code: @Override
      protected boolean prepare(final Context2D context, final Attributes attr, final double alpha)
      {
          final double ord = attr.getOuterRadius();
  
          final double ird = attr.getInnerRadius();
  
          if ((ord > 0) && (ird > 0) && (ord > ird))
          {
              context.beginPath();
  
              context.arc(0, 0, ord, 0, Math.PI * 2, false);
  
              context.arc(0, 0, ird, 0, Math.PI * 2, true);
  
              context.closePath();
  
              return true;
          }
          return false;
      }
docs: Draws this slice.
  
  @param context