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