/*
* Copyright (C) 2014 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.systemui.statusbar;
import android.animation.Animator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.view.ViewPropertyAnimator;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;
import android.view.animation.PathInterpolator;
/**
* Utility class to calculate general fling animation when the finger is released.
*/
public class FlingAnimationUtils {
private static final float LINEAR_OUT_SLOW_IN_X2 = 0.35f;
private static final float LINEAR_OUT_FASTER_IN_X2 = 0.5f;
private static final float LINEAR_OUT_FASTER_IN_Y2_MIN = 0.4f;
private static final float LINEAR_OUT_FASTER_IN_Y2_MAX = 0.5f;
private static final float MIN_VELOCITY_DP_PER_SECOND = 250;
private static final float HIGH_VELOCITY_DP_PER_SECOND = 3000;
/**
* Crazy math. http://en.wikipedia.org/wiki/B%C3%A9zier_curve
*/
private static final float LINEAR_OUT_SLOW_IN_START_GRADIENT = 1.0f / LINEAR_OUT_SLOW_IN_X2;
private Interpolator mLinearOutSlowIn;
private Interpolator mFastOutSlowIn;
private Interpolator mFastOutLinearIn;
private float mMinVelocityPxPerSecond;
private float mMaxLengthSeconds;
private float mHighVelocityPxPerSecond;
private AnimatorProperties mAnimatorProperties = new AnimatorProperties();
public FlingAnimationUtils(Context ctx, float maxLengthSeconds) {
mMaxLengthSeconds = maxLengthSeconds;
mLinearOutSlowIn = new PathInterpolator(0, 0, LINEAR_OUT_SLOW_IN_X2, 1);
mFastOutSlowIn
= AnimationUtils.loadInterpolator(ctx, android.R.interpolator.fast_out_slow_in);
mFastOutLinearIn
= AnimationUtils.loadInterpolator(ctx, android.R.interpolator.fast_out_linear_in);
mMinVelocityPxPerSecond
= MIN_VELOCITY_DP_PER_SECOND * ctx.getResources().getDisplayMetrics().density;
mHighVelocityPxPerSecond
= HIGH_VELOCITY_DP_PER_SECOND * ctx.getResources().getDisplayMetrics().density;
}
/**
* Applies the interpolator and length to the animator, such that the fling animation is
* consistent with the finger motion.
*
* @param animator the animator to apply
* @param currValue the current value
* @param endValue the end value of the animator
* @param velocity the current velocity of the motion
*/
public void apply(Animator animator, float currValue, float endValue, float velocity) {
apply(animator, currValue, endValue, velocity, Math.abs(endValue - currValue));
}
/**
* Applies the interpolator and length to the animator, such that the fling animation is
* consistent with the finger motion.
*
* @param animator the animator to apply
* @param currValue the current value
* @param endValue the end value of the animator
* @param velocity the current velocity of the motion
*/
public void apply(ViewPropertyAnimator animator, float currValue, float endValue,
float velocity) {
apply(animator, currValue, endValue, velocity, Math.abs(endValue - currValue));
}
/**
* Applies the interpolator and length to the animator, such that the fling animation is
* consistent with the finger motion.
*
* @param animator the animator to apply
* @param currValue the current value
* @param endValue the end value of the animator
* @param velocity the current velocity of the motion
* @param maxDistance the maximum distance for this interaction; the maximum animation length
* gets multiplied by the ratio between the actual distance and this value
*/
public void apply(Animator animator, float currValue, float endValue, float velocity,
float maxDistance) {
AnimatorProperties properties = getProperties(currValue, endValue, velocity,
maxDistance);
animator.setDuration(properties.duration);
animator.setInterpolator(properties.interpolator);
}
/**
* Applies the interpolator and length to the animator, such that the fling animation is
* consistent with the finger motion.
*
* @param animator the animator to apply
* @param currValue the current value
* @param endValue the end value of the animator
* @param velocity the current velocity of the motion
* @param maxDistance the maximum distance for this interaction; the maximum animation length
* gets multiplied by the ratio between the actual distance and this value
*/
public void apply(ViewPropertyAnimator animator, float currValue, float endValue,
float velocity, float maxDistance) {
AnimatorProperties properties = getProperties(currValue, endValue, velocity,
maxDistance);
animator.setDuration(properties.duration);
animator.setInterpolator(properties.interpolator);
}
private AnimatorProperties getProperties(float currValue,
float endValue, float velocity, float maxDistance) {
float maxLengthSeconds = (float) (mMaxLengthSeconds
* Math.sqrt(Math.abs(endValue - currValue) / maxDistance));
float diff = Math.abs(endValue - currValue);
float velAbs = Math.abs(velocity);
float durationSeconds = LINEAR_OUT_SLOW_IN_START_GRADIENT * diff / velAbs;
if (durationSeconds <= maxLengthSeconds) {
mAnimatorProperties.interpolator = mLinearOutSlowIn;
} else if (velAbs >= mMinVelocityPxPerSecond) {
// Cross fade between fast-out-slow-in and linear interpolator with current velocity.
durationSeconds = maxLengthSeconds;
VelocityInterpolator velocityInterpolator
= new VelocityInterpolator(durationSeconds, velAbs, diff);
InterpolatorInterpolator superInterpolator = new InterpolatorInterpolator(
velocityInterpolator, mLinearOutSlowIn, mLinearOutSlowIn);
mAnimatorProperties.interpolator = superInterpolator;
} else {
// Just use a normal interpolator which doesn't take the velocity into account.
durationSeconds = maxLengthSeconds;
mAnimatorProperties.interpolator = mFastOutSlowIn;
}
mAnimatorProperties.duration = (long) (durationSeconds * 1000);
return mAnimatorProperties;
}
/**
* Applies the interpolator and length to the animator, such that the fling animation is
* consistent with the finger motion for the case when the animation is making something
* disappear.
