1/* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except 5 * in compliance with the License. You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software distributed under the License 10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express 11 * or implied. See the License for the specific language governing permissions and limitations under 12 * the License. 13 */ 14package android.support.v17.leanback.animation; 15 16import android.animation.TimeInterpolator; 17 18/** 19 * @hide 20 */ 21public class LogAccelerateInterpolator implements TimeInterpolator { 22 23 int mBase; 24 int mDrift; 25 final float mLogScale; 26 27 public LogAccelerateInterpolator(int base, int drift) { 28 mBase = base; 29 mDrift = drift; 30 mLogScale = 1f / computeLog(1, mBase, mDrift); 31 } 32 33 static float computeLog(float t, int base, int drift) { 34 return (float) -Math.pow(base, -t) + 1 + (drift * t); 35 } 36 37 @Override 38 public float getInterpolation(float t) { 39 return 1 - computeLog(1 - t, mBase, mDrift) * mLogScale; 40 } 41} 42