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      1 /*
      2  * Copyright (C) 2011 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.gallery3d.gadget;
     18 
     19 import android.graphics.Bitmap;
     20 import android.net.Uri;
     21 import android.os.Binder;
     22 
     23 import com.android.gallery3d.common.Utils;
     24 import com.android.gallery3d.data.ContentListener;
     25 import com.android.gallery3d.data.MediaItem;
     26 import com.android.gallery3d.data.MediaObject;
     27 import com.android.gallery3d.data.MediaSet;
     28 
     29 import java.util.ArrayList;
     30 import java.util.Arrays;
     31 
     32 public class MediaSetSource implements WidgetSource, ContentListener {
     33     private static final int CACHE_SIZE = 32;
     34 
     35     @SuppressWarnings("unused")
     36     private static final String TAG = "MediaSetSource";
     37 
     38     private MediaSet mSource;
     39     private MediaItem mCache[] = new MediaItem[CACHE_SIZE];
     40     private int mCacheStart;
     41     private int mCacheEnd;
     42     private long mSourceVersion = MediaObject.INVALID_DATA_VERSION;
     43 
     44     private ContentListener mContentListener;
     45 
     46     public MediaSetSource(MediaSet source) {
     47         mSource = Utils.checkNotNull(source);
     48         mSource.addContentListener(this);
     49     }
     50 
     51     @Override
     52     public void close() {
     53         mSource.removeContentListener(this);
     54     }
     55 
     56     private void ensureCacheRange(int index) {
     57         if (index >= mCacheStart && index < mCacheEnd) return;
     58 
     59         long token = Binder.clearCallingIdentity();
     60         try {
     61             mCacheStart = index;
     62             ArrayList<MediaItem> items = mSource.getMediaItem(mCacheStart, CACHE_SIZE);
     63             mCacheEnd = mCacheStart + items.size();
     64             items.toArray(mCache);
     65         } finally {
     66             Binder.restoreCallingIdentity(token);
     67         }
     68     }
     69 
     70     @Override
     71     public synchronized Uri getContentUri(int index) {
     72         ensureCacheRange(index);
     73         if (index < mCacheStart || index >= mCacheEnd) return null;
     74         return mCache[index - mCacheStart].getContentUri();
     75     }
     76 
     77     @Override
     78     public synchronized Bitmap getImage(int index) {
     79         ensureCacheRange(index);
     80         if (index < mCacheStart || index >= mCacheEnd) return null;
     81         return WidgetUtils.createWidgetBitmap(mCache[index - mCacheStart]);
     82     }
     83 
     84     @Override
     85     public void reload() {
     86         long version = mSource.reload();
     87         if (mSourceVersion != version) {
     88             mSourceVersion = version;
     89             mCacheStart = 0;
     90             mCacheEnd = 0;
     91             Arrays.fill(mCache, null);
     92         }
     93     }
     94 
     95     @Override
     96     public void setContentListener(ContentListener listener) {
     97         mContentListener = listener;
     98     }
     99 
    100     @Override
    101     public int size() {
    102         long token = Binder.clearCallingIdentity();
    103         try {
    104             return mSource.getMediaItemCount();
    105         } finally {
    106             Binder.restoreCallingIdentity(token);
    107         }
    108     }
    109 
    110     @Override
    111     public void onContentDirty() {
    112         if (mContentListener != null) mContentListener.onContentDirty();
    113     }
    114 }
    115