content: /*
   * 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 android.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);
          }
      }
  }
  