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 * Copyright (c) 2011, 2018, 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
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 */

package sun.lwawt;

import java.awt.Point;
import java.awt.Choice;

import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.peer.ChoicePeer;

import javax.accessibility.Accessible;
import javax.swing.JComboBox;
import javax.swing.SwingUtilities;
import javax.swing.JPopupMenu;

Lightweight implementation of ChoicePeer. Delegates most of the work to the JComboBox. /**
 * Lightweight implementation of {@link ChoicePeer}. Delegates most of the work
 * to the {@link JComboBox}.
 */
final class LWChoicePeer extends LWComponentPeer<Choice, JComboBox<String>>
        implements ChoicePeer, ItemListener {

    
According to Choice specification item events are sent in response to
user input, but not in response to calls to select(). But JComboBox are
sent item events in both cases. Should be used under delegateLock.
/**
     * According to Choice specification item events are sent in response to
     * user input, but not in response to calls to select(). But JComboBox are
     * sent item events in both cases. Should be used under delegateLock.
     */
    private boolean skipPostMessage;

    LWChoicePeer(final Choice target,
                 final PlatformComponent platformComponent) {
        super(target, platformComponent);
    }

    @Override
    JComboBox<String> createDelegate() {
        return new JComboBoxDelegate();
    }

    @Override
    void initializeImpl() {
        super.initializeImpl();
        final Choice choice = getTarget();
        final JComboBox<String> combo = getDelegate();
        synchronized (getDelegateLock()) {
            final int count = choice.getItemCount();
            for (int i = 0; i < count; ++i) {
                combo.addItem(choice.getItem(i));
            }
            select(choice.getSelectedIndex());

            // NOTE: the listener must be added at the very end, otherwise it
            // fires events upon initialization of the combo box.
            combo.addItemListener(this);
        }
    }

    @Override
    public void itemStateChanged(final ItemEvent e) {
        // AWT Choice sends SELECTED event only whereas JComboBox
        // sends both SELECTED and DESELECTED.
        if (e.getStateChange() == ItemEvent.SELECTED) {
            synchronized (getDelegateLock()) {
                if (skipPostMessage) {
                    return;
                }
                getTarget().select(getDelegate().getSelectedIndex());
            }
            postEvent(new ItemEvent(getTarget(), ItemEvent.ITEM_STATE_CHANGED,
                                    e.getItem(), ItemEvent.SELECTED));
        }
    }

    @Override
    public void add(final String item, final int index) {
        synchronized (getDelegateLock()) {
            getDelegate().insertItemAt(item, index);
        }
    }

    @Override
    public void remove(final int index) {
        synchronized (getDelegateLock()) {
            // We shouldn't post event, if selected item was removed.
            skipPostMessage = true;
            getDelegate().removeItemAt(index);
            skipPostMessage = false;
        }
    }

    @Override
    public void removeAll() {
        synchronized (getDelegateLock()) {
            getDelegate().removeAllItems();
        }
    }

    @Override
    public void select(final int index) {
        synchronized (getDelegateLock()) {
            if (index != getDelegate().getSelectedIndex()) {
                skipPostMessage = true;
                getDelegate().setSelectedIndex(index);
                skipPostMessage = false;
            }
        }
    }

    @Override
    public boolean isFocusable() {
        return true;
    }

    @SuppressWarnings("serial")// Safe: outer class is non-serializable.
    private final class JComboBoxDelegate extends JComboBox<String> {

        @Override
        public boolean hasFocus() {
            return getTarget().hasFocus();
        }

        //Needed for proper popup menu location
        @Override
        public Point getLocationOnScreen() {
            return LWChoicePeer.this.getLocationOnScreen();
        }

        @Override
        public void firePopupMenuWillBecomeVisible() {
            super.firePopupMenuWillBecomeVisible();
            SwingUtilities.invokeLater(() -> {
                JPopupMenu popupMenu = getPopupMenu();
                // Need to override the invoker for proper grab handling
                if (popupMenu != null
                        && popupMenu.isShowing()
                        && popupMenu.getInvoker() != getTarget()) {
                    // The popup is now visible with correct location
                    // Save it and restore after toggling visibility and changing invoker
                    Point loc = popupMenu.getLocationOnScreen();
                    SwingUtilities.convertPointFromScreen(loc, this);
                    popupMenu.setVisible(false);
                    popupMenu.show(getTarget(), loc.x, loc.y);
                }
            });
        }

        private JPopupMenu getPopupMenu() {
            for (int i = 0; i < getAccessibleContext().getAccessibleChildrenCount(); i++) {
                Accessible child = getAccessibleContext().getAccessibleChild(i);
                if (child instanceof JPopupMenu) {
                    return  (JPopupMenu) child;
                }
            }
            return null;
        }
    }
}