/*
* 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.Utilities.SINGLE_FRAME_MS;
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_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 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;
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 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("lowerBound must be less than 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) {
velocityPxPerMs = Math.abs(velocityPxPerMs);
start = startProgress;
int startPx = (int) (start * totalDistancePx);
// Overshoot by about half a frame.
float overshootBy = OVERSHOOT_FACTOR * velocityPxPerMs *
SINGLE_FRAME_MS / 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);
}
}
}