//  DrawingRectanglesApplet.java  (c) Kari Laitinen

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

//  2004-12-13  File created.
//  2007-03-29  Last modification.

//  This program is very much similar to DrawingLinesApplet.java.
//  The difference between these two programs is that this one draws
//  rectangles while the other one draws lines.

//  This program is able to draw a rectangle "in a correct way" 
//  regardless of the direction to which the mouse moves.
//  Various drawing programs usually produce rectangles in this way.

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

public class DrawingRectanglesApplet extends JApplet
                                     implements MouseListener,
                                                MouseMotionListener
{
   final int MAXIMUM_NUMBER_OF_RECTANGLES = 10 ; 
   Point starting_points[]  =  new Point[ MAXIMUM_NUMBER_OF_RECTANGLES ] ;
   Point ending_points[]    =  new Point[ MAXIMUM_NUMBER_OF_RECTANGLES ] ;
   Point new_starting_point ;
   Point new_ending_point ;
   int   current_number_of_rectangles   =  0 ;

   public void init()
   {
      getContentPane().setBackground( Color.white ) ;

      //  Event listeners must be registered.

      addMouseListener( this ) ;
      addMouseMotionListener( this ) ;
   }

   //  The following dummy functions are needed
   //  to satisfy 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 ( current_number_of_rectangles  <  MAXIMUM_NUMBER_OF_RECTANGLES )
      {
          new_starting_point  =  event.getPoint() ;
      }
   }

   public void mouseReleased( MouseEvent event )
   {
      if ( current_number_of_rectangles  <  MAXIMUM_NUMBER_OF_RECTANGLES ) 
      {
        starting_points[ current_number_of_rectangles ]  =  new_starting_point;
        ending_points[ current_number_of_rectangles ]    =  event.getPoint() ;

        current_number_of_rectangles ++ ;
        new_ending_point    = null ;
        new_starting_point  = null ;
        repaint() ;
      }
   }

   public void mouseDragged( MouseEvent event )
   {
      if ( current_number_of_rectangles  <  MAXIMUM_NUMBER_OF_RECTANGLES )
      {
         new_ending_point = event.getPoint() ;

         repaint();
      }
   }


   //  The following method adjusts coordinates so that the rectangle
   //  is shown "in a correct way" in relation to the mouse movement.

   void draw_rectangle( Graphics graphics,
                        Point starting_point,
                        Point ending_point )
   {
      int drawing_point_x = starting_point.x ;
      int drawing_point_y = starting_point.y ;
      int rectangle_width  = ending_point.x - starting_point.x ;
      int rectangle_height = ending_point.y - starting_point.y ;

      if ( rectangle_width < 0 )
      {
         rectangle_width  = - rectangle_width ;
         drawing_point_x -= rectangle_width ;
      }

      if ( rectangle_height < 0 )
      {
         rectangle_height  =  - rectangle_height ;
         drawing_point_y  -=  rectangle_height ;         
      }

      graphics.drawRect( drawing_point_x,
                         drawing_point_y,
                         rectangle_width,
                         rectangle_height ) ;
   }

   public void paint( Graphics graphics )
   {
      super.paint( graphics ) ;

      for ( int rectangle_index  =  0 ;
                rectangle_index  <  current_number_of_rectangles ;
                rectangle_index  ++ )
      {

         draw_rectangle( graphics,
                         starting_points[ rectangle_index ],
                         ending_points[ rectangle_index ]  ) ;
      }

      graphics.setColor( Color.red ) ;

      if ( new_ending_point != null )
      {
         draw_rectangle( graphics,
                         new_starting_point,
                         new_ending_point ) ;
      }

      if ( current_number_of_rectangles  ==  MAXIMUM_NUMBER_OF_RECTANGLES )
      {
         graphics.drawString( "Cannot draw more rectangles", 0, 300 ) ;
      }
   }
}