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