1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package android.animation; 17 18 /** 19 * Abstract base class used convert type T to another type V and back again. This 20 * is necessary when the value types of in animation are different from the property 21 * type. BidirectionalTypeConverter is needed when only the final value for the 22 * animation is supplied to animators. 23 * @see PropertyValuesHolder#setConverter(TypeConverter) 24 */ 25 public abstract class BidirectionalTypeConverter<T, V> extends TypeConverter<T, V> { 26 private BidirectionalTypeConverter mInvertedConverter; 27 28 public BidirectionalTypeConverter(Class<T> fromClass, Class<V> toClass) { 29 super(fromClass, toClass); 30 } 31 32 /** 33 * Does a conversion from the target type back to the source type. The subclass 34 * must implement this when a TypeConverter is used in animations and current 35 * values will need to be read for an animation. 36 * @param value The Object to convert. 37 * @return A value of type T, converted from <code>value</code>. 38 */ 39 public abstract T convertBack(V value); 40 41 /** 42 * Returns the inverse of this converter, where the from and to classes are reversed. 43 * The inverted converter uses this convert to call {@link #convertBack(Object)} for 44 * {@link #convert(Object)} calls and {@link #convert(Object)} for 45 * {@link #convertBack(Object)} calls. 46 * @return The inverse of this converter, where the from and to classes are reversed. 47 */ 48 public BidirectionalTypeConverter<V, T> invert() { 49 if (mInvertedConverter == null) { 50 mInvertedConverter = new InvertedConverter(this); 51 } 52 return mInvertedConverter; 53 } 54 55 private static class InvertedConverter<From, To> extends BidirectionalTypeConverter<From, To> { 56 private BidirectionalTypeConverter<To, From> mConverter; 57 58 public InvertedConverter(BidirectionalTypeConverter<To, From> converter) { 59 super(converter.getTargetType(), converter.getSourceType()); 60 mConverter = converter; 61 } 62 63 @Override 64 public From convertBack(To value) { 65 return mConverter.convert(value); 66 } 67 68 @Override 69 public To convert(From value) { 70 return mConverter.convertBack(value); 71 } 72 } 73 } 74
