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 5

LRESULT 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：