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 private static final ArgbEvaluator sInstance = new ArgbEvaluator(); 25 26 /** 27 * Returns an instance of <code>ArgbEvaluator</code> that may be used in 28 * {@link ValueAnimator#setEvaluator(TypeEvaluator)}. The same instance may 29 * be used in multiple <code>Animator</code>s because it holds no state. 30 * @return An instance of <code>ArgbEvalutor</code>. 31 * 32 * @hide 33 */ getInstance()34 public static ArgbEvaluator getInstance() { 35 return sInstance; 36 } 37 38 /** 39 * This function returns the calculated in-between value for a color 40 * given integers that represent the start and end values in the four 41 * bytes of the 32-bit int. Each channel is separately linearly interpolated 42 * and the resulting calculated values are recombined into the return value. 43 * 44 * @param fraction The fraction from the starting to the ending values 45 * @param startValue A 32-bit int value representing colors in the 46 * separate bytes of the parameter 47 * @param endValue A 32-bit int value representing colors in the 48 * separate bytes of the parameter 49 * @return A value that is calculated to be the linearly interpolated 50 * result, derived by separating the start and end values into separate 51 * color channels and interpolating each one separately, recombining the 52 * resulting values in the same way. 53 */ evaluate(float fraction, Object startValue, Object endValue)54 public Object evaluate(float fraction, Object startValue, Object endValue) { 55 int startInt = (Integer) startValue; 56 int startA = (startInt >> 24) & 0xff; 57 int startR = (startInt >> 16) & 0xff; 58 int startG = (startInt >> 8) & 0xff; 59 int startB = startInt & 0xff; 60 61 int endInt = (Integer) endValue; 62 int endA = (endInt >> 24) & 0xff; 63 int endR = (endInt >> 16) & 0xff; 64 int endG = (endInt >> 8) & 0xff; 65 int endB = endInt & 0xff; 66 67 return (int)((startA + (int)(fraction * (endA - startA))) << 24) | 68 (int)((startR + (int)(fraction * (endR - startR))) << 16) | 69 (int)((startG + (int)(fraction * (endG - startG))) << 8) | 70 (int)((startB + (int)(fraction * (endB - startB)))); 71 } 72 }