com.sun.javafx.scene.traversal

Class TraversalEngine

java.lang.Object

com.sun.javafx.scene.traversal.TraversalEngine

Direct Known Subclasses:

ParentTraversalEngine, TopMostTraversalEngine

public abstract class TraversalEngine
extends Object

This is abstract class for a traversal engine. There are 2 types : ParentTraversalEngine to be used in Parent.setImpl_traversalEngine(ParentTraversalEngine) to override default behavior and TopMostTraversalEngine that is the default traversal engine for scene and subscene. Every engine is basically a wrapper of an algorithm + some specific parent (or scene/subscene), which define engine's root.

Field Summary

Fields

Modifier and Type	Field and Description
protected Algorithm	algorithm

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	TraversalEngine() Creates engine with no algorithm.
protected	TraversalEngine(Algorithm algorithm) Creates engine with the specified algorithm

Method Summary

Modifier and Type	Method and Description
void	addTraverseListener(TraverseListener listener) Add a listener to traversal engine.
boolean	canTraverse() Returns true only if there's specified algorithm for this engine.
protected abstract Parent	getRoot() The root of this engine's context.
Node	select(Node from, Direction dir) Returns the node that is in the direction dir starting from the Node from using the engine's algorithm.
Node	selectFirst() Returns the first node in this engine's context (scene/parent) using the engine's algorithm.
Node	selectLast() Returns the last node in this engine's context (scene/parent) using the engine's algorithm.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

algorithm

protected final Algorithm algorithm

Constructor Detail

TraversalEngine

protected TraversalEngine(Algorithm algorithm)

Creates engine with the specified algorithm

Parameters:

algorithm -

TraversalEngine

protected TraversalEngine()

Creates engine with no algorithm. This makes all the select* calls invalid.

See Also:

canTraverse()

Method Detail

addTraverseListener

public final void addTraverseListener(TraverseListener listener)

Add a listener to traversal engine. The listener is notified whenever focus is changed by traversal inside the associated scene or parent. This can be used with ParentTraversalEngine that has no algorithm to observe changes to the focus inside the parent.

Parameters:

listener -

select

public final Node select(Node from,
                         Direction dir)

Returns the node that is in the direction dir starting from the Node from using the engine's algorithm. Null means there is no Node in that direction

Parameters:

from - the node to start traversal from

dir - the direction of traversal

Returns:

the subsequent node in the specified direction or null if none

Throws:

NullPointerException - if there is no algorithm

selectFirst

public final Node selectFirst()

Returns the first node in this engine's context (scene/parent) using the engine's algorithm. This can be null only if there are no traversable nodes

Returns:

The first node or null if none exists

Throws:

NullPointerException - if there is no algorithm

selectLast

public final Node selectLast()

Returns the last node in this engine's context (scene/parent) using the engine's algorithm. This can be null only if there are no traversable nodes

Returns:

The last node or null if none exists

Throws:

NullPointerException - if there is no algorithm

getRoot

protected abstract Parent getRoot()

The root of this engine's context. This is the node that is the root of the tree that is traversed by this engine.

Returns:

This engine's root

canTraverse

public final boolean canTraverse()

Returns true only if there's specified algorithm for this engine. Otherwise, this engine cannot be used for traversal. The engine might be still useful however, e.g. for listening on traversal changes.

Returns: