Xj3D Browser Applet Screen Capture Example

HTML Modifications

No modifications need to be made for this page as all the functionality is performed in the Java code. However, if you wish to have an element on the web page trigger the save action, then you can use the techniques learnt in the previous tutorial for this.

Java Code Modifications

Most of the work in capturing a screen is performed within the browser. The result is returned to your user code as an AWT BufferedImage, which you can then do with as you wish. Note that saving an image to disk requires the highest level of security permissions that an applet can have, and many users may not like your code doing this.

Capturing an image of the screen requires two parts - implementing the Xj3DScreenCaptureListener interface, and instructing the browser on how many frames to capture. Once you have the capture image, you are free to do with is as you wish.

The listener has one method that you need to implement: screenCaptures(BufferedImage img). In addition, we're going to add a Swing JButton to the UI so that we have a way of telling the browser when to capture that screenshot. The button will, of course, require you to implement the ActionListener interface as well. In the actionPerformed() method, we tell the browser how many frames that we want to capture using the captureFrames() method. In this case we just want to grab the next frame, so pass in a value of 1.

The final piece of new code is contained in the screenCaptured() method. Once you have the BufferedImage, you can do whatever you like with it. In this example, we'll use Java's ImageIO class to write it out to a file name that you have selected. This code leaves out all the security checks and exception handling that real code should have in it.

public class Xj3DAppletTutorial6 extends Applet
     implements ActionListener, Xj3DScreenCaptureListener {
    Xj3DBrowser browser;

public void init() {
    setLayout(new BorderLayout());
    browser = (Xj3DBrowser) getBrowser();
    browser.setScreenCaptureListener(this);

    JButton b = new JButton("Capture Now");
    b.addActionListener(this);
    add(b, BorderLayout.SOUTH);

    loadScene();
}

public boolean actionPerformed(ActionEvent evt) {
    browser.captureFrames(1);
}

public boolean screenCaptured(BufferedImage img) {
    JFileChooser chooser = new JFileChooser();

    if(chooser.showSaveDialog(this) != JFileChooser.APPROVE_OPTION)
        return;

    File out_file = chooser.getSelectedFile();
    try {
        ImageIO.write(img, "PNG", out_file);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

X3D Modifications

No X3D modifications are needed for this tutorial. In fact, it doesn't matter what X3D file you use for the content here - be it simple or complex.

Source Files