/* * Copyright (C) 2017 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.android.launcher3.anim; import static com.android.launcher3.util.DefaultDisplay.getSingleFrameMs; import android.content.Context; import android.graphics.Path; import android.view.animation.AccelerateDecelerateInterpolator; import android.view.animation.AccelerateInterpolator; import android.view.animation.DecelerateInterpolator; import android.view.animation.Interpolator; import android.view.animation.LinearInterpolator; import android.view.animation.OvershootInterpolator; import android.view.animation.PathInterpolator; import com.android.launcher3.Utilities; /** * Common interpolators used in Launcher */ public class Interpolators { public static final Interpolator LINEAR = new LinearInterpolator(); public static final Interpolator ACCEL = new AccelerateInterpolator(); public static final Interpolator ACCEL_0_75 = new AccelerateInterpolator(0.75f); public static final Interpolator ACCEL_1_5 = new AccelerateInterpolator(1.5f); public static final Interpolator ACCEL_2 = new AccelerateInterpolator(2); public static final Interpolator DEACCEL = new DecelerateInterpolator(); public static final Interpolator DEACCEL_1_5 = new DecelerateInterpolator(1.5f); public static final Interpolator DEACCEL_1_7 = new DecelerateInterpolator(1.7f); public static final Interpolator DEACCEL_2 = new DecelerateInterpolator(2); public static final Interpolator DEACCEL_2_5 = new DecelerateInterpolator(2.5f); public static final Interpolator DEACCEL_3 = new DecelerateInterpolator(3f); public static final Interpolator DEACCEL_5 = new DecelerateInterpolator(5f); public static final Interpolator ACCEL_DEACCEL = new AccelerateDecelerateInterpolator(); public static final Interpolator FAST_OUT_SLOW_IN = new PathInterpolator(0.4f, 0f, 0.2f, 1f); public static final Interpolator AGGRESSIVE_EASE = new PathInterpolator(0.2f, 0f, 0f, 1f); public static final Interpolator AGGRESSIVE_EASE_IN_OUT = new PathInterpolator(0.6f,0, 0.4f, 1); public static final Interpolator EXAGGERATED_EASE; public static final Interpolator INSTANT = t -> 1; private static final int MIN_SETTLE_DURATION = 200; private static final float OVERSHOOT_FACTOR = 0.9f; static { Path exaggeratedEase = new Path(); exaggeratedEase.moveTo(0, 0); exaggeratedEase.cubicTo(0.05f, 0f, 0.133333f, 0.08f, 0.166666f, 0.4f); exaggeratedEase.cubicTo(0.225f, 0.94f, 0.5f, 1f, 1f, 1f); EXAGGERATED_EASE = new PathInterpolator(exaggeratedEase); } public static final Interpolator OVERSHOOT_1_2 = new OvershootInterpolator(1.2f); public static final Interpolator OVERSHOOT_1_7 = new OvershootInterpolator(1.7f); public static final Interpolator TOUCH_RESPONSE_INTERPOLATOR = new PathInterpolator(0.3f, 0f, 0.1f, 1f); /** * Inversion of ZOOM_OUT, compounded with an ease-out. */ public static final Interpolator ZOOM_IN = new Interpolator() { @Override public float getInterpolation(float v) { return DEACCEL_3.getInterpolation(1 - ZOOM_OUT.getInterpolation(1 - v)); } }; public static final Interpolator ZOOM_OUT = new Interpolator() { private static final float FOCAL_LENGTH = 0.35f; @Override public float getInterpolation(float v) { return zInterpolate(v); } /** * This interpolator emulates the rate at which the perceived scale of an object changes * as its distance from a camera increases. When this interpolator is applied to a scale * animation on a view, it evokes the sense that the object is shrinking due to moving away * from the camera. */ private float zInterpolate(float input) { return (1.0f - FOCAL_LENGTH / (FOCAL_LENGTH + input)) / (1.0f - FOCAL_LENGTH / (FOCAL_LENGTH + 1.0f)); } }; public static final Interpolator SCROLL = new Interpolator() { @Override public float getInterpolation(float t) { t -= 1.0f; return t*t*t*t*t + 1; } }; public static final Interpolator SCROLL_CUBIC = new Interpolator() { @Override public float getInterpolation(float t) { t -= 1.0f; return t*t*t + 1; } }; private static final float FAST_FLING_PX_MS = 10; public static Interpolator scrollInterpolatorForVelocity(float velocity) { return Math.abs(velocity) > FAST_FLING_PX_MS ? SCROLL : SCROLL_CUBIC; } /** * Create an OvershootInterpolator with tension directly related to the velocity (in px/ms). * @param velocity The start velocity of the animation we want to overshoot. */ public static Interpolator overshootInterpolatorForVelocity(float velocity) { return new OvershootInterpolator(Math.min(Math.abs(velocity), 3f)); } /** * Runs the given interpolator such that the entire progress is set between the given bounds. * That is, we