鼠标(4)

看看这个简单的程序(还需要改进)

#include<windows.h>#include<windowsx.h>#define DIVISIONS 5LRESULT CALLBACK WindowProc(  HWND hwnd,      // handle to window  UINT uMsg,      // message identifier  WPARAM wParam,  // first message parameter  LPARAM lParam   // second message parameter);int WINAPI WinMain(  HINSTANCE hInstance,      // handle to current instance  HINSTANCE hPrevInstance,  // handle to previous instance  LPSTR lpCmdLine,          // command line  int nCmdShow              // show state){static TCHAR szAppName[]=TEXT("leidemingzi");HWND hwnd;MSG msg;WNDCLASS wndclass;wndclass.cbClsExtra=0;wndclass.cbWndExtra=0;wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);wndclass.hIcon=LoadIcon(NULL,IDI_ERROR);wndclass.hInstance=hInstance;wndclass.lpfnWndProc=WindowProc;wndclass.lpszClassName=szAppName;wndclass.lpszMenuName=NULL;wndclass.style=CS_HREDRAW|CS_VREDRAW;if(!RegisterClass(&wndclass)){MessageBox(NULL,TEXT("the program require window NT"),TEXT("just tip"),MB_ICONERROR);return 0;}hwnd=CreateWindow(   szAppName,  // registered class name  TEXT("this is title"), // window name  WS_OVERLAPPEDWINDOW,        // window style  CW_USEDEFAULT,                // horizontal position of window  CW_USEDEFAULT,                // vertical position of window  CW_USEDEFAULT,           // window width  CW_USEDEFAULT,          // window height  NULL,      // handle to parent or owner window  NULL,          // menu handle or child identifier  hInstance,  // handle to application instance  NULL        // window-creation data);ShowWindow(hwnd,nCmdShow);UpdateWindow(hwnd);while(GetMessage(&msg,NULL,0,0)){TranslateMessage(&msg);DispatchMessage(&msg);}return msg.wParam;}void DrawBoxOutLine(HWND hwnd,POINT ptBeg,POINT ptEnd)//定义个画矩形的函数{HDC hdc;hdc=GetDC(hwnd);SetROP2(hdc,R2_NOT);//设置画笔SelectObject(hdc,GetStockObject(NULL_BRUSH));//不使用画刷Rectangle(hdc,ptBeg.x,ptBeg.y,ptEnd.x,ptEnd.y);//画矩形ReleaseDC(hwnd,hdc);}LRESULT CALLBACK WindowProc(  HWND hwnd,      // handle to window  UINT uMsg,      // message identifier  WPARAM wParam,  // first message parameter  LPARAM lParam   // second message parameter){static BOOL fBlocking,fValidBox;static POINT ptBeg,ptEnd,ptBoxBeg,ptBoxEnd;HDC hdc;PAINTSTRUCT ps;switch(uMsg){case WM_LBUTTONDOWN:ptBeg.x=ptEnd.x=GET_X_LPARAM(lParam);//获取开始坐标ptBeg.y=ptEnd.y=GET_Y_LPARAM(lParam);DrawBoxOutLine(hwnd,ptBeg,ptEnd);//画矩形，其实不要这句也行SetCursor(LoadCursor(NULL,IDC_CROSS));//把鼠标设置成为十字形状fBlocking=TRUE;//设标志为真return 0;case WM_MOUSEMOVE:if(fBlocking)//判断是否按下鼠标左键{SetCursor(LoadCursor(NULL,IDC_CROSS));//设置鼠标为十字形状DrawBoxOutLine(hwnd,ptBeg,ptEnd);//画矩形ptEnd.x=GET_X_LPARAM(lParam);//不断的获取移动后的坐标(矩形的右下方坐标)ptEnd.y=GET_Y_LPARAM(lParam);DrawBoxOutLine(hwnd,ptBeg,ptEnd);//不断的画矩形}return 0;case WM_LBUTTONUP:if(fBlocking)//判断是否先有按下鼠标{DrawBoxOutLine(hwnd,ptBeg,ptEnd);//画出矩形ptBoxBeg=ptBeg;ptBoxEnd.x=GET_X_LPARAM(lParam);//获取终点坐标ptBoxEnd.y=GET_Y_LPARAM(lParam);SetCursor(LoadCursor(NULL,IDC_ARROW));//设置鼠标为正常状态fBlocking=FALSE;//设置标志为假fValidBox=TRUE;InvalidateRect(hwnd,NULL,TRUE);//使矩形区域无效，触发WM_PAINT事件}return 0;case WM_CHAR:if(fBlocking & (wParam=='\x1B'))//是否为ESC键{DrawBoxOutLine(hwnd,ptBeg,ptEnd);SetCursor(LoadCursor(NULL,IDC_ARROW));fBlocking=FALSE;//设置标志为假}return 0;case WM_PAINT:hdc=BeginPaint(hwnd,&ps);if(fValidBox){SelectObject(hdc,GetStockObject(BLACK_BRUSH));//设置黑色画刷Rectangle(hdc,ptBoxBeg.x,ptBoxBeg.y,ptBoxEnd.x,ptBoxEnd.y);//填充矩形}if(fBlocking){SetROP2(hdc,R2_NOT);SelectObject(hdc,GetStockObject(NULL_BRUSH));Rectangle(hdc,ptBeg.x,ptBeg.y,ptEnd.x,ptEnd.y);}EndPaint(hwnd,&ps);return 0;case WM_DESTROY:PostQuitMessage(0);return 0;}return DefWindowProc(hwnd,uMsg,wParam,lParam);}

