question: protected void drawAxisLine ( Graphics2D g2 , double cursor , Rectangle2D dataArea , RectangleEdge edge ) { Line2D axisLine = null ; double x = dataArea . getX ( ) ; double y = dataArea . getY ( ) ; if ( edge == RectangleEdge . TOP ) { axisLine = new Line2D . Double ( x , cursor , dataArea . getMaxX ( ) , cursor ) ; } else if ( edge == RectangleEdge . BOTTOM ) { axisLine = new Line2D . Double ( x , cursor , dataArea . getMaxX ( ) , cursor ) ; } else if ( edge == RectangleEdge . LEFT ) { axisLine = new Line2D . Double ( cursor , y , cursor , dataArea . getMaxY ( ) ) ; } else if ( edge == RectangleEdge . RIGHT ) { axisLine = new Line2D . Double ( cursor , y , cursor , dataArea . getMaxY ( ) ) ; } g2 . setPaint ( this . axisLinePaint ) ; g2 . setStroke ( this . axisLineStroke ) ; Object saved = g2 . getRenderingHint ( RenderingHints . KEY_STROKE_CONTROL ) ; g2 . setRenderingHint ( RenderingHints . KEY_STROKE_CONTROL , RenderingHints . VALUE_STROKE_NORMALIZE ) ; g2 . draw ( axisLine ) ; g2 . setRenderingHint ( RenderingHints . KEY_STROKE_CONTROL , saved ) ; }
target:  Draws an axis line at the current cursor position and edge.