), "Cannot rename the color '" + String(p_old_name) + "' because the new name '" + String(p_name) + "' already exists.");
+	ERR_FAIL_COND_MSG(!color_map[p_node_type].has(p_old_name), "Cannot rename the color '" + String(p_old_name) + "' because it does not exist.");
+
+	color_map[p_node_type][p_name] = color_map[p_node_type][p_old_name];
+	color_map[p_node_type].erase(p_old_name);
+
+	notify_property_list_changed();
+	emit_changed();
+}
+
 void Theme::clear_color(const StringName &p_name, const StringName &p_node_type) {
-	ERR_FAIL_COND(!color_map.has(p_node_type));
-	ERR_FAIL_COND(!color_map[p_node_type].has(p_name));
+	ERR_FAIL_COND_MSG(!color_map.has(p_node_type), "Cannot clear the color '" + String(p_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(!color_map[p_node_type].has(p_name), "Cannot clear the color '" + String(p_name) + "' because it does not exist.");
 
 	color_map[p_node_type].erase(p_name);
 	notify_property_list_changed();
@@ -725,6 +861,10 @@ void Theme::get_color_list(StringName p_node_type, List<StringName> *p_list) con
 	}
 }
 
+void Theme::add_color_type(const StringName &p_node_type) {
+	color_map[p_node_type] = HashMap<StringName, Color>();
+}
+
 void Theme::get_color_type_list(List<StringName> *p_list) const {
 	ERR_FAIL_NULL(p_list);
 
@@ -756,9 +896,21 @@ bool Theme::has_constant(const StringName &p_name, const StringName &p_node_type
 	return (constant_map.has(p_node_type) && constant_map[p_node_type].has(p_name));
 }
 
+void Theme::rename_constant(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type) {
+	ERR_FAIL_COND_MSG(!constant_map.has(p_node_type), "Cannot rename the constant '" + String(p_old_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(constant_map[p_node_type].has(p_name), "Cannot rename the constant '" + String(p_old_name) + "' because the new name '" + String(p_name) + "' already exists.");
+	ERR_FAIL_COND_MSG(!constant_map[p_node_type].has(p_old_name), "Cannot rename the constant '" + String(p_old_name) + "' because it does not exist.");
+
+	constant_map[p_node_type][p_name] = constant_map[p_node_type][p_old_name];
+	constant_map[p_node_type].erase(p_old_name);
+
+	notify_property_list_changed();
+	emit_changed();
+}
+
 void Theme::clear_constant(const StringName &p_name, const StringName &p_node_type) {
-	ERR_FAIL_COND(!constant_map.has(p_node_type));
-	ERR_FAIL_COND(!constant_map[p_node_type].has(p_name));
+	ERR_FAIL_COND_MSG(!constant_map.has(p_node_type), "Cannot clear the constant '" + String(p_name) + "' because the node type '" + String(p_node_type) + "' does not exist.");
+	ERR_FAIL_COND_MSG(!constant_map[p_node_type].has(p_name), "Cannot clear the constant '" + String(p_name) + "' because it does not exist.");
 
 	constant_map[p_node_type].erase(p_name);
 	notify_property_list_changed();
@@ -779,6 +931,10 @@ void Theme::get_constant_list(StringName p_node_type, List<StringName> *p_list)
 	}
 }
 
+void Theme::add_constant_type(const StringName &p_node_type) {
+	constant_map[p_node_type] = HashMap<StringName, int>();
+}
+
 void Theme::get_constant_type_list(List<StringName> *p_list) const {
 	ERR_FAIL_NULL(p_list);
 
@@ -788,6 +944,216 @@ void Theme::get_constant_type_list(List<StringName> *p_list) const {
 	}
 }
 
