TreeDragSource.java

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/*
 * Gridarta MMORPG map editor for Crossfire, Daimonin and similar games.
 * Copyright (C) 2000-2023 The Gridarta Developers.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
package net.sf.gridarta.gui.mapmenu;
 
import java.awt.Cursor;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragSource;
import java.awt.dnd.DragSourceDragEvent;
import java.awt.dnd.DragSourceDropEvent;
import java.awt.dnd.DragSourceEvent;
import java.awt.dnd.DragSourceListener;
import javax.swing.JTree;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.MutableTreeNode;
import javax.swing.tree.TreePath;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
 
public class TreeDragSource {
 
    @NotNull
    private final JTree tree;
 
    @NotNull
    private final DragSource dragSource = new DragSource();
 
    @Nullable
    private MutableTreeNode draggedTreeNode;
 
    @NotNull
    private final DragSourceListener dragSourceListener = new DragSourceListener() {
 
        @Override
        public void dragEnter(@NotNull final DragSourceDragEvent dsde) {
            // ignore
        }
 
        @Override
        public void dragOver(@NotNull final DragSourceDragEvent dsde) {
            // ignore
        }
 
        @Override
        public void dropActionChanged(@NotNull final DragSourceDragEvent dsde) {
            // ignore
        }
 
        @Override
        public void dragExit(@NotNull final DragSourceEvent dse) {
            // ignore
        }
 
        @Override
        public void dragDropEnd(@NotNull final DragSourceDropEvent dsde) {
            if (draggedTreeNode == null) {
                return;
            }
 
            if (dsde.getDropSuccess()) {
                switch (dsde.getDropAction()) {
                case DnDConstants.ACTION_COPY:
                    break;
 
                case DnDConstants.ACTION_MOVE:
                    ((DefaultTreeModel) tree.getModel()).removeNodeFromParent(draggedTreeNode);
                    break;
                }
            }
            draggedTreeNode = null;
        }
 
    };
 
    public TreeDragSource(@NotNull final JTree tree, final int actions) {
        this.tree = tree;
 
        final DragGestureListener dragGestureListener = dge -> {
            final TreePath selectionPath = tree.getSelectionPath();
            if (selectionPath == null || selectionPath.getPathCount() <= 1) {
                return;
            }
 
            draggedTreeNode = (MutableTreeNode) selectionPath.getLastPathComponent();
            final Cursor cursor;
            switch (dge.getDragAction()) {
            case DnDConstants.ACTION_COPY:
                cursor = DragSource.DefaultCopyDrop;
                break;
 
            case DnDConstants.ACTION_MOVE:
                cursor = DragSource.DefaultMoveDrop;
                break;
 
            default:
                return;
            }
            dragSource.startDrag(dge, cursor, new TransferableTreeNode(selectionPath), dragSourceListener);
        };
        dragSource.createDefaultDragGestureRecognizer(tree, actions, dragGestureListener);
    }
 
}