import java.applet.*;
import java.awt.*;
import java.util.Vector;

public class Drawing extends Applet
 { static DrawPanel dp;

   public void init()
    { setLayout(new BorderLayout());
      add("Center", dp = new DrawPanel());
      add("South", new Controls(dp));
    }

   public void start()
    { dp.start(); } // start the dp=DrawPanel ie run() it

   public void stop()
    { dp.stop(); }  // kill the dp=DrawPanel thread

   public static void main(String args[]) // only for stand-alone program
    { Frame f = new Frame("Drawing");
      Drawing scr = new Drawing();
      scr.init(); scr.start();

      dp.start(); dp.run();
      f.add("Center", scr);
      f.show();
    }
 }

//----------------------------------------------------------------------------
class Curve
 { public boolean closed; public Vector points; //of class Point (see awt)
   public Curve(boolean closed, int x0, int y0)
    { this.closed = closed;
      points = new Vector(); points.addElement(new Point(x0, y0));
 }  }

//-----------------------------------------------------------------------------
class DrawPanel extends Panel implements Runnable  // the drawing area
 { private Thread kicker;
   private int last_x = 0, last_y = 0, x=0, y=0;
   private int pause = 100;
   private boolean isClosed = false; // ??? closed or open lines
   private Vector lines = new Vector(); // Vector of Curve

   public void faster()
    { pause = (pause*9)/10; if(pause < 10) pause=10;
      repaint();
    }

   public void slower() { pause = (pause*10)/9; repaint(); }

   public void closedOpen() { isClosed = ! isClosed; repaint(); }

   public void clear ()
    { for(int i = 0; i < lines.size(); i++)
         ((Curve)lines.elementAt(i)).points.removeAllElements();
      lines.removeAllElements();
      repaint();
    }

   public void start()
    { kicker = new Thread(this);  kicker.start(); //ie run()
    }

   public void run()
    { Graphics g = getGraphics();
      while(true)
       { try{kicker.sleep(pause); } catch (Exception e) { break; }
	 if((x != last_x) || (y != last_y))
	  { ((Curve)lines.lastElement()).points.addElement(new Point(x, y));
	    repaint(pause); // within this mSec
	    last_x = x; last_y = y;
       }  }
    }

   public void stop() { kicker.stop(); }

   public boolean mouseDown(Event e, int xPos, int yPos)
    { x = xPos; y = yPos; last_x = x; last_y = y;
      Curve c = new Curve(false, x, y);
      lines.addElement(c);
      return true;  // indicate Event was handled
    }

   public boolean mouseDrag(Event e, int xPos, int yPos)
    { x = xPos; y = yPos;
      return true;  // indicate Event was handled
    }

   public boolean mouseUp(Event e, int xPos, int yPos)
    { x = xPos; y = yPos;
      ((Curve)lines.lastElement()).closed = isClosed; repaint();
      return true;  // indicate Event was handled
    }

   public void paint(Graphics g)
    { Dimension d = size();
      g.drawRect(0, 0, d.width-1, d.height-1); // an enclosing rectangle
      if(isClosed) g.drawString("(Closed)", d.width-80, d.height-2);
      else         g.drawString("(Open)",   d.width-80, d.height-2);
      g.drawString("Pause=" + Integer.toString(pause) + "msec", 2, d.height-2);
      int nLines = lines.size();
      for(int i = 0; i < nLines; i++)  // each Curve
       { Curve c = (Curve)lines.elementAt(i);
	 int nPts = c.points.size();
	 Point p1 = (Point)c.points.elementAt(0);
	 for (int j = 0; j < nPts; j++)  // each Point
	  { Point p2 = (Point)c.points.elementAt(j);
	    g.drawLine( p1.x, p1.y, p2.x, p2.y );
	    g.drawLine( p2.x-1, p2.y, p2.x+1, p2.y ); // draw a
	    g.drawLine( p2.x, p2.y-1, p2.x, p2.y+1 ); // small +
	    p1 = p2;
          }
         if( c.closed )
	  { Point p2 = (Point)c.points.elementAt(0);
	    g.drawLine(p1.x, p1.y, p2.x, p2.y);
       }  }
    } // end paint()
 }

//-----------------------------------------------------------------------------
class Controls extends Panel  // the control panel for faster, slower and clear
 { DrawPanel drawPanel;
   Button faster, slower, closedOpen, clear;

   public Controls(DrawPanel d)
    { drawPanel = d;
      setLayout(new FlowLayout());
      add(faster = new Button("faster"));
      add(slower = new Button("slower"));
      add(closedOpen = new Button("closed/open"));
      add(clear  = new Button("clear" ));
    }

   public boolean action(Event e, Object arg)
    {      if( e.target == faster     ) drawPanel.faster();
      else if( e.target == slower     ) drawPanel.slower();
      else if( e.target == clear      ) drawPanel.clear();
      else if( e.target == closedOpen ) drawPanel.closedOpen();
      return true;
    }
 }

// L.Allison 1996
// Dept. Computer Science, Monash University, Australia 3168
// home page: http://www.cs.monash.edu.au/~lloyd/