+void Theme::set_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_node_type, const Variant &p_value) {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR: {
+			ERR_FAIL_COND_MSG(p_value.get_type() != Variant::COLOR, "Theme item's data type (Color) does not match Variant's type (" + Variant::get_type_name(p_value.get_type()) + ").");
+
+			Color color_value = p_value;
+			set_color(p_name, p_node_type, color_value);
+		} break;
+		case DATA_TYPE_CONSTANT: {
+			ERR_FAIL_COND_MSG(p_value.get_type() != Variant::INT, "Theme item's data type (int) does not match Variant's type (" + Variant::get_type_name(p_value.get_type()) + ").");
+
+			int constant_value = p_value;
+			set_constant(p_name, p_node_type, constant_value);
+		} break;
+		case DATA_TYPE_FONT: {
+			ERR_FAIL_COND_MSG(p_value.get_type() != Variant::OBJECT, "Theme item's data type (Object) does not match Variant's type (" + Variant::get_type_name(p_value.get_type()) + ").");
+
+			Ref<Font> font_value = Object::cast_to<Font>(p_value.get_validated_object());
+			set_font(p_name, p_node_type, font_value);
+		} break;
+		case DATA_TYPE_FONT_SIZE: {
+			ERR_FAIL_COND_MSG(p_value.get_type() != Variant::INT, "Theme item's data type (int) does not match Variant's type (" + Variant::get_type_name(p_value.get_type()) + ").");
+
+			int font_size_value = p_value;
+			set_font_size(p_name, p_node_type, font_size_value);
+		} break;
+		case DATA_TYPE_ICON: {
+			ERR_FAIL_COND_MSG(p_value.get_type() != Variant::OBJECT, "Theme item's data type (Object) does not match Variant's type (" + Variant::get_type_name(p_value.get_type()) + ").");
+
+			Ref<Texture2D> icon_value = Object::cast_to<Texture2D>(p_value.get_validated_object());
+			set_icon(p_name, p_node_type, icon_value);
+		} break;
+		case DATA_TYPE_STYLEBOX: {
+			ERR_FAIL_COND_MSG(p_value.get_type() != Variant::OBJECT, "Theme item's data type (Object) does not match Variant's type (" + Variant::get_type_name(p_value.get_type()) + ").");
+
+			Ref<StyleBox> stylebox_value = Object::cast_to<StyleBox>(p_value.get_validated_object());
+			set_stylebox(p_name, p_node_type, stylebox_value);
+		} break;
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+}
+
+Variant Theme::get_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_node_type) const {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			return get_color(p_name, p_node_type);
+		case DATA_TYPE_CONSTANT:
+			return get_constant(p_name, p_node_type);
+		case DATA_TYPE_FONT:
+			return get_font(p_name, p_node_type);
+		case DATA_TYPE_FONT_SIZE:
+			return get_font_size(p_name, p_node_type);
+		case DATA_TYPE_ICON:
+			return get_icon(p_name, p_node_type);
+		case DATA_TYPE_STYLEBOX:
+			return get_stylebox(p_name, p_node_type);
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+
+	return Variant();
+}
+
+bool Theme::has_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_node_type) const {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			return has_color(p_name, p_node_type);
+		case DATA_TYPE_CONSTANT:
+			return has_constant(p_name, p_node_type);
+		case DATA_TYPE_FONT:
+			return has_font(p_name, p_node_type);
+		case DATA_TYPE_FONT_SIZE:
+			return has_font_size(p_name, p_node_type);
+		case DATA_TYPE_ICON:
+			return has_icon(p_name, p_node_type);
+		case DATA_TYPE_STYLEBOX:
+			return has_stylebox(p_name, p_node_type);
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+
+	return false;
+}
+
