Applications also can specify a type of viewing window for the presentation page smaller than the page. This window is known as the graphics field. To define a graphics field, use GpiSetGraphicsField. By default, no graphics field is specified. If a graphics field is defined, the picture assembled within it is the picture that is visible on the output device.
An application can determine the current values for the viewing transformation by calling GpiQueryViewingTransformMatrix, which returns the transformation values in a one-dimensional array representing elements in the MATRIXLF structure. The application can set the values by calling GpiSetViewingTransformMatrix, and passing the transformation values in a one-dimensional array representing elements in MATRIXLF structure.