//Purpose:  Create an applet that will listen to Mouse Events
// so that whenever the user clicks down on the mouse and
// drags it and clicks up...a straignt line will be drawn
// from the points of where they clicked down and clicked up.
// Also, a current straigth line is drawn as the user is
// dragging the mouse from the start (clicked down) to the
// currently dragged position.  You may assume that a maximum
// of 20 lines will be draw on the Applet's graphics.

import java.awt.*;
import java.applet.*;
import java.awt.event.*;


public class test9 extends Applet implements MouseListener,MouseMotionListener{


    //Variables
    Point Start[] = new Point[20];   //X,Y info of start of lines
    Point End[] = new Point[20];     //X,Y info of end of lines
    Point current_start; 
    Point current_point; 
    int numlines= 0;
    Point boundary;   //to represent the boundary of the applet

    
    //Set background to yellow, register listeners
    // get boundary of applet
    public void init() {
      setBackground(Color.yellow);
      addMouseListener(this);
      addMouseMotionListener(this);
      current_point = null;
      boundary = new Point(this.size().width,this.size().height);
    }

   
    //Mouse Clicked Down...save in current_start
    public void mousePressed(MouseEvent e) {
       if(numlines < 20)
          current_start = new Point(e.getX(), e.getY()); 
       else
          System.out.println("Can Not Take Any More Input Lines");
    }

    //Mouse Drag....reset current_point to current position
    public void mouseDragged(MouseEvent e) {
        if(numlines <20) {
          current_point = new Point(e.getX(), e.getY());
          repaint();  //will draw this current line
        }
    }

    //Mouse Up ...save created line if can and call repaint 
    //  to draw it.  Make sure the end point is inside the applet
    public void mouseReleased(MouseEvent e) {
       if( (numlines < 20) && (e.getX() < boundary.x) &&
           (e.getY() < boundary.y) )
         {  Start[numlines] = current_start;
            End[numlines] = new Point(e.getX(), e.getY());
            numlines++;
            //Reset current points to empty
            current_point = null;
            current_start = null;
            //repaint will draw all lines including this one
            // just created.
            repaint();
          }
     }

                 


    //Draw all of the lines stored in Start[], End[].
    //Draw the current line from current_start to current_point 
    public void paint(Graphics g) {
         //set drawing color
         g.setColor(Color.red);
      
         //Draw stored lines
         for (int i=0; i<numlines; i++) {
            g.drawLine(Start[i].x, Start[i].y,
                       End[i].x, End[i].y);
          }

         //Draw current line if one exists
         g.setColor(Color.blue);
         if (current_point != null)
            g.drawLine(current_start.x, current_start.y, 
                       current_point.x, current_point.y);
      

    }

    
   
    //Set numlines back to zero
   public void start() {
       numlines=0;
   }

   //In case mouse exits the applet region...reset current points
   public void mouseExited(MouseEvent e) {
        current_point = null; }


    //OTHER methods need to implement interfaces DO NOTHING
    public void mouseMoved(MouseEvent e) {}
    public void mouseClicked(MouseEvent e) {}
    public void mouseEntered(MouseEvent e) {}
   


}