ABOUT1中的简单对话框展示了设计和执行一个对话框的要点，现在让我们来看一个稍微复杂的例子。程序11-2给出的ABOUT2程序展示了如何在对话框程序中管理控件（这里用单选按钮）以及如何在对话框的显示区域中绘图。
程序11-2 ABOUT2
ABOUT2.C /*-------------------------------------------------------------------------- ABOUT2.C -- About Box Demo Program No. 2 (c) Charles Petzold, 1998 ---------------------------------------------------------------------------*/ #include <windows.h> #include "resource.h" LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; BOOL CALLBACK AboutDlgProc (HWND, UINT, WPARAM, LPARAM) ; int iCurrentColor = IDC_BLACK, iCurrentFigure = IDC_RECT ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("About2") ; 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 ; } 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 ; } void PaintWindow (HWND hwnd, int iColor, int iFigure) { static COLORREF crColor[8] = { RGB ( 0, 0, 0), RGB ( 0, 0, 255), RGB ( 0, 255, 0), RGB ( 0, 255, 255), RGB (255, 0, 0), RGB (255, 0, 255), RGB (255, 255, 0), RGB (255, 255, 255)} ; HBRUSH hBrush ; HDC hdc ; RECT rect ; hdc = GetDC (hwnd) ; GetClientRect (hwnd, &rect) ; hBrush = CreateSolidBrush (crColor[iColor - IDC_BLACK]) ; hBrush = (HBRUSH) SelectObject (hdc, hBrush) ; if (iFigure == IDC_RECT) Rectangle (hdc, rect.left, rect.top, rect.right, rect.bottom) ; else Ellipse (hdc, rect.left, rect.top, rect.right, rect.bottom) ; DeleteObject (SelectObject (hdc, hBrush)) ; ReleaseDC (hwnd, hdc) ; } void PaintTheBlock (HWND hCtrl, int iColor, int iFigure) { InvalidateRect (hCtrl, NULL, TRUE) ; UpdateWindow (hCtrl) ; PaintWindow (hCtrl, iColor, iFigure) ; } LRESULT CALLBACK WndProc ( HWND hwnd, UINT message, WPARAM wParam,LPARAM lParam) { static HINSTANCE hInstance ; PAINTSTRUCT ps ; switch (message) { case WM_CREATE: hInstance = ((LPCREATESTRUCT) lParam)->hInstance ; return 0 ; case WM_COMMAND: switch (LOWORD (wParam)) { case IDM_APP_ABOUT: if (DialogBox (hInstance, TEXT ("AboutBox"), hwnd, AboutDlgProc)) InvalidateRect (hwnd, NULL, TRUE) ; return 0 ; } break ; case WM_PAINT: BeginPaint (hwnd, &ps) ; EndPaint (hwnd, &ps) ; PaintWindow (hwnd, iCurrentColor, iCurrentFigure) ; return 0 ; case WM_DESTROY: PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; } BOOL CALLBACK AboutDlgProc (HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam) { static HWND hCtrlBlock ; static int iColor, iFigure ; switch (message) { case WM_INITDIALOG: iColor = iCurrentColor ; iFigure = iCurrentFigure ; CheckRadioButton (hDlg, IDC_BLACK, IDC_WHITE, iColor) ; CheckRadioButton (hDlg, IDC_RECT, IDC_ELLIPSE, iFigure) ; hCtrlBlock = GetDlgItem (hDlg, IDC_PAINT) ; SetFocus (GetDlgItem (hDlg, iColor)) ; return FALSE ; case WM_COMMAND: switch (LOWORD (wParam)) { case IDOK: iCurrentColor = iColor ; iCurrentFigure = iFigure ; EndDialog (hDlg, TRUE) ; return TRUE ; case IDCANCEL: EndDialog (hDlg, FALSE) ; return TRUE ; case IDC_BLACK: case IDC_RED: case IDC_GREEN: case IDC_YELLOW: case IDC_BLUE: case IDC_MAGENTA: case IDC_CYAN: case IDC_WHITE: iColor = LOWORD (wParam) ; CheckRadioButton (hDlg, IDC_BLACK, IDC_WHITE, LOWORD (wParam)) ; PaintTheBlock (hCtrlBlock, iColor, iFigure) ; return TRUE ; case IDC_RECT: case IDC_ELLIPSE: iFigure = LOWORD (wParam) ; CheckRadioButton (hDlg, IDC_RECT, IDC_ELLIPSE, LOWORD (wParam)) ; PaintTheBlock (hCtrlBlock, iColor, iFigure) ; return TRUE ; } break ; case WM_PAINT: PaintTheBlock (hCtrlBlock, iColor, iFigure) ; break ; } return FALSE ; }