George Mount | 42516d1 | 2014-05-19 15:49:29 -0700 | [diff] [blame] | 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 | } |