+void Theme::rename_theme_item(DataType p_data_type, const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type) {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			rename_color(p_old_name, p_name, p_node_type);
+			break;
+		case DATA_TYPE_CONSTANT:
+			rename_constant(p_old_name, p_name, p_node_type);
+			break;
+		case DATA_TYPE_FONT:
+			rename_font(p_old_name, p_name, p_node_type);
+			break;
+		case DATA_TYPE_FONT_SIZE:
+			rename_font_size(p_old_name, p_name, p_node_type);
+			break;
+		case DATA_TYPE_ICON:
+			rename_icon(p_old_name, p_name, p_node_type);
+			break;
+		case DATA_TYPE_STYLEBOX:
+			rename_stylebox(p_old_name, p_name, p_node_type);
+			break;
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+}
+
+void Theme::clear_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_node_type) {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			clear_color(p_name, p_node_type);
+			break;
+		case DATA_TYPE_CONSTANT:
+			clear_constant(p_name, p_node_type);
+			break;
+		case DATA_TYPE_FONT:
+			clear_font(p_name, p_node_type);
+			break;
+		case DATA_TYPE_FONT_SIZE:
+			clear_font_size(p_name, p_node_type);
+			break;
+		case DATA_TYPE_ICON:
+			clear_icon(p_name, p_node_type);
+			break;
+		case DATA_TYPE_STYLEBOX:
+			clear_stylebox(p_name, p_node_type);
+			break;
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+}
+
+void Theme::get_theme_item_list(DataType p_data_type, StringName p_node_type, List<StringName> *p_list) const {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			get_color_list(p_node_type, p_list);
+			break;
+		case DATA_TYPE_CONSTANT:
+			get_constant_list(p_node_type, p_list);
+			break;
+		case DATA_TYPE_FONT:
+			get_font_list(p_node_type, p_list);
+			break;
+		case DATA_TYPE_FONT_SIZE:
+			get_font_size_list(p_node_type, p_list);
+			break;
+		case DATA_TYPE_ICON:
+			get_icon_list(p_node_type, p_list);
+			break;
+		case DATA_TYPE_STYLEBOX:
+			get_stylebox_list(p_node_type, p_list);
+			break;
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+}
+
+void Theme::add_theme_item_type(DataType p_data_type, const StringName &p_node_type) {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			add_color_type(p_node_type);
+			break;
+		case DATA_TYPE_CONSTANT:
+			add_constant_type(p_node_type);
+			break;
+		case DATA_TYPE_FONT:
+			add_font_type(p_node_type);
+			break;
+		case DATA_TYPE_FONT_SIZE:
+			add_font_size_type(p_node_type);
+			break;
+		case DATA_TYPE_ICON:
+			add_icon_type(p_node_type);
+			break;
+		case DATA_TYPE_STYLEBOX:
+			add_stylebox_type(p_node_type);
+			break;
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+}
+
+void Theme::get_theme_item_type_list(DataType p_data_type, List<StringName> *p_list) const {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			get_color_type_list(p_list);
+			break;
+		case DATA_TYPE_CONSTANT:
+			get_constant_type_list(p_list);
+			break;
+		case DATA_TYPE_FONT:
+			get_font_type_list(p_list);
+			break;
+		case DATA_TYPE_FONT_SIZE:
+			get_font_size_type_list(p_list);
+			break;
+		case DATA_TYPE_ICON:
+			get_icon_type_list(p_list);
+			break;
+		case DATA_TYPE_STYLEBOX:
+			get_stylebox_type_list(p_list);
+			break;
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+}
+
 void Theme::clear() {
 	//these need disconnecting
 	{
@@ -847,11 +1213,10 @@ void Theme::copy_default_theme() {
 void Theme::copy_theme(const Ref<Theme> &p_other) {
 	if (p_other.is_null()) {
 		clear();
-
 		return;
 	}
 
