1 /* 2 * Copyright (C) 2013 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 17 package android.animation; 18 19 /** 20 * This evaluator can be used to perform type interpolation between <code>float[]</code> values. 21 * Each index into the array is treated as a separate value to interpolate. For example, 22 * evaluating <code>{100, 200}</code> and <code>{300, 400}</code> will interpolate the value at 23 * the first index between 100 and 300 and the value at the second index value between 200 and 400. 24 */ 25 public class FloatArrayEvaluator implements TypeEvaluator<float[]> { 26 27 private float[] mArray; 28 29 /** 30 * Create a FloatArrayEvaluator that does not reuse the animated value. Care must be taken 31 * when using this option because on every evaluation a new <code>float[]</code> will be 32 * allocated. 33 * 34 * @see #FloatArrayEvaluator(float[]) 35 */ 36 public FloatArrayEvaluator() { 37 } 38 39 /** 40 * Create a FloatArrayEvaluator that reuses <code>reuseArray</code> for every evaluate() call. 41 * Caution must be taken to ensure that the value returned from 42 * {@link android.animation.ValueAnimator#getAnimatedValue()} is not cached, modified, or 43 * used across threads. The value will be modified on each <code>evaluate()</code> call. 44 * 45 * @param reuseArray The array to modify and return from <code>evaluate</code>. 46 */ 47 public FloatArrayEvaluator(float[] reuseArray) { 48 mArray = reuseArray; 49 } 50 51 /** 52 * Interpolates the value at each index by the fraction. If 53 * {@link #FloatArrayEvaluator(float[])} was used to construct this object, 54 * <code>reuseArray</code> will be returned, otherwise a new <code>float[]</code> 55 * will be returned. 56 * 57 * @param fraction The fraction from the starting to the ending values 58 * @param startValue The start value. 59 * @param endValue The end value. 60 * @return A <code>float[]</code> where each element is an interpolation between 61 * the same index in startValue and endValue. 62 */ 63 @Override 64 public float[] evaluate(float fraction, float[] startValue, float[] endValue) { 65 float[] array = mArray; 66 if (array == null) { 67 array = new float[startValue.length]; 68 } 69 70 for (int i = 0; i < array.length; i++) { 71 float start = startValue[i]; 72 float end = endValue[i]; 73 array[i] = start + (fraction * (end - start)); 74 } 75 return array; 76 } 77 } 78
