FileDocCategorySizeDatePackage
Grapher.javaAPI DocExample3856Sat Apr 21 15:44:02 BST 2001None

Grapher

public class Grapher extends JPanel
Simple Graphing program.
author
Ian F. Darwin, ian@darwinsys.com
version
$Id: Grapher.java,v 1.8 2001/04/21 18:44:03 ian Exp $

Fields Summary
public static final float
BORDERFACTOR
Multiplier for range to allow room for a border
protected Vector
data
The list of Apoint points.
protected float
minx
The minimum and maximum X values
protected float
maxx
protected float
miny
The minimum and maximum Y values
protected float
maxy
protected int
n
The number of data points
protected float
xrange
The range of X and Y values
protected float
yrange
Constructors Summary
public Grapher()


	  
		data = new Vector();
Methods Summary
public java.awt.DimensiongetPreferredSize()

		return new Dimension(150, 150);
public static voidmain(java.lang.String[] rgs)

		final JFrame f = new JFrame("Grapher");
        f.addWindowListener(new WindowAdapter() {
			public void windowClosing(WindowEvent e) {
				f.setVisible(false);
				f.dispose();
				System.exit(0);
			}
		});
		Grapher g = new Grapher();
		f.setContentPane(g);
		f.setLocation(100, 100);
		f.pack();
		if (rgs.length == 0)
			g.read("Grapher.dat");
		else
			g.read(rgs[0]);
		f.setVisible(true);
public voidpaintComponent(java.awt.Graphics g)
Called when the window needs painting. Computes X and Y range, scales.

		super.paintComponent(g);
		Dimension s = getSize();
		if (n < 2) {
			g.drawString("Insufficient data", 10, 40);
			return;
		}

		// Compute scale factors
		float xfact =  s.width  / xrange;
		float yfact =  s.height / yrange;

		// Scale and plot the data
        for (int i=0 ; i < n; i++) {
			Apoint d = (Apoint)data.elementAt(i);
			float x = (d.x-minx) * xfact;
			float y = (d.y-miny) * yfact;
			Debug.println("point", "AT " + i + " " + d + "; " +
				"x = " + x + "; y = " + y);
			// Draw a 5-pixel rectangle centered, so -2 both x and y.
			// AWT numbers Y from 0 down, so invert:
			g.drawRect(((int)x)-2, s.height-2-(int)y, 5, 5);
		}
public voidread(java.lang.String fname)
Read the data file named. Each line has an x and a y coordinate.

		LineNumberReader is = null;
		try {
			is = new LineNumberReader(new FileReader(fname));

			String txt;
			// Read the file a line at a time, parse it, save the data.
			while ((txt = is.readLine()) != null) {
				StringTokenizer st = new StringTokenizer(txt);
				try {
					Apoint d = new Apoint();
					d.x = Float.parseFloat(st.nextToken());
					d.y = Float.parseFloat(st.nextToken());
					data.add(d);
				} catch(NumberFormatException nfe) {
					System.err.println("Invalid number on line " +
						is.getLineNumber());
				} // XXX catch out of range exception
			}
		} catch (FileNotFoundException e) {
			System.err.println("File " + fname + " unreadable: " + e);
		} catch (IOException e) {
			System.err.println("I/O error on line " + is.getLineNumber());
		}
		n = data.size();
		if (n < 2) {
			System.err.println("Not enough data points!");
			return;
		}

		// find min & max
        for (int i=0 ; i < n; i++) {
			Apoint d = (Apoint)data.elementAt(i);
			if (d.x < minx) minx = d.x;
			if (d.x > maxx) maxx = d.x;
			if (d.y < miny) miny = d.y;
			if (d.y > maxy) maxy = d.y;
        }

		// Compute ranges
		xrange = (maxx - minx) * BORDERFACTOR;
		yrange = (maxy - miny) * BORDERFACTOR;
		Debug.println("range", "minx,x,r = " + minx +' "+ maxx +' "+ xrange);
		Debug.println("range", "miny,y,r = " + miny +' "+ maxy +' "+ yrange);