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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.tv;
     18 
     19 import android.support.annotation.MainThread;
     20 import android.support.annotation.NonNull;
     21 import android.support.annotation.Nullable;
     22 import android.util.ArraySet;
     23 import com.android.tv.data.api.Channel;
     24 import java.util.Set;
     25 
     26 /**
     27  * A wrapper for safely getting the current {@link MainActivity}. Note that this class is not
     28  * thread-safe. All the public methods should be called on main thread.
     29  */
     30 @MainThread
     31 public final class MainActivityWrapper {
     32     private MainActivity mActivity;
     33 
     34     private final Set<OnCurrentChannelChangeListener> mListeners = new ArraySet<>();
     35 
     36     /**
     37      * Returns the current main activity. <b>WARNING</b> do not keep a reference to MainActivity,
     38      * leaking activities is expensive.
     39      */
     40     MainActivity getMainActivity() {
     41         return mActivity;
     42     }
     43 
     44     /** Checks if the given {@code activity} is the current main activity. */
     45     boolean isCurrent(MainActivity activity) {
     46         return activity != null && mActivity == activity;
     47     }
     48 
     49     /** Sets the currently created main activity instance. */
     50     public void onMainActivityCreated(@NonNull MainActivity activity) {
     51         mActivity = activity;
     52     }
     53 
     54     /** Unsets the main activity instance. */
     55     public void onMainActivityDestroyed(@NonNull MainActivity activity) {
     56         if (mActivity == activity) {
     57             mActivity = null;
     58         }
     59     }
     60 
     61     /** Notifies the current channel change. */
     62     void notifyCurrentChannelChange(@NonNull MainActivity caller, @Nullable Channel channel) {
     63         if (mActivity == caller) {
     64             for (OnCurrentChannelChangeListener listener : mListeners) {
     65                 listener.onCurrentChannelChange(channel);
     66             }
     67         }
     68     }
     69 
     70     /** Checks if the main activity is created. */
     71     public boolean isCreated() {
     72         return mActivity != null;
     73     }
     74 
     75     /** Checks if the main activity is started. */
     76     public boolean isStarted() {
     77         return mActivity != null && mActivity.isActivityStarted();
     78     }
     79 
     80     /** Checks if the main activity is resumed. */
     81     public boolean isResumed() {
     82         return mActivity != null && mActivity.isActivityResumed();
     83     }
     84 
     85     /** Adds OnCurrentChannelChangeListener. */
     86     public void addOnCurrentChannelChangeListener(OnCurrentChannelChangeListener listener) {
     87         mListeners.add(listener);
     88     }
     89 
     90     /** Removes OnCurrentChannelChangeListener. */
     91     public void removeOnCurrentChannelChangeListener(OnCurrentChannelChangeListener listener) {
     92         mListeners.remove(listener);
     93     }
     94 
     95     /** Listener for the current channel change in main activity. */
     96     public interface OnCurrentChannelChangeListener {
     97         /** Called when the current channel changes. */
     98         void onCurrentChannelChange(@Nullable Channel channel);
     99     }
    100 }
    101