MGHGRCOMPOSITEEXAMPLE__DEFINE
Class Name
      MGHgrCompositeExample
Purpose
  
   This class was written as a prototype for a typical composite graphics
  
   object. It implements a grey rectangle with a black outline. It has
      properties LOCATION and DIMENSIONS. It has no practical use.
Category
      Object graphics.
Superclasses
  
   This class inherits from IDLgrModel.
Properties
  
   The following properties are supported: 
    
     DELTAZ (Init,Get,Set) 
      
       Vertical spacing in normalised units between the rectangle and the
      
       outline, needed to ensure the outline is visible. If this property is
      
       not set, then the spacing is set at draw time, based on the view's
      
       ZCLIP property--the value is 2*(ZCLIP[0] - ZCLIP[1])/65536, which
      
       for the default ZCLIP is 6.1E-5. DELTAZ should only need to be
      
       set explicitly if the object or its parent is transformed before
              drawing. 
    
     LOCATION (Init,Get,Set) 
      
       Location of the lower left corner of the rectangle in data units.
          DIMENSIONS (Init,Get,Set) 
      
       Horizontal & vertical dimensions of the rectangle in data units.
          XCOORD_CONV (Init,Get,Set) 
    
     YCOORD_CONV (Init,Get,Set) 
    
     ZCOORD_CONV (Init,Get,Set) 
      
       Coordinate transformations specifying the relationship between
              normalised & data units. 
    
     XRANGE (Get) 
          YRANGE (Get) 
    
     ZRANGE (Get) 
      
       Position of the extremes of the object in data units. ZRANGE is
              not finalised until the object is drawn.
Methods
      The usual. 
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    This software is provided subject to the following conditions:
    1.  NIWA makes no representations or warranties regarding the
    
     accuracy of the software, the use to which the software may
    
     be put or the results to be obtained from the use of the
    
     software.  Accordingly NIWA accepts no liability for any loss
    
     or damage (whether direct of indirect) incurred by any person
          through the use of or reliance on the software.
    2.  NIWA is to be acknowledged as the original author of the
    
     software where the software is used or presented in any form. 
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Modification History
  
   Mark Hadfield, 1998-08: 
          Written. 
  
   Mark Hadfield, 2004-03: 
    
     Overhauled keyword handling and updated for IDL 6.0. 
  
   Mark Hadfield, 2004-07: 
    
     Added support for property registration.