Add submenu support to EditorContextMenuPlugin

doc/classes/EditorContextMenuPlugin.xml

@@ -47,6 +47,24 @@
 				[/codeblock]
 			</description>
 		</method>
+		<method name="add_context_submenu_item">
+			<return type="void" />
+			<param index="0" name="name" type="String" />
+			<param index="1" name="menu" type="PopupMenu" />
+			<param index="2" name="icon" type="Texture2D" default="null" />
+			<description>
+				Add a submenu to the context menu of the plugin's specified slot. The submenu is not automatically handled, you need to connect to its signals yourself. Also the submenu is freed on every popup, so provide a new [PopupMenu] every time.
+				[codeblock]
+				func _popup_menu(paths):
+				    var popup_menu = PopupMenu.new()
+				    popup_menu.add_item("Blue")
+				    popup_menu.add_item("White")
+				    popup_menu.id_pressed.connect(_on_color_submenu_option)
+
+				    add_context_menu_item("Set Node Color", popup_menu)
+				[/codeblock]
+			</description>
+		</method>
 		<method name="add_menu_shortcut">
 			<return type="void" />
 			<param index="0" name="shortcut" type="Shortcut" />

editor/plugins/editor_context_menu_plugin.cpp

@@ -67,10 +67,21 @@ void EditorContextMenuPlugin::add_context_menu_item_from_shortcut(const String &
 	context_menu_items.insert(p_name, item);
 }
 
+void EditorContextMenuPlugin::add_context_submenu_item(const String &p_name, PopupMenu *p_menu, const Ref<Texture2D> &p_texture) {
+	ERR_FAIL_NULL(p_menu);
+
+	ContextMenuItem item;
+	item.item_name = p_name;
+	item.icon = p_texture;
+	item.submenu = p_menu;
+	context_menu_items.insert(p_name, item);
+}
+
 void EditorContextMenuPlugin::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("add_menu_shortcut", "shortcut", "callback"), &EditorContextMenuPlugin::add_menu_shortcut);
 	ClassDB::bind_method(D_METHOD("add_context_menu_item", "name", "callback", "icon"), &EditorContextMenuPlugin::add_context_menu_item, DEFVAL(Ref<Texture2D>()));
 	ClassDB::bind_method(D_METHOD("add_context_menu_item_from_shortcut", "name", "shortcut", "icon"), &EditorContextMenuPlugin::add_context_menu_item_from_shortcut, DEFVAL(Ref<Texture2D>()));
+	ClassDB::bind_method(D_METHOD("add_context_submenu_item", "name", "menu", "icon"), &EditorContextMenuPlugin::add_context_submenu_item, DEFVAL(Ref<Texture2D>()));
 
 	GDVIRTUAL_BIND(_popup_menu, "paths");
 
@@ -117,12 +128,17 @@ void EditorContextMenuPluginManager::add_options_from_plugins(PopupMenu *p_popup
 			EditorContextMenuPlugin::ContextMenuItem &item = E.value;
 			item.id = id;
 
-			if (item.icon.is_valid()) {
+			if (item.submenu) {
-				p_popup->add_icon_item(item.icon, item.item_name, id);
+				p_popup->add_submenu_node_item(item.item_name, item.submenu, id);
-				p_popup->set_item_icon_max_width(-1, icon_size);
 			} else {
 				p_popup->add_item(item.item_name, id);
 			}
+
+			if (item.icon.is_valid()) {
+				p_popup->set_item_icon(-1, item.icon);
+				p_popup->set_item_icon_max_width(-1, icon_size);
+			}
+
 			if (item.shortcut.is_valid()) {
 				p_popup->set_item_shortcut(-1, item.shortcut, true);
 			}

editor/plugins/editor_context_menu_plugin.h

@@ -65,6 +65,7 @@ public:
 		Callable callable;
 		Ref<Texture2D> icon;
 		Ref<Shortcut> shortcut;
+		PopupMenu *submenu = nullptr;
 	};
 	HashMap<String, ContextMenuItem> context_menu_items;
 	HashMap<Ref<Shortcut>, Callable> context_menu_shortcuts;
@@ -80,6 +81,7 @@ public:
 	void add_menu_shortcut(const Ref<Shortcut> &p_shortcut, const Callable &p_callable);
 	void add_context_menu_item(const String &p_name, const Callable &p_callable, const Ref<Texture2D> &p_texture);
 	void add_context_menu_item_from_shortcut(const String &p_name, const Ref<Shortcut> &p_shortcut, const Ref<Texture2D> &p_texture);
+	void add_context_submenu_item(const String &p_name, PopupMenu *p_menu, const Ref<Texture2D> &p_texture);
 };
 
 VARIANT_ENUM_CAST(EditorContextMenuPlugin::ContextMenuSlot);