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package net.sf.cuf.model.ui;

import net.sf.cuf.model.ValueModel;

import javax.swing.event.ChangeListener;
import javax.swing.event.ChangeEvent;
import javax.swing.SpinnerModel;

/**
 * A SpinnerModelAdapter connects the value of a ValueModel to the
 * value of a SpinnerModel. Whenever one of the model's changes,
 * the other is adjusted accordingly.
 * A SpinnerModelAdapter is itself not a ValueModel, but connects a
 * ValueModel to a SpinnerModel.
 */
public class SpinnerModelAdapter implements ChangeListener
{
    // the vallue model we adapt to, never null
    private ValueModel   mValueModel;
    // the button model we adapt to, never null
    private SpinnerModel mSpinnerModel;
    // marker if we are in stateChange
    private boolean      mInStateChanged;

    /**
     * Creates a new adapter between a ValueModel and a SpinnerModel.
     * Whenever one of the models changes, the other is adjusted accordingly.
     * The initial selection state is taken from the value model.
     * @param pValueModel the value model
     * @param pSpinnerModel the spinner model
     */
    public SpinnerModelAdapter(final ValueModel pValueModel, final SpinnerModel pSpinnerModel)
    {
        if (pValueModel==null)
            throw new IllegalArgumentException("value model must not be null");
        if (pSpinnerModel==null)
            throw new IllegalArgumentException("spinner model must not be null");

        mValueModel  = pValueModel;
        mSpinnerModel= pSpinnerModel;
        mInStateChanged= false;
        mSpinnerModel.addChangeListener(this);
        mValueModel.  addChangeListener(this);
    }

    /**
     * Invoked when either the value model or the spinner model changed its state.
     * @param pEvent a ChangeEvent object
     */
    public void stateChanged(final ChangeEvent pEvent)
    {
        if (mInStateChanged)
        {
            return;
        }

        mInStateChanged= true;
        try
        {
            Object source= pEvent.getSource();
            if (source == mValueModel)
            {
                // ValueModel callback, update the SpinnerModel
                mSpinnerModel.setValue(mValueModel.getValue());
            }
            else if (source== mSpinnerModel)
            {
                // SpinnerModel callback, update the ValueModel
                mValueModel.setValue(mSpinnerModel.getValue());
            }
            else
            {
                // should never happen
                throw new IllegalStateException("stateChanged with wrong source"+source);
            }
        }
        finally
        {
            mInStateChanged= false;
        }
    }
}