import java.awt.*;

public class LogoCanvas extends Canvas {
  Image im;
  int w, h;
  double x=100, y=100, ang;
  boolean penDown, autoRepaint=true;
  Rectangle clipRect=new Rectangle();
  
  protected Rectangle turtleRect() {
    return new Rectangle((int)x-4, (int)y-4, 10, 10);
  }
  
  public void penUp() {
    penDown = false;
  }
  public void penDown() {
    penDown = true;
  }
  public void back(double d) {
    forward(-d);
  }
  public void forward(double d) {
    double px=x, py=y;
    Rectangle r = turtleRect();
    x += d*Math.cos(ang);
    y += d*Math.sin(ang);
    if (penDown) {
      Graphics g = im.getGraphics();
      g.setColor(getForeground());
      g.setClip(r.union(turtleRect()));
      g.drawLine((int)px, (int)py, (int)x, (int)y);
    }
    clipRect = turtleRect().union(clipRect);
    if (autoRepaint) repaint();
  }
  public void right(double d) {
    ang += d*Math.PI/180;
    if (autoRepaint) repaint();
  }
  public void left(double d) {
    ang -= d*Math.PI/180;
    if (autoRepaint) repaint();
  }
  
  public void clear() {
    Graphics g = im.getGraphics();
    g.setColor(getBackground());
    g.fillRect(0,0,w,h);
    clipRect = new Rectangle(0,0,w,h);
    repaint();
  }
  
  public void update(Graphics g) { paint(g); }
  public void paint(Graphics g) {
    if (im==null) setSize(getSize());
    if (g.getClip() == null) g.setClip(clipRect);
    else if (g.getClip() instanceof Rectangle) g.setClip(clipRect.union((Rectangle)g.getClip()));
    else g.setClip(new Rectangle(0,0,w,h));
    g.drawImage(im,0,0,this);
    g.setColor(getBackground());
    if (penDown) g.setColor(new Color(255, 223, 0));
    else g.setColor(Color.yellow);
    g.fillOval((int)x-4, (int)y-4, 9, 9);
    g.setColor(getForeground());
    g.setColor(Color.black);
    g.drawOval((int)x-4, (int)y-4, 9, 9);
    g.drawLine((int)x, (int)y, (int)(x+3*Math.cos(ang)), (int)(y+3*Math.sin(ang)));
    clipRect = turtleRect();
  }
  public void setSize(Dimension d) { setSize(d.width, d.height); }
  public void setSize(int x, int y) {
    if (im == null) {
      if (x<=0) x = 300;
      if (y<=0) y = 300;
      im = createImage(x, y);
    }
    else if (im.getWidth(this) < x || im.getWidth(this) < y) {
      Image im2 = createImage(x, y);
      Graphics g = im2.getGraphics();
      g.drawImage(im,0,0,this);
      im = im2;
    }
    w=x; h=y; 
    super.setSize(x, y);
  }
}