Home | History | Annotate | Download | only in device 
      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.camera.device;
     18 
     19 import com.android.camera.debug.Log;
     20 import com.android.camera.debug.Log.Tag;
     21 import com.google.common.annotations.VisibleForTesting;
     22 
     23 import javax.annotation.ParametersAreNonnullByDefault;
     24 import javax.annotation.concurrent.GuardedBy;
     25 
     26 /**
     27  * Shared object for tracking the active camera device across multiple
     28  * implementations.
     29  */
     30 @ParametersAreNonnullByDefault
     31 public class ActiveCameraDeviceTracker {
     32     private static final Tag TAG = new Tag("ActvCamDevTrckr");
     33 
     34     /**
     35      * Singleton instance.
     36      */
     37     private static class Singleton {
     38         public static final ActiveCameraDeviceTracker INSTANCE = new ActiveCameraDeviceTracker();
     39     }
     40 
     41     public static ActiveCameraDeviceTracker instance() {
     42         return Singleton.INSTANCE;
     43     }
     44 
     45     private final Object mLock;
     46 
     47     @GuardedBy("mLock")
     48     private CameraId mActiveCamera;
     49 
     50     @GuardedBy("mLock")
     51     private CameraId mPreviousCamera;
     52 
     53     @VisibleForTesting
     54     ActiveCameraDeviceTracker() {
     55         mLock = new Object();
     56     }
     57 
     58     public CameraId getActiveCamera() {
     59         synchronized (mLock) {
     60             return mActiveCamera;
     61         }
     62     }
     63 
     64     public CameraId getActiveOrPreviousCamera() {
     65         synchronized (mLock) {
     66             if (mActiveCamera != null) {
     67 
     68                 return mActiveCamera;
     69             }
     70             Log.v(TAG, "Returning previously active camera: " + mPreviousCamera);
     71             return mPreviousCamera;
     72         }
     73     }
     74 
     75     public void onCameraOpening(CameraId key) {
     76         synchronized (mLock) {
     77             if (mActiveCamera != null && !mActiveCamera.equals(key)) {
     78                 mPreviousCamera = mActiveCamera;
     79             }
     80 
     81             Log.v(TAG, "Tracking active camera: " + mActiveCamera);
     82             mActiveCamera = key;
     83         }
     84     }
     85 
     86     public void onCameraClosed(CameraId key) {
     87         synchronized (mLock) {
     88             if (mActiveCamera != null && mActiveCamera.equals(key)) {
     89                 mPreviousCamera = mActiveCamera;
     90                 mActiveCamera = null;
     91             }
     92         }
     93     }
     94 }
     95