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/*
* Copyright (c) 2002-2013 JGoodies Software GmbH. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* o Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* o Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* o Neither the name of JGoodies Software GmbH nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.jgoodies.binding.value;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
/**
* A ValueModel that converts the values of a wrapped ValueModel.
* The conversion is used when reading values, writing values,
* and in change notification.
*
* More formally, a converting ValueModel VM1 converts the type
* T2 of an object being held as a value in one ValueModel VM2
* into another type T1. When reading a value from VM1,
* instances of T2 are read from VM2 and are converted to T1. When storing
* a new value to VM1, the type converter will perform the inverse conversion
* and will convert an instance of T1 to T2.
*
* @author Karsten Lentzsch
* @version $Revision: 1.15 $
*
* @see ValueModel
*
* @since 2.7
*/
public final class ConverterValueModel extends AbstractWrappedValueModel {
/**
* Holds the ValueModel that in turn holds the source value.
*/
private final ValueModel source;
/**
* Converts values from the source to the target and vice versa.
*/
private final BindingConverter converter;
// Instance creation ******************************************************
/**
* Constructs a ConverterValueModel on the given source ValueModel and
* BindingConverter.
*
* @param source the ValueModel that holds the source value
* @param converter converts source values to target values and vice versa
* @throws NullPointerException if {@code source} is {@code null}
*/
public ConverterValueModel(ValueModel source, BindingConverter converter) {
super(source);
this.source = source;
this.converter = converter;
}
// Abstract Behavior ******************************************************
/**
* Converts a value from the subject to the type or format used
* by this converter.
*
* @param sourceValue the source's value
* @return the converted value in the type or format used by this converter
*/
public Object convertFromSubject(Object sourceValue) {
return converter.targetValue(sourceValue);
}
@Override
public void setValue(Object targetValue) {
source.setValue(converter.sourceValue(targetValue));
}
// ValueModel Implementation **********************************************
/**
* Converts the subject's value and returns the converted value.
*
* @return the converted subject value
*/
@Override
public Object getValue() {
return convertFromSubject(source.getValue());
}
// AbstractWrappedValueModel Behavior *************************************
@Override
protected PropertyChangeListener createValueChangeHandler() {
return new ValueChangeHandler();
}
// Helper Class ***********************************************************
/**
* Listens to value changes in the wrapped model, converts the old and
* new value - if any - and fires a value change for this converter.
*/
private final class ValueChangeHandler implements PropertyChangeListener {
/**
* Notifies listeners about a change in the underlying subject.
* The old and new value used in the PropertyChangeEvent to be fired
* are converted versions of the observed old and new values.
* The observed old and new value are converted only
* if they are non-null. This is because {@code null}
* may be a valid value or may indicate not available.
*
* TODO: We may need to check the identity, not equity.
*
* @param evt the property change event to be handled
*/
@Override
public void propertyChange(PropertyChangeEvent evt) {
Object convertedOldValue = evt.getOldValue() == null
? null
: convertFromSubject(evt.getOldValue());
Object convertedNewValue = evt.getNewValue() == null
? null
: convertFromSubject(evt.getNewValue());
fireValueChange(convertedOldValue, convertedNewValue);
}
}
}