AutoCompleter.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.mvnsearch.snippet.plugin.util;

import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.JTextComponent;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;

/**
 * auto completer
 */
public abstract class AutoCompleter {
    protected JList list = new JList();
    protected JPopupMenu popup = new JPopupMenu();
    protected JTextComponent textComp;
    private static final String AUTOCOMPLETER = "AUTOCOMPLETER"; //NOI18N

    /**
     * construct completion on text component
     *
     * @param comp text component
     */
    public AutoCompleter(JTextComponent comp) {
        textComp = comp;
        textComp.putClientProperty(AUTOCOMPLETER, this);
        JScrollPane scroll = new JScrollPane(list);
        scroll.setBorder(null);
        list.setFocusable(false);
        scroll.getVerticalScrollBar().setFocusable(false);
        scroll.getHorizontalScrollBar().setFocusable(false);
        popup.setBorder(BorderFactory.createLineBorder(Color.black));
        popup.add(scroll);
        if (textComp instanceof JTextField) {
            textComp.registerKeyboardAction(showAction, KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), JComponent.WHEN_FOCUSED);
            textComp.getDocument().addDocumentListener(documentListener);
        } else {
            textComp.registerKeyboardAction(showAction, KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, KeyEvent.CTRL_MASK), JComponent.WHEN_FOCUSED);
        }
        textComp.registerKeyboardAction(upAction, KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), JComponent.WHEN_FOCUSED);
        textComp.registerKeyboardAction(hidePopupAction, KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0), JComponent.WHEN_FOCUSED);

        popup.addPopupMenuListener(new PopupMenuListener() {
            public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
            }

            public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
                textComp.unregisterKeyboardAction(KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0));
            }

            public void popupMenuCanceled(PopupMenuEvent e) {
            }
        });
        list.setRequestFocusEnabled(false);
    }

    static Action acceptAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            JComponent tf = (JComponent) e.getSource();
            AutoCompleter completer = (AutoCompleter) tf.getClientProperty(AUTOCOMPLETER);
            completer.popup.setVisible(false);
            completer.acceptedListItem((String) completer.list.getSelectedValue());
        }
    };

    DocumentListener documentListener = new DocumentListener() {
        public void insertUpdate(DocumentEvent e) {
            showPopup();
        }

        public void removeUpdate(DocumentEvent e) {
            showPopup();
        }

        public void changedUpdate(DocumentEvent e) {
        }
    };

    private void showPopup() {
        if (!textComp.isShowing()) return;
        popup.setVisible(false);
        if (textComp.isEnabled() && updateListData() && list.getModel().getSize() != 0) {
            if (!(textComp instanceof JTextField))
                textComp.getDocument().addDocumentListener(documentListener);
            textComp.registerKeyboardAction(acceptAction, KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0), JComponent.WHEN_FOCUSED);
            int size = list.getModel().getSize();
            list.setVisibleRowCount(size < 10 ? size : 10);
            int x = 0;
            try {
                int pos = Math.min(textComp.getCaret().getDot(), textComp.getCaret().getMark());
                x = textComp.getUI().modelToView(textComp, pos).x;
            } catch (BadLocationException e) {
                e.printStackTrace();
            }
            popup.show(textComp, x, textComp.getHeight());
        } else
            popup.setVisible(false);
        textComp.requestFocus();
    }

    static Action showAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            JComponent tf = (JComponent) e.getSource();
            AutoCompleter completer = (AutoCompleter) tf.getClientProperty(AUTOCOMPLETER);
            if (tf.isEnabled()) {
                if (completer.popup.isVisible())
                    completer.selectNextPossibleValue();
                else
                    completer.showPopup();
            }
        }
    };

    static Action upAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            JComponent tf = (JComponent) e.getSource();
            AutoCompleter completer = (AutoCompleter) tf.getClientProperty(AUTOCOMPLETER);
            if (tf.isEnabled()) {
                if (completer.popup.isVisible())
                    completer.selectPreviousPossibleValue();
            }
        }
    };

    static Action hidePopupAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            JComponent tf = (JComponent) e.getSource();
            AutoCompleter completer = (AutoCompleter) tf.getClientProperty(AUTOCOMPLETER);
            if (tf.isEnabled())
                completer.popup.setVisible(false);
        }
    };

    /**
     * Selects the next item in the list.  It won't change the selection if the
     * currently selected item is already the last item.
     */
    protected void selectNextPossibleValue() {
        int si = list.getSelectedIndex();

        if (si < list.getModel().getSize() - 1) {
            list.setSelectedIndex(si + 1);
            list.ensureIndexIsVisible(si + 1);
        }
    }

    /**
     * Selects the previous item in the list.  It won't change the selection if the
     * currently selected item is already the first item.
     */
    protected void selectPreviousPossibleValue() {
        int si = list.getSelectedIndex();

        if (si > 0) {
            list.setSelectedIndex(si - 1);
            list.ensureIndexIsVisible(si - 1);
        }
    }

    /**
     * update list model depending on the data in textfield
     *
     * @return data updated or not
     */
    protected abstract boolean updateListData();

    /**
     * user has selected some item in the list. update textfield accordingly
     *
     * @param selected item
     */
    protected abstract void acceptedListItem(String selected);
}