| /* |
| * 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; |
| import androidx.recyclerview.widget.RecyclerView; |
| |
| /** |
| * 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 RecyclerView mRecyclerView; |
| private boolean mIsScrollWatcherAttached; |
| |
| /** |
| * Wire up the animation to to an {@link Activity}. Shadow will be applied to activity's |
| * action bar. |
| */ |
| public static ActionBarShadowController attachToRecyclerView( |
| Activity activity, Lifecycle lifecycle, RecyclerView recyclerView) { |
| return new ActionBarShadowController(activity, lifecycle, recyclerView); |
| } |
| |
| /** |
| * Wire up the animation to to a {@link View}. Shadow will be applied to the view. |
| */ |
| public static ActionBarShadowController attachToRecyclerView( |
| View anchorView, Lifecycle lifecycle, RecyclerView recyclerView) { |
| return new ActionBarShadowController(anchorView, lifecycle, recyclerView); |
| } |
| |
| private ActionBarShadowController(Activity activity, Lifecycle lifecycle, |
| RecyclerView recyclerView) { |
| mScrollChangeWatcher = |
| new ActionBarShadowController.ScrollChangeWatcher(activity); |
| mRecyclerView = recyclerView; |
| attachScrollWatcher(); |
| lifecycle.addObserver(this); |
| } |
| |
| private ActionBarShadowController(View anchorView, Lifecycle lifecycle, |
| RecyclerView recyclerView) { |
| mScrollChangeWatcher = |
| new ActionBarShadowController.ScrollChangeWatcher(anchorView); |
| mRecyclerView = recyclerView; |
| attachScrollWatcher(); |
| lifecycle.addObserver(this); |
| } |
| |
| @OnLifecycleEvent(ON_START) |
| private void attachScrollWatcher() { |
| if (!mIsScrollWatcherAttached) { |
| mIsScrollWatcherAttached = true; |
| mRecyclerView.addOnScrollListener(mScrollChangeWatcher); |
| mScrollChangeWatcher.updateDropShadow(mRecyclerView); |
| } |
| } |
| |
| @OnLifecycleEvent(ON_STOP) |
| private void detachScrollWatcher() { |
| mRecyclerView.removeOnScrollListener(mScrollChangeWatcher); |
| mIsScrollWatcherAttached = false; |
| } |
| |
| /** |
| * Update the drop shadow as the scrollable entity is scrolled. |
| */ |
| final class ScrollChangeWatcher extends RecyclerView.OnScrollListener { |
| |
| private final Activity mActivity; |
| private final View mAnchorView; |
| |
| ScrollChangeWatcher(Activity activity) { |
| mActivity = activity; |
| mAnchorView = null; |
| } |
| |
| ScrollChangeWatcher(View anchorView) { |
| mAnchorView = anchorView; |
| mActivity = null; |
| } |
| |
| // RecyclerView scrolled. |
| @Override |
| public void onScrolled(RecyclerView view, int dx, int dy) { |
| 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); |
| } |
| } |
| } |
| } |
| } |