Pie Chart

[Gaz1634]

Could someone tell me how to create a pie chart for a swing application, the pie chart I require must show 4 segments.

Any help is appreciated

Many Thanks, Gaz

 

[hologram]

Use one of the following :

java.awt.geom.Arc2D.Double
java.awt.geom.Arc2D.Float

This is rather criptic, but now you know where to look.

 

[Gaz1634]

Thanks for the pointer hologram

Have you got more of an idea what I need to do, it is just that my maths is not 100% and at the moment I have not a clue where to start.

 

[hologram]

Another possibility :

import java.awt.*;
import java.util.*;
import javax.swing.*;

public class PieChart extends JPanel {

  float pixelWidth = 400f;
  float pixelHeight = 400f;
  float margin = 20f;
  float pieHeight = pixelHeight - (2 * margin);
  float pieWidth = pixelWidth - (2 * margin);
  private Color[] colors;
  private float[] values;
  float totalValue = 0f;

  public PieChart(Color[] colors, float[] values) {
    this.colors = colors;
    this.values = values;
    setSize((int)pixelWidth,(int)pixelHeight);
    for (int i=0; i<values.length; i++)
      totalValue += values[i];
  }

  public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D)g;
    float startAngle = 0f;
    float arcAngle;
    for (int i=0; i<values.length; i++) {
      arcAngle = 360f * (values[i] / totalValue);
      g2.setColor(colors[i]);
      if(i == 0) {
              g2.fillArc((int)margin,(int)margin,
                              (int)pieWidth,(int)pieHeight,
                              (int)startAngle - 5,(int)arcAngle + 5);
      } else {
              g2.fillArc((int)margin,(int)margin,
                              (int)pieWidth,(int)pieHeight,
                              (int)startAngle,(int)arcAngle);
      }
      startAngle += arcAngle;
    }
  }

}

==================================
To be called like :

import java.awt.*;
import javax.swing.*;
import java.util.Vector;

public class PieChartMain {

  private Color[] colors = { Color.blue, Color.green, Color.yellow, Color.cyan };
  private float[] values = { 70.0f, 50.0f, 20.0f, 30.0f };

  public PieChartMain() {
  }

  public static void main(String[] args) {
    PieChartMain pieChartMain = new PieChartMain();
    pieChartMain.doIt();
  }

  public void doIt() {
    JFrame f = new JFrame("PieChartExample");
    PieChart pc = new PieChart(colors, values);
    f.setSize(500,500);
    f.getContentPane().add(pc);
    f.setVisible(true);
  }

}

 

[Gaz1634]

Thanks hologram, I think that is spot on what I was looking for.