在客户区可以任意画矩形，然后自动用黑色画刷去填充，但是鼠标不能超过窗口边界，否则，你自己调试吧

 

下面这个是改进版的：只在上面的函数增加了三行.

使用了SetCapture和ReleaseCapture函数

#include <windows.h>#include <windowsx.h>LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,                    PSTR szCmdLine, int iCmdShow){     static TCHAR szAppName[] = TEXT ("BlokOut2") ;     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 ;     }          hwnd = CreateWindow (szAppName, TEXT ("Mouse Button & Capture 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 ;}void DrawBoxOutline (HWND hwnd, POINT ptBeg, POINT ptEnd){     HDC hdc ;          hdc = GetDC (hwnd) ;          SetROP2 (hdc, R2_NOT) ;     SelectObject (hdc, GetStockObject (NULL_BRUSH)) ;     Rectangle (hdc, ptBeg.x, ptBeg.y, ptEnd.x, ptEnd.y) ;          ReleaseDC (hwnd, hdc) ;}LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam){     static BOOL  fBlocking, fValidBox ;     static POINT ptBeg, ptEnd, ptBoxBeg, ptBoxEnd ;     HDC          hdc ;     PAINTSTRUCT  ps ;          switch (message)     {     case WM_LBUTTONDOWN :          ptBeg.x = ptEnd.x = GET_X_LPARAM (lParam) ;          ptBeg.y = ptEnd.y = GET_Y_LPARAM (lParam) ;                    DrawBoxOutline (hwnd, ptBeg, ptEnd) ;                    SetCapture (hwnd) ;//新增加的          SetCursor (LoadCursor (NULL, IDC_CROSS)) ;                    fBlocking = TRUE ;          return 0 ;               case WM_MOUSEMOVE :          if (fBlocking)          {               SetCursor (LoadCursor (NULL, IDC_CROSS)) ;                              DrawBoxOutline (hwnd, ptBeg, ptEnd) ;                              ptEnd.x = GET_X_LPARAM (lParam) ;               ptEnd.y = GET_Y_LPARAM (lParam) ;                              DrawBoxOutline (hwnd, ptBeg, ptEnd) ;          }          return 0 ;               case WM_LBUTTONUP :          if (fBlocking)          {               DrawBoxOutline (hwnd, ptBeg, ptEnd) ;                              ptBoxBeg   = ptBeg ;               ptBoxEnd.x = GET_X_LPARAM (lParam) ;               ptBoxEnd.y = GET_Y_LPARAM (lParam) ;                              ReleaseCapture () ;//新增加的               SetCursor (LoadCursor (NULL, IDC_ARROW)) ;                              fBlocking = FALSE ;               fValidBox  = TRUE ;                              InvalidateRect (hwnd, NULL, TRUE) ;          }          return 0 ;               case WM_CHAR :          if (fBlocking & (wParam == '\x1B'))     // i.e., Escape          {               DrawBoxOutline (hwnd, ptBeg, ptEnd) ;               ReleaseCapture () ;//新增加的               SetCursor (LoadCursor (NULL, IDC_ARROW)) ;                              fBlocking = FALSE ;          }          return 0 ;               case WM_PAINT :          hdc = BeginPaint (hwnd, &ps) ;                    if (fValidBox)          {               SelectObject (hdc, GetStockObject (BLACK_BRUSH)) ;               Rectangle (hdc, ptBoxBeg.x, ptBoxBeg.y,                               ptBoxEnd.x, ptBoxEnd.y) ;          }                    if (fBlocking)          {               SetROP2 (hdc, R2_NOT) ;               SelectObject (hdc, GetStockObject (NULL_BRUSH)) ;               Rectangle (hdc, ptBeg.x, ptBeg.y, ptEnd.x, ptEnd.y) ;          }                    EndPaint (hwnd, &ps) ;          return 0 ;               case WM_DESTROY :          PostQuitMessage (0) ;          return 0 ;     }     return DefWindowProc (hwnd, message, wParam, lParam) ;}

可以处理鼠标超过边界的问题了：