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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 android.service.media;
     18 
     19 import android.app.Service;
     20 import android.content.Intent;
     21 import android.os.Handler;
     22 import android.os.IBinder;
     23 import android.os.Message;
     24 import android.os.Messenger;
     25 
     26 /**
     27  * Extend this class to implement a camera prewarm service. See
     28  * {@link android.provider.MediaStore#META_DATA_STILL_IMAGE_CAMERA_PREWARM_SERVICE}.
     29  */
     30 public abstract class CameraPrewarmService extends Service {
     31 
     32     /**
     33      * Intent action to bind the service as a prewarm service.
     34      * @hide
     35      */
     36     public static final String ACTION_PREWARM =
     37             "android.service.media.CameraPrewarmService.ACTION_PREWARM";
     38 
     39     /**
     40      * Message sent by the client indicating that the camera intent has been fired.
     41      * @hide
     42      */
     43     public static final int MSG_CAMERA_FIRED = 1;
     44 
     45     private final Handler mHandler = new Handler() {
     46 
     47         @Override
     48         public void handleMessage(Message msg) {
     49             switch (msg.what) {
     50                 case MSG_CAMERA_FIRED:
     51                     mCameraIntentFired = true;
     52                     break;
     53                 default:
     54                     super.handleMessage(msg);
     55             }
     56         }
     57     };
     58     private boolean mCameraIntentFired;
     59 
     60     @Override
     61     public IBinder onBind(Intent intent) {
     62         if (ACTION_PREWARM.equals(intent.getAction())) {
     63             onPrewarm();
     64             return new Messenger(mHandler).getBinder();
     65         } else {
     66             return null;
     67         }
     68     }
     69 
     70     @Override
     71     public boolean onUnbind(Intent intent) {
     72         if (ACTION_PREWARM.equals(intent.getAction())) {
     73             onCooldown(mCameraIntentFired);
     74         }
     75         return false;
     76     }
     77 
     78     /**
     79      * Called when the camera should be prewarmed.
     80      */
     81     public abstract void onPrewarm();
     82 
     83     /**
     84      * Called when prewarm phase is done, either because the camera launch intent has been fired
     85      * at this point or prewarm is no longer needed. A client should close the camera
     86      * immediately in the latter case.
     87      * <p>
     88      * In case the camera launch intent has been fired, there is no guarantee about the ordering
     89      * of these two events. Cooldown might happen either before or after the activity has been
     90      * created that handles the camera intent.
     91      *
     92      * @param cameraIntentFired Indicates whether the intent to launch the camera has been
     93      *                          fired.
     94      */
     95     public abstract void onCooldown(boolean cameraIntentFired);
     96 }
     97