CMPT 212 Object-Oriented Applications Design in C++ Fall 1997

Menus

• Menus are defined in the resource file.

• There are two types of menu items:
  1. popup submenus,
  2. final selections.

• Suppose we want to define this menu:

• Here is what the .rc file would contain:

     #include "menu.h"
  
     MYMENU MENU
     {
        POPUP "&File"
        {
  	 MENUITEM "&Open",  IDM_OPEN
  	 MENUITEM "&Close", IDM_CLOSE
  	 MENUITEM "&Quit",  IDM_QUIT
        }
        POPUP "&Edit"
        {
  	 MENUITEM "Cop&y",  IDM_COPY
  	 MENUITEM "&Paste", IDM_PASTE
        }
        MENUITEM "&Help",     IDM_HELP
     }
  	 

  • MYMENU is the name of the menu. Your application will use this name to specify to MS-Windows what menu it wants to use.

  • The IDM_ names refer to constants defined in your file menu.h. Your .cpp file will include menu.h because the IDM_ values are values passed to your application by MS-Windows when the user chooses items from the menu.

  • The & in the item string causes MS-Windows to underline that letter. The user can then press the letter to select the item instead of using the mouse. The letter is called the shortcut key.

• Here is the file menu.h:

     #define IDM_OPEN    101
     #define IDM_CLOSE   102
     #define IDM_QUIT    103
     #define IDM_COPY    104
     #define IDM_PASTE   105
     #define IDM_HELP    106
  	 

• Here is how your application specifies what menu it wants to use:

     int WINAPI WinMain(HINSTANCE hThisInst,
  		      HINSTANCE hPrevInst,
  		      LPSTR     lpszArgs,
  		      int       WinMode) {
  
        ...
  
        WNDCLASS wcl;
  
        ...
        
        wcl.lpszMenuName = "MYMENU";
  
        ...
  
     }
  	 

• Here is how your application can respond to menu messages:

     #include "menu.h"
  
     LRESULT CALLBACK WindowFunc(HWND   hwnd,
  			       UINT   message,
  			       WPARAM wParam,
  			       LPARAM lParam) {
  
        switch (message) {
  
  	 ...
  
  	 case WM_COMMAND:
  
  	    switch (LOWORD(wParam)) {
  
  	       case IDM_OPEN:
  		  ...
  		  break;
  
  	       case IDM_CLOSE:
  		  ...
  		  break;
  
  	       case IDM_QUIT:
  		  ...
  		  break;
  
  	       case IDM_COPY:
  		  ...
  		  break;
  
  	       case IDM_PASTE:
  		  ...
  		  break;
  
  	       case IDM_HELP:
  		  ...
  		  break;
  
                 }
  
              ...
  
  	 }
  
       return 0;
     }
  	 

  • When the user makes a menu selection, your application is sent a WM_COMMAND message. LOWORD(wParam) contains the value associated with that menu selection.

Dialog Boxes

• A dialog box is a window which allows the user to interact wht the application through controls.
  • Examples of controls are:
    • push button,
    • check box,
    • radio button,
    • list box,
    • edit box,
    • static control.

• Example of different controls in a dialog box:

• A dialog box can be modal or modeless.
  • A modal dialog box does not allow the user to use the parent window until the dialog box is closed.

  • A modeless dialog box allows the user to interact with the parent window while the dialog box is open.

• Dialog boxes are defined in resource files.

• Suppose we want to define this dialog box:

• Here is what the .rc file contains:

     #include "mydialog.h"
  
     ENTER_NAME_DIALOG DIALOG 10, 10, 150, 60
     STYLE DS_MODALFRAME | WS_POPUP | WS_CAPTION | WS_SYSMENU
     CAPTION "Enter your name"
     {
        LTEXT "Name:", -1, 15, 15, 25, 8
        EDITTEXT IDC_NAME, 50, 15, 60, 12
        PUSHBUTTON "OK", IDC_OK_BUTTON, 15, 40, 50, 14
        PUSHBUTTON "Cancel", IDC_CANCEL_BUTTON, 80, 40, 50, 14
     }
  	 

• Here is the file mydialog.h:

     #define IDC_NAME           101
     #define IDC_OK_BUTTON      102
     #define IDC_CANCEL_BUTTON  103
  	 

• Here is how your application uses the dialog box:

     ...
     DialogBox(hInst, "ENTER_NAME_DIALOG", hwnd, (DLGPROC) AddNameFunc);
     ...
  	 

  • hInst is a handle of the instance of your application. Normally this is a module variable which is set in WinMain to be equal to hThisInst.

  • AddNameFunc is the callback function for the dialog box.

• Here is how we could define AddNameFunc:

     BOOL CALLBACK AddNameFunc(HWND   hwnd,
  			     UINT   message,
  			     WPARAM wParam,
  			     LPARAM lParam) {
       
        const int nameLen = 80;
        char      name[NameLen];
  
        switch (message) {
  
  	 case WM_COMMAND:
  
  	    switch (LOWORD(wParam)) {
  
  	       case IDC_CANCEL_BUTTON:
  		  EndDialog(hwnd, 0);
  		  return 1;
  
                 case IDC_OK_BUTTON:
  		  GetDlgItemText(hwnd, IDC_NAME, name, nameLen);
  		  ...   // use "name".
  		  EndDialog(hwnd, 0);
  		  return 1;
  
                 }
  
           case WM_INITDIALOG:
  	    return 1;
  
           }
  
        return 0;
     }
  	 

  • The dialog box callback function returns true or 1 if it responds to a message, and false or 0 if it does not.

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