2D graph in java as a picture

fs11 · 02-03-2011, 01:59 PM

Hi All,

I am trying to build a 2D plot for my data and I have the code for it. However, I want to save it as a jpg/png file so that I can have a link to it for my webpage. Any pointers would be much appreciable. Below is the code:

Quote:

import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;
import javax.swing.*;

public class GraphingData extends JPanel {
int[] data = {
21, 14, 18, 03, 86, 88, 74, 87, 54, 77,
61, 55, 48, 60, 49, 36, 38, 27, 20, 18
};
final int PAD = 20;

protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
int w = getWidth();
int h = getHeight();
// Draw ordinate.
g2.draw(new Line2D.Double(PAD, PAD, PAD, h-PAD));
// Draw abcissa.
g2.draw(new Line2D.Double(PAD, h-PAD, w-PAD, h-PAD));
// Draw labels.
Font font = g2.getFont();
FontRenderContext frc = g2.getFontRenderContext();
LineMetrics lm = font.getLineMetrics("0", frc);
float sh = lm.getAscent() + lm.getDescent();
// Ordinate label.
String s = "data";
float sy = PAD + ((h - 2*PAD) - s.length()*sh)/2 + lm.getAscent();
for(int i = 0; i < s.length(); i++) {
String letter = String.valueOf(s.charAt(i));
float sw = (float)font.getStringBounds(letter, frc).getWidth();
float sx = (PAD - sw)/2;
g2.drawString(letter, sx, sy);
sy += sh;
}
// Abcissa label.
s = "x axis";
sy = h - PAD + (PAD - sh)/2 + lm.getAscent();
float sw = (float)font.getStringBounds(s, frc).getWidth();
float sx = (w - sw)/2;
g2.drawString(s, sx, sy);
// Draw lines.
double xInc = (double)(w - 2*PAD)/(data.length-1);
double scale = (double)(h - 2*PAD)/getMax();
g2.setPaint(Color.green.darker());
for(int i = 0; i < data.length-1; i++) {
double x1 = PAD + i*xInc;
double y1 = h - PAD - scale*data[i];
double x2 = PAD + (i+1)*xInc;
double y2 = h - PAD - scale*data[i+1];
g2.draw(new Line2D.Double(x1, y1, x2, y2));
}
// Mark data points.
g2.setPaint(Color.red);
for(int i = 0; i < data.length; i++) {
double x = PAD + i*xInc;
double y = h - PAD - scale*data[i];
g2.fill(new Ellipse2D.Double(x-2, y-2, 4, 4));
}
}

private int getMax() {
int max = -Integer.MAX_VALUE;
for(int i = 0; i < data.length; i++) {
if(data[i] > max)
max = data[i];
}
return max;
}

public static void main(String[] args) {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new GraphingData());
f.setSize(400,400);
f.setLocation(200,200);
f.setVisible(true);
}
}

paulsm4 · 02-03-2011, 06:45 PM

It sounds like the standard class "ImageIO" might be what you're looking for:

Code:

// http://download.oracle.com/javase/tutorial/2d/images/saveimage.html

try {
    BufferedImage bi = getMyImage(); // retrieve image
    File outputfile = new File("saved.png");
    ImageIO.write(bi, "png", outputfile);
} catch (IOException e) {
    ...
}

'Hope that helps .. PSM