com.sun.javafx.scene.traversal.TopMostTraversalEngine Maven / Gradle / Ivy
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package com.sun.javafx.scene.traversal;
import com.sun.javafx.scene.NodeHelper;
import com.sun.javafx.scene.ParentHelper;
import javafx.scene.Node;
import javafx.scene.Parent;
/**
* This is the class for all top-level traversal engines in scenes and subscenes.
* These traversal engines are created automatically and can only have the default algorithm.
*
* These engines should be used by calling {@link #trav(javafx.scene.Node, Direction)}, {@link #traverseToFirst()} and
* {@link #traverseToLast()} methods. These methods do the actual traversal - selecting the Node that's should be focused next and
* focusing it. Also, listener calls are handled by top-most traversal engines.
* select* methods can be used as well, but will *not* transfer the focus to the result, they are just query methods.
*/
public abstract class TopMostTraversalEngine extends TraversalEngine{
protected TopMostTraversalEngine() {
/*
* for 2d behaviour from TAB use :
* algorithm = new WeightedClosestCorner();
* for Container sequence TAB behaviour and 2d arrow behaviour use :
* algorithm = new ContainerTabOrder();
* for 2D arrow behaviour with a target bias and a stack use :
* algorithm = new Biased2DWithStack();
*/
super(DEFAULT_ALGORITHM);
}
/**
* For testing purposes only!
*/
TopMostTraversalEngine(Algorithm algorithm) {
super(algorithm);
}
/**
* Traverse the focus to the next node in the specified direction.
*
* @param node The starting node to traverse from
* @param dir the traversal direction
* @param method the traversal method
* @return the new focus owner or null if none found (in that case old focus owner is still valid)
*/
public final Node trav(Node node, Direction dir, TraversalMethod method) {
Node newNode = null;
Parent p = node.getParent();
Node traverseNode = node;
while (p != null) {
// First find the nearest traversal engine override (i.e. a ParentTraversalEngine that is traversable)
ParentTraversalEngine engine = ParentHelper.getTraversalEngine(p);
if (engine != null && engine.canTraverse()) {
newNode = engine.select(node, dir);
if (newNode != null) {
break;
} else {
// The inner traversal engine wasn't able to select anything in the specified direction.
// So now we try to traverse from the whole parent (associated with that traversal engine)
// by a traversal engine that's higher in the hierarchy
traverseNode = p;
if (dir == Direction.NEXT) {
dir = Direction.NEXT_IN_LINE;
}
}
}
p = p.getParent();
}
// No engine override was able to find the Node in the specified direction, so
if (newNode == null) {
newNode = select(traverseNode, dir);
}
if (newNode == null) {
if (dir == Direction.NEXT || dir == Direction.NEXT_IN_LINE) {
newNode = selectFirst();
} else if (dir == Direction.PREVIOUS) {
newNode = selectLast();
}
}
if (newNode != null) {
focusAndNotify(newNode, method);
}
return newNode;
}
private void focusAndNotify(Node newNode, TraversalMethod method) {
if (method == TraversalMethod.KEY) {
NodeHelper.requestFocusVisible(newNode);
} else {
newNode.requestFocus();
}
notifyTreeTraversedTo(newNode);
}
private void notifyTreeTraversedTo(Node newNode) {
Parent p = newNode.getParent();
while (p != null) {
final ParentTraversalEngine traversalEngine = ParentHelper.getTraversalEngine(p);
if (traversalEngine != null) {
traversalEngine.notifyTraversedTo(newNode);
}
p = p.getParent();
}
notifyTraversedTo(newNode);
}
/**
* Set focus on the first Node in this context (if any)
* @return the first node or null if there's none
*/
public final Node traverseToFirst() {
Node n = selectFirst();
if (n != null) focusAndNotify(n, TraversalMethod.DEFAULT);
return n;
}
/**
* Set focus on the last Node in this context (if any)
* @return the last node or null if there's none
*/
public final Node traverseToLast() {
Node n = selectLast();
if (n != null) focusAndNotify(n, TraversalMethod.DEFAULT);
return n;
}
}