codewin.java

Reader Writer Problem to solve synchronization issues

/* $Id: CodeWin.java,v 1.2 1996/06/28 04:09:39 kmillik1 Exp $ */

/* $Log: CodeWin.java,v $
# Revision 1.2  1996/06/28  04:09:39  kmillik1
# Fixed $Log$ comment.
#
# Revision 1.1  1996/06/28  04:00:02  kmillik1
# Initial revision
#
*/

import java.awt.*;

public class CodeWin extends Canvas {
  private String[] text;
  private int num_threads;
  private int line_height;
  private int line_ascent;
  private int height;
  private int width;
  private int[] pos;
  private Image[] img;

  public CodeWin(int n, String[] t, Image[] im, Font f) {
    text = t;
    setFont(f);
    num_threads = n;

    // find the height of a single line
    FontMetrics fm = getFontMetrics(getFont());
    line_height = fm.getHeight();
    line_ascent = fm.getAscent();

    // find the height of the entire object
    height = line_height * text.length;

    // find the width of the object, i.e. the width of the longest line
    int max_width = 0;
    int cur_width;
    for (int i = 0; i < text.length; ++i) {
      cur_width = fm.stringWidth(text[i]);
      if (cur_width > max_width)
	max_width = cur_width;
    }
    width = max_width;

    // create an array of ints to represent the line number of each thread
    pos = new int[num_threads];
    for (int i = 0; i < num_threads; ++i)
      pos[i] = 0;

    img = im;
  }

  public CodeWin(int n, String[] t, Image[] im) {
    this(n, t, im, new Font("Courier", Font.PLAIN, 12));
  }

  public Dimension minimumSize() {
    return new Dimension(width+15*num_threads+10, height+line_height);
  }

  public Dimension preferredSize() {
    // preferred size and minimum size are the same
    return minimumSize();
  }

  public void paint(Graphics g) {
    Dimension d = size();
    g.setColor(getBackground());
    g.draw3DRect(0, 0, d.width-1, d.height-1, false);

    g.setColor(getForeground());

    int y = line_height;
    for (int i = 0; i < text.length; ++i) {
      g.drawString(text[i], 15*num_threads+5, y);
      y += line_height;
    }
    for (int i = 0; i < num_threads; ++i)
      g.drawImage(img[i], 15*i+1, pos[i]*line_height, this);
  }

  public void step(int n) {
    step(n, 1);
  }

  public void step(int n, int num_steps) {
    Graphics g = getGraphics();
    g.clearRect(15*n+2, pos[n]*line_height+1, 15, line_height);

    for (int i = 0; i < num_steps; ++i) {
      do
	pos[n] = (pos[n] + 1 == text.length) ? 0 : pos[n] + 1;
      while (text[pos[n]].compareTo("") == 0);
    }
    
    g.drawImage(img[n], 15*n+1, pos[n]*line_height, this);
    g.dispose();
  }
    

  public void reset() {
    for (int i = 0; i < num_threads; ++i)
      pos[i] = 0;
    repaint();
  }

}