com.sun.javafx.scene.traversal.Algorithm Maven / Gradle / Ivy
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package com.sun.javafx.scene.traversal;
import javafx.scene.Node;
/**
* An algorithm to be used in a traversal engine.
*
* Note that in order to avoid cycles or dead-ends in traversal the algorithms should respect the following order:
* * for NEXT: node -> node's subtree -> node siblings (first sibling then it's subtree) -> NEXT_IN_LINE for node's parent
* * for NEXT_IN_LINE: node -> node siblings (first sibling then it's subtree) -> NEXT_IN_LINE for node's parent
* * for PREVIOUS: node -> node siblings ( ! first subtree then the node itself ! ) -> PREVIOUS for node's parent
*
* Basically it ensures that next direction will traverse the same nodes as previous, in the opposite order.
*
*/
public interface Algorithm {
/**
* Traverse from owner, in direction dir.
* Return a the new target Node or null if no suitable target is found.
*
* Typically, the implementation of override algorithm handles only parent's direct children and looks like this:
* 1) Find the nearest parent of the "owner" that is handled by this algorithm (i.e. it's a direct child of the root).
* 2) select the next node within this direct child using the context.selectInSubtree() and return it
* 2a) if no such node exists, move to the next direct child in the direction (this is where the different order of direct children is defined)
* or if direct children are not traversable, the select the first node in the next direct child
*/
public Node select(Node owner, Direction dir, TraversalContext context);
/**
* Return the first traversable node for the specified context (root).
* @param context the context that contains the root
* @return the first node
*/
public Node selectFirst(TraversalContext context);
/**
* Return the last traversable node for the specified context (root).
* @param context the context that contains the root
* @return the last node
*/
public Node selectLast(TraversalContext context);
}