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.util.DefaultDisplay.getSingleFrameMs; 20 21 import android.content.Context; 22 import android.graphics.Path; 23 import android.view.animation.AccelerateDecelerateInterpolator; 24 import android.view.animation.AccelerateInterpolator; 25 import android.view.animation.DecelerateInterpolator; 26 import android.view.animation.Interpolator; 27 import android.view.animation.LinearInterpolator; 28 import android.view.animation.OvershootInterpolator; 29 import android.view.animation.PathInterpolator; 30 31 import com.android.launcher3.Utilities; 32 33 34 /** 35 * Common interpolators used in Launcher 36 */ 37 public class Interpolators { 38 39 public static final Interpolator LINEAR = new LinearInterpolator(); 40 41 public static final Interpolator ACCEL = new AccelerateInterpolator(); 42 public static final Interpolator ACCEL_0_75 = new AccelerateInterpolator(0.75f); 43 public static final Interpolator ACCEL_1_5 = new AccelerateInterpolator(1.5f); 44 public static final Interpolator ACCEL_2 = new AccelerateInterpolator(2); 45 46 public static final Interpolator DEACCEL = new DecelerateInterpolator(); 47 public static final Interpolator DEACCEL_1_5 = new DecelerateInterpolator(1.5f); 48 public static final Interpolator DEACCEL_1_7 = new DecelerateInterpolator(1.7f); 49 public static final Interpolator DEACCEL_2 = new DecelerateInterpolator(2); 50 public static final Interpolator DEACCEL_2_5 = new DecelerateInterpolator(2.5f); 51 public static final Interpolator DEACCEL_3 = new DecelerateInterpolator(3f); 52 public static final Interpolator DEACCEL_5 = new DecelerateInterpolator(5f); 53 54 public static final Interpolator ACCEL_DEACCEL = new AccelerateDecelerateInterpolator(); 55 56 public static final Interpolator FAST_OUT_SLOW_IN = new PathInterpolator(0.4f, 0f, 0.2f, 1f); 57 58 public static final Interpolator AGGRESSIVE_EASE = new PathInterpolator(0.2f, 0f, 0f, 1f); 59 public static final Interpolator AGGRESSIVE_EASE_IN_OUT = new PathInterpolator(0.6f,0, 0.4f, 1); 60 61 public static final Interpolator EXAGGERATED_EASE; 62 63 public static final Interpolator INSTANT = t -> 1; 64 /** 65 * All values of t map to 0 until t == 1. This is primarily useful for setting view visibility, 66 * which should only happen at the very end of the animation (when it's already hidden). 67 */ 68 public static final Interpolator FINAL_FRAME = t -> t < 1 ? 0 : 1; 69 70 private static final int MIN_SETTLE_DURATION = 200; 71 private static final float OVERSHOOT_FACTOR = 0.9f; 72 73 static { 74 Path exaggeratedEase = new Path(); 75 exaggeratedEase.moveTo(0, 0); 76 exaggeratedEase.cubicTo(0.05f, 0f, 0.133333f, 0.08f, 0.166666f, 0.4f); 77 exaggeratedEase.cubicTo(0.225f, 0.94f, 0.5f, 1f, 1f, 1f); 78 EXAGGERATED_EASE = new PathInterpolator(exaggeratedEase); 79 } 80 81 public static final Interpolator OVERSHOOT_1_2 = new OvershootInterpolator(1.2f); 82 public static final Interpolator OVERSHOOT_1_7 = new OvershootInterpolator(1.7f); 83 84 public static final Interpolator TOUCH_RESPONSE_INTERPOLATOR = 85 new PathInterpolator(0.3f, 0f, 0.1f, 1f); 86 87 /** 88 * Inversion of ZOOM_OUT, compounded with an ease-out. 89 */ 90 public static final Interpolator ZOOM_IN = new Interpolator() { 91 @Override 92 public float getInterpolation(float v) { 93 return DEACCEL_3.getInterpolation(1 - ZOOM_OUT.getInterpolation(1 - v)); 94 } 95 }; 96 97 public static final Interpolator ZOOM_OUT = new Interpolator() { 98 99 private static final float FOCAL_LENGTH = 0.35f; 100 101 @Override 102 public float getInterpolation(float v) { 103 return zInterpolate(v); 104 } 105 106 /** 107 * This interpolator emulates the rate at which the perceived scale of an object changes 108 * as its distance from a camera increases. When this interpolator is applied to a scale 109 * animation on a view, it evokes the sense that the object is shrinking due to moving away 110 * from the camera. 111 */ 112 private float zInterpolate(float input) { 113 return (1.0f - FOCAL_LENGTH / (FOCAL_LENGTH + input)) / 114 (1.0f - FOCAL_LENGTH / (FOCAL_LENGTH + 1.0f)); 115 } 116 }; 117 118 public static final Interpolator SCROLL = new Interpolator() { 119 @Override 120 public float getInterpolation(float t) { 121 t -= 1.0f; 122 return t*t*t*t*t + 1; 123 } 124 }; 125 126 public static final Interpolator SCROLL_CUBIC = new Interpolator() { 127 @Override 128 public float getInterpolation(float t) { 129 t -= 1.0f; 130 return t*t*t + 1; 131 } 132 }; 133 134 private static final float FAST_FLING_PX_MS = 10; 135 136 public static Interpolator scrollInterpolatorForVelocity(float velocity) { 137 return Math.abs(velocity) > FAST_FLING_PX_MS ? SCROLL : SCROLL_CUBIC; 138 } 139 140 /** 141 * Create an OvershootInterpolator with tension directly related to the velocity (in px/ms). 142 * @param velocity The start velocity of the animation we want to overshoot. 143 */ overshootInterpolatorForVelocity(float velocity)144 public static Interpolator overshootInterpolatorForVelocity(float velocity) { 145 return new OvershootInterpolator(Math.min(Math.abs(velocity), 3f)); 146 } 147 148 /** 149 * Runs the given interpolator such that the entire progress is set between the given bounds. 