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.camera.ui.motion; 18 19 /** 20 * Various static helper functions for interpolating between values. 21 */ 22 public class InterpolateUtils { 23 InterpolateUtils()24 private InterpolateUtils() { 25 } 26 27 /** 28 * Linear interpolation from v0 to v1 as t goes from 0...1 29 * 30 * @param v0 the value at t=0 31 * @param v1 the value at t=1 32 * @param t value in the range of 0 to 1. 33 * @return the value between v0 and v1 as a ratio between 0 and 1 defined by t. 34 */ lerp(float v0, float v1, float t)35 public static float lerp(float v0, float v1, float t) { 36 return v0 + t * (v1 - v0); 37 } 38 39 /** 40 * Project a value that is within the in(Min/Max) number space into the to(Min/Max) number 41 * space. 42 * 43 * @param v value to scale into the 'to' number space. 44 * @param vMin min value of the values number space. 45 * @param vMax max value of the values number space. 46 * @param pMin min value of the projection number space. 47 * @param pMax max value of the projection number space. 48 * @return the ratio of the value in the source number space as a value in the to(Min/Max) 49 * number space. 50 */ scale(float v, float vMin, float vMax, float pMin, float pMax)51 public static float scale(float v, float vMin, float vMax, float pMin, float pMax) { 52 return (pMax - pMin) * (v - vMin) / (vMax - vMin) + pMin; 53 } 54 55 /** 56 * Value between 0 and 1 as a ratio between tBegin over tDuration 57 * with no upper bound. 58 */ unitRatio(long t, long tBegin, float tDuration)59 public static float unitRatio(long t, long tBegin, float tDuration) { 60 if (t <= tBegin) { 61 return 0.0f; 62 } 63 64 return (t - tBegin) / tDuration; 65 } 66 } 67