content: /*
   * 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;
      }
  }
  