1/* 2 * Copyright (C) 2017 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 17package android.support.transition; 18 19import android.animation.TypeEvaluator; 20 21/** 22 * This evaluator can be used to perform type interpolation between <code>float[]</code> values. 23 * Each index into the array is treated as a separate value to interpolate. For example, 24 * evaluating <code>{100, 200}</code> and <code>{300, 400}</code> will interpolate the value at 25 * the first index between 100 and 300 and the value at the second index value between 200 and 400. 26 */ 27class FloatArrayEvaluator implements TypeEvaluator<float[]> { 28 29 private float[] mArray; 30 31 /** 32 * Create a FloatArrayEvaluator that reuses <code>reuseArray</code> for every evaluate() call. 33 * Caution must be taken to ensure that the value returned from 34 * {@link android.animation.ValueAnimator#getAnimatedValue()} is not cached, modified, or 35 * used across threads. The value will be modified on each <code>evaluate()</code> call. 36 * 37 * @param reuseArray The array to modify and return from <code>evaluate</code>. 38 */ 39 FloatArrayEvaluator(float[] reuseArray) { 40 mArray = reuseArray; 41 } 42 43 /** 44 * Interpolates the value at each index by the fraction. If 45 * {@link #FloatArrayEvaluator(float[])} was used to construct this object, 46 * <code>reuseArray</code> will be returned, otherwise a new <code>float[]</code> 47 * will be returned. 48 * 49 * @param fraction The fraction from the starting to the ending values 50 * @param startValue The start value. 51 * @param endValue The end value. 52 * @return A <code>float[]</code> where each element is an interpolation between 53 * the same index in startValue and endValue. 54 */ 55 @Override 56 public float[] evaluate(float fraction, float[] startValue, float[] endValue) { 57 float[] array = mArray; 58 if (array == null) { 59 array = new float[startValue.length]; 60 } 61 62 for (int i = 0; i < array.length; i++) { 63 float start = startValue[i]; 64 float end = endValue[i]; 65 array[i] = start + (fraction * (end - start)); 66 } 67 return array; 68 } 69 70} 71