org.eclipse.papyrus.infra.widgets.databinding.ComboObservableValue.java Source code

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Here is the source code for org.eclipse.papyrus.infra.widgets.databinding.ComboObservableValue.java

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/*****************************************************************************
 * Copyright (c) 2011 CEA LIST.
 *    
 * 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:
 *  Camille Letavernier (CEA LIST) camille.letavernier@cea.fr - Initial API and implementation
 *****************************************************************************/
package org.eclipse.papyrus.infra.widgets.databinding;

import org.eclipse.core.databinding.observable.value.AbstractObservableValue;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.databinding.observable.value.ValueDiff;
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.papyrus.infra.tools.databinding.AggregatedObservable;
import org.eclipse.papyrus.infra.widgets.providers.ComboLabelProvider;
import org.eclipse.papyrus.infra.widgets.providers.UnchangedObject;
import org.eclipse.papyrus.infra.widgets.providers.UnsetObject;

public class ComboObservableValue extends AbstractObservableValue implements ISelectionChangedListener {

    protected ComboViewer viewer;

    protected Object currentValue;

    protected AggregatedObservable modelProperty;

    public ComboObservableValue(ComboViewer viewer, IObservableValue modelProperty) {
        this.viewer = viewer;
        viewer.setLabelProvider(new ComboLabelProvider(viewer.getLabelProvider()));
        if (modelProperty instanceof AggregatedObservable) {
            this.modelProperty = (AggregatedObservable) modelProperty;
        }
        viewer.addSelectionChangedListener(this);
    }

    public Object getValueType() {
        return Object.class;
    }

    @Override
    protected Object doGetValue() {
        ISelection selection = viewer.getSelection();
        if (!selection.isEmpty() && selection instanceof IStructuredSelection) {
            IStructuredSelection structuredSelection = (IStructuredSelection) selection;
            Object firstElement = structuredSelection.getFirstElement();
            if (firstElement == UnsetObject.instance) {
                return null;
            }
            if (firstElement == UnchangedObject.instance) {
                return null;
            }
            return firstElement;
        }

        return null;
    }

    @Override
    protected void doSetValue(Object value) {
        currentValue = value;

        if (modelProperty != null && modelProperty.hasDifferentValues()) {
            viewer.setSelection(new StructuredSelection(UnchangedObject.instance));
        } else if (value == null) {
            viewer.setSelection(new StructuredSelection(UnsetObject.instance));
        } else {
            viewer.setSelection(new StructuredSelection(value));
        }
    }

    @Override
    public void dispose() {
        viewer.removeSelectionChangedListener(this);
        super.dispose();
    }

    public void selectionChanged(SelectionChangedEvent event) {
        if (((IStructuredSelection) event.getSelection()).getFirstElement() != UnchangedObject.instance) {

            final Object oldValue = currentValue;
            final Object newValue = doGetValue();
            currentValue = newValue;

            fireValueChange(new ValueDiff() {

                @Override
                public Object getOldValue() {
                    return oldValue;
                }

                @Override
                public Object getNewValue() {
                    return newValue;
                }

            });
        }
    }

}