import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Point;

import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;


public abstract class GraphicsFunction implements GraphicsObject      ,
                                                  MouseListener       ,
                                                  MouseMotionListener {

    protected Container container = null;

    protected Point startPoint = new Point(0, 0);
    protected Point prevPoint  = new Point(0, 0);
    protected Point currPoint  = new Point(0, 0);

    protected Color color = Color.black;

    protected boolean done = true;


    ////////////////////////////////////////
    // MouseListener Methods

    public void mouseReleased( MouseEvent e ) {

	currPoint.x = e.getX();
	currPoint.y = e.getY();

	done = true;
	draw( );

	container.removeMouseListener( this );
	container.removeMouseMotionListener( this );
    }

    public void mousePressed( MouseEvent e ) { }

    public void mouseClicked( MouseEvent e ) { }
    
    public void mouseEntered( MouseEvent e ) { }
    
    public void mouseExited( MouseEvent e )  { }


    ////////////////////////////////////////
    // MouseMotionListener Methods

    public void mouseDragged( MouseEvent e ) {

	prevPoint.x = currPoint.x;
	prevPoint.y = currPoint.y;

	currPoint.x = e.getX();
	currPoint.y = e.getY();
    
	draw( );
    }


    public void mouseMoved( MouseEvent e ) { }


    ////////////////////////////////////////
    // GraphicsFunction Methods

    public void setColor( Color c ) {
	color = c;
    }
						      
    public void setContainer( Container container ) {
	this.container = container;

	this.container.addMouseListener( this );
	this.container.addMouseMotionListener( this );
    }
						      
    public void setLocation( int x, int y ) {

	startPoint.x = x;
	startPoint.y = y;

	currPoint.x  = x;
	currPoint.y  = y;
	
	prevPoint.x  = x;
	prevPoint.y  = y;

	done = false;
    }


    public void draw( ) {
	Graphics g = container.getGraphics( );

	if (done == false) {

	    Color background = container.getBackground();

	    g.setColor( color );
	    g.setXORMode( background );

	    drawClear( g );
	    drawFinal( g );

	} else {

	    g.setColor( color );
	    g.setPaintMode( );

	    drawFinal( g );
	}

	g.dispose( );
    }

    
    protected abstract void drawClear( Graphics g );
    protected abstract void drawFinal( Graphics g );

}