Menus

1
Menus

• Jim Fawcett
• CSE 791 Advanced Windows Programming
• Summer 2002

2
Topics

• Menu Definition and Classification
• Creating and Loading a Menu
• Responding to Menu Commands
• Updating Items in a Menu
• Keyboard Accelerators
• Creating Menu Programmatically

3
Menus Definition and Classification

• Menu is a text or graphical list of commands from
  which an user can easily make a selection
• Menu classification
• system menu
• top-level menu
• drop-down menu
• popup menu
• cascading menu
• Windows operating system does menu management

4
Creating a Menu

• Three ways to create in an MFC Application
• Create a menu resource file and load the
  resulting menu into the application at run time.
  
• Create a menu programmatically using CreateMenu,
  InsertMenu, and other CMenu functions.
• Initialize a series of data structures defining
  menus contents and create the menu with
• MenuLoadMenuIndirect.

5
Menu Resources

• You can build a menu in the Resource View of the
  IDE.
• A resource file is a scriptlike text file that
  defines an applications resources.
• A resource is a binary object, Windows supports
  several types of resources
• A compiler, Rc.exe, compiles the resource file
  and links the resulting resources into the
  applications executable file.

6
SDI Application Built with App Wizard
7
Menus in Resource View
8
Hooking to an Event Handler
9
Creating Event Handler
10
Menu in Action
11
Menu Resource Codes

• IDR_MAINFRAME MENU PRELOAD DISCARDABLE
• BEGIN
• POPUP "File"
• BEGIN
• MENUITEM "Save\tCtrlS",
  ID_FILE_SAVE
• MENUITEM "Save As...",
  ID_FILE_SAVE_AS
• MENUITEM SEPARATOR
• MENUITEM "Recent File",
  ID_FILE_MRU_FILE1,GRAYED
• MENUITEM "Exit", ID_APP_EXIT
• END
• POPUP "Edit"
• BEGIN
• MENUITEM "Undo\tCtrlZ", ID_EDIT_
  UNDO
• MENUITEM SEPARATOR
• MENUITEM "Cut\tCtrlX", ID_EDIT_C
  UT
• END
• END

12
Ways to Load a Menu

• Pass the menus resource ID to CFrameWndCreate
• Create (NULL, _T ("My Application"),
• WS_OVERLAPPEDWINDOW, rectDefault, NULL,
• MAKEINTRESOURCE (IDR_MAINFRAME))
• Pass the menus resource ID to FrameWndLoadFrame
  
• LoadFrame (IDR_MAINFRAME,
• WS_OVERLAPPEDWINDOW, NULL, NULL)
• Load a top-level menu and attach it to a window
• CMenu menu
• menu.LoadMenu (IDR_MAINFRAME)
• SetMenu (menu)
• menu.Detach ()

13
Processing WM_Command Message

• WM_Command Message has a parameter(wParam) whose
  low word is the ID of selected menu item
• // In header file
• afx_msg void OnFileExit( )
• // In implementation file
• BEGIN_MESSAGE_MAP (App Class Name, Base
  Class Name)
• ON_COMMAND (ID_FILE_EXIT, OnFileExit)
  
• END_MESSAGE_MAP( )
• void CMainWindowOnFileExit ()
• PostMessage (WM_CLOSE, 0, 0)

14
Command Range

• One handler for a group of menu items
• // In CMainWindow's message map
• ON_COMMAND (ID_COLOR_RED,
  OnColorRed)ON_COMMAND (ID_COLOR_GREEN,
  OnColorGreen)ON_COMMAND (ID_COLOR_BLUE,
  OnColorBlue )
• Or
• // In CMainWindow's message map
• ON_COMMAND_RANGE (ID_COLOR_RED,
  ID_COLOR_BLUE, OnColor )

15
Menu States

• A menu can be in one of the following states
• Value Meaning
• CHECKED The menu item is currently
  checked.
• DISABLED The menu item is currently
  disabled.
• GRAYED The menu item is currently grayed
  out.
• SELECTED The menu item is currently
  selected.

16
Updating Items in a Menu

• Update a menu using ON_UPDATE_COMMAND_UI macro
• ON_UPDATE_COMMAND_UI (ID_COLOR_RED,
  OnUpdateColorRed)
• void CMainWindowOnUpdateColorRed (CCmdUI
  pCmdUI) // Implementation
• Update Range
• ON_UPDATE_COMMAND_UI_RANGE (ID_COLOR_BLACK,
• ID_COLOR_WHITE, OnUpdateColorUI)
• void CMainWindowOnUpdateColorUI (CCmdUI
  pCmdUI) // Implementation

17
Keyboard Accelerator

• Keyboard accelerator provides application
  simplicity
• Create an accelerator table resource
• IDR_MAINFRAME ACCELERATORS PRELOAD MOVEABLE
  BEGIN
• "N", ID_FILE_NEW,
  VIRTKEY,CONTROL
• "Z", ID_EDIT_UNDO,
  VIRTKEY,CONTROL
• VK_BACK, ID_EDIT_UNDO,
  VIRTKEY,ALT
• END
• Like menus, keyboard accelerators must be loaded
  and attached to a window before they'll do
  anything.
• LoadAccelTable (MAKEINTRESOURCE
  (IDR_MAINFRAME))

18
Prosises Shape Application

• Use AppWizard and ClassWizard to build an
  application.
• Shows how to use menus, accelerators and MFCs
  UI update mechanism.
• Examines application structures and code.

19
Creating Menus Programmatically

• Use a combination of CMenuCreateMenu,
  CMenuCreatePopupMenu, and CMenuAppendMenu.
• CMenu menuMain
• menuMain.CreateMenu () // create an empty
  top-level menu CMenu menuPopupmenuPopup.CreateP
  opupMenu () menuPopup.AppendMenu (MF_STRING,
  ID_FILE_EXIT, "Exit")menuMain.AppendMenu
  (MF_POPUP, (UINT) menuPopup.Detach (), "File")
  SetMenu (menuMain) // to attach menu to a
  windowmenuMain.Detach () // to dissociate
  CMenu object and menu

20
Modifying Menus Programmatically

• Function Description
• AppendMenu Adds an item to the end of a menu
• InsertMenu Inserts an item into a menu at a
  specified location
• ModifyMenu Changes the command ID, text, or other
  characteristics of a menu item
• DeleteMenu Deletes a menu item and the submenu
  associated with it, if any
• RemoveMenu Deletes a menu item

21
Owner-Draw Menusa too brief synopsis

• Often used to display bitmaps in menu items.
• Stamp conventional items with the label
  MF_OWNERDRAW using CMenuModifyMenu
• Add an OnMeasureitem handler for WM_MEASUREITEM
  message
• Provide an OnDrawItem handler for WM_DRAWITEM
  message

22
Context Menus

• A context menu is just a submenu that isnt
  attached to a top-level menu.
• MFC's CMenuTrackPopupMenu function displays a
  context menu.
• BOOL TrackPopupMenu (UINT nFlags, int x,
  int y, CWnd
• pWnd, LPCRECT
  lpRect NULL)
• TrackPopupMenu is typically called in response to
  WM_CONTEXTMENU messages.
• Uses conventional menu processing to process the
  context menu commands

23
The Color Application

• Shows how to
• use AppWizard and ClassWizard to build an
  application
• use owner-draw menus and context menu
• analyzes application structures and code