import java.awt.*;
import java.applet.*;
import java.lang.*;

public class OneArrow extends Applet
{
      Graphics      bG;
      Graphics      sG;
      Image         bI;

      Color         back         = new Color(247, 243, 234);
      Color         gback        = new Color(192, 192, 255);
      Color         glines       = new Color(0, 0, 255);
      Color         black        = new Color(0, 0, 0);

      int           x = -1;
      int           y = -1;
      int           dx, dy;

      double        sx, sy, mag;
      double        p, q;

      public void init()
      {
             bI = createImage(this.size().width, this.size().height);
             bG = bI.getGraphics();
             drawback();
      }

      public void paint(Graphics g)
      {
             g.drawImage(bI, 0, 0, this);
             sG = getGraphics();
      }

      public void update(Graphics g)
      {
             g.drawImage(bI, 0, 0, this);
      }

      
      public void drawback()
      {
             bG.setColor(back);
             bG.fillRect(0, 0, 211, 211);
             bG.setColor(gback);
             bG.fillRect(5, 5, 201, 201);
             bG.setColor(glines);
             for (int i = 0; i < 201; i = i + 20)
             {
                 bG.drawLine(i + 5, 5, i + 5, 210);
                 bG.drawLine(0, i + 5, 205, i + 5);
             }
             if (x > -0.001)
             {
                 bG.setColor(black);
                 bG.fillOval(x - 3, y - 3, 7, 7);
             }
      }

      public boolean mouseDown(Event evt, int mx, int my)
      {
             if ((my > 4) && (my < 206) && (mx > 4) && (mx < 206))
             {
                  x = mx;
                  y = my;
                  p = x - 5;
                  q = 205 - y;
                  sx = 0.50 * (1 - 0.01 * p - 0.005 * q) * p;
                  sy = 0.50 * (1 - 0.005 * p - 0.01 * q) * q;
                  drawback();
                  mag = java.lang.Math.sqrt(sx * sx + sy * sy);
                  if (mag > 0.0001)
                  {  
                     dx = (int) java.lang.Math.round(20.0 * sx/mag);
                     dy = (int) java.lang.Math.round(20.0 * sy/mag);
                     bG.drawLine(x, y, x + dx, y - dy);
                  }
                  sG.drawImage(bI, 0, 0,this);
             }
             return true;
      }

}