//  MovingBallApplet.java  (c) Kari Laitinen

//  http://www.naturalprogramming.com

//  2001-03-31  File created.
//  2009-11-05  Latest modification.

//  This program is a Java applet that draws a ball
//  onto the screen. There is also a "control panel" which provides
//  buttons to move the ball and a possibility to change the
//  color of the ball.

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

public class MovingBallApplet extends    JApplet
                              implements ActionListener,
                                         ItemListener
{
   JButton  left_button, up_button, down_button, right_button ;

   int  applet_width, applet_height ;

   int  ball_center_point_x, ball_center_point_y ;

   Color  current_ball_color   =  Color.red ;

   public void init()
   {
      setLayout( new BorderLayout() ) ;

      JPanel operations_panel  =  new  JPanel() ;

      left_button     =  new JButton( " < " ) ;
      up_button       =  new JButton( " Up " ) ;
      down_button     =  new JButton( " Down " ) ;
      right_button    =  new JButton( " > " ) ;

      left_button.addActionListener( this ) ;
      up_button.addActionListener( this ) ;
      down_button.addActionListener( this ) ;
      right_button.addActionListener( this ) ;

      operations_panel.add( left_button ) ;
      operations_panel.add( up_button ) ;
      operations_panel.add( down_button ) ;
      operations_panel.add( right_button ) ;

      JComboBox  color_selection_menu  =  new JComboBox() ;

      color_selection_menu.addItem( "red" ) ;
      color_selection_menu.addItem( "orange" ) ;
      color_selection_menu.addItem( "yellow" ) ;
      color_selection_menu.addItem( "green" ) ;
      color_selection_menu.addItem( "blue" ) ;
      color_selection_menu.addItem( "magenta" ) ;
      color_selection_menu.addItem( "cyan" ) ;
      color_selection_menu.addItem( "pink" ) ;
      color_selection_menu.addItem( "lightGray" ) ;

      color_selection_menu.addItemListener( this ) ;

      operations_panel.add( color_selection_menu ) ;

      add( "South", operations_panel ) ;


      //  Let's get the size of the applet (defined in .html file)

      applet_width   =  getSize().width ;
      applet_height  =  getSize().height ;

      ball_center_point_x  =  applet_width / 2 ;
      ball_center_point_y  =  applet_height / 2 ;

   }

   public void actionPerformed( ActionEvent event )
   {
      if ( event.getSource() instanceof JButton )
      {
         if ( event.getSource()  ==  left_button )
         {
            ball_center_point_x  -=  3 ;
         }
         else if ( event.getSource()  ==  up_button )
         {
            ball_center_point_y  -=  3 ;
         }
         else if ( event.getSource()  ==  down_button )
         {
            ball_center_point_y  +=  3 ;
         }
         else if ( event.getSource()  ==  right_button )
         {
            ball_center_point_x  +=  3 ;
         }

         repaint() ;
      }
   }

   public void itemStateChanged( ItemEvent menu_selection )
   {
      String selected_color  =  (String) menu_selection.getItem() ;

      if ( selected_color.equals( "red" ) )
      {
         current_ball_color  =  Color.red ;
      }
      else if ( selected_color.equals( "orange" ) )
      {
         current_ball_color  =  Color.orange ;
      }
      else if ( selected_color.equals( "yellow" ) )
      {
         current_ball_color  =  Color.yellow ;
      }
      else if ( selected_color.equals( "green" ) )
      {
         current_ball_color  =  Color.green ;
      }
      else if ( selected_color.equals( "blue" ) )
      {
         current_ball_color  =  Color.blue ;
      }
      else if ( selected_color.equals( "magenta" ) )
      {
         current_ball_color  =  Color.magenta ;
      }
      else if ( selected_color.equals( "cyan" ) )
      {
         current_ball_color  =  Color.cyan ;
      }
      else if ( selected_color.equals( "pink" ) )
      {
         current_ball_color  =  Color.pink ;
      }
      else if ( selected_color.equals( "lightGray" ) )
      {
         current_ball_color  =  Color.lightGray ;
      }

      repaint() ;
   }

   public void paint( Graphics graphics )
   {
      //  The superclass version of paint() method draws the buttons
      //  and the color selection menu to the screen.

      super.paint( graphics ) ;

      graphics.setColor( current_ball_color ) ;

      graphics.fillOval( ball_center_point_x - 50, ball_center_point_y - 50,
                         100, 100 ) ;

      graphics.setColor( Color.black ) ;

      graphics.drawString( "("   +  ball_center_point_x  +
                           ", "  +  ball_center_point_y  +
                           ")",  20, 20 ) ;

      graphics.drawOval( ball_center_point_x - 50, ball_center_point_y - 50,
                         100, 100 ) ;
   }
}