//  DrawingLinesPanelApplet.java  (c) Kari Laitinen

//  http://www.naturalprogramming.com/

//  2006-01-20  File created.
//  2007-02-28  Last modification.

//  This is the 'Panel' version of DrawingLinesApplet.java

import java.awt.* ;
import java.awt.event.*;
import javax.swing.* ;

class DrawingLinesPanel extends JPanel
                        implements MouseListener, MouseMotionListener
{
   final int MAXIMUM_NUMBER_OF_LINES = 10 ; 
   Point[] starting_points  =  new Point[ MAXIMUM_NUMBER_OF_LINES ] ;
   Point[] ending_points    =  new Point[ MAXIMUM_NUMBER_OF_LINES ] ;
   Point start_of_new_line ;
   Point end_of_new_line ;
   int   number_of_lines    =  0 ;

   public DrawingLinesPanel()
   {
      //  Event listeners must be registered.

      addMouseListener( this ) ;
      addMouseMotionListener( this ) ;
   }

   //  The following dummy methods are needed
   //  to fully implement the listener interfaces.
   public void mouseMoved( MouseEvent event ) {}
   public void mouseClicked( MouseEvent event ) {}
   public void mouseEntered( MouseEvent event ) {}
   public void mouseExited( MouseEvent event ) {}

   public void mousePressed( MouseEvent event )
   {
      if ( number_of_lines  <  MAXIMUM_NUMBER_OF_LINES )
      {
          start_of_new_line  =  event.getPoint() ;
      }
   }

   public void mouseReleased( MouseEvent event )
   {
      if ( number_of_lines  <  MAXIMUM_NUMBER_OF_LINES ) 
      {
        starting_points[ number_of_lines ]  =  start_of_new_line;
        ending_points[ number_of_lines ]    =  event.getPoint() ;
        number_of_lines ++ ;
        end_of_new_line   = null ;
        start_of_new_line = null ;
        repaint() ;
      }
   }

   public void mouseDragged( MouseEvent event )
   {
      if ( number_of_lines  <  MAXIMUM_NUMBER_OF_LINES )
      {
         end_of_new_line = event.getPoint() ;
         repaint();
      }
   }


   public void paintComponent( Graphics graphics )
   {
      //  The superclass version of paintComponent() clears the
      //  component area and does other necessary things.

      super.paintComponent( graphics ) ;

      for ( int line_index  =  0 ;
                line_index  <  number_of_lines ;
                line_index  ++ )
      {
         graphics.drawLine( starting_points[ line_index ].x,
                            starting_points[ line_index ].y,
                            ending_points[ line_index ].x,
                            ending_points[ line_index ].y ) ;
      }

      graphics.setColor( Color.red ) ;

      if ( end_of_new_line != null )
      {
         graphics.drawLine( start_of_new_line.x,
                            start_of_new_line.y,
                            end_of_new_line.x,
                            end_of_new_line.y ) ;
      }

      if ( number_of_lines  ==  MAXIMUM_NUMBER_OF_LINES )
      {
         graphics.drawString( "Cannot draw more lines", 0, 300 ) ;
      }
   }
}


public class DrawingLinesPanelApplet extends JApplet
{
   public void init()
   {
      getContentPane().add( new DrawingLinesPanel() ) ; 
   }
}