Create User Interfaces - JavaFX: Developing Rich Internet Applications - page 105

Image
There is a special url syntax for defining images.

background-image: url(http://jfxbook.com/NASA/nasa.jpg);

This actually creates a java.awt.image.BufferedImage object that can then be
used to create a javafx.scene.Image . A JavaFX example to handle this is
shown in Listing 5.12.

Listing 5.12 JavaFX Example for Creating Image from BufferedImage

var image: Image;
public var backgroundImage:
java.awt.image.BufferedImage on replace {
if(backgroundImage != null) {
image = Image{}.
fromBufferedImage(backgroundImage);

}
}

Nodes

As we already mentioned, a scene graph is a representation of a display scene. It is
represented as a tree data structure with a set of linked nodes. Nodes may be either
inner nodes, sometimes called branch nodes or leaf nodes that have no children.
The javafx.scene.Node class is the base class for all the scene graph nodes.
In JavaFX, the Scene is the root node and contains a set of direct child nodes;
inner nodes are either a javafx.scene.Group or javafx.scene.CustomNode .
The leaf nodes are all the other nodes like shapes, controls, text, and the Swing
Extension nodes.

Each node may be given an ID represented as a string. A lookup function is pro-
vided to find a node with a specific ID. Already, we saw ID used in conjunction
with style sheets and the developer should take care to assign unique IDs when
they are used.
Nodes have a set of instance variables of function type that can be assigned and
are called when certain input events occur. These include the onKey XXXX and
onMouse XXXX instance variables that hold functions to handle key or mouse events,
where XXXX represents the specific type of event. The blocksMouse instance
variable indicates whether mouse events should be delivered to the parent. These
will be discussed in more depth in the section Input Events, later in this chapter.