-	//these need reconnecting, so add normally
+	// These items need reconnecting, so add them normally.
 	{
 		const StringName *K = nullptr;
 		while ((K = p_other->icon_map.next(K))) {
@@ -882,8 +1247,8 @@ void Theme::copy_theme(const Ref<Theme> &p_other) {
 		}
 	}
 
-	//these are ok to just copy
-
+	// These items can be simply copied.
+	font_size_map = p_other->font_size_map;
 	color_map = p_other->color_map;
 	constant_map = p_other->constant_map;
 
@@ -937,6 +1302,7 @@ void Theme::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_icon", "name", "node_type", "texture"), &Theme::set_icon);
 	ClassDB::bind_method(D_METHOD("get_icon", "name", "node_type"), &Theme::get_icon);
 	ClassDB::bind_method(D_METHOD("has_icon", "name", "node_type"), &Theme::has_icon);
+	ClassDB::bind_method(D_METHOD("rename_icon", "old_name", "name", "node_type"), &Theme::rename_icon);
 	ClassDB::bind_method(D_METHOD("clear_icon", "name", "node_type"), &Theme::clear_icon);
 	ClassDB::bind_method(D_METHOD("get_icon_list", "node_type"), &Theme::_get_icon_list);
 	ClassDB::bind_method(D_METHOD("get_icon_type_list"), &Theme::_get_icon_type_list);
@@ -944,6 +1310,7 @@ void Theme::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_stylebox", "name", "node_type", "texture"), &Theme::set_stylebox);
 	ClassDB::bind_method(D_METHOD("get_stylebox", "name", "node_type"), &Theme::get_stylebox);
 	ClassDB::bind_method(D_METHOD("has_stylebox", "name", "node_type"), &Theme::has_stylebox);
+	ClassDB::bind_method(D_METHOD("rename_stylebox", "old_name", "name", "node_type"), &Theme::rename_stylebox);
 	ClassDB::bind_method(D_METHOD("clear_stylebox", "name", "node_type"), &Theme::clear_stylebox);
 	ClassDB::bind_method(D_METHOD("get_stylebox_list", "node_type"), &Theme::_get_stylebox_list);
 	ClassDB::bind_method(D_METHOD("get_stylebox_type_list"), &Theme::_get_stylebox_type_list);
@@ -951,6 +1318,7 @@ void Theme::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_font", "name", "node_type", "font"), &Theme::set_font);
 	ClassDB::bind_method(D_METHOD("get_font", "name", "node_type"), &Theme::get_font);
 	ClassDB::bind_method(D_METHOD("has_font", "name", "node_type"), &Theme::has_font);
+	ClassDB::bind_method(D_METHOD("rename_font", "old_name", "name", "node_type"), &Theme::rename_font);
 	ClassDB::bind_method(D_METHOD("clear_font", "name", "node_type"), &Theme::clear_font);
 	ClassDB::bind_method(D_METHOD("get_font_list", "node_type"), &Theme::_get_font_list);
 	ClassDB::bind_method(D_METHOD("get_font_type_list"), &Theme::_get_font_type_list);
@@ -958,12 +1326,15 @@ void Theme::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_font_size", "name", "node_type", "font_size"), &Theme::set_font_size);
 	ClassDB::bind_method(D_METHOD("get_font_size", "name", "node_type"), &Theme::get_font_size);
 	ClassDB::bind_method(D_METHOD("has_font_size", "name", "node_type"), &Theme::has_font_size);
+	ClassDB::bind_method(D_METHOD("rename_font_size", "old_name", "name", "node_type"), &Theme::rename_font_size);
 	ClassDB::bind_method(D_METHOD("clear_font_size", "name", "node_type"), &Theme::clear_font_size);
 	ClassDB::bind_method(D_METHOD("get_font_size_list", "node_type"), &Theme::_get_font_size_list);
+	ClassDB::bind_method(D_METHOD("get_font_size_type_list"), &Theme::_get_font_size_type_list);
 
 	ClassDB::bind_method(D_METHOD("set_color", "name", "node_type", "color"), &Theme::set_color);
 	ClassDB::bind_method(D_METHOD("get_color", "name", "node_type"), &Theme::get_color);
 	ClassDB::bind_method(D_METHOD("has_color", "name", "node_type"), &Theme::has_color);
+	ClassDB::bind_method(D_METHOD("rename_color", "old_name", "name", "node_type"), &Theme::rename_color);
 	ClassDB::bind_method(D_METHOD("clear_color", "name", "node_type"), &Theme::clear_color);
 	ClassDB::bind_method(D_METHOD("get_color_list", "node_type"), &Theme::_get_color_list);
 	ClassDB::bind_method(D_METHOD("get_color_type_list"), &Theme::_get_color_type_list);
@@ -971,6 +1342,7 @@ void Theme::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_constant", "name", "node_type", "constant"), &Theme::set_constant);
 	ClassDB::bind_method(D_METHOD("get_constant", "name", "node_type"), &Theme::get_constant);
 	ClassDB::bind_method(D_METHOD("has_constant", "name", "node_type"), &Theme::has_constant);
+	ClassDB::bind_method(D_METHOD("rename_constant", "old_name", "name", "node_type"), &Theme::rename_constant);
 	ClassDB::bind_method(D_METHOD("clear_constant", "name", "node_type"), &Theme::clear_constant);
 	ClassDB::bind_method(D_METHOD("get_constant_list", "node_type"), &Theme::_get_constant_list);
 	ClassDB::bind_method(D_METHOD("get_constant_type_list"), &Theme::_get_constant_type_list);
@@ -983,6 +1355,14 @@ void Theme::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("set_default_font_size", "font_size"), &Theme::set_default_theme_font_size);
 	ClassDB::bind_method(D_METHOD("get_default_font_size"), &Theme::get_default_theme_font_size);
 
