Generating Contours C#

[JohnNelson3]

Is there an easy way to generate contours from a DEM based on the screen extent rather than DEM extent? Do I need to clip the DEM first or is there a faster method?

http://resources.esri.com/help/9.3/arcgisdesktop/com/gp_toolref/spatial_analyst_tools/contour.htm
http://help.arcgis.com/en/sdk/10.0/arcobjects_net/componenthelp/index.html#//0024000000n300000