set the interpolation to 0 until lowerBound and reach 1 by upperBound. */ public static Interpolator clampToProgress(Interpolator interpolator, float lowerBound, float upperBound) { if (upperBound <= lowerBound) { throw new IllegalArgumentException(String.format( "lowerBound (%f) must be less than upperBound (%f)", lowerBound, upperBound)); } return t -> { if (t < lowerBound) { return 0; } if (t > upperBound) { return 1; } return interpolator.getInterpolation((t - lowerBound) / (upperBound - lowerBound)); }; } /** * Runs the given interpolator such that the interpolated value is mapped to the given range. * This is useful, for example, if we only use this interpolator for part of the animation, * such as to take over a user-controlled animation when they let go. */ public static Interpolator mapToProgress(Interpolator interpolator, float lowerBound, float upperBound) { return t -> Utilities.mapRange(interpolator.getInterpolation(t), lowerBound, upperBound); } /** * Computes parameters necessary for an overshoot effect. */ public static class OvershootParams { public Interpolator interpolator; public float start; public float end; public long duration; /** * Given the input params, sets OvershootParams variables to be used by the caller. * @param startProgress The progress from 0 to 1 that the overshoot starts from. * @param overshootPastProgress The progress from 0 to 1 where we overshoot past (should * either be equal to startProgress or endProgress, depending on if we want to * overshoot immediately or only once we reach the end). * @param endProgress The final progress from 0 to 1 that we will settle to. * @param velocityPxPerMs The initial velocity that causes this overshoot. * @param totalDistancePx The distance against which progress is calculated. */ public OvershootParams(float startProgress, float overshootPastProgress, float endProgress, float velocityPxPerMs, int totalDistancePx, Context context) { velocityPxPerMs = Math.abs(velocityPxPerMs); start = startProgress; int startPx = (int) (start * totalDistancePx); // Overshoot by about half a frame. float overshootBy = OVERSHOOT_FACTOR * velocityPxPerMs * getSingleFrameMs(context) / totalDistancePx / 2; overshootBy = Utilities.boundToRange(overshootBy, 0.02f, 0.15f); end = overshootPastProgress + overshootBy; int endPx = (int) (end * totalDistancePx); int overshootDistance = endPx - startPx; // Calculate deceleration necessary to reach overshoot distance. // Formula: velocityFinal^2 = velocityInitial^2 + 2 * acceleration * distance // 0 = v^2 + 2ad (velocityFinal == 0) // a = v^2 / -2d float decelerationPxPerMs = velocityPxPerMs * velocityPxPerMs / (2 * overshootDistance); // Calculate time necessary to reach peak of overshoot. // Formula: acceleration = velocity / time // time = velocity / acceleration duration = (long) (velocityPxPerMs / decelerationPxPerMs); // Now that we're at the top of the overshoot, need to settle back to endProgress. float settleDistance = end - endProgress; int settleDistancePx = (int) (settleDistance * totalDistancePx); // Calculate time necessary for the settle. // Formula: distance = velocityInitial * time + 1/2 * acceleration * time^2 // d = 1/2at^2 (velocityInitial = 0, since we just stopped at the top) // t = sqrt(2d/a) // Above formula assumes constant acceleration. Since we use ACCEL_DEACCEL, we actually // have acceleration to halfway then deceleration the rest. So the formula becomes: // t = sqrt(d/a) * 2 (half the distance for accel, half for deaccel) long settleDuration = (long) Math.sqrt(settleDistancePx / decelerationPxPerMs) * 4; settleDuration = Math.max(MIN_SETTLE_DURATION, settleDuration); // How much of the animation to devote to playing the overshoot (the rest is for settle). float overshootFraction = (float) duration / (duration + settleDuration); duration += settleDuration; // Finally, create the interpolator, composed of two interpolators: an overshoot, which // reaches end > 1, and then a settle to endProgress. Interpolator overshoot = Interpolators.clampToProgress(DEACCEL, 0, overshootFraction); // The settle starts at 1, where 1 is the top of the overshoot, and maps to a fraction // such that final progress is endProgress. For example, if we overshot to 1.1 but want // to end at 1, we need to map to 1/1.1. Interpolator settle = Interpolators.clampToProgress(Interpolators.mapToProgress( ACCEL_DEACCEL, 1, (endProgress - start) / (end - start)), overshootFraction, 1); interpolator = t -> t <= overshootFraction ? overshoot.getInterpolation(t) : settle.getInterpolation(t); } } }