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;
  
  import android.graphics.PointF;
  
  /**
   * This evaluator can be used to perform type interpolation between <code>PointF</code> values.
   */
  public class PointFEvaluator implements TypeEvaluator<PointF> {
  
      /**
       * When null, a new PointF is returned on every evaluate call. When non-null,
       * mPoint will be modified and returned on every evaluate.
       */
      private PointF mPoint;
  
      /**
       * Construct a PointFEvaluator that returns a new PointF on every evaluate call.
       * To avoid creating an object for each evaluate call,
       * {@link PointFEvaluator#PointFEvaluator(android.graphics.PointF)} should be used
       * whenever possible.
       */
      public PointFEvaluator() {
      }
  
      /**
       * Constructs a PointFEvaluator that modifies and returns <code>reuse</code>
       * in {@link #evaluate(float, android.graphics.PointF, android.graphics.PointF)} calls.
       * The value returned from
       * {@link #evaluate(float, android.graphics.PointF, android.graphics.PointF)} should
       * not be cached because it will change over time as the object is reused on each
       * call.
       *
       * @param reuse A PointF to be modified and returned by evaluate.
       */
      public PointFEvaluator(PointF reuse) {
          mPoint = reuse;
      }
  
      /**
       * This function returns the result of linearly interpolating the start and
       * end PointF values, with <code>fraction</code> representing the proportion
       * between the start and end values. The calculation is a simple parametric
       * calculation on each of the separate components in the PointF objects
       * (x, y).
       *
       * <p>If {@link #PointFEvaluator(android.graphics.PointF)} was used to construct
       * this PointFEvaluator, the object returned will be the <code>reuse</code>
       * passed into the constructor.</p>
       *
       * @param fraction   The fraction from the starting to the ending values
       * @param startValue The start PointF
       * @param endValue   The end PointF
       * @return A linear interpolation between the start and end values, given the
       *         <code>fraction</code> parameter.
       */
      @Override
      public PointF evaluate(float fraction, PointF startValue, PointF endValue) {
          float x = startValue.x + (fraction * (endValue.x - startValue.x));
          float y = startValue.y + (fraction * (endValue.y - startValue.y));
  
          if (mPoint != null) {
              mPoint.set(x, y);
              return mPoint;
          } else {
              return new PointF(x, y);
          }
      }
  }
  