JAVA – JFreeChart – How To Save a JFreeChart to JPEG File

 

A quick how to use JFreeChart quide can be found at- https://robbamforth.wordpress.com/2008/10/30/java-jfreechart-graphs-and-charts-in-java/

I wanted to be able to output the the charts to a picture file (JPEG) programatically. After a bit of research I got the following methods to paint the chart and output the image to a file.

Add these 2 methods to the class that creates the charts:

Method 1 saveToFile():

public static void saveToFile(JFreeChart chart,

    String aFileName,

    int width,

    int height,

    double quality)

    throws FileNotFoundException, IOException

    {

        BufferedImage img = draw( chart, width, height );

 

        FileOutputStream fos = new FileOutputStream(aFileName);

        JPEGImageEncoder encoder2 =

        JPEGCodec.createJPEGEncoder(fos);

        JPEGEncodeParam param2 =

        encoder2.getDefaultJPEGEncodeParam(img);

        param2.setQuality((float) quality, true);

        encoder2.encode(img,param2);

        fos.close();

    }

 

Method 2 draw():

    protected static BufferedImage draw(JFreeChart chart, int width, int height)

    {

        BufferedImage img =

        new BufferedImage(width , height,

        BufferedImage.TYPE_INT_RGB);

        Graphics2D g2 = img.createGraphics();

                       

        chart.draw(g2, new Rectangle2D.Double(0, 0, width, height));

 

        g2.dispose();

        return img;

    }

 

Call the saveToFile method to save the chart to a JPEG:

try{

    saveToFile(pieChart,”c:/test.jpg”,500,300,100);
}catch(Exception e){

    e.printStackTrace();

}

This tells the application to save the current pieChart to a file called c:/test.jpg, with a width of 500 a height of 300 and a quality of 100.

The createPiePanel() method will now look like:

public static JPanel createPiePanel(int ring, int call, int off, String title) {      

        JFreeChart pieChart = createPieChart(createPieDataset(ring, call, off), title); 

        try{

            saveToFile(pieChart,”c:/test.jpg”,500,300,100);

        }catch(Exception e){

            e.printStackTrace();

        }

        return new ChartPanel(pieChart);

    }

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