1 /* 2 * Copyright (C) 2010 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 integer 21 * values that represent ARGB colors. 22 */ 23 public class ArgbEvaluator implements TypeEvaluator { 24 25 /** 26 * This function returns the calculated in-between value for a color 27 * given integers that represent the start and end values in the four 28 * bytes of the 32-bit int. Each channel is separately linearly interpolated 29 * and the resulting calculated values are recombined into the return value. 30 * 31 * @param fraction The fraction from the starting to the ending values 32 * @param startValue A 32-bit int value representing colors in the 33 * separate bytes of the parameter 34 * @param endValue A 32-bit int value representing colors in the 35 * separate bytes of the parameter 36 * @return A value that is calculated to be the linearly interpolated 37 * result, derived by separating the start and end values into separate 38 * color channels and interpolating each one separately, recombining the 39 * resulting values in the same way. 40 */ 41 public Object evaluate(float fraction, Object startValue, Object endValue) { 42 int startInt = (Integer) startValue; 43 int startA = (startInt >> 24) & 0xff; 44 int startR = (startInt >> 16) & 0xff; 45 int startG = (startInt >> 8) & 0xff; 46 int startB = startInt & 0xff; 47 48 int endInt = (Integer) endValue; 49 int endA = (endInt >> 24) & 0xff; 50 int endR = (endInt >> 16) & 0xff; 51 int endG = (endInt >> 8) & 0xff; 52 int endB = endInt & 0xff; 53 54 return (int)((startA + (int)(fraction * (endA - startA))) << 24) | 55 (int)((startR + (int)(fraction * (endR - startR))) << 16) | 56 (int)((startG + (int)(fraction * (endG - startG))) << 8) | 57 (int)((startB + (int)(fraction * (endB - startB)))); 58 } 59 }
