1 files changed, 73 insertions, 0 deletions
diff --git a/android/animation/BidirectionalTypeConverter.java b/android/animation/BidirectionalTypeConverter.java
new file mode 100644
index 00000000..960650ed
--- /dev/null
+++ b/android/animation/BidirectionalTypeConverter.java
@@ -0,0 +1,73 @@
+/*
+ * 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);
+        }
+    }
+}