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
17package com.android.gallery3d.gadget;
18
19import android.graphics.Bitmap;
20import android.net.Uri;
21import android.os.Binder;
22
23import com.android.gallery3d.common.Utils;
24import com.android.gallery3d.data.ContentListener;
25import com.android.gallery3d.data.MediaItem;
26import com.android.gallery3d.data.MediaObject;
27import com.android.gallery3d.data.MediaSet;
28
29import java.util.ArrayList;
30import java.util.Arrays;
31
32public 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