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      1 /*
      2  * Copyright (C) 2013 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.data;
     18 
     19 import java.util.ArrayList;
     20 
     21 import android.content.Context;
     22 import android.net.Uri;
     23 
     24 import com.android.camera.util.PhotoSphereHelper;
     25 import com.android.camera.util.PhotoSphereHelper.PanoramaMetadata;
     26 
     27 /**
     28  * This class breaks out the off-thread panorama support.
     29  */
     30 public class PanoramaMetadataLoader {
     31     /**
     32      * Classes implementing this interface can get information about loaded
     33      * photo sphere metadata.
     34      */
     35     public static interface PanoramaMetadataCallback {
     36         /**
     37          * Called with the loaded metadata or <code>null</code>.
     38          */
     39         public void onPanoramaMetadataLoaded(PanoramaMetadata metadata);
     40     }
     41 
     42     private PanoramaMetadata mPanoramaMetadata;
     43     private ArrayList<PanoramaMetadataCallback> mCallbacksWaiting;
     44     private Uri mMediaUri;
     45 
     46     /**
     47      * Instantiated the meta data loader for the image resource with the given
     48      * URI.
     49      */
     50     public PanoramaMetadataLoader(Uri uri) {
     51         mMediaUri = uri;
     52     }
     53 
     54     /**
     55      * Asynchronously extract and return panorama metadata from the item with
     56      * the given URI.
     57      * <p>
     58      * NOTE: This call is backed by a cache to speed up successive calls, which
     59      * will return immediately. Use {@link #clearCachedValues()} is called.
     60      */
     61     public synchronized void getPanoramaMetadata(final Context context,
     62             PanoramaMetadataCallback callback) {
     63         if (mPanoramaMetadata != null) {
     64             // Return the cached data right away, no need to fetch it again.
     65             callback.onPanoramaMetadataLoaded(mPanoramaMetadata);
     66         } else {
     67             if (mCallbacksWaiting == null) {
     68                 mCallbacksWaiting = new ArrayList<PanoramaMetadataCallback>();
     69 
     70                 // TODO: Don't create a new thread each time, use a pool or
     71                 // single instance.
     72                 (new Thread() {
     73                     @Override
     74                     public void run() {
     75                         onLoadingDone(PhotoSphereHelper.getPanoramaMetadata(context,
     76                                 mMediaUri));
     77                     }
     78                 }).start();
     79             }
     80             mCallbacksWaiting.add(callback);
     81         }
     82     }
     83 
     84     /**
     85      * Clear cached value and stop all running loading threads.
     86      */
     87     public synchronized void clearCachedValues() {
     88         if (mPanoramaMetadata != null) {
     89             mPanoramaMetadata = null;
     90         }
     91 
     92         // TODO: Cancel running loading thread if active.
     93      }
     94 
     95     private synchronized void onLoadingDone(PanoramaMetadata metadata) {
     96         mPanoramaMetadata = metadata;
     97         if (mPanoramaMetadata == null) {
     98             // Error getting panorama data from file. Treat as not panorama.
     99             mPanoramaMetadata = PhotoSphereHelper.NOT_PANORAMA;
    100         }
    101         for (PanoramaMetadataCallback cb : mCallbacksWaiting) {
    102             cb.onPanoramaMetadataLoaded(mPanoramaMetadata);
    103         }
    104         mCallbacksWaiting = null;
    105     }
    106 }
    107