为CHECKER3添加键盘接口就像CHECKER系列构想中的最后一步。但在这样做的时候，可能有更适当的做法。在CHECKER2中，鼠标光标的位置决定按下Spacebar键时哪个区域将获得标记符号。当我们处理子窗口时，我们能从对话框功能中获得提示。在对话框中，带有闪烁的插入符号或点划的矩形的子窗口表示它有输入焦点（当然也可以用键盘进行定位）。
我们不需要把Windows内部已有的对话框处理方式重新写过，我只是要告诉您大致上应该如何在应用程序中仿真对话框。研究过程中，您会发现这样一件事：父窗口和子窗口可能要共享同键盘消息处理。按下Spacebar键和Enter键时，子窗口将锁定复选标记。按下方向键时，父窗口将在子窗口之间移动输入焦点。实际上，当您在子窗口上单击时，情况会有些复杂，这时是父窗口而不是子窗口获得输入焦点。
程序7-5 CHECKER4
CHECKER4.C /*--------------------------------------------------------------------------- CHECKER4.C -- Mouse Hit-Test Demo Program No. 4 (c) Charles Petzold, 1998 ---------------------------------------------------------------------------*/ #include <windows.h> #define DIVISIONS 5 LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; LRESULT CALLBACK ChildWndProc (HWND, UINT, WPARAM, LPARAM) ; int idFocus = 0 ; TCHAR szChildClass[] = TEXT ("Checker4_Child") ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("Checker4") ; 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 ("Program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } wndclass.lpfnWndProc = ChildWndProc ; wndclass.cbWndExtra = sizeof (long) ; wndclass.hIcon = NULL ; wndclass.lpszClassName = szChildClass ; RegisterClass (&wndclass) ; hwnd = CreateWindow (szAppName, TEXT ("Checker4 Mouse Hit-Test Demo"), 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 HWND hwndChild[DIVISIONS][DIVISIONS] ; int cxBlock, cyBlock, x, y ; switch (message) { case WM_CREATE : for (x = 0 ; x < DIVISIONS ; x++) for (y = 0 ; y < DIVISIONS ; y++) hwndChild[x][y] = CreateWindow (szChildClass, NULL, WS_CHILDWINDOW | WS_VISIBLE, 0, 0, 0, 0, hwnd, (HMENU) (y << 8 | x), HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE), NULL) ; return 0 ; case WM_SIZE : cxBlock = LOWORD (lParam) / DIVISIONS ; cyBlock = HIWORD (lParam) / DIVISIONS ; for (x = 0 ; x < DIVISIONS ; x++) for (y = 0 ; y < DIVISIONS ; y++) MoveWindow ( hwndChild[x][y], x * cxBlock, y * cyBlock, cxBlock, cyBlock, TRUE) ; return 0 ; case WM_LBUTTONDOWN : MessageBeep (0) ; return 0 ; // On set-focus message, set focus to child window case WM_SETFOCUS: SetFocus (GetDlgItem (hwnd, idFocus)) ; return 0 ; // On key-down message, possibly change the focus window case WM_KEYDOWN: x = idFocus & 0xFF ; y = idFocus >> 8 ; switch (wParam) { case VK_UP: y-- ; break ; case VK_DOWN: y++ ; break ; case VK_LEFT: x-- ; break ; case VK_RIGHT: x++ ; break ; case VK_HOME: x = y = 0 ; break ; case VK_END: x = y = DIVISIONS - 1 ; break ; default: return 0 ; } x = (x + DIVISIONS) % DIVISIONS ; y = (y + DIVISIONS) % DIVISIONS ; idFocus = y << 8 | x ; SetFocus (GetDlgItem (hwnd, idFocus)) ; return 0 ; case WM_DESTROY : PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; } LRESULT CALLBACK ChildWndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { HDC hdc ; PAINTSTRUCT ps ; RECT rect ; switch (message) { case WM_CREATE : SetWindowLong (hwnd, 0, 0) ; // on/off flag return 0 ; case WM_KEYDOWN: // Send most key presses to the parent window if (wParam != VK_RETURN && wParam != VK_SPACE) { SendMessage (GetParent (hwnd), message, wParam, lParam) ; return 0 ; } // For Return and Space, fall through to toggle the square case WM_LBUTTONDOWN : SetWindowLong (hwnd, 0, 1 ^ GetWindowLong (hwnd, 0)) ; SetFocus (hwnd) ; InvalidateRect (hwnd, NULL, FALSE) ; return 0 ; // For focus messages, invalidate the window for repaint case WM_SETFOCUS: idFocus = GetWindowLong (hwnd, GWL_ID) ; // Fall through case WM_KILLFOCUS: InvalidateRect (hwnd, NULL, TRUE) ; return 0 ; case WM_PAINT : hdc = BeginPaint (hwnd, &ps) ; GetClientRect (hwnd, &rect) ; Rectangle (hdc, 0, 0, rect.right, rect.bottom) ; // Draw the "x" mark if (GetWindowLong (hwnd, 0)) { MoveToEx (hdc, 0, 0, NULL) ; LineTo (hdc, rect.right, rect.bottom) ; MoveToEx (hdc, 0, rect.bottom, NULL) ; LineTo (hdc, rect.right, 0) ; } // Draw the "focus" rectangle if (hwnd == GetFocus ()) { rect.left += rect.right / 10 ; rect.right -= rect.left ; rect.top += rect.bottom / 10 ; rect.bottom -= rect.top ; SelectObject (hdc, GetStockObject (NULL_BRUSH)) ; SelectObject (hdc, CreatePen (PS_DASH, 0, 0)) ; Rectangle (hdc, rect.left, rect.top, rect.right, rect.bottom) ; DeleteObject (SelectObject (hdc, GetStockObject (BLACK_PEN))) ; } EndPaint (hwnd, &ps) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; }