1 /* 2 * Copyright (C) 2017 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.launcher3.anim; 18 19 import static com.android.launcher3.Utilities.SINGLE_FRAME_MS; 20 21 import android.graphics.Path; 22 import android.view.animation.AccelerateDecelerateInterpolator; 23 import android.view.animation.AccelerateInterpolator; 24 import android.view.animation.DecelerateInterpolator; 25 import android.view.animation.Interpolator; 26 import android.view.animation.LinearInterpolator; 27 import android.view.animation.OvershootInterpolator; 28 import android.view.animation.PathInterpolator; 29 30 import com.android.launcher3.Utilities; 31 32 33 /** 34 * Common interpolators used in Launcher 35 */ 36 public class Interpolators { 37 38 public static final Interpolator LINEAR = new LinearInterpolator(); 39 40 public static final Interpolator ACCEL = new AccelerateInterpolator(); 41 public static final Interpolator ACCEL_1_5 = new AccelerateInterpolator(1.5f); 42 public static final Interpolator ACCEL_2 = new AccelerateInterpolator(2); 43 44 public static final Interpolator DEACCEL = new DecelerateInterpolator(); 45 public static final Interpolator DEACCEL_1_5 = new DecelerateInterpolator(1.5f); 46 public static final Interpolator DEACCEL_1_7 = new DecelerateInterpolator(1.7f); 47 public static final Interpolator DEACCEL_2 = new DecelerateInterpolator(2); 48 public static final Interpolator DEACCEL_2_5 = new DecelerateInterpolator(2.5f); 49 public static final Interpolator DEACCEL_3 = new DecelerateInterpolator(3f); 50 51 public static final Interpolator ACCEL_DEACCEL = new AccelerateDecelerateInterpolator(); 52 53 public static final Interpolator FAST_OUT_SLOW_IN = new PathInterpolator(0.4f, 0f, 0.2f, 1f); 54 55 public static final Interpolator AGGRESSIVE_EASE = new PathInterpolator(0.2f, 0f, 0f, 1f); 56 public static final Interpolator AGGRESSIVE_EASE_IN_OUT = new PathInterpolator(0.6f,0, 0.4f, 1); 57 58 public static final Interpolator EXAGGERATED_EASE; 59 60 public static final Interpolator INSTANT = t -> 1; 61 62 private static final int MIN_SETTLE_DURATION = 200; 63 private static final float OVERSHOOT_FACTOR = 0.9f; 64 65 static { 66 Path exaggeratedEase = new Path(); 67 exaggeratedEase.moveTo(0, 0); 68 exaggeratedEase.cubicTo(0.05f, 0f, 0.133333f, 0.08f, 0.166666f, 0.4f); 69 exaggeratedEase.cubicTo(0.225f, 0.94f, 0.5f, 1f, 1f, 1f); 70 EXAGGERATED_EASE = new PathInterpolator(exaggeratedEase); 71 } 72 73 public static final Interpolator OVERSHOOT_1_2 = new OvershootInterpolator(1.2f); 74 public static final Interpolator OVERSHOOT_1_7 = new OvershootInterpolator(1.7f); 75 76 public static final Interpolator TOUCH_RESPONSE_INTERPOLATOR = 77 new PathInterpolator(0.3f, 0f, 0.1f, 1f); 78 79 /** 80 * Inversion of ZOOM_OUT, compounded with an ease-out. 81 */ 82 public static final Interpolator ZOOM_IN = new Interpolator() { 83 @Override 84 public float getInterpolation(float v) { 85 return DEACCEL_3.getInterpolation(1 - ZOOM_OUT.getInterpolation(1 - v)); 86 } 87 }; 88 89 public static final Interpolator ZOOM_OUT = new Interpolator() { 90 91 private static final float FOCAL_LENGTH = 0.35f; 92 93 @Override 94 public float getInterpolation(float v) { 95 return zInterpolate(v); 96 } 97 98 /** 99 * This interpolator emulates the rate at which the perceived scale of an object changes 100 * as its distance from a camera increases. When this interpolator is applied to a scale 101 * animation on a view, it evokes the sense that the object is shrinking due to moving away 102 * from the camera. 103 */ 104 private float zInterpolate(float input) { 105 return (1.0f - FOCAL_LENGTH / (FOCAL_LENGTH + input)) / 106 (1.0f - FOCAL_LENGTH / (FOCAL_LENGTH + 1.0f)); 107 } 108 }; 109 110 public static final Interpolator SCROLL = new Interpolator() { 111 @Override 112 public float getInterpolation(float t) { 113 t -= 1.0f; 114 return t*t*t*t*t + 1; 115 } 116 }; 117 118 public static final Interpolator SCROLL_CUBIC = new Interpolator() { 119 @Override 120 public float getInterpolation(float t) { 121 t -= 1.0f; 122 return t*t*t + 1; 123 } 124 }; 125 126 private static final float FAST_FLING_PX_MS = 10; 127 scrollInterpolatorForVelocity(float velocity)128 public static Interpolator scrollInterpolatorForVelocity(float velocity) { 129 return Math.abs(velocity) > FAST_FLING_PX_MS ? SCROLL : SCROLL_CUBIC; 130 } 131 132 /** 133 * Create an OvershootInterpolator with tension directly related to the velocity (in px/ms). 134 * @param velocity The start velocity of the animation we want to overshoot. 135 */ overshootInterpolatorForVelocity(float velocity)136 public static Interpolator overshootInterpolatorForVelocity(float velocity) { 137 return new OvershootInterpolator(Math.min(Math.abs(velocity), 3f)); 138 } 139 140 /** 141 * Runs the given interpolator such that the entire progress is set between the given bounds. 142 * That is, we set the interpolation to 0 until lowerBound and reach 1 by upperBound. 