Yesterday Josh Marinacci announced that a library called Scene Graph has been spun out of the JavaFX project and open sourced on java.net. According to the site, the library "provides 'scene graph' functionality at the Java level, as well as providing one of the important runtime elements that the JavaFX Script language depends upon from the underlying platform. This project is released in very early access form, so that people can see what we're doing and play with it as we continue developing."

For the full details on the terminology involved in this library, such as "what is a scene graph", and so on, see Josh's blog entry on this subject . The seamless integration with Java of work done for JavaFX is great news. An absolutely wonderful part of his blog entry is where he says: "The API is useful not only from JavaFX and Java applications, but also from Groovy, Python, Ruby, and any other JVM based language." Of course, personally, as someone interested in Groovy, I'm very keen to try this out there. The fact that Josh contrasts this particular API with others in terms of speed indicates that this one is (unlike the others) fast , in addition to being open source and cool. The fact that it is built by the same guys that are behind Java2D tells me that this API must have benefited from lessons that they learnt while working on Java2D, which can only be a very good thing indeed.

David Herron's blog also weighs in with sounds of acclamation. He writes: "Even someone like me who barely knows how to draw graphics can see my way to using this." I highly recommend that anyone interested in this API take a look at Chet Haase's presentation on this subject delivered at Javapolis. Click here to get it; note that it is in PDF format. The presentation is really good in giving a high level overview, as well as some juicy code morsels at the end.

However, all this is talk, even the references to code morsels. In fact, they should make you want to see more, and in context, in the context of a complete little application. So let's put it all together into a small scenario. We will create a JFrame , add a scene, and then add new nodes to the scene. A variety of different types of nodes can be added, from text to shapes to actual Swing components (wrapped in nodes). In this case, we will add a background, a rectangle, and a circle:

However, when the circle is clicked twice, it will blink from blue to red (which you can't see here, obviously) and it will also move:

Here is all the code for the above, with comments interspersed as explanations:

public class SceneGraphDemo {
 
    public static void main(String[] args) {
 
        JFrame f = new JFrame("Moving & Blinking Blue Circle Demo");
 
        //Special panel for holding our scene:
        JSGPanel panel = new JSGPanel();
 
        //Our scene, which will group our nodes:
        SGGroup scene = new SGGroup();
 
        //The first node, which will make the background orange:
        SGShape back = new SGShape();
        back.setShape(new Rectangle(0, 0, 500, 500));
        back.setFillPaint(Color.ORANGE);
        
        //Add the background to the scene:
        scene.add(back);
 
        //The next node, which will be a rectangle:
        SGShape rect = new SGShape();
        rect.setShape(new Rectangle(20, 20, 100, 100));
        rect.setFillPaint(Color.RED);
        rect.setDrawPaint(Color.RED.darker().darker());
        rect.setDrawStroke(new BasicStroke(3));
        rect.setMode(SGAbstractShape.Mode.STROKE_FILL);
        
        //Add the rectangle to the scene:
        scene.add(rect);
 
        //The next node, which will be a circle:
        final SGShape circ = new SGShape();
        circ.setShape(new Ellipse2D.Double(100, 100, 50, 50));
        circ.setFillPaint(Color.BLUE);
        circ.setAntialiasingHint(RenderingHints.VALUE_ANTIALIAS_ON);
 
        //Prepare the circle for transformation:
        final SGTransform.Translate trans = SGTransform.createTranslation(0, 0, circ);
 
        //Add the transformed circle to the scene:
        scene.add(trans);
 
        //Add a mouse adapter, provided by the library:
        trans.addMouseListener(new SGMouseAdapter() {
 
            //Override the mouse clicked event:
            @Override
            public void mouseClicked(MouseEvent evt, SGNode arg1) {
                //Make it blink:
                Clip clip = Clip.create(1000, Clip.INDEFINITE, circ, "fillPaint", Color.RED, Color.BLUE);
                //Make it move:
                Clip clip2 = Clip.create(1000, 1, trans, "translateX", trans.getTranslateX(), 
                  trans.getTranslateX() + 100);
                //...but only if user clicks heels twice to make it so:
                if (evt.getClickCount() == 2) {
                    clip.start();
                    clip2.start();
                }
            }
        });
 
        //Set the panel's scene, which contains all our nodes:
        panel.setScene(scene);
 
        //Add the panel to the frame:
        f.add(panel);
 
        //Show the frame:
        f.pack();
        f.setSize(400, 200);
        f.setVisible(true);
 
    }
}

To run the above, all you need is the JAR from the java.net site. Then run the class above and you'll have the result described. And how would one add Swing components? By wrapping them in the library's SGComponent :

JButton jbutton = new JButton("a button");
SGComponent button = new SGComponent();
button.setComponent(jbutton);
scene.add(button);

When asked how this new library relates to the NetBeans Visual Library, Josh says: "While they are similar in implementation I think they serve different purposes. The Visual Library in the NetBeans Platform was designed for specific types of applications, like the UML modeler. It works at a higher level than a more general purpose Scene Graph. However, in the future I'd like to see the Visual Library sit on top of the Scene Graph to take advantage of the hardware acceleration hooks that will be added in the future."

To get started with the Scene Graph Library, go here on java.net and simply download the JAR. Javadoc is also available, as well as mailing lists where you can ask your questions. Looking forward to seeing how this library develops! I'm also looking forward to (many more) samples.

        SGShape rect = new SGShape();
        rect.setShape(new Rectangle(20, 20, 100, 100));
        rect.setFillPaint(Color.RED);
        rect.setDrawPaint(Color.RED.darker().darker());
        rect.setDrawStroke(new BasicStroke(3));
        rect.setMode(SGAbstractShape.Mode.STROKE_FILL);
        scene.add(rect);

scene.add(new ShapeBuilder()
        .shape(new Rectangle(20, 20, 100, 100))
        .fillPaint(Color.RED)
        .drawPaint(Color.RED.darker().darker())
        .drawStroke(new BasicStroke(3))
        .mode(SGAbstractShape.Mode.STROKE_FILL).build());

scene.add(new ShapeBuilder()
        .shape(new Rectangle(20, 20, 100, 100))
        .fillPaint(RED)
        .drawPaint(RED.darker().darker())
        .drawStroke(new BasicStroke(3))
        .mode(Mode.STROKE_FILL).build());