CMenu replace item with submenu

Question

I have a MFC CMenu with some items. I would like to convert or replace a single menu item with a sub-menu, with additional menu items. Is there an easy way to do that ?

Answer 1

The CMenu class provides the class member CMenu::SetMenuItemInfo to modify an existing menu item by passing it a properly initialized MENUITEMINFO structure.

To replace a menu item with a pop-up menu (sub menu) you have to perform 3 steps.

1. Create a new pop-up menu

You can either create the menu dynamically by calling CMenu::CreatePopupMenu and populate it with CMenu::InsertMenuItem or load an existing pop-up menu from a resource using CMenu::LoadMenu:

CMenu MyMenu;
MyMenu.CreatePopupMenu();
MENUITEMINFO mii = { 0 };
mii.cbSize = sizeof( MENUITEMINFO );
mii.fMask = MIIM_ID | MIIM_STRING;
mii.wID = IDM_MY_MENU_ITEM1;   // #define this in your Resource.h file
mii.dwTypeData = _T( "Menu Item 1" );
MyMenu.InsertMenuItem( 0, &mii, TRUE );

2. Initialize a MENUITEMINFO structure

MENUITEMINFO miiNew = { 0 };
miiNew.cbSize = sizeof( MENUITEMINFO );
miiNew.fMask = MIIM_SUBMENU | MIIM_STRING;
miiNew.hSubMenu = MyMenu.Detach();   // Detach() to keep the pop-up menu alive
                                     // when MyMenu goes out of scope
miiNew.dwTypeData = _T( "Some text" );

3. Replace existing menu item

MyMainMenu.SetMenuItemInfo( IDM_ITEM_TO_BE_REPLACED,
                            &miiNew,
                            FALSE );
DrawMenuBar( hWnd );

The call to DrawMenuBar is required whenever a window's menu is modified.