我想写一个程序要使鼠标在窗口外移动时也能捕获鼠标在屏幕上的位置坐标,可是总是不能实现如果将SetCapture(hdlg)放在WM_LBUTTONDOWN 消息下然后在WM_MOUSEMOVE判断就能在窗口外捕获鼠标 而如果将SetCapture(hdlg)直接放在WM_MOUSEMOVE消息下就不能在窗口外捕获鼠标 请各位指点一下究竟是什么原因 谢谢!如下:
case WM_LBUTTONDOWN :
ptBeg.x = ptEnd.x = LOWORD (lParam) ;
ptBeg.y = ptEnd.y = HIWORD (lParam) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
SetCapture (hwnd) ;
SetCursor (LoadCursor (NULL, IDC_CROSS)) ;
fBlocking = TRUE ;
return 0 ;
case WM_MOUSEMOVE :
if (fBlocking)
{ SetCapture (hwnd) ;
SetCursor (LoadCursor (NULL, IDC_CROSS)) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
ptEnd.x = LOWORD (lParam) ;
ptEnd.y = HIWORD (lParam) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
}
return 0 ;上述代码就能捕获 而以下代码就不能捕获 case WM_LBUTTONDOWN :
ptBeg.x = ptEnd.x = LOWORD (lParam) ;
ptBeg.y = ptEnd.y = HIWORD (lParam) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
SetCursor (LoadCursor (NULL, IDC_CROSS)) ;
fBlocking = TRUE ;
return 0 ;
case WM_MOUSEMOVE :
{ SetCapture (hwnd) ;
SetCursor (LoadCursor (NULL, IDC_CROSS)) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
ptEnd.x = LOWORD (lParam) ;
ptEnd.y = HIWORD (lParam) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
}
return 0 ;
case WM_LBUTTONDOWN :
ptBeg.x = ptEnd.x = LOWORD (lParam) ;
ptBeg.y = ptEnd.y = HIWORD (lParam) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
SetCapture (hwnd) ;
SetCursor (LoadCursor (NULL, IDC_CROSS)) ;
fBlocking = TRUE ;
return 0 ;
case WM_MOUSEMOVE :
if (fBlocking)
{ SetCapture (hwnd) ;
SetCursor (LoadCursor (NULL, IDC_CROSS)) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
ptEnd.x = LOWORD (lParam) ;
ptEnd.y = HIWORD (lParam) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
}
return 0 ;上述代码就能捕获 而以下代码就不能捕获 case WM_LBUTTONDOWN :
ptBeg.x = ptEnd.x = LOWORD (lParam) ;
ptBeg.y = ptEnd.y = HIWORD (lParam) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
SetCursor (LoadCursor (NULL, IDC_CROSS)) ;
fBlocking = TRUE ;
return 0 ;
case WM_MOUSEMOVE :
{ SetCapture (hwnd) ;
SetCursor (LoadCursor (NULL, IDC_CROSS)) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
ptEnd.x = LOWORD (lParam) ;
ptEnd.y = HIWORD (lParam) ;
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
}
return 0 ;
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