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/*
* Copyright (C) 2018 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.views;
import android.content.Context;
import android.graphics.Canvas;
import android.support.animation.DynamicAnimation;
import android.support.animation.FloatPropertyCompat;
import android.support.animation.SpringAnimation;
import android.support.animation.SpringForce;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.RecyclerView.EdgeEffectFactory;
import android.util.AttributeSet;
import android.util.SparseBooleanArray;
import android.view.View;
import android.widget.EdgeEffect;
import android.widget.RelativeLayout;
import static android.support.animation.SpringForce.DAMPING_RATIO_MEDIUM_BOUNCY;
import static android.support.animation.SpringForce.STIFFNESS_LOW;
import static android.support.animation.SpringForce.STIFFNESS_MEDIUM;
public class SpringRelativeLayout extends RelativeLayout {
private static final float STIFFNESS = (STIFFNESS_MEDIUM + STIFFNESS_LOW) / 2;
private static final float DAMPING_RATIO = DAMPING_RATIO_MEDIUM_BOUNCY;
private static final float VELOCITY_MULTIPLIER = 0.3f;
private static final FloatPropertyCompat<SpringRelativeLayout> DAMPED_SCROLL =
new FloatPropertyCompat<SpringRelativeLayout>("value") {
@Override
public float getValue(SpringRelativeLayout object) {
return object.mDampedScrollShift;
}
@Override
public void setValue(SpringRelativeLayout object, float value) {
object.setDampedScrollShift(value);
}
};
protected final SparseBooleanArray mSpringViews = new SparseBooleanArray();
private final SpringAnimation mSpring;
private float mDampedScrollShift = 0;
private SpringEdgeEffect mActiveEdge;
public SpringRelativeLayout(Context context) {
this(context, null);
}
public SpringRelativeLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public SpringRelativeLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
mSpring = new SpringAnimation(this, DAMPED_SCROLL, 0);
mSpring.setSpring(new SpringForce(0)
.setStiffness(STIFFNESS)
.setDampingRatio(DAMPING_RATIO));
}
public void addSpringView(int id) {
mSpringViews.put(id, true);
}
public void removeSpringView(int id) {
mSpringViews.delete(id);
invalidate();
}
/**
* Used to clip the canvas when drawing child views during overscroll.
*/
public int getCanvasClipTopForOverscroll() {
return 0;
}
@Override
protected boolean drawChild(Canvas canvas, View child, long drawingTime) {
if (mDampedScrollShift != 0 && mSpringViews.get(child.getId())) {
int saveCount = canvas.save();
canvas.clipRect(0, getCanvasClipTopForOverscroll(), getWidth(), getHeight());
canvas.translate(0, mDampedScrollShift);
boolean result = super.drawChild(canvas, child, drawingTime);
canvas.restoreToCount(saveCount);
return result;
}
return super.drawChild(canvas, child, drawingTime);
}
private void setActiveEdge(SpringEdgeEffect edge) {
if (mActiveEdge != edge && mActiveEdge != null) {
mActiveEdge.mDistance = 0;
}
mActiveEdge = edge;
}
protected void setDampedScrollShift(float shift) {
if (shift != mDampedScrollShift) {
mDampedScrollShift = shift;
invalidate();
}
}
private void finishScrollWithVelocity(float velocity) {
mSpring.setStartVelocity(velocity);
mSpring.setStartValue(mDampedScrollShift);
mSpring.start();
}
protected void finishWithShiftAndVelocity(float shift, float velocity,
DynamicAnimation.OnAnimationEndListener listener) {
setDampedScrollShift(shift);
mSpring.addEndListener(listener);
finishScrollWithVelocity(velocity);
}
public EdgeEffectFactory createEdgeEffectFactory() {
return new SpringEdgeEffectFactory();
}
private class SpringEdgeEffectFactory extends EdgeEffectFactory {
@NonNull @Override
protected EdgeEffect createEdgeEffect(RecyclerView view, int direction) {
switch (direction) {
case DIRECTION_TOP:
return new SpringEdgeEffect(getContext(), +VELOCITY_MULTIPLIER);
case DIRECTION_BOTTOM:
return new SpringEdgeEffect(getContext(), -VELOCITY_MULTIPLIER);
}
return super.createEdgeEffect(view, direction);
}
}
private class SpringEdgeEffect extends EdgeEffect {
private final float mVelocityMultiplier;
private float mDistance;
public SpringEdgeEffect(Context context, float velocityMultiplier) {
super(context);
mVelocityMultiplier = velocityMultiplier;
}
@Override
public boolean draw(Canvas canvas) {
return false;
}
@Override
public void onAbsorb(int velocity) {
finishScrollWithVelocity(velocity * mVelocityMultiplier);
}
@Override
public void onPull(float deltaDistance, float displacement) {
setActiveEdge(this);
mDistance += deltaDistance * (mVelocityMultiplier / 3f);
setDampedScrollShift(mDistance * getHeight());
}
@Override
public void onRelease() {
mDistance = 0;
finishScrollWithVelocity(0);
}
}
}
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