// Grafisk biografsal, med reservation og afbestilling af stole
// Dobbeltbufring for at undgå flimren

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

public class Biograf5B {

  public static void main(String[] args) {
    boolean[][] sal1 = { { false, false, true,  true,  false, false },
                         { false, true,  true,  true,  true,  true  },
                         { false, false, true,  true,  false, false },
                         { true,  true,  false, true,  false, true  },
                         { false, false, false, false, false, false } };

    Frame f = new ClosableFrame("Sal 1");
    BiografCanvas biocanvas = new BiografCanvas(sal1);
    f.add(biocanvas);
    f.pack(); f.show();
  }
}

class BiografCanvas extends Canvas {
  boolean[][] bio;
  Image imbuf;			// Ekstra skærmbuffer
  Graphics gbuf;		// Dens grafikkomponent

  BiografCanvas(boolean[][] bio) { 
    this.bio = bio; 
    addMouseListener(new ReservationListener());
  }

  class ReservationListener extends MouseAdapter {
    public void mouseClicked(MouseEvent e) {
      int r = (e.getY() - 10) / 20;
      int s = (e.getX() - 10) / 20;
      if (0 <= r  && 0 <= s && r < bio.length && s < bio[r].length)
        if (e.getClickCount() > 1)
          bio[r][s] = false;      
        else
          bio[r][s] = true;       
      repaint();
    }
  }

  public void update(Graphics gr)
  { paint(gr); }

  public void paint(Graphics gr) { 
    setBackground(Color.white);
    if (gbuf == null) { // Opret imbuf og gbuf, men kun én gang
      imbuf = createImage(300, 300);
      gbuf = imbuf.getGraphics();
    }
    gbuf.clearRect(0, 0, imbuf.getWidth(null), imbuf.getHeight(null));
    for (int r=0; r<bio.length; r=r+1) {
      for (int s=0; s<bio[r].length; s=s+1) {
	if (bio[r][s])                  // Optaget
	  gbuf.setColor(Color.gray);
	else                            // Ledig
	  gbuf.setColor(Color.yellow);
	gbuf.fillOval(10+s*20, 10+r*20, 15, 15);
      }
    }
    gr.drawImage(imbuf, 0, 0, null);
  }

  public Dimension getPreferredSize() 
  { return new Dimension(300, 300); }

  public Dimension getMinimumSize()
  { return getPreferredSize(); }
}