content: /*
   * Copyright (C) 2010 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 com.hx.curtain.drawer.nineoldandroids.animation;
  
  /**
   * This evaluator can be used to perform type interpolation between integer
   * values that represent ARGB colors.
   */
  public class ArgbEvaluator implements TypeEvaluator {
  
      /**
       * This function returns the calculated in-between value for a color
       * given integers that represent the start and end values in the four
       * bytes of the 32-bit int. Each channel is separately linearly interpolated
       * and the resulting calculated values are recombined into the return value.
       *
       * @param fraction The fraction from the starting to the ending values
       * @param startValue A 32-bit int value representing colors in the
       * separate bytes of the parameter
       * @param endValue A 32-bit int value representing colors in the
       * separate bytes of the parameter
       * @return A value that is calculated to be the linearly interpolated
       * result, derived by separating the start and end values into separate
       * color channels and interpolating each one separately, recombining the
       * resulting values in the same way.
       */
      public Object evaluate(float fraction, Object startValue, Object endValue) {
          int startInt = (Integer) startValue;
          int startA = (startInt >> 24);
          int startR = (startInt >> 16) & 0xff;
          int startG = (startInt >> 8) & 0xff;
          int startB = startInt & 0xff;
  
          int endInt = (Integer) endValue;
          int endA = (endInt >> 24);
          int endR = (endInt >> 16) & 0xff;
          int endG = (endInt >> 8) & 0xff;
          int endB = endInt & 0xff;
  
          return (int)((startA + (int)(fraction * (endA - startA))) << 24) |
                  (int)((startR + (int)(fraction * (endR - startR))) << 16) |
                  (int)((startG + (int)(fraction * (endG - startG))) << 8) |
                  (int)((startB + (int)(fraction * (endB - startB))));
      }
  }