+	ClassDB::bind_method(D_METHOD("set_theme_item", "data_type", "name", "node_type", "value"), &Theme::set_theme_item);
+	ClassDB::bind_method(D_METHOD("get_theme_item", "data_type", "name", "node_type"), &Theme::get_theme_item);
+	ClassDB::bind_method(D_METHOD("has_theme_item", "data_type", "name", "node_type"), &Theme::has_theme_item);
+	ClassDB::bind_method(D_METHOD("rename_theme_item", "data_type", "old_name", "name", "node_type"), &Theme::rename_theme_item);
+	ClassDB::bind_method(D_METHOD("clear_theme_item", "data_type", "name", "node_type"), &Theme::clear_theme_item);
+	ClassDB::bind_method(D_METHOD("get_theme_item_list", "data_type", "node_type"), &Theme::_get_theme_item_list);
+	ClassDB::bind_method(D_METHOD("get_theme_item_type_list", "data_type"), &Theme::_get_theme_item_type_list);
+
 	ClassDB::bind_method(D_METHOD("get_type_list"), &Theme::_get_type_list);
 
 	ClassDB::bind_method("copy_default_theme", &Theme::copy_default_theme);
@@ -990,6 +1370,14 @@ void Theme::_bind_methods() {
 
 	ADD_PROPERTY(PropertyInfo(Variant::OBJECT, "default_font", PROPERTY_HINT_RESOURCE_TYPE, "Font"), "set_default_font", "get_default_font");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "default_font_size"), "set_default_font_size", "get_default_font_size");
+
+	BIND_ENUM_CONSTANT(DATA_TYPE_ICON);
+	BIND_ENUM_CONSTANT(DATA_TYPE_STYLEBOX);
+	BIND_ENUM_CONSTANT(DATA_TYPE_FONT);
+	BIND_ENUM_CONSTANT(DATA_TYPE_FONT_SIZE);
+	BIND_ENUM_CONSTANT(DATA_TYPE_COLOR);
+	BIND_ENUM_CONSTANT(DATA_TYPE_CONSTANT);
+	BIND_ENUM_CONSTANT(DATA_TYPE_MAX);
 }
 
 Theme::Theme() {
diff --git a/scene/resources/theme.h b/scene/resources/theme.h
index 35481126ea..eb918fac69 100644
--- a/scene/resources/theme.h
+++ b/scene/resources/theme.h
@@ -41,6 +41,18 @@ class Theme : public Resource {
 	GDCLASS(Theme, Resource);
 	RES_BASE_EXTENSION("theme");
 
+public:
+	enum DataType {
+		DATA_TYPE_COLOR,
+		DATA_TYPE_CONSTANT,
+		DATA_TYPE_FONT,
+		DATA_TYPE_FONT_SIZE,
+		DATA_TYPE_ICON,
+		DATA_TYPE_STYLEBOX,
+		DATA_TYPE_MAX
+	};
+
+private:
 	void _emit_theme_changed();
 
 	HashMap<StringName, HashMap<StringName, Ref<Texture2D>>> icon_map;
@@ -57,10 +69,14 @@ class Theme : public Resource {
 	Vector<String> _get_font_list(const String &p_node_type) const;
 	Vector<String> _get_font_type_list() const;
 	Vector<String> _get_font_size_list(const String &p_node_type) const;
+	Vector<String> _get_font_size_type_list() const;
 	Vector<String> _get_color_list(const String &p_node_type) const;
 	Vector<String> _get_color_type_list() const;
 	Vector<String> _get_constant_list(const String &p_node_type) const;
 	Vector<String> _get_constant_type_list() const;
+
+	Vector<String> _get_theme_item_list(DataType p_data_type, const String &p_node_type) const;
+	Vector<String> _get_theme_item_type_list(DataType p_data_type) const;
 	Vector<String> _get_type_list() const;
 
