|  | Home · Examples

# Code for Tree Model Example

    /****************************************************************************
    **
    ** Copyright (C) 1992-2008 Nokia. All rights reserved.
    **
    ** This file is part of Qt Jambi.
    **
    ** * Commercial Usage
    * Licensees holding valid Qt Commercial licenses may use this file in
    * accordance with the Qt Commercial License Agreement provided with the
    * Software or, alternatively, in accordance with the terms contained in
    * a written agreement between you and Nokia.
    *
    *
    * GNU General Public License Usage
    * Alternatively, this file may be used under the terms of the GNU
    * General Public License versions 2.0 or 3.0 as published by the Free
    * Software Foundation and appearing in the file LICENSE.GPL included in
    * the packaging of this file.  Please review the following information
    * to ensure GNU General Public Licensing requirements will be met:
    * http://www.fsf.org/licensing/licenses/info/GPLv2.html and
    * http://www.gnu.org/copyleft/gpl.html.  In addition, as a special
    * exception, Nokia gives you certain additional rights. These rights
    * are described in the Nokia Qt GPL Exception version 1.2, included in
    * the file GPL_EXCEPTION.txt in this package.
    *
    * Qt for Windows(R) Licensees
    * As a special exception, Nokia, as the sole copyright holder for Qt
    * Designer, grants users of the Qt/Eclipse Integration plug-in the
    * right for the Qt/Eclipse Integration to link to functionality
    * provided by Qt Designer and its related libraries.
    *
    *
    * If you are unsure which license is appropriate for your use, please
    * contact the sales department at qt-sales@nokia.com.

    **
    ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
    **
    ****************************************************************************/

    package com.trolltech.examples;

    import com.trolltech.qt.core.*;
    import com.trolltech.qt.gui.*;

    import java.util.*;

    @QtJambiExample(name = "A Jambi Tree Model")
    public class TreeModel extends QTreeView
    {
        private static class Model extends QTreeModel {
            public Model(QObject parent) {
                super(parent);
            }

            /**
             * Returns the number of children this parent has.
             */
            @Override
            public int childCount(Object parent) {
                return entryList(dir(parent)).size();
            }

            /**
             * Converts the parent to a QDir and accesses its entry list to
             * create a new QDir as the child.
             */
            @Override
            public Object child(Object parent, int row) {
                QDir d = dir(parent);
                return new QDir(d.absoluteFilePath(entryList(d).get(row)));
            }

            /**
             * Converts the directory to a QDir and returns it.
             */
            @Override
            public String text(Object value) {
                return ((QDir) value).dirName();
            }

            /**
             * Convenience method for getting the entry list of a
             * directory. This method also caches the previous entry list, as
             * the same entry list is often used again and again.
             */
            private List<String> entryList(QDir dir) {
                if (dir == lastDirectory) {
                    return lastEntryList;
                }
                lastEntryList = dir.entryList(entryListFlags);
                lastDirectory = dir;
                return lastEntryList;
            }

            /**
             * Convenience method for converting the object to a QDir. If the
             * value is null, its the root.
             */
            private QDir dir(Object value) {
                return value != null ? (QDir) value : QDir.root();
            }

            private QDir lastDirectory;
            private List<String> lastEntryList;
            private QDir.Filters entryListFlags = new QDir.Filters(QDir.Filter.NoDotAndDotDot,
                                                                   QDir.Filter.Dirs,
                                                                   QDir.Filter.Files);
        }

        public TreeModel() {
            this(null);
        }

        public TreeModel(QWidget parent) {
            // Hide my header...
            header().hide();

            // Create our jambi file model
            Model model = new Model(this);
            setModel(model);
            show();

            // The QTreeModel does some caching of datastructures
            // behind the scenes. To avoid memory pooling of this
            // datastructure we can call the releaseChildren method to
            // release parts of this pool when its no longer needed. One
            // such case is when the view collapses a subtree and it is no
            // longer visible.
            collapsed.connect(model, "releaseChildren(QModelIndex)");
            setWindowTitle("A Qt Jambi Tree Model");
            setWindowIcon(new QIcon("classpath:com/trolltech/images/qt-logo.png"));
        }

        public static void main(String args[]) {
            QApplication.initialize(args);

            // Create the tree view.
            TreeModel view = new TreeModel();
            view.show();

            // Spin the event loop
            QApplication.exec();
        }
    }