Getting Started > For Beginners > Zooming In on a Selection > Zooming In on a Selection: Step 4

Zooming In on a Selection: Step 4

HDC ThisWindowDC; 
/* Use GDI functions to outline the area to be cropped. */ 
if (nFlags == MK_LBUTTON) 
{ 
   ThisWindowDC = ::GetDC(this->m_hWnd); 
   SavedPen = (HPEN)::SelectObject(ThisWindowDC, GetStockObject(WHITE_PEN)); 
   SavedBrush = (HBRUSH)::SelectObject(ThisWindowDC, GetStockObject(NULL_BRUSH)); 
   DisplayMode = GetROP2(ThisWindowDC); 
   SetROP2(ThisWindowDC, R2_NOT); 
   if (FirstDraw == FALSE) 
      Rectangle(ThisWindowDC, StartGDIX, StartGDIY, EndGDIX, EndGDIY); 
   EndGDIX = point.x; 
   EndGDIY = point.y; 
   Rectangle(ThisWindowDC, StartGDIX, StartGDIY, EndGDIX, EndGDIY); 
   FirstDraw = FALSE; 
   SetROP2(ThisWindowDC, DisplayMode); 
   ::ReleaseDC(this->m_hWnd, ThisWindowDC); 
}