LogDecelerateInterpolator.java revision c39d9c75590eca86a5e7e32a8824ba04a0d42e9b
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; 17import android.support.annotation.RestrictTo; 18 19import static android.support.annotation.RestrictTo.Scope.GROUP_ID; 20 21/** 22 * @hide 23 */ 24@RestrictTo(GROUP_ID) 25public class LogDecelerateInterpolator implements TimeInterpolator { 26 27 int mBase; 28 int mDrift; 29 final float mLogScale; 30 31 public LogDecelerateInterpolator(int base, int drift) { 32 mBase = base; 33 mDrift = drift; 34 35 mLogScale = 1f / computeLog(1, mBase, mDrift); 36 } 37 38 static float computeLog(float t, int base, int drift) { 39 return (float) -Math.pow(base, -t) + 1 + (drift * t); 40 } 41 42 @Override 43 public float getInterpolation(float t) { 44 return computeLog(t, mBase, mDrift) * mLogScale; 45 } 46} 47