ComboViewerBinding.java

/*
 * ====================================================================
 * 
 * The ObjectStyle Group Software License, Version 1.0
 * 
 * Copyright (c) 2006 The ObjectStyle Group and individual authors of the
 * software. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
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 * 1. Redistributions of source code must retain the above copyright notice,
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 * 2. Redistributions in binary form must reproduce the above copyright notice,
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 * 3. The end-user documentation included with the redistribution, if any, must
 * include the following acknowlegement: "This product includes software
 * developed by the ObjectStyle Group (http://objectstyle.org/)." Alternately,
 * this acknowlegement may appear in the software itself, if and wherever such
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 * 5. Products derived from this software may not be called "ObjectStyle" nor
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 * Group, please see <http://objectstyle.org/>.
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package org.objectstyle.wolips.eomodeler.utils;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.HashMap;
import java.util.Map;

import org.eclipse.jface.viewers.ComboViewer;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionChangedListener;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.SelectionChangedEvent;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.swt.widgets.Display;
import org.objectstyle.wolips.baseforplugins.util.ComparisonUtils;
import org.objectstyle.wolips.baseforuiplugins.utils.ErrorUtils;
import org.objectstyle.wolips.eomodeler.core.kvc.CachingKeyPath;
import org.objectstyle.wolips.eomodeler.core.kvc.IKey;
import org.objectstyle.wolips.eomodeler.core.utils.IPropertyChangeSource;

public class ComboViewerBinding implements ISelectionChangedListener, PropertyChangeListener {
	private ComboViewer myViewer;

	private IPropertyChangeSource myObj;

	private String myPropertyName;

	private IPropertyChangeSource myListObj;

	private String myListPropertyName;

	private Object myBlankValue;

	private Map<String, IKey> myKeys;

	public ComboViewerBinding(ComboViewer _viewer, IPropertyChangeSource _obj, String _propertyName, IPropertyChangeSource _listObj, String _listPropertyName, Object _blankValue) {
		myViewer = _viewer;
		myKeys = new HashMap<String, IKey>();
		myObj = _obj;
		myPropertyName = _propertyName;
		myListObj = _listObj;
		myListPropertyName = _listPropertyName;
		myBlankValue = _blankValue;
		Object initialValue = getKey(myPropertyName).getValue(myObj);
		setSelectedValue(initialValue);

		myViewer.addSelectionChangedListener(this);
		myObj.addPropertyChangeListener(myPropertyName, this);
		if (myListObj != null) {
			myListObj.addPropertyChangeListener(myListPropertyName, this);
		}
	}

	protected synchronized IKey getKey(String _property) {
		IKey key = myKeys.get(_property);
		if (key == null) {
			key = new CachingKeyPath(_property);
			myKeys.put(_property, key);
		}
		return key;
	}

	public void dispose() {
		myViewer.removeSelectionChangedListener(this);
		myObj.removePropertyChangeListener(myPropertyName, this);
		if (myListObj != null) {
			myListObj.removePropertyChangeListener(myListPropertyName, this);
		}
	}

	public void propertyChange(PropertyChangeEvent _event) {
		Object source = _event.getSource();
		String propertyName = _event.getPropertyName();
		if (source == myObj && myPropertyName.equals(propertyName)) {
			Object newValue = _event.getNewValue();
			setSelectedValue(newValue);
		} else if (myListObj != null && source == myListObj && myListPropertyName.equals(propertyName)) {
			ISelection selection = myViewer.getSelection();
			if (myViewer.getContentProvider() != null) {
				myViewer.setInput(myListObj);
				myViewer.setSelection(selection);
			}
		}
	}

	public void selectionChanged(SelectionChangedEvent _event) {
		try {
			Object newValue = ((IStructuredSelection) _event.getSelection()).getFirstElement();
			if (ComparisonUtils.equals(myBlankValue, newValue)) {
				newValue = null;
			}
			IKey key = getKey(myPropertyName);
			Object existingValue = key.getValue(myObj);
			if (!ComparisonUtils.equals(existingValue, newValue)) {
				key.setValue(myObj, newValue);
			}
		} catch (Exception e) {
			ErrorUtils.openErrorDialog(Display.getDefault().getActiveShell(), e);
		}
	}

	protected void setSelectedValue(Object _newValue) {
		if (_newValue == null || _newValue == myBlankValue || (myBlankValue != null && myBlankValue.equals(_newValue))) {
			if (myBlankValue == null) {
				// DO NOTHING
			} else {
				myViewer.setSelection(new StructuredSelection(myBlankValue), true);
			}
		} else {
			myViewer.setSelection(new StructuredSelection(_newValue), true);
		}
	}
}