bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/swt/ScaleObservableValue.java

/*******************************************************************************
 * Copyright (c) 2005, 2008 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *     Peter Centgraf - bug 175763
 *******************************************************************************/
package org.eclipse.jface.internal.databinding.swt;

import org.eclipse.core.databinding.observable.Diffs;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.internal.databinding.provisional.swt.AbstractSWTObservableValue;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.widgets.Scale;

/**
 * @since 1.0
 * 
 */
public class ScaleObservableValue extends AbstractSWTObservableValue {

	private final Scale scale;

	private final String attribute;

	private boolean updating = false;

	private int currentSelection;
	
	private SelectionListener listener;

	/**
	 * @param scale
	 * @param attribute
	 */
	public ScaleObservableValue(Scale scale, String attribute) {
		super(scale);
		this.scale = scale;
		this.attribute = attribute;
		init();
	}
	
	/**
	 * @param realm
	 * @param scale
	 * @param attribute
	 */
	public ScaleObservableValue(Realm realm, Scale scale, String attribute) {
		super(realm, scale);
		this.scale = scale;
		this.attribute = attribute;
		init();
	}
	
	private void init() {		
		if (attribute.equals(SWTProperties.SELECTION)) {
			currentSelection = scale.getSelection();
			scale.addSelectionListener(listener = new SelectionAdapter() {
				public void widgetSelected(SelectionEvent e) {
					if (!updating) {
						int newSelection = ScaleObservableValue.this.scale
						.getSelection();
						notifyIfChanged(currentSelection, newSelection);
						currentSelection = newSelection;
					}
				}
			});
		} else if (!attribute.equals(SWTProperties.MIN)
				&& !attribute.equals(SWTProperties.MAX)) {
			throw new IllegalArgumentException(
					"Attribute name not valid: " + attribute); //$NON-NLS-1$
		}
	}

	public void doSetValue(final Object value) {
		int oldValue;
		int newValue;
		try {
			updating = true;
			newValue = ((Integer) value).intValue();
			if (attribute.equals(SWTProperties.SELECTION)) {
				oldValue = scale.getSelection();
				scale.setSelection(newValue);
				currentSelection = newValue;
			} else if (attribute.equals(SWTProperties.MIN)) {
				oldValue = scale.getMinimum();
				scale.setMinimum(newValue);
			} else if (attribute.equals(SWTProperties.MAX)) {
				oldValue = scale.getMaximum();
				scale.setMaximum(newValue);
			} else {
				Assert.isTrue(false, "invalid attribute name:" + attribute); //$NON-NLS-1$
				return;
			}
			
			notifyIfChanged(oldValue, newValue);
		} finally {
			updating = false;
		}
	}

	public Object doGetValue() {
		int value = 0;
		if (attribute.equals(SWTProperties.SELECTION)) {
			value = scale.getSelection();
		} else if (attribute.equals(SWTProperties.MIN)) {
			value = scale.getMinimum();
		} else if (attribute.equals(SWTProperties.MAX)) {
			value = scale.getMaximum();
		}
		return new Integer(value);
	}

	public Object getValueType() {
		return Integer.TYPE;
	}

	/**
	 * @return attribute being observed
	 */
	public String getAttribute() {
		return attribute;
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.core.databinding.observable.value.AbstractObservableValue#dispose()
	 */
	public synchronized void dispose() {
		super.dispose();
		
		if (listener != null && !scale.isDisposed()) {
			scale.removeSelectionListener(listener);
		}
		listener = null;
	}
	
	private void notifyIfChanged(int oldValue, int newValue) {
		if (oldValue != newValue) {
			fireValueChange(Diffs.createValueDiff(new Integer(oldValue),
					new Integer(newValue)));
		}
	}
}