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/*
* Copyright (C) 2019 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.settingslib.widget;
import static androidx.lifecycle.Lifecycle.Event.ON_START;
import static androidx.lifecycle.Lifecycle.Event.ON_STOP;
import android.app.ActionBar;
import android.app.Activity;
import android.view.View;
import androidx.annotation.VisibleForTesting;
import androidx.lifecycle.Lifecycle;
import androidx.lifecycle.LifecycleObserver;
import androidx.lifecycle.OnLifecycleEvent;
/**
* UI controller that adds a shadow appear/disappear animation to action bar scroll.
*/
public class ActionBarShadowController implements LifecycleObserver {
@VisibleForTesting
static final float ELEVATION_HIGH = 8;
@VisibleForTesting
static final float ELEVATION_LOW = 0;
@VisibleForTesting
ScrollChangeWatcher mScrollChangeWatcher;
private View mScrollView;
private boolean mIsScrollWatcherAttached;
/**
* Wire up the animation to to an {@link Activity}. Shadow will be applied to activity's
* action bar.
*/
public static ActionBarShadowController attachToView(
Activity activity, Lifecycle lifecycle, View scrollView) {
return new ActionBarShadowController(activity, lifecycle, scrollView);
}
/**
* Wire up the animation to to a {@link View}. Shadow will be applied to the view.
*/
public static ActionBarShadowController attachToView(
View anchorView, Lifecycle lifecycle, View scrollView) {
return new ActionBarShadowController(anchorView, lifecycle, scrollView);
}
private ActionBarShadowController(Activity activity, Lifecycle lifecycle, View scrollView) {
mScrollChangeWatcher = new ActionBarShadowController.ScrollChangeWatcher(activity);
mScrollView = scrollView;
attachScrollWatcher();
lifecycle.addObserver(this);
}
private ActionBarShadowController(View anchorView, Lifecycle lifecycle, View scrollView) {
mScrollChangeWatcher = new ActionBarShadowController.ScrollChangeWatcher(anchorView);
mScrollView = scrollView;
attachScrollWatcher();
lifecycle.addObserver(this);
}
@OnLifecycleEvent(ON_START)
private void attachScrollWatcher() {
if (!mIsScrollWatcherAttached) {
mIsScrollWatcherAttached = true;
mScrollView.setOnScrollChangeListener(mScrollChangeWatcher);
mScrollChangeWatcher.updateDropShadow(mScrollView);
}
}
@OnLifecycleEvent(ON_STOP)
private void detachScrollWatcher() {
mScrollView.setOnScrollChangeListener(null);
mIsScrollWatcherAttached = false;
}
/**
* Update the drop shadow as the scrollable entity is scrolled.
*/
final class ScrollChangeWatcher implements View.OnScrollChangeListener {
private final Activity mActivity;
private final View mAnchorView;
ScrollChangeWatcher(Activity activity) {
mActivity = activity;
mAnchorView = null;
}
ScrollChangeWatcher(View anchorView) {
mAnchorView = anchorView;
mActivity = null;
}
@Override
public void onScrollChange(View view, int scrollX, int scrollY, int oldScrollX,
int oldScrollY) {
updateDropShadow(view);
}
public void updateDropShadow(View view) {
final boolean shouldShowShadow = view.canScrollVertically(-1);
if (mAnchorView != null) {
mAnchorView.setElevation(shouldShowShadow ? ELEVATION_HIGH : ELEVATION_LOW);
} else if (mActivity != null) { // activity can become null when running monkey
final ActionBar actionBar = mActivity.getActionBar();
if (actionBar != null) {
actionBar.setElevation(shouldShowShadow ? ELEVATION_HIGH : ELEVATION_LOW);
}
}
}
}
}
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