您还可以定义自己的子窗口控件，并将它们用到对话框中。例如，假定您特别不喜欢普通的矩形按键，而倾向于建立椭圆形按键，那么您可以通过注册一个窗口类别，并使用自己编写的窗口消息处理程序处理来自您所建立窗口的消息，从而建立椭圆形按键。在Developer Studio中，您可以在与自订控件相联系的「Properties」对话框中指定这个窗口类别，这将转换成对话框模板中的CONTROL叙述。程序11-3所示的ABOUT3程序正是这样做的。
程序11-3 ABOUT3
ABOUT3.C /*----------------------------------------------------------------------------- ABOUT3.C -- About Box Demo Program No. 3 (c) Charles Petzold, 1998 ----------------------------------------------------------------------------*/ #include <windows.h> #include "resource.h" LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; BOOL CALLBACK AboutDlgProc (HWND, UINT, WPARAM, LPARAM) ; LRESULT CALLBACK EllipPushWndProc (HWND, UINT, WPARAM, LPARAM) ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("About3") ; MSG msg ; HWND hwnd ; WNDCLASS wndclass ; wndclass.style = CS_HREDRAW | CS_VREDRAW ; wndclass.lpfnWndProc = WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon = LoadIcon (hInstance, szAppName) ; wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ; wndclass.lpszMenuName = szAppName ; wndclass.lpszClassName = szAppName ; if (!RegisterClass (&wndclass)) { MessageBox ( NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } wndclass.style = CS_HREDRAW | CS_VREDRAW ; wndclass.lpfnWndProc = EllipPushWndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon = NULL ; wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) (COLOR_BTNFACE + 1) ; wndclass.lpszMenuName = NULL ; wndclass.lpszClassName = TEXT ("EllipPush") ; RegisterClass (&wndclass) ; hwnd = CreateWindow ( szAppName, TEXT ("About Box Demo Program"), 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 HINSTANCE hInstance ; switch (message) { case WM_CREATE : hInstance = ((LPCREATESTRUCT) lParam)->hInstance ; return 0 ; case WM_COMMAND : switch (LOWORD (wParam)) { case IDM_APP_ABOUT : DialogBox (hInstance, TEXT ("AboutBox"), hwnd, AboutDlgProc) ; return 0 ; } break ; case WM_DESTROY : PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; } BOOL CALLBACK AboutDlgProc (HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) { switch (message) { case WM_INITDIALOG : return TRUE ; case WM_COMMAND : switch (LOWORD (wParam)) { case IDOK : EndDialog (hDlg, 0) ; return TRUE ; } break ; } return FALSE ; } LRESULT CALLBACK EllipPushWndProc (HWND hwnd, UINT message,WPARAM wParam, LPARAM lParam) { TCHAR szText[40] ; HBRUSH hBrush ; HDC hdc ; PAINTSTRUCT ps ; RECT rect ; switch (message) { case WM_PAINT : GetClientRect (hwnd, &rect) ; GetWindowText (hwnd, szText, sizeof (szText)) ; hdc = BeginPaint (hwnd, &ps) ; hBrush = CreateSolidBrush (GetSysColor (COLOR_WINDOW)) ; hBrush = (HBRUSH) SelectObject (hdc, hBrush) ; SetBkColor (hdc, GetSysColor (COLOR_WINDOW)) ; SetTextColor (hdc, GetSysColor (COLOR_WINDOWTEXT)) ; Ellipse (hdc, rect.left, rect.top, rect.right, rect.bottom) ; DrawText (hdc, szText, -1, &rect, DT_SINGLELINE | DT_CENTER | DT_VCENTER) ; DeleteObject (SelectObject (hdc, hBrush)) ; EndPaint (hwnd, &ps) ; return 0 ; case WM_KEYUP : if (wParam != VK_SPACE) break ;// fall through case WM_LBUTTONUP : SendMessage (GetParent (hwnd), WM_COMMAND, GetWindowLong (hwnd, GWL_ID), (LPARAM) hwnd) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; }