CPaintDC in CStatic not cutting of drawing

Question

My OnPaint() method in a derived CStatic-control is supposed to be cutting of parts of the drawing which are bigger than the control, as far as I know. However it doesn't do this.

void CGraph::OnPaint ()
{
   CPaintDC dc(this);
   dc.SetViewportOrg (0, 400);
   dc.SetMapMode(MM_ISOTROPIC);
   dc.SetWindowExt(1000, 800);
   dc.SetViewportExt(1000, -800);

   // MessageBox(L"OnPaint");
   ProcessData ();
   DrawCoordinateSystem (&dc);
   DrawGrid (&dc);
   DrawGraph (&dc);
}

Answer 1

@JohnCz Got it now.

CDC* pDC = GetDC();
CRect rClient();
GetClientRect(rClient);
CRgn ClipRgn;
if (ClipRgn.CreateRectRgnIndirect(&rClient))
{
    pDC->SelectClipRgn(&ClipRgn);
}


// Drawing content


pDC->SelectClipRgn(NULL);
ReleaseDC(pDC);

Thanks for your answer