SetViewPortExt( hDC, nWidth, nHeight )-> <aPrevDimensions>
------------------------------------------------------------------------------


 PARAMETER:

  <hDC>                Identifies the device context

  <nWidth .. nHeight>  Specifies the y-extent and x-extent, in device
                       units, of the viewport.


 RETURNS:

  <aPrevDimensions> is an array with the previous dimensions {nWidth,nHeight}


 DESCRIPTION:

  The SetViewportExt function sets the x- and y-extents of the viewport of
  the given device context. The viewport, along with the window, defines
  how points are converted from logical coordinates to device coordinates. 

  The x- and y-extents of the window define how much the graphics device
  interface (GDI) must stretch or compress units in the logical coordinate
  system to fit units in the device coordinate system. For example, if the
  x-extent of the window is 2 and the x-extent of the viewport is 4, GDI
  converts two logical units (measured from the x-axis) into four device
  units. Similarly, if the y-extent of the window is 2 and the y-extent of
  the viewport is -1, GDI converts two logical units (measured from the
  y-axis) into one device unit. 

  The extents also define the relative orientation of the x- and y-axes in
  both coordinate systems. If the signs of matching window and viewport
  extents are the same, the axes have the same orientation. If the signs are
  different, the orientation is reversed. For example, if the y-extent of 
  the window is 2 and the y-extent of the viewport is -1, GDI converts the
  positive y-axis in the logical coordinate system to the negative y-axis in
  the device coordinate system. If the x-extents are 2 and 4, GDI converts
  the positive x-axis in the logical coordinate system to the positive
  x-axis in the device coordinate system. 

 SOURCE:

  SOURCE\WINAPI\DC.C