import org.abego.treelayout.NodeExtentProvider; //导入依赖的package包/类
/**
 * Creates a TreeLayout for a given tree.
 * <p>
 * In addition to the tree the {@link NodeExtentProvider} and the
 * {@link Configuration} must be given.
 * 
 * @param useIdentity
 *            [default: false] when true, identity ("==") is used instead of
 *            equality ("equals(...)") when checking nodes. Within a tree
 *            each node must only be once (using this check).
 */
public TreeLayout(TreeForTreeLayout<TreeNode> tree,
		NodeExtentProvider<TreeNode> nodeExtentProvider,
		Configuration<TreeNode> configuration, boolean useIdentity) {
	this.tree = tree;
	this.nodeExtentProvider = nodeExtentProvider;
	this.configuration = configuration;
	this.useIdentity = useIdentity;

	if (this.useIdentity) {
		this.mod = new IdentityHashMap<TreeNode, Double>();
		this.thread = new IdentityHashMap<TreeNode, TreeNode>();
		this.prelim = new IdentityHashMap<TreeNode, Double>();
		this.change = new IdentityHashMap<TreeNode, Double>();
		this.shift = new IdentityHashMap<TreeNode, Double>();
		this.ancestor = new IdentityHashMap<TreeNode, TreeNode>();
		this.number = new IdentityHashMap<TreeNode, Integer>();
		this.positions = new IdentityHashMap<TreeNode, Point2D>();
	} else {
		this.mod = new HashMap<TreeNode, Double>();
		this.thread = new HashMap<TreeNode, TreeNode>();
		this.prelim = new HashMap<TreeNode, Double>();
		this.change = new HashMap<TreeNode, Double>();
		this.shift = new HashMap<TreeNode, Double>();
		this.ancestor = new HashMap<TreeNode, TreeNode>();
		this.number = new HashMap<TreeNode, Integer>();
		this.positions = new HashMap<TreeNode, Point2D>();
	}
	
	// No need to explicitly set mod, thread and ancestor as their getters
	// are taking care of the initial values. This avoids a full tree walk
	// through and saves some memory as no entries are added for
	// "initial values".

	TreeNode r = tree.getRoot();
	firstWalk(r, null);
	calcSizeOfLevels(r, 0);
	secondWalk(r, -getPrelim(r), 0, 0);
}
 

import org.abego.treelayout.NodeExtentProvider; //导入依赖的package包/类
/**
 * Returns the {@link NodeExtentProvider} used by this {@link TreeLayout}.
 */
public NodeExtentProvider<TreeNode> getNodeExtentProvider() {
	return nodeExtentProvider;
}