org.eclipse.dltk.internal.databinging.RadioButtonListValue.java Source code

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Here is the source code for org.eclipse.dltk.internal.databinging.RadioButtonListValue.java

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/*******************************************************************************
 * Copyright (c) 2009 xored software, Inc.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     xored software, Inc. - initial API and Implementation (Alex Panchenko)
 *******************************************************************************/
package org.eclipse.dltk.internal.databinging;

import java.util.Map;

import org.eclipse.core.databinding.observable.Diffs;
import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
import org.eclipse.jface.databinding.swt.SWTObservables;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;

public class RadioButtonListValue<V> extends AbstractObservableValue {

    private final Class<V> valueType;
    private final Map<Button, V> buttons;
    private V selectionValue;

    private Listener updateListener = new Listener() {
        public void handleEvent(Event event) {
            V oldSelectionValue = selectionValue;
            selectionValue = getSelection();
            notifyIfChanged(oldSelectionValue, selectionValue);
        }
    };

    private Listener disposeListener = new Listener() {
        public void handleEvent(Event e) {
            RadioButtonListValue.this.dispose();
        }
    };

    private V getSelection() {
        for (Map.Entry<Button, V> entry : buttons.entrySet()) {
            if (entry.getKey().getSelection()) {
                return entry.getValue();
            }
        }
        return null;
    }

    /**
     * @param button
     */
    public RadioButtonListValue(Class<V> valueType, Map<Button, V> buttons) {
        super(SWTObservables.getRealm(buttons.keySet().iterator().next().getDisplay()));
        this.valueType = valueType;
        this.buttons = buttons;
        init();
    }

    private void init() {
        for (Button button : buttons.keySet()) {
            button.addListener(SWT.Selection, updateListener);
            button.addListener(SWT.DefaultSelection, updateListener);
            button.addListener(SWT.Dispose, disposeListener);
        }
    }

    @SuppressWarnings("unchecked")
    public void doSetValue(final Object value) {
        V oldSelectionValue = selectionValue;
        selectionValue = (V) value;
        boolean buttonUpdated = false;
        for (Map.Entry<Button, V> entry : buttons.entrySet()) {
            if (entry.getValue() == selectionValue) {
                entry.getKey().setSelection(true);
                buttonUpdated = true;
                break;
            }
        }
        if (!buttonUpdated) {
            for (Button button : buttons.keySet()) {
                button.setSelection(false);
            }
        }
        notifyIfChanged(oldSelectionValue, selectionValue);
    }

    public Object doGetValue() {
        return getSelection();
    }

    public Object getValueType() {
        return valueType;
    }

    /*
     * @see AbstractObservableValue #dispose()
     */
    public synchronized void dispose() {
        super.dispose();
        for (Button button : buttons.keySet()) {
            if (!button.isDisposed()) {
                button.removeListener(SWT.Selection, updateListener);
                button.removeListener(SWT.DefaultSelection, updateListener);
            }
        }
    }

    /**
     * Notifies consumers with a value change event only if a change occurred.
     * 
     * @param oldValue
     * @param newValue
     */
    private void notifyIfChanged(V oldValue, V newValue) {
        if (oldValue != newValue) {
            fireValueChange(Diffs.createValueDiff(oldValue, newValue));
        }
    }
}