Basic Commands

• (open-graphics)
  Initializes the library's graphics routines. It must be called before any other graphics operations.
• (close-graphics)
  Closes all of the windows and until open-graphics is called again, no graphics routines will work.
• (open-viewport name horiz vert)
  Takes a string name and integers horiz and vert and creates a new window called name. The window is horiz pixels wide and vert pixels high. The scale value is used for all drawing commands, so the drawing area is horix by vert units. The scale argument can be omitted; it defaults to 1.0. For backward compatibility, a single posn value (see below) can be submitted in the place of horiz and vert. (In this case, the scale argument is not allowed.) open-viewport returns a viewport descriptor.
• (open-pixmap name horiz vert scale)
  Like open-viewport, but the resulting viewport is not displayed on the screen. Offscreen pixmaps are useful for executing a sequence of drawing commands and displaying them all at once with copy-viewport.
• (close-viewport viewport)
  Takes a viewport descriptor. It removes the viewport from the screen and makes subsequent operations dealing with the viewport illegal.
• (set-viewport-scale viewport scale)
  Takes a viewport descriptor and a scale factor. It clears the viewport and changes its scale for drawing commands.