150 * That is, we set the interpolation to 0 until lowerBound and reach 1 by upperBound. 151 */ clampToProgress(Interpolator interpolator, float lowerBound, float upperBound)152 public static Interpolator clampToProgress(Interpolator interpolator, float lowerBound, 153 float upperBound) { 154 if (upperBound <= lowerBound) { 155 throw new IllegalArgumentException(String.format( 156 "lowerBound (%f) must be less than upperBound (%f)", lowerBound, upperBound)); 157 } 158 return t -> { 159 if (t < lowerBound) { 160 return 0; 161 } 162 if (t > upperBound) { 163 return 1; 164 } 165 return interpolator.getInterpolation((t - lowerBound) / (upperBound - lowerBound)); 166 }; 167 } 168 169 /** 170 * Runs the given interpolator such that the interpolated value is mapped to the given range. 171 * This is useful, for example, if we only use this interpolator for part of the animation, 172 * such as to take over a user-controlled animation when they let go. 173 */ 174 public static Interpolator mapToProgress(Interpolator interpolator, float lowerBound, 175 float upperBound) { 176 return t -> Utilities.mapRange(interpolator.getInterpolation(t), lowerBound, upperBound); 177 } 178 179 /** 180 * Computes parameters necessary for an overshoot effect. 181 */ 182 public static class OvershootParams { 183 public Interpolator interpolator; 184 public float start; 185 public float end; 186 public long duration; 187 188 /** 189 * Given the input params, sets OvershootParams variables to be used by the caller. 190 * @param startProgress The progress from 0 to 1 that the overshoot starts from. 191 * @param overshootPastProgress The progress from 0 to 1 where we overshoot past (should 192 * either be equal to startProgress or endProgress, depending on if we want to 193 * overshoot immediately or only once we reach the end). 194 * @param endProgress The final progress from 0 to 1 that we will settle to. 195 * @param velocityPxPerMs The initial velocity that causes this overshoot. 196 * @param totalDistancePx The distance against which progress is calculated. 197 */ 198 public OvershootParams(float startProgress, float overshootPastProgress, 199 float endProgress, float velocityPxPerMs, int totalDistancePx, Context context) { 200 velocityPxPerMs = Math.abs(velocityPxPerMs); 201 start = startProgress; 202 int startPx = (int) (start * totalDistancePx); 203 // Overshoot by about half a frame. 204 float overshootBy = OVERSHOOT_FACTOR * velocityPxPerMs * 205 getSingleFrameMs(context) / totalDistancePx / 2; 206 overshootBy = Utilities.boundToRange(overshootBy, 0.02f, 0.15f); 207 end = overshootPastProgress + overshootBy; 208 int endPx = (int) (end * totalDistancePx); 209 int overshootDistance = endPx - startPx; 210 // Calculate deceleration necessary to reach overshoot distance. 211 // Formula: velocityFinal^2 = velocityInitial^2 + 2 * acceleration * distance 212 // 0 = v^2 + 2ad (velocityFinal == 0) 213 // a = v^2 / -2d 214 float decelerationPxPerMs = velocityPxPerMs * velocityPxPerMs / (2 * overshootDistance); 215 // Calculate time necessary to reach peak of overshoot. 216 // Formula: acceleration = velocity / time 217 // time = velocity / acceleration 218 duration = (long) (velocityPxPerMs / decelerationPxPerMs); 219 220 // Now that we're at the top of the overshoot, need to settle back to endProgress. 221 float settleDistance = end - endProgress; 222 int settleDistancePx = (int) (settleDistance * totalDistancePx); 223 // Calculate time necessary for the settle. 224 // Formula: distance = velocityInitial * time + 1/2 * acceleration * time^2 225 // d = 1/2at^2 (velocityInitial = 0, since we just stopped at the top) 226 // t = sqrt(2d/a) 227 // Above formula assumes constant acceleration. Since we use ACCEL_DEACCEL, we actually 228 // have acceleration to halfway then deceleration the rest. So the formula becomes: 229 // t = sqrt(d/a) * 2 (half the distance for accel, half for deaccel) 230 long settleDuration = (long) Math.sqrt(settleDistancePx / decelerationPxPerMs) * 4; 231 232 settleDuration = Math.max(MIN_SETTLE_DURATION, settleDuration); 233 // How much of the animation to devote to playing the overshoot (the rest is for settle). 234 float overshootFraction = (float) duration / (duration + settleDuration); 235 duration += settleDuration; 236 // Finally, create the interpolator, composed of two interpolators: an overshoot, which 237 // reaches end > 1, and then a settle to endProgress. 238 Interpolator overshoot = Interpolators.clampToProgress(DEACCEL, 0, overshootFraction); 239 // The settle starts at 1, where 1 is the top of the overshoot, and maps to a fraction 240 // such that final progress is endProgress. For example, if we overshot to 1.1 but want 241 // to end at 1, we need to map to 1/1.1. 242 Interpolator settle = Interpolators.clampToProgress(Interpolators.mapToProgress( 243 ACCEL_DEACCEL, 1, (endProgress - start) / (end - start)), overshootFraction, 1); 244 interpolator = t -> t <= overshootFraction 245 ? overshoot.getInterpolation(t) 246 : settle.getInterpolation(t); 247 } 248 } 249 } 250