1 /* 2 * Copyright (C) 2015 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.dialer.compat; 18 19 import android.graphics.Path; 20 import android.graphics.PathMeasure; 21 import android.os.Build; 22 import android.view.animation.Interpolator; 23 import android.view.animation.PathInterpolator; 24 25 public class PathInterpolatorCompat { 26 create( float controlX1, float controlY1, float controlX2, float controlY2)27 public static Interpolator create( 28 float controlX1, float controlY1, float controlX2, float controlY2) { 29 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { 30 return new PathInterpolator(controlX1, controlY1, controlX2, controlY2); 31 } 32 return new PathInterpolatorBase(controlX1, controlY1, controlX2, controlY2); 33 } 34 35 private static class PathInterpolatorBase implements Interpolator { 36 37 /** Governs the accuracy of the approximation of the {@link Path}. */ 38 private static final float PRECISION = 0.002f; 39 40 private final float[] mX; 41 private final float[] mY; 42 PathInterpolatorBase(Path path)43 public PathInterpolatorBase(Path path) { 44 final PathMeasure pathMeasure = new PathMeasure(path, false /* forceClosed */); 45 46 final float pathLength = pathMeasure.getLength(); 47 final int numPoints = (int) (pathLength / PRECISION) + 1; 48 49 mX = new float[numPoints]; 50 mY = new float[numPoints]; 51 52 final float[] position = new float[2]; 53 for (int i = 0; i < numPoints; ++i) { 54 final float distance = (i * pathLength) / (numPoints - 1); 55 pathMeasure.getPosTan(distance, position, null /* tangent */); 56 57 mX[i] = position[0]; 58 mY[i] = position[1]; 59 } 60 } 61 PathInterpolatorBase(float controlX, float controlY)62 public PathInterpolatorBase(float controlX, float controlY) { 63 this(createQuad(controlX, controlY)); 64 } 65 PathInterpolatorBase( float controlX1, float controlY1, float controlX2, float controlY2)66 public PathInterpolatorBase( 67 float controlX1, float controlY1, float controlX2, float controlY2) { 68 this(createCubic(controlX1, controlY1, controlX2, controlY2)); 69 } 70 createQuad(float controlX, float controlY)71 private static Path createQuad(float controlX, float controlY) { 72 final Path path = new Path(); 73 path.moveTo(0.0f, 0.0f); 74 path.quadTo(controlX, controlY, 1.0f, 1.0f); 75 return path; 76 } 77 createCubic( float controlX1, float controlY1, float controlX2, float controlY2)78 private static Path createCubic( 79 float controlX1, float controlY1, float controlX2, float controlY2) { 80 final Path path = new Path(); 81 path.moveTo(0.0f, 0.0f); 82 path.cubicTo(controlX1, controlY1, controlX2, controlY2, 1.0f, 1.0f); 83 return path; 84 } 85 86 @Override getInterpolation(float t)87 public float getInterpolation(float t) { 88 if (t <= 0.0f) { 89 return 0.0f; 90 } else if (t >= 1.0f) { 91 return 1.0f; 92 } 93 94 // Do a binary search for the correct x to interpolate between. 95 int startIndex = 0; 96 int endIndex = mX.length - 1; 97 while (endIndex - startIndex > 1) { 98 int midIndex = (startIndex + endIndex) / 2; 99 if (t < mX[midIndex]) { 100 endIndex = midIndex; 101 } else { 102 startIndex = midIndex; 103 } 104 } 105 106 final float xRange = mX[endIndex] - mX[startIndex]; 107 if (xRange == 0) { 108 return mY[startIndex]; 109 } 110 111 final float tInRange = t - mX[startIndex]; 112 final float fraction = tInRange / xRange; 113 114 final float startY = mY[startIndex]; 115 final float endY = mY[endIndex]; 116 117 return startY + (fraction * (endY - startY)); 118 } 119 } 120 } 121