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.phone.common.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 { create(float controlX1, float controlY1, float controlX2, float controlY2)26 public static Interpolator create(float controlX1, float controlY1, 27 float controlX2, float controlY2) { 28 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { 29 return new PathInterpolator(controlX1, controlY1, controlX2, controlY2); 30 } 31 return new PathInterpolatorBase(controlX1, controlY1, controlX2, controlY2); 32 } 33 34 private static class PathInterpolatorBase implements Interpolator { 35 /** 36 * Governs the accuracy of the approximation of the {@link Path}. 37 */ 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(float controlX1, float controlY1, 67 float controlX2, float controlY2) { 68 this(createCubic(controlX1, controlY1, controlX2, controlY2)); 69 } 70 71 @Override getInterpolation(float t)72 public float getInterpolation(float t) { 73 if (t <= 0.0f) { 74 return 0.0f; 75 } else if (t >= 1.0f) { 76 return 1.0f; 77 } 78 79 // Do a binary search for the correct x to interpolate between. 80 int startIndex = 0; 81 int endIndex = mX.length - 1; 82 while (endIndex - startIndex > 1) { 83 int midIndex = (startIndex + endIndex) / 2; 84 if (t < mX[midIndex]) { 85 endIndex = midIndex; 86 } else { 87 startIndex = midIndex; 88 } 89 } 90 91 final float xRange = mX[endIndex] - mX[startIndex]; 92 if (xRange == 0) { 93 return mY[startIndex]; 94 } 95 96 final float tInRange = t - mX[startIndex]; 97 final float fraction = tInRange / xRange; 98 99 final float startY = mY[startIndex]; 100 final float endY = mY[endIndex]; 101 102 return startY + (fraction * (endY - startY)); 103 } 104 createQuad(float controlX, float controlY)105 private static Path createQuad(float controlX, float controlY) { 106 final Path path = new Path(); 107 path.moveTo(0.0f, 0.0f); 108 path.quadTo(controlX, controlY, 1.0f, 1.0f); 109 return path; 110 } 111 createCubic(float controlX1, float controlY1, float controlX2, float controlY2)112 private static Path createCubic(float controlX1, float controlY1, 113 float controlX2, float controlY2) { 114 final Path path = new Path(); 115 path.moveTo(0.0f, 0.0f); 116 path.cubicTo(controlX1, controlY1, controlX2, controlY2, 1.0f, 1.0f); 117 return path; 118 } 119 } 120 121 } 122 123