Windows应用程序对键盘与鼠标的响应

编写程序: 设计一个窗口, 当单击鼠标左键时, 窗口中显示"LEFT BUTTON"; 当单击鼠标右键时, 窗口中显示"RIGHT BUTTON"; 当单击向上箭头键时, 窗口中显示"UP Key"; 当单击Ctrl键时, 窗口中显示"CTRL Key"; 当单击 Ctrl+A 键时, 窗口中显示"CTRL+A Key": 程序主要代码如下: LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {     int wmId, wmEvent;     PAINTSTRUCT ps;     HDC hDC;     //TCHAR szHello[MAX_LOADSTRING];     //LoadString(hInst, IDS_HELLO, szHello, MAX_LOADSTRING);     static char cLEFT[]="LEFT BUTTON";     static char cRIGHT[]="RIGHT BUTTON";     static char cUp[]="UP key";     static char cCTRL[]="CTRL key";     static char cCTRLA[]="CTRL+A key";     static BOOL nUpKeyDown=FALSE, nCtrlKeyDown=FALSE, nCtrlAKeyDown=FALSE,nLeftDown=FALSE,nRightDown=FALSE;     int xOrg,yOrg;     switch (message)     {         case WM_KEYDOWN:         {             switch(wParam)             {             case VK_UP:                 nUpKeyDown=TRUE;                 break;             case VK_CONTROL:                 nCtrlKeyDown=TRUE;                 break;                          default:                 break;             }         }             break;           case WM_KEYUP:             InvalidateRect(hWnd,NULL,TRUE);    //刷新用户区。             break;         case WM_CHAR:             {                     if(wParam==(65&VK_CONTROL))                         {                         if(nCtrlKeyDown == TRUE)                         {                             nCtrlAKeyDown = TRUE;                             nCtrlKeyDown = FALSE;                         }                     }                                      }                 break;         case WM_LBUTTONDOWN:             nLeftDown=TRUE;             InvalidateRect(hWnd,NULL,TRUE);    //刷新用户区。             break;         case WM_RBUTTONDOWN:             nRightDown=TRUE;             InvalidateRect(hWnd,NULL,TRUE);    //刷新用户区。             break;           case WM_COMMAND:             wmId = LOWORD(wParam);             wmEvent = HIWORD(wParam);             // Parse the menu selections:             switch (wmId)             {                 case IDM_ABOUT:                  DialogBox(hInst, (LPCTSTR)IDD_ABOUTBOX, hWnd, (DLGPROC)About);                  break;                 case IDM_EXIT:                  DestroyWindow(hWnd);                  break;                 default:                  return DefWindowProc(hWnd, message, wParam, lParam);             }             break;         case WM_PAINT:             hDC = BeginPaint(hWnd, &ps);             // TODO: Add any drawing code here...             RECT rt;             GetClientRect(hWnd, &rt);             xOrg=(rt.left+rt.right)/2;             yOrg=(rt.top +rt.bottom)/2;             if(nUpKeyDown == TRUE)             {                 TextOut(hDC,xOrg,yOrg,cUp,strlen(cUp));                 nUpKeyDown = FALSE;

（续前表） }             else if(nCtrlAKeyDown == TRUE)             {                 TextOut(hDC,xOrg,yOrg,cCTRLA,strlen(cCTRLA));                 nCtrlAKeyDown = FALSE;                 nCtrlKeyDown = FALSE;             }             else if(nCtrlKeyDown == TRUE&&nCtrlAKeyDown == FALSE)             {                 TextOut(hDC,xOrg,yOrg,cCTRL,strlen(cCTRL));                 nCtrlKeyDown = FALSE;             }             else if(nLeftDown == TRUE)             {                 TextOut(hDC,xOrg,yOrg,cLEFT,strlen(cLEFT));                 nLeftDown = FALSE;             }             else if(nRightDown == TRUE)             {                 TextOut(hDC,xOrg,yOrg,cRIGHT,strlen(cRIGHT));                 nRightDown = FALSE;             }                    //DrawText(hdc, lpString, _tcsclen(lpString), &rt, DT_CENTER);             EndPaint(hWnd, &ps);             break;         case WM_DESTROY:             PostQuitMessage(0);             break;         default:             return DefWindowProc(hWnd, message, wParam, lParam); } return 0; }   编译并调试程序

程序运行结果运行结果如下图： 单击鼠标左键 单击鼠标右键 单击向上箭头 单击Ctrl键 单击Ctrl+A 刚开始刷新客户区时使用 InvalidateRect(hWnd,NULL,FALSE); 结果导致背景客户区背景不更新，输出的文本重叠，了解了InvalidateRect()的使用方式后，将语句改为 InvalidateRect(hWnd,NULL,TRUE); 即成功解决了问题；