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      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 
     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      */
     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      */
     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      */
     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