/*
* Copyright (C) 2013 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;
/**
* This evaluator can be used to perform type interpolation between <code>float[]</code> values.
* Each index into the array is treated as a separate value to interpolate. For example,
* evaluating <code>{100, 200}</code> and <code>{300, 400}</code> will interpolate the value at
* the first index between 100 and 300 and the value at the second index value between 200 and 400.
*/
public class FloatArrayEvaluator implements TypeEvaluator<float[]> {
private float[] mArray;
/**
* Create a FloatArrayEvaluator that does not reuse the animated value. Care must be taken
* when using this option because on every evaluation a new <code>float[]</code> will be
* allocated.
*
* @see #FloatArrayEvaluator(float[])
*/
public FloatArrayEvaluator() {
}
/**
* Create a FloatArrayEvaluator that reuses <code>reuseArray</code> for every evaluate() call.
* Caution must be taken to ensure that the value returned from
* {@link android.animation.ValueAnimator#getAnimatedValue()} is not cached, modified, or
* used across threads. The value will be modified on each <code>evaluate()</code> call.
*
* @param reuseArray The array to modify and return from <code>evaluate</code>.
*/
public FloatArrayEvaluator(float[] reuseArray) {
mArray = reuseArray;
}
/**
* Interpolates the value at each index by the fraction. If
* {@link #FloatArrayEvaluator(float[])} was used to construct this object,
* <code>reuseArray</code> will be returned, otherwise a new <code>float[]</code>
* will be returned.
*
* @param fraction The fraction from the starting to the ending values
* @param startValue The start value.
* @param endValue The end value.
* @return A <code>float[]</code> where each element is an interpolation between
* the same index in startValue and endValue.
*/
@Override
public float[] evaluate(float fraction, float[] startValue, float[] endValue) {
float[] array = mArray;
if (array == null) {
array = new float[startValue.length];
}
for (int i = 0; i < array.length; i++) {
float start = startValue[i];
float end = endValue[i];
array[i] = start + (fraction * (end - start));
}
return array;
}
}