想要达到的效果:鼠标按下为起始点,鼠标移动时画线(要清除上次绘制的直线再绘制),鼠标松开时,清除直线。
坐标指针POINT down,move,up;
能否指点一下,如何实现“清除上次绘制的直线再绘制”
PS:google的网页,一般都是用VC写的,SetROP2函数,还是有些看不懂,能否给个winAPI的代码呢?
坐标指针POINT down,move,up;
能否指点一下,如何实现“清除上次绘制的直线再绘制”
PS:google的网页,一般都是用VC写的,SetROP2函数,还是有些看不懂,能否给个winAPI的代码呢?
m_textStart=point;
m_textCurrent=point;
MouseMove的时候画两次:
pDC->Rectangle(m_textStart.x, m_textStart.y,m_textCurrent.x, m_textCurrent.y);
m_textCurrent=point;
pDC->Rectangle(m_textStart.x, m_textStart.y,point.x, point.y);//绘新图形
Up的时候再画一次:
pDC->Rectangle(pOldPoint.x, pOldPoint.y, point.x, point.y);
pDC->Rectangle(m_textStart.x, m_textStart.y, point.x, point.y);
LineTo(hdc,ptBeg.x+50,ptBeg.y);
MoveToEx(hdc,ptEnd.x,ptEnd.y,NULL);
LineTo(hdc,ptEnd.x+50,ptEnd.y);
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 = 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)
{
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_LBUTTONUP :
if (fBlocking)
{
DrawBoxOutline (hwnd, ptBeg, ptEnd) ;
ptBoxBeg = ptBeg ;
ptBoxEnd.x = LOWORD (lParam) ;
ptBoxEnd.y = HIWORD (lParam) ;
ReleaseCapture () ;
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 () ;
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) ;
}