1 /* 2 * Copyright (C) 2014 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 com.android.tv.settings.widget; 18 19 /** 20 * Lerper model tracks target position by adding (target - source) / divisor to source position 21 */ 22 public final class Lerper { 23 24 public static final float DEFAULT_DIVISOR = 2.0f; 25 26 private float mDivisor = DEFAULT_DIVISOR; 27 private float mMinDelta = 1 / DEFAULT_DIVISOR; 28 setDivisor(float divisor)29 public void setDivisor(float divisor) { 30 if (divisor < 1f) throw new IllegalArgumentException(); 31 mDivisor = divisor; 32 mMinDelta = 1 / divisor; 33 } 34 getDivisor()35 public float getDivisor() { 36 return mDivisor; 37 } 38 getMinDelta()39 public float getMinDelta() { 40 return mMinDelta; 41 } 42 getValue(int currentValue, int targetValue)43 public int getValue(int currentValue, int targetValue) { 44 int delta = targetValue - currentValue; 45 int retValue; 46 if (delta > 0) { 47 // make sure change currentValue and not exceeding targetValue 48 delta = (int)(Math.ceil(delta / mDivisor)); 49 if (delta == 0) { 50 delta = 1; 51 } 52 retValue = currentValue + delta; 53 if (retValue > targetValue) { 54 retValue = targetValue; 55 } 56 } else if (delta < 0) { 57 // make sure change currentValue and not exceeding targetValue 58 delta = (int)(Math.floor(delta / mDivisor)); 59 if (delta == 0) { 60 delta = -1; 61 } 62 retValue = currentValue + delta; 63 if (retValue < targetValue) { 64 retValue = targetValue; 65 } 66 } else { 67 retValue = targetValue; 68 } 69 return retValue; 70 } 71 getValue(float currentValue, float targetValue)72 public float getValue(float currentValue, float targetValue) { 73 float delta = targetValue - currentValue; 74 float retValue; 75 if (delta > mMinDelta) { 76 // make sure change currentValue and not exceeding targetValue 77 delta = delta / mDivisor; 78 retValue = currentValue + delta; 79 if (retValue > targetValue) { 80 retValue = targetValue; 81 } 82 } else if (delta < -mMinDelta) { 83 // make sure change currentValue and not exceeding targetValue 84 delta = delta / mDivisor; 85 retValue = currentValue + delta; 86 if (retValue < targetValue) { 87 retValue = targetValue; 88 } 89 } else { 90 retValue = targetValue; 91 } 92 return retValue; 93 } 94 } 95