[JAVA][Beginning Java 8 Games Development]

Chapter 4 ■ An Introduction to JavaFX 8: Exploring the Capabilities of the Java 8 Multimedia Engine
Figure 4-3. JavaFX Scene Graph hierarchy, starting with the root node and progressing to branch and leaf nodes
The root node is the topmost node, which is why it is called the root, even though it is at the top, not the bottom,
like a root would be in the plant world. A root node has no parent, that is, nothing above it in the Scene Graph
hierarchy. A root node is itself a parent to the branch nodes and leaf nodes below it.
The next most powerful (and complex) construct in the Scene Graph tree is the branch node, which uses the
javafx.scene.Parent class as its superclass and which can contain children (this is logical, as it extends a class aptly
named Parent). A branch node can contain other branch nodes, as well as leaf nodes, so it can be used to create some
very complicated and powerful Scene Graph hierarchy (or Scene Graph architecture) constructs.
The last level in the hierarchy is the leaf node. A leaf node is the end of the branch and, as such, cannot have
children. It is important to note that leaf nodes can come directly off the root node, as you can see in Figure 4-3.
Branch nodes can be created by using the Parent, Group, or SubScene classes (see Figure 4-2) or any of their
subclasses, such as the WebView, PopupControl, Region, Pane, or StackPane class.
Examples of leaf nodes include JavaFX classes (as objects), which can be configured using parameters, such as
shapes, text, or an ImageView, but which are design or content components, in and of themselves, and have not been
designed to have children (child objects).
A leaf node will therefore always contain a JavaFX class that has not been subclassed (extended) from the Parent
class, and that has not itself been specifically designed to have child elements (child objects) within it, or below it, in
the JavaFX Scene Graph hierarchy.
The four subclasses of the Parent class can all be used as branch nodes and include the Group class, for grouping
child (leaf node) objects, so that opacity, transforms, and effects can be applied to them; the Region class, for
grouping child (leaf node) objects to form screen layouts, which can also be styled using CSS; the Control class, which
can be used to create custom user interface elements (called controls in JavaFX); and the WebView class, which is
used to contain the JavaFX WebEngine class (this class renders HTML5 and CSS3 content into a WebView).
JavaFX Scene Content: Lights, Camera, Cursor, Action!
Next, let’s take a look at the eight classes listed in the center column in Figure 4-2. They provide powerful multimedia
tools for controlling your application’s cursor as well as custom lighting special effects and custom camera capabilities
for your 2D and 3D JavaFX applications (in this case, games, but they could also be e-books, or iTV shows, or anything
else that requires the powerful new media capabilities that JavaFX offers via the Java language).
The more generalized classes (Cursor, LightBase, Camera) in the figure are parent classes, and the more
specialized ones (ImageCursor, PointLight, ParallelCamera, and so on) listed after each of those are the subclasses
of those parent classes. Except the LightBase class, that seems to be stating the obvious!
As you may have guessed (correctly), the JavaFX Cursor class can be used to control the application cursor
graphic (arrow, hand, closed hand, crosshair, and so on) being used at any given time. The ImageCursor subclass can
be used to define and supply a custom image-based cursor as well as an x and a y location within the custom cursor
image that defines where its point (also called the cursor hot spot) is located.
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