143 */ clampToProgress(Interpolator interpolator, float lowerBound, float upperBound)144 public static Interpolator clampToProgress(Interpolator interpolator, float lowerBound, 145 float upperBound) { 146 if (upperBound <= lowerBound) { 147 throw new IllegalArgumentException("lowerBound must be less than upperBound"); 148 } 149 return t -> { 150 if (t < lowerBound) { 151 return 0; 152 } 153 if (t > upperBound) { 154 return 1; 155 } 156 return interpolator.getInterpolation((t - lowerBound) / (upperBound - lowerBound)); 157 }; 158 } 159 160 /** 161 * Runs the given interpolator such that the interpolated value is mapped to the given range. 162 * This is useful, for example, if we only use this interpolator for part of the animation, 163 * such as to take over a user-controlled animation when they let go. 164 */ 165 public static Interpolator mapToProgress(Interpolator interpolator, float lowerBound, 166 float upperBound) { 167 return t -> Utilities.mapRange(interpolator.getInterpolation(t), lowerBound, upperBound); 168 } 169 170 /** 171 * Computes parameters necessary for an overshoot effect. 172 */ 173 public static class OvershootParams { 174 public Interpolator interpolator; 175 public float start; 176 public float end; 177 public long duration; 178 179 /** 180 * Given the input params, sets OvershootParams variables to be used by the caller. 181 * @param startProgress The progress from 0 to 1 that the overshoot starts from. 182 * @param overshootPastProgress The progress from 0 to 1 where we overshoot past (should 183 * either be equal to startProgress or endProgress, depending on if we want to 184 * overshoot immediately or only once we reach the end). 185 * @param endProgress The final progress from 0 to 1 that we will settle to. 186 * @param velocityPxPerMs The initial velocity that causes this overshoot. 187 * @param totalDistancePx The distance against which progress is calculated. 188 */ 189 public OvershootParams(float startProgress, float overshootPastProgress, 190 float endProgress, float velocityPxPerMs, int totalDistancePx) { 191 velocityPxPerMs = Math.abs(velocityPxPerMs); 192 start = startProgress; 193 int startPx = (int) (start * totalDistancePx); 194 // Overshoot by about half a frame. 195 float overshootBy = OVERSHOOT_FACTOR * velocityPxPerMs * 196 SINGLE_FRAME_MS / totalDistancePx / 2; 197 overshootBy = Utilities.boundToRange(overshootBy, 0.02f, 0.15f); 198 end = overshootPastProgress + overshootBy; 199 int endPx = (int) (end * totalDistancePx); 200 int overshootDistance = endPx - startPx; 201 // Calculate deceleration necessary to reach overshoot distance. 202 // Formula: velocityFinal^2 = velocityInitial^2 + 2 * acceleration * distance 203 // 0 = v^2 + 2ad (velocityFinal == 0) 204 // a = v^2 / -2d 205 float decelerationPxPerMs = velocityPxPerMs * velocityPxPerMs / (2 * overshootDistance); 206 // Calculate time necessary to reach peak of overshoot. 207 // Formula: acceleration = velocity / time 208 // time = velocity / acceleration 209 duration = (long) (velocityPxPerMs / decelerationPxPerMs); 210 211 // Now that we're at the top of the overshoot, need to settle back to endProgress. 212 float settleDistance = end - endProgress; 213 int settleDistancePx = (int) (settleDistance * totalDistancePx); 214 // Calculate time necessary for the settle. 215 // Formula: distance = velocityInitial * time + 1/2 * acceleration * time^2 216 // d = 1/2at^2 (velocityInitial = 0, since we just stopped at the top) 217 // t = sqrt(2d/a) 218 // Above formula assumes constant acceleration. Since we use ACCEL_DEACCEL, we actually 219 // have acceleration to halfway then deceleration the rest. So the formula becomes: 220 // t = sqrt(d/a) * 2 (half the distance for accel, half for deaccel) 221 long settleDuration = (long) Math.sqrt(settleDistancePx / decelerationPxPerMs) * 4; 222 223 settleDuration = Math.max(MIN_SETTLE_DURATION, settleDuration); 224 // How much of the animation to devote to playing the overshoot (the rest is for settle). 225 float overshootFraction = (float) duration / (duration + settleDuration); 226 duration += settleDuration; 227 // Finally, create the interpolator, composed of two interpolators: an overshoot, which 228 // reaches end > 1, and then a settle to endProgress. 229 Interpolator overshoot = Interpolators.clampToProgress(DEACCEL, 0, overshootFraction); 230 // The settle starts at 1, where 1 is the top of the overshoot, and maps to a fraction 231 // such that final progress is endProgress. For example, if we overshot to 1.1 but want 232 // to end at 1, we need to map to 1/1.1. 233 Interpolator settle = Interpolators.clampToProgress(Interpolators.mapToProgress( 234 ACCEL_DEACCEL, 1, (endProgress - start) / (end - start)), overshootFraction, 1); 235 interpolator = t -> t <= overshootFraction 236 ? overshoot.getInterpolation(t) 237 : settle.getInterpolation(t); 238 } 239 } 240 } 241