二、Windows自己的窗口—HELLOWIN程序
建立一个窗口首先需要注册一个窗口类别,那需要一个窗口消息处理程序来处理窗口消息。处理窗口消息对每个Windows程序都带来了些负担。程序3-1所示的HELLOWIN程序中整个做的事情差不多就是料理这些事情。
程序3-1 HELLOWIN
HELLOWIN.C /*------------------------------------------------------------------------ HELLOWIN.C -- Displays "Hello, Windows 98!" in client area (c) Charles Petzold, 1998 -----------------------------------------------------------------------*/ #include <windows.h> LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("HelloWin") ; HWND hwnd ; MSG msg ; WNDCLASwndclass ; 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.lpszMenuNam = NULL ; wndclass.lpszClassName= szAppName ; if (!RegisterClass (&wndclass)) { MessageBox ( NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow( szAppName, // window class name TEXT ("The Hello Program"), // window caption WS_OVERLAPPEDWINDOW, // window style CW_USEDEFAULT,// initial x position CW_USEDEFAULT,// initial y position CW_USEDEFAULT,// initial x size CW_USEDEFAULT,// initial y size NULL, // parent window handle NULL, // window menu handle hInstance, // program instance handle NULL) ; // creation parameters 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) { HDC hdc ; PAINTSTRUCT ps ; RECT rect ; switch (message) { case WM_CREATE: PlaySound (TEXT ("hellowin.wav"), NULL, SND_FILENAME | SND_ASYNC) ; return 0 ; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; GetClientRect (hwnd, &rect) ; DrawText (hdc, TEXT ("Hello, Windows 98!"), -1, &rect, DT_SINGLELINE | DT_CENTER | DT_VCENTER) ; EndPaint (hwnd, &ps) ; return 0 ; case WM_DESTROY: PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; }
程序建立一个普通的应用程序窗口,如图3-1所示。在窗口显示区域的中央显示「Hello, Windows 98!」。如果安装了声卡,那么您还可以听到相应的朗读声音。
提醒您注意:如果您使用Microsoft Visual C++ 为此程序建立新项目,那么您得加上连结程序所需的链接库文件。从Project菜单选择 Setting选项,然后选取Link页面标签。从 Category清单方块中选择General,然后在 Object/Library Modules文字方块添加WINMM.LIB(Windows multimedia-Windows多媒体)。您这样做是因为HELLOWIN将使用多媒体功能呼叫,而内定的项目中又不包括多媒体链接库文件。不然连结程序报告了错误信息,表明PlaySound函数不可用。
HELLOWIN将存取文件HELLOWIN.WAV,该文件在本书所附光盘的HELLOWIN目录中。执行HELLOWIN.EXE时,内定的目录必须是HELLOWIN。在Visual C++中执行此程序时,虽然执行文件会产生在HELLOWIN的RELEASE或DEBUG子目录中,但执行程序的目录还是必须在HELLOWIN中。