/*
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* Copyright (C) 2018 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.views;
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import static androidx.dynamicanimation.animation.SpringForce.DAMPING_RATIO_MEDIUM_BOUNCY;
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import static androidx.dynamicanimation.animation.SpringForce.STIFFNESS_LOW;
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import static androidx.dynamicanimation.animation.SpringForce.STIFFNESS_MEDIUM;
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import android.content.Context;
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import android.graphics.Canvas;
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import android.util.AttributeSet;
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import android.util.SparseBooleanArray;
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import android.view.View;
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import android.widget.EdgeEffect;
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import android.widget.RelativeLayout;
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import androidx.annotation.NonNull;
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import androidx.dynamicanimation.animation.DynamicAnimation;
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import androidx.dynamicanimation.animation.FloatPropertyCompat;
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import androidx.dynamicanimation.animation.SpringAnimation;
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import androidx.dynamicanimation.animation.SpringForce;
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import androidx.recyclerview.widget.RecyclerView;
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import androidx.recyclerview.widget.RecyclerView.EdgeEffectFactory;
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public class SpringRelativeLayout extends RelativeLayout {
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private static final float STIFFNESS = (STIFFNESS_MEDIUM + STIFFNESS_LOW) / 2;
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private static final float DAMPING_RATIO = DAMPING_RATIO_MEDIUM_BOUNCY;
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private static final float VELOCITY_MULTIPLIER = 0.3f;
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private static final FloatPropertyCompat<SpringRelativeLayout> DAMPED_SCROLL =
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new FloatPropertyCompat<SpringRelativeLayout>("value") {
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@Override
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public float getValue(SpringRelativeLayout object) {
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return object.mDampedScrollShift;
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}
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@Override
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public void setValue(SpringRelativeLayout object, float value) {
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object.setDampedScrollShift(value);
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}
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};
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protected final SparseBooleanArray mSpringViews = new SparseBooleanArray();
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private final SpringAnimation mSpring;
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private float mDampedScrollShift = 0;
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private SpringEdgeEffect mActiveEdge;
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public SpringRelativeLayout(Context context) {
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this(context, null);
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}
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public SpringRelativeLayout(Context context, AttributeSet attrs) {
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this(context, attrs, 0);
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}
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public SpringRelativeLayout(Context context, AttributeSet attrs, int defStyleAttr) {
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super(context, attrs, defStyleAttr);
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mSpring = new SpringAnimation(this, DAMPED_SCROLL, 0);
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mSpring.setSpring(new SpringForce(0)
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.setStiffness(STIFFNESS)
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.setDampingRatio(DAMPING_RATIO));
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}
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public void addSpringView(int id) {
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mSpringViews.put(id, true);
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}
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public void removeSpringView(int id) {
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mSpringViews.delete(id);
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invalidate();
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}
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/**
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* Used to clip the canvas when drawing child views during overscroll.
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*/
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public int getCanvasClipTopForOverscroll() {
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return 0;
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}
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@Override
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protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
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if (mDampedScrollShift != 0 && mSpringViews.get(child.getId())) {
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int saveCount = canvas.save();
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canvas.clipRect(0, getCanvasClipTopForOverscroll(), getWidth(), getHeight());
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canvas.translate(0, mDampedScrollShift);
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boolean result = super.drawChild(canvas, child, drawingTime);
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canvas.restoreToCount(saveCount);
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return result;
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}
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return super.drawChild(canvas, child, drawingTime);
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}
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private void setActiveEdge(SpringEdgeEffect edge) {
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if (mActiveEdge != edge && mActiveEdge != null) {
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mActiveEdge.mDistance = 0;
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}
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mActiveEdge = edge;
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}
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protected void setDampedScrollShift(float shift) {
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if (shift != mDampedScrollShift) {
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mDampedScrollShift = shift;
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invalidate();
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}
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}
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private void finishScrollWithVelocity(float velocity) {
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mSpring.setStartVelocity(velocity);
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mSpring.setStartValue(mDampedScrollShift);
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mSpring.start();
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}
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protected void finishWithShiftAndVelocity(float shift, float velocity,
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DynamicAnimation.OnAnimationEndListener listener) {
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setDampedScrollShift(shift);
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mSpring.addEndListener(listener);
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finishScrollWithVelocity(velocity);
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}
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public EdgeEffectFactory createEdgeEffectFactory() {
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return new SpringEdgeEffectFactory();
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}
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private class SpringEdgeEffectFactory extends EdgeEffectFactory {
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@NonNull @Override
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protected EdgeEffect createEdgeEffect(RecyclerView view, int direction) {
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switch (direction) {
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case DIRECTION_TOP:
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return new SpringEdgeEffect(getContext(), +VELOCITY_MULTIPLIER);
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case DIRECTION_BOTTOM:
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return new SpringEdgeEffect(getContext(), -VELOCITY_MULTIPLIER);
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}
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return super.createEdgeEffect(view, direction);
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}
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}
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private class SpringEdgeEffect extends EdgeEffect {
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private final float mVelocityMultiplier;
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private float mDistance;
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public SpringEdgeEffect(Context context, float velocityMultiplier) {
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super(context);
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mVelocityMultiplier = velocityMultiplier;
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}
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@Override
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public boolean draw(Canvas canvas) {
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return false;
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}
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@Override
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public void onAbsorb(int velocity) {
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finishScrollWithVelocity(velocity * mVelocityMultiplier);
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}
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@Override
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public void onPull(float deltaDistance, float displacement) {
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setActiveEdge(this);
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mDistance += deltaDistance * (mVelocityMultiplier / 3f);
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setDampedScrollShift(mDistance * getHeight());
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}
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@Override
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public void onRelease() {
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mDistance = 0;
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finishScrollWithVelocity(0);
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}
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}
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}
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