Windows 编程[15] - 菜单消息: WM_COMMAND

本例效果图:

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点击任一个菜单项, 都会发出一个 WM_COMMAND 消息, 消息的 wParam 参数的低两位就是标识菜单项的那个整数!

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本例使用的资源文件(TestRes.rc):

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#define IDM_New   101
#define IDM_Open  102
#define IDM_Save  103
#define IDM_Exit  104
#define IDM_Cut   201
#define IDM_Copy  202
#define IDM_Paste 203
#define IDM_About 301

MyMenu1 MENUEX DISCARDABLE
BEGIN
  POPUP "&File"        ,65535
  BEGIN
    MENUITEM "&New"    ,IDM_New
    MENUITEM "&Open"   ,IDM_Open
    MENUITEM "&Save"   ,IDM_Save
    MENUITEM SEPARATOR
    MENUITEM "E&xit"   ,IDM_Exit
  END
  POPUP "&Edit"        ,65535
  BEGIN
    MENUITEM "Cu&t"    ,IDM_Cut
    MENUITEM "&Copy"   ,IDM_Copy
    MENUITEM "&Paste"  ,IDM_Paste
  END
  POPUP "&Help"        ,65535
  BEGIN
    MENUITEM "&About"  ,IDM_About
  END
END

本例代码文件:

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program Project1;

{$R 'TestRes.res' 'TestRes.rc'}

uses
  Windows, Messages;

{供 WM_COMMAND 消息调用的自定义过程}
procedure OnCommand(wParam: Integer);
begin
  case LoWord(wParam) of
    101: MessageBox(0, 'is New',  '', 0);
    102: MessageBox(0, 'is Open', '', 0);
    103: MessageBox(0, 'is Save', '', 0);
    104: MessageBox(0, 'is Exit', '', 0);
  end;
end;

function WndProc(wnd: HWND; msg: UINT; wParam,lParam: Integer): Integer; stdcall;
begin
  Result := 0;
  case msg of
    WM_COMMAND : OnCommand(wParam);  {收到 WM_COMMAND 消息后调用 OnCommand 过程}
    WM_DESTROY : PostQuitMessage(0);
  else
    Result := DefWindowProc(wnd, msg, wParam, lParam);
  end;
end;

function RegMyWndClass: Boolean;
var
  cls: TWndClass;
begin
  cls.style         := CS_HREDRAW or CS_VREDRAW;
  cls.lpfnWndProc   := @WndProc;
  cls.cbClsExtra    := 0;
  cls.cbWndExtra    := 0;
  cls.hInstance     := HInstance;
  cls.hIcon         := 0;
  cls.hCursor       := LoadCursor(0, IDC_ARROW);
  cls.hbrBackground := HBRUSH(COLOR_WINDOW + 1);
  cls.lpszMenuName  := 'MyMenu1';
  cls.lpszClassName := 'MyWnd';
  Result := RegisterClass(cls) <> 0;
end;

{程序入口}
const
  tit = 'New Form';
  ws = WS_OVERLAPPEDWINDOW;
  x = 100; y = 100; w = 300; h = 180;
var
  hWnd: THandle;
  Msg : TMsg;
begin
  RegMyWndClass;
  hWnd := CreateWindow('MyWnd', tit, ws, x, y, w, h, 0, 0, HInstance, nil);
  ShowWindow(hWnd, SW_SHOWNORMAL);
  UpdateWindow(hWnd);

  while(GetMessage(Msg, 0, 0, 0)) do
  begin
    TranslateMessage(Msg);
    DispatchMessage(Msg);
  end;
end.