*
* @param animator the animator to apply
* @param currValue the current value
* @param endValue the end value of the animator
* @param velocity the current velocity of the motion
* @param maxDistance the maximum distance for this interaction; the maximum animation length
* gets multiplied by the ratio between the actual distance and this value
*/
public void applyDismissing(Animator animator, float currValue, float endValue,
float velocity, float maxDistance) {
AnimatorProperties properties = getDismissingProperties(currValue, endValue, velocity,
maxDistance);
animator.setDuration(properties.duration);
animator.setInterpolator(properties.interpolator);
}
/**
* Applies the interpolator and length to the animator, such that the fling animation is
* consistent with the finger motion for the case when the animation is making something
* disappear.
*
* @param animator the animator to apply
* @param currValue the current value
* @param endValue the end value of the animator
* @param velocity the current velocity of the motion
* @param maxDistance the maximum distance for this interaction; the maximum animation length
* gets multiplied by the ratio between the actual distance and this value
*/
public void applyDismissing(ViewPropertyAnimator animator, float currValue, float endValue,
float velocity, float maxDistance) {
AnimatorProperties properties = getDismissingProperties(currValue, endValue, velocity,
maxDistance);
animator.setDuration(properties.duration);
animator.setInterpolator(properties.interpolator);
}
private AnimatorProperties getDismissingProperties(float currValue, float endValue,
float velocity, float maxDistance) {
float maxLengthSeconds = (float) (mMaxLengthSeconds
* Math.pow(Math.abs(endValue - currValue) / maxDistance, 0.5f));
float diff = Math.abs(endValue - currValue);
float velAbs = Math.abs(velocity);
float y2 = calculateLinearOutFasterInY2(velAbs);
float startGradient = y2 / LINEAR_OUT_FASTER_IN_X2;
Interpolator mLinearOutFasterIn = new PathInterpolator(0, 0, LINEAR_OUT_FASTER_IN_X2, y2);
float durationSeconds = startGradient * diff / velAbs;
if (durationSeconds <= maxLengthSeconds) {
mAnimatorProperties.interpolator = mLinearOutFasterIn;
} else if (velAbs >= mMinVelocityPxPerSecond) {
// Cross fade between linear-out-faster-in and linear interpolator with current
// velocity.
durationSeconds = maxLengthSeconds;
VelocityInterpolator velocityInterpolator
= new VelocityInterpolator(durationSeconds, velAbs, diff);
InterpolatorInterpolator superInterpolator = new InterpolatorInterpolator(
velocityInterpolator, mLinearOutFasterIn, mLinearOutSlowIn);
mAnimatorProperties.interpolator = superInterpolator;
} else {
// Just use a normal interpolator which doesn't take the velocity into account.
durationSeconds = maxLengthSeconds;
mAnimatorProperties.interpolator = mFastOutLinearIn;
}
mAnimatorProperties.duration = (long) (durationSeconds * 1000);
return mAnimatorProperties;
}
/**
* Calculates the y2 control point for a linear-out-faster-in path interpolator depending on the
* velocity. The faster the velocity, the more "linear" the interpolator gets.
*
* @param velocity the velocity of the gesture.
* @return the y2 control point for a cubic bezier path interpolator
*/
private float calculateLinearOutFasterInY2(float velocity) {
float t = (velocity - mMinVelocityPxPerSecond)
/ (mHighVelocityPxPerSecond - mMinVelocityPxPerSecond);
t = Math.max(0, Math.min(1, t));
return (1 - t) * LINEAR_OUT_FASTER_IN_Y2_MIN + t * LINEAR_OUT_FASTER_IN_Y2_MAX;
}
/**
* @return the minimum velocity a gesture needs to have to be considered a fling
*/
public float getMinVelocityPxPerSecond() {
return mMinVelocityPxPerSecond;
}
/**
* An interpolator which interpolates two interpolators with an interpolator.
*/
private static final class InterpolatorInterpolator implements Interpolator {
private Interpolator mInterpolator1;
private Interpolator mInterpolator2;
private Interpolator mCrossfader;
InterpolatorInterpolator(Interpolator interpolator1, Interpolator interpolator2,
Interpolator crossfader) {
mInterpolator1 = interpolator1;
mInterpolator2 = interpolator2;
mCrossfader = crossfader;
}
@Override
public float getInterpolation(float input) {
float t = mCrossfader.getInterpolation(input);
return (1 - t) * mInterpolator1.getInterpolation(input)
+ t * mInterpolator2.getInterpolation(input);
}
}
/**
* An interpolator which interpolates with a fixed velocity.
*/
private static final class VelocityInterpolator implements Interpolator {
private float mDurationSeconds;
private float mVelocity;
private float mDiff;
private VelocityInterpolator(float durationSeconds, float velocity, float diff) {
mDurationSeconds = durationSeconds;
mVelocity = velocity;
mDiff = diff;
}
@Override
public float getInterpolation(float input) {
float time = input * mDurationSeconds;
return time * mVelocity / mDiff;
}
}
private static class AnimatorProperties {
Interpolator interpolator;
long duration;
}
}
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