Advanced MFC Programming

Chapter 2. Menu
void CMenuDoc::OnFileClose()
{
CMenu menu;
}
menu.LoadMenu(IDR_MAINFRAME);
AfxGetMainWnd()->SetMenu(&menu);
AfxGetMainWnd()->DrawMenuBar();
menu.Detach();
In the above three member functions, we use a local variable menu to load the menu resource. It will be
destroyed after the function exits. So before the variable goes out of scope, we must call function
CMenu::Detach() to release the loaded menu resource so that it can continue to be used by the application.
Otherwise, the menu resource will be destroyed automatically.
Summary
1) In order to execute commands, we need to handle message WM_COMMAND. In order to update user
interfaces of menu, we need to handle message UPDATE_COMMAND_UI.
1) To implement right-click menu, we need to first prepare a menu resource, then trap WM_RBUTTONDOWN
message. Within the message handler, we can use CMenu type variable to load the menu resource, and
call CMenu::TrackPopupMenu(…) to activate the menu and track mouse activities. Before the menu is
shown, we can call functions CMenu::EnableMenuItem(…) and CMenu::CheckMenuItem(…) to set the
states of the menu items.
1) To add or remove a menu item dynamically, we need to call functions CMenu::InsertMenu(…) and
CMenu::RemoveMenu(…).
1) With function CMenu::SetMenuItemBitmaps(…), we can use bitmap images to implement checked and
unchecked states for a menu item.
1) A window’s standard menu can be obtained by calling function CWnd::GetMenu(), and the
application’s system menu can be obtained by calling function CWnd::GetSysMenu(…).
1) We can change a normal menu item to a bitmap menu item, a separator, or a sub-menu by calling
function CMenu::ModifyMenu(…).
1) Owner-draw menu can be implemented by setting MF_OWNERDRAW style then overriding functions
CMenu::MeasureItem(…) and CMenu::DrawItem(…).
1) We can change the whole menu attached to a window by calling function CWnd::SetMenu(…).
56