 protected:
@@ -103,44 +119,66 @@ public:
 	void set_icon(const StringName &p_name, const StringName &p_node_type, const Ref<Texture2D> &p_icon);
 	Ref<Texture2D> get_icon(const StringName &p_name, const StringName &p_node_type) const;
 	bool has_icon(const StringName &p_name, const StringName &p_node_type) const;
+	void rename_icon(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type);
 	void clear_icon(const StringName &p_name, const StringName &p_node_type);
 	void get_icon_list(StringName p_node_type, List<StringName> *p_list) const;
+	void add_icon_type(const StringName &p_node_type);
 	void get_icon_type_list(List<StringName> *p_list) const;
 
 	void set_stylebox(const StringName &p_name, const StringName &p_node_type, const Ref<StyleBox> &p_style);
 	Ref<StyleBox> get_stylebox(const StringName &p_name, const StringName &p_node_type) const;
 	bool has_stylebox(const StringName &p_name, const StringName &p_node_type) const;
+	void rename_stylebox(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type);
 	void clear_stylebox(const StringName &p_name, const StringName &p_node_type);
 	void get_stylebox_list(StringName p_node_type, List<StringName> *p_list) const;
+	void add_stylebox_type(const StringName &p_node_type);
 	void get_stylebox_type_list(List<StringName> *p_list) const;
 
 	void set_font(const StringName &p_name, const StringName &p_node_type, const Ref<Font> &p_font);
 	Ref<Font> get_font(const StringName &p_name, const StringName &p_node_type) const;
 	bool has_font(const StringName &p_name, const StringName &p_node_type) const;
+	void rename_font(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type);
 	void clear_font(const StringName &p_name, const StringName &p_node_type);
 	void get_font_list(StringName p_node_type, List<StringName> *p_list) const;
+	void add_font_type(const StringName &p_node_type);
 	void get_font_type_list(List<StringName> *p_list) const;
 
 	void set_font_size(const StringName &p_name, const StringName &p_node_type, int p_font_size);
 	int get_font_size(const StringName &p_name, const StringName &p_node_type) const;
 	bool has_font_size(const StringName &p_name, const StringName &p_node_type) const;
+	void rename_font_size(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type);
 	void clear_font_size(const StringName &p_name, const StringName &p_node_type);
 	void get_font_size_list(StringName p_node_type, List<StringName> *p_list) const;
+	void add_font_size_type(const StringName &p_node_type);
+	void get_font_size_type_list(List<StringName> *p_list) const;
 
 	void set_color(const StringName &p_name, const StringName &p_node_type, const Color &p_color);
 	Color get_color(const StringName &p_name, const StringName &p_node_type) const;
 	bool has_color(const StringName &p_name, const StringName &p_node_type) const;
+	void rename_color(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type);
 	void clear_color(const StringName &p_name, const StringName &p_node_type);
 	void get_color_list(StringName p_node_type, List<StringName> *p_list) const;
+	void add_color_type(const StringName &p_node_type);
 	void get_color_type_list(List<StringName> *p_list) const;
 
 	void set_constant(const StringName &p_name, const StringName &p_node_type, int p_constant);
 	int get_constant(const StringName &p_name, const StringName &p_node_type) const;
 	bool has_constant(const StringName &p_name, const StringName &p_node_type) const;
+	void rename_constant(const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type);
 	void clear_constant(const StringName &p_name, const StringName &p_node_type);
 	void get_constant_list(StringName p_node_type, List<StringName> *p_list) const;
+	void add_constant_type(const StringName &p_node_type);
 	void get_constant_type_list(List<StringName> *p_list) const;
 
+	void set_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_node_type, const Variant &p_value);
+	Variant get_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_node_type) const;
+	bool has_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_node_type) const;
+	void rename_theme_item(DataType p_data_type, const StringName &p_old_name, const StringName &p_name, const StringName &p_node_type);
+	void clear_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_node_type);
+	void get_theme_item_list(DataType p_data_type, StringName p_node_type, List<StringName> *p_list) const;
+	void add_theme_item_type(DataType p_data_type, const StringName &p_node_type);
+	void get_theme_item_type_list(DataType p_data_type, List<StringName> *p_list) const;
+
 	void get_type_list(List<StringName> *p_list) const;
 
 	void copy_default_theme();
@@ -151,4 +189,6 @@ public:
 	~Theme();
 };
 
+VARIANT_ENUM_CAST(Theme::DataType);
+
 #endif