C / C++ / MFC

Hi Everyone:
I try to explan folows,and please help me to judge if it is correct or not.
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SetWindowOrgEx(hdc,0,50,NULL);
->map the logical point (0,50) to the device point (0,0)
-><a href="http://mail.ntust.edu.tw/~B9007036/Q_1.gif" target="_blank">result</a>
SetViewportOrgEx(hdc,0,50,NULL);
->map the logical point (0,0) to the device point (0,50)
-><a href="http://mail.ntust.edu.tw/~B9007036/Q_2.gif" target="_blank">result</a>
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But I don't know how to understand and explain when using function 
"SetWindowOrgEx" and "SetViewportOrgEx" together in program like follow:
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case WM_PAINT:
         hdc = BeginPaint (hwnd, &ps) ;

         SetMapMode (hdc, MM_ISOTROPIC) ;
         SetWindowExtEx (hdc, 276, 72, NULL) ;
         SetViewportExtEx (hdc, cxClient, cyClient, NULL) ;
         SetWindowOrgEx (hdc, 138, 36, NULL) ;
         SetViewportOrgEx (hdc, cxClient / 2, cyClient / 2, NULL) ;

         SelectObject (hdc, GetStockObject (NULL_PEN)) ;
         SelectObject (hdc, hBrushRed) ;

         DisplayTime (hdc, f24Hour, fSuppress) ;

         EndPaint (hwnd, &ps) ;
         return 0 ;
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Could someone tell me?Thanks!