/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.glview.animation;
/**
* Abstract base class used convert type T to another type V and back again. This
* is necessary when the value types of in animation are different from the property
* type. BidirectionalTypeConverter is needed when only the final value for the
* animation is supplied to animators.
* @see PropertyValuesHolder#setConverter(TypeConverter)
*/
public abstract class BidirectionalTypeConverter<T, V> extends TypeConverter<T, V> {
private BidirectionalTypeConverter mInvertedConverter;
public BidirectionalTypeConverter(Class<T> fromClass, Class<V> toClass) {
super(fromClass, toClass);
}
/**
* Does a conversion from the target type back to the source type. The subclass
* must implement this when a TypeConverter is used in animations and current
* values will need to be read for an animation.
* @param value The Object to convert.
* @return A value of type T, converted from <code>value</code>.
*/
public abstract T convertBack(V value);
/**
* Returns the inverse of this converter, where the from and to classes are reversed.
* The inverted converter uses this convert to call {@link #convertBack(Object)} for
* {@link #convert(Object)} calls and {@link #convert(Object)} for
* {@link #convertBack(Object)} calls.
* @return The inverse of this converter, where the from and to classes are reversed.
*/
public BidirectionalTypeConverter<V, T> invert() {
if (mInvertedConverter == null) {
mInvertedConverter = new InvertedConverter(this);
}
return mInvertedConverter;
}
private static class InvertedConverter<From, To> extends BidirectionalTypeConverter<From, To> {
private BidirectionalTypeConverter<To, From> mConverter;
public InvertedConverter(BidirectionalTypeConverter<To, From> converter) {
super(converter.getTargetType(), converter.getSourceType());
mConverter = converter;
}
@Override
public From convertBack(To value) {
return mConverter.convert(value);
}
@Override
public To convert(From value) {
return mConverter.convertBack(value);
}
}
}