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/*
 * Copyright (c) 2013, 2022, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package javafx.scene.control.cell;

import javafx.beans.InvalidationListener;
import javafx.beans.Observable;
import javafx.beans.WeakInvalidationListener;
import javafx.scene.Node;
import javafx.scene.control.TreeCell;
import javafx.scene.control.TreeItem;
import javafx.scene.layout.HBox;

import java.lang.ref.WeakReference;

/*
 * Package-protected class used by cell implementations to handle graphics changes
 * to TreeItem.
 */
class DefaultTreeCell extends TreeCell {

    private HBox hbox;

    private WeakReference> treeItemRef;

    private InvalidationListener treeItemGraphicListener = observable -> {
        updateDisplay(getItem(), isEmpty());
    };

    private InvalidationListener treeItemListener = new InvalidationListener() {
        @Override public void invalidated(Observable observable) {
            TreeItem oldTreeItem = treeItemRef == null ? null : treeItemRef.get();
            if (oldTreeItem != null) {
                oldTreeItem.graphicProperty().removeListener(weakTreeItemGraphicListener);
            }

            TreeItem newTreeItem = getTreeItem();
            if (newTreeItem != null) {
                newTreeItem.graphicProperty().addListener(weakTreeItemGraphicListener);
                treeItemRef = new WeakReference<>(newTreeItem);
            }
        }
    };

    private WeakInvalidationListener weakTreeItemGraphicListener =
            new WeakInvalidationListener(treeItemGraphicListener);

    private WeakInvalidationListener weakTreeItemListener =
            new WeakInvalidationListener(treeItemListener);

    public DefaultTreeCell() {
        treeItemProperty().addListener(weakTreeItemListener);

        if (getTreeItem() != null) {
            getTreeItem().graphicProperty().addListener(weakTreeItemGraphicListener);
        }
    }

    void updateDisplay(T item, boolean empty) {
        if (item == null || empty) {
            hbox = null;
            setText(null);
            setGraphic(null);
        } else {
            // update the graphic if one is set in the TreeItem
            TreeItem treeItem = getTreeItem();
            if (treeItem != null && treeItem.getGraphic() != null) {
                if (item instanceof Node) {
                    setText(null);

                    // the item is a Node, and the graphic exists, so
                    // we must insert both into an HBox and present that
                    // to the user (see RT-15910)
                    if (hbox == null) {
                        hbox = new HBox(3);
                    }
                    hbox.getChildren().setAll(treeItem.getGraphic(), (Node)item);
                    setGraphic(hbox);
                } else {
                    hbox = null;
                    setText(item.toString());
                    setGraphic(treeItem.getGraphic());
                }
            } else {
                hbox = null;
                if (item instanceof Node) {
                    setText(null);
                    setGraphic((Node)item);
                } else {
                    setText(item.toString());
                    setGraphic(null);
                }
            }
        }
    }

    @Override public void updateItem(T item, boolean empty) {
        super.updateItem(item, empty);
        updateDisplay(item, empty);
    }
}