二、Windows菜单—建立菜单的非正统方法
现在让我们稍微偏离我们所讨论的主题。如果在您的程序中没有下拉式菜单，而是建立了多个没有弹出式菜单的顶层菜单，并呼叫SetMenu在顶层菜单之间切换，那会是什么样的情形呢？就像Lotus 1-2-3中老式的文字模式菜单那样。程序10-8中的NOPOPUPS程序展示了处理这种情况。在这个程序中，「File」和「Edit」项与MENUDEMO程序中的类似，但是却以另一种顶层菜单显示出来。
程序10-8 NOPOPUPS
NOPOPUPS.C
/*-------------------------------------------------------------------------
NOPOPUPS.C -- Demonstrates No-Popup Nested Menu
(c) Charles Petzold, 1998
-------------------------------------------------------------------------*/
#include <windows.h>
#include "resource.h"
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("NoPopUps") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ;
if (!RegisterClass (&wndclass))
{
MessageBox ( NULL, TEXT ("This program requires Windows NT!"),
szAppName, MB_ICONERROR) ;
return 0 ;
}
hwnd = CreateWindow (szAppName,
TEXT ("No-Popup Nested Menu Demonstration"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT,
CW_USEDEFAULT, CW_USEDEFAULT,
NULL, NULL, hInstance, NULL) ;
ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ;
while (GetMessage (&msg, NULL, 0, 0))
{
TranslateMessage (&msg) ;
DispatchMessage (&msg) ;
}
return msg.wParam ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam,LPARAM lParam)
{
static HMENU hMenuMain, hMenuEdit, hMenuFile ;
HINSTANCE hInstance ;
switch (message)
{
case WM_CREATE:
hInstance = (HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE) ;
hMenuMain = LoadMenu (hInstance, TEXT ("MenuMain")) ;
hMenuFile = LoadMenu (hInstance, TEXT ("MenuFile")) ;
hMenuEdit = LoadMenu (hInstance, TEXT ("MenuEdit")) ;
SetMenu (hwnd, hMenuMain) ;
return 0 ;
case WM_COMMAND:
switch (LOWORD (wParam))
{
case IDM_MAIN:
SetMenu (hwnd, hMenuMain) ;
return 0 ;
case IDM_FILE:
SetMenu (hwnd, hMenuFile) ;
return 0 ;
case IDM_EDIT:
SetMenu (hwnd, hMenuEdit) ;
return 0 ;
case IDM_FILE_NEW:
case IDM_FILE_OPEN:
case IDM_FILE_SAVE:
case IDM_FILE_SAVE_AS:
case IDM_EDIT_UNDO:
case IDM_EDIT_CUT:
case IDM_EDIT_COPY:
case IDM_EDIT_PASTE:
case IDM_EDIT_CLEAR:
MessageBeep (0) ;
return 0 ;
}
break ;
case WM_DESTROY:
SetMenu (hwnd, hMenuMain) ;
DestroyMenu (hMenuFile) ;
DestroyMenu (hMenuEdit) ;
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}
NOPOPUPS.RC （摘录）
//Microsoft Developer Studio generated resource script.
#include "resource.h"
#include "afxres.h"
/////////////////////////////////////////////////////////////////////////////
// Menu
MENUMAIN MENU DISCARDABLE
BEGIN
MENUITEM "MAIN:", 0, INACTIVE
MENUITEM "&File...", IDM_FILE
MENUITEM "&Edit...", IDM_EDIT
END
MENUFILE MENU DISCARDABLE
BEGIN
MENUITEM "FILE:", 0, INACTIVE
MENUITEM "&New", IDM_FILE_NEW
MENUITEM "&Open...", IDM_FILE_OPEN
MENUITEM "&Save", IDM_FILE_SAVE
MENUITEM "Save &As", IDM_FILE_SAVE_AS
MENUITEM "(&Main)", IDM_MAIN
END
MENUEDIT MENU DISCARDABLE
BEGIN
MENUITEM "EDIT:", 0, INACTIVE
MENUITEM "&Undo", IDM_EDIT_UNDO
MENUITEM "Cu&t", IDM_EDIT_CUT
MENUITEM "&Copy", IDM_EDIT_COPY
MENUITEM "&Paste", IDM_EDIT_PASTE
MENUITEM "De&lete", IDM_EDIT_CLEAR
MENUITEM "(&Main)", IDM_MAIN
END
RESOURCE.H （摘录）
// Microsoft Developer Studio generated include file.
// Used by NoPopups.rc
#define IDM_FILE 40001
#define IDM_EDIT 40002
#define IDM_FILE_NEW 40003
#define IDM_FILE_OPEN 40004
#define IDM_FILE_SAVE 40005
#define IDM_FILE_SAVE_AS 40006
#define IDM_MAIN 40007
#define IDM_EDIT_UNDO 40008
#define IDM_EDIT_CUT 40009
#define IDM_EDIT_COPY 40010
#define IDM_EDIT_PASTE 40011
#define IDM_EDIT_CLEAR 40012
在Microsoft Developer Studio中，您建立了三个菜单，而不是一个。从「Insert」中选择「Resource」三次，每个菜单有一个不同的名称。当窗口消息处理程序处理WM_CREATE消息时，Windows将每个菜单资源加载内存：
hMenuMain = LoadMenu (hInstance, TEXT ("MenuMain")) ;
hMenuFile = LoadMenu (hInstance, TEXT ("MenuFile")) ;
hMenuEdit = LoadMenu (hInstance, TEXT ("MenuEdit")) ;
开始时，程序只显示主菜单：
SetMenu (hwnd, hMenuMain) ;
主菜单使用字符串「MAIN:」、「File...」和「Edit...」列出这三个选项。然而，「MAIN:」是禁用的，因此它不能使WM_COMMAND消息被发送到窗口消息处理程序。「File」和「Edit」菜单项以「FILE:」和「EDIT:」开始，表示它们是子菜单。每个菜单的最后一项都是字符串「(Main)」，表示传回到主菜单。在这三个菜单之间进行切换是很简单的：
case WM_COMMAND :
switch (wParam)
{
case IDM_MAIN :
SetMenu (hwnd, hMenuMain) ;
return 0 ;
case IDM_FILE :
SetMenu (hwnd, hMenuFile) ;
return 0 ;
case IDM_EDIT :
SetMenu (hwnd, hMenuEdit) ;
return 0 ;
其它行程序
}
break ;
在WM_DESTROY消息处理期间，NOPOPUPS将程序的菜单设定为主菜单，并呼叫DestroyMenu来清除「File」和「Edit」菜单。当窗口被清除时，主菜单将被自动清除。
