question: public synchronized OMGraphicList prepare ( ) { OMGraphicList list = getList ( ) ; if ( list != null ) { list . clear ( ) ; } else { list = new OMGraphicList ( ) ; } if ( spatialIndex == null ) return list ; try { if ( bufferedList == null ) { bufferedList = getWholePlanet ( ) ; } } catch ( FormatException fe ) { if ( logger . isLoggable ( Level . FINE ) ) { logger . fine ( fe . getMessage ( ) ) ; } return list ; } catch ( IOException ioe ) { if ( logger . isLoggable ( Level . FINE ) ) { logger . fine ( ioe . getMessage ( ) ) ; } return list ; } Projection proj = getProjection ( ) ; Point2D ul = proj . getUpperLeft ( ) ; Point2D lr = proj . getLowerRight ( ) ; double ulLat = ul . getY ( ) ; double ulLon = ul . getX ( ) ; double lrLat = lr . getY ( ) ; double lrLon = lr . getX ( ) ; try { if ( ProjMath . isCrossingDateline ( ulLon , lrLon , proj . getScale ( ) ) ) { if ( logger . isLoggable ( Level . FINE ) ) { logger . fine ( getName ( ) + ": Dateline is on screen" ) ; } double ymin = Math . min ( ulLat , lrLat ) ; double ymax = Math . max ( ulLat , lrLat ) ; checkSpatialIndexEntries ( ulLon , ymin , 180.0d , ymax , list , proj ) ; checkSpatialIndexEntries ( - 180.0d , ymin , lrLon , ymax , list , proj ) ; } else { double xmin = Math . min ( ulLon , lrLon ) ; double xmax = Math . max ( ulLon , lrLon ) ; double ymin = Math . min ( ulLat , lrLat ) ; double ymax = Math . max ( ulLat , lrLat ) ; checkSpatialIndexEntries ( xmin , ymin , xmax , ymax , list , proj ) ; } } catch ( FormatException fe ) { if ( logger . isLoggable ( Level . FINE ) ) { logger . fine ( fe . getMessage ( ) ) ; } } catch ( IOException ioe ) { if ( logger . isLoggable ( Level . FINE ) ) { logger . fine ( ioe . getMessage ( ) ) ; } } return list ; }
target:  This overridden method checks to see if the buffered OMGraphicList is created, and then returns a subset of OMGraphics that are actually on the map. If the buffered OMGraphicList hasn't been created yet, it gets created here.