WallpaperBackupHelper.java revision 44bc17c6b517aef35a390c81b5aa79c4f284f744 
1/*
2 * Copyright (C) 2010 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 android.app.backup;
18
19import android.app.WallpaperManager;
20import android.content.Context;
21import android.graphics.BitmapFactory;
22import android.graphics.Point;
23import android.os.ParcelFileDescriptor;
24import android.util.Slog;
25import android.view.Display;
26import android.view.WindowManager;
27
28import java.io.File;
29
30/**
31 * Helper for backing up / restoring wallpapers.  Basically an AbsoluteFileBackupHelper,
32 * but with logic for deciding what to do with restored wallpaper images.
33 *
34 * @hide
35 */
36public class WallpaperBackupHelper extends FileBackupHelperBase implements BackupHelper {
37    private static final String TAG = "WallpaperBackupHelper";
38    private static final boolean DEBUG = true;
39
40    // This path must match what the WallpaperManagerService uses
41    private static final String WALLPAPER_IMAGE = "/data/data/com.android.settings/files/wallpaper";
42
43    // Stage file - should be adjacent to the WALLPAPER_IMAGE location.  The wallpapers
44    // will be saved to this file from the restore stream, then renamed to the proper
45    // location if it's deemed suitable.
46    private static final String STAGE_FILE = "/data/data/com.android.settings/files/wallpaper-tmp";
47
48    Context mContext;
49    String[] mFiles;
50    double mDesiredMinWidth;
51    double mDesiredMinHeight;
52
53    /**
54     * Construct a helper for backing up / restoring the files at the given absolute locations
55     * within the file system.
56     *
57     * @param context
58     * @param files
59     */
60    public WallpaperBackupHelper(Context context, String... files) {
61        super(context);
62
63        mContext = context;
64        mFiles = files;
65
66        WallpaperManager wpm;
67        wpm = (WallpaperManager) context.getSystemService(Context.WALLPAPER_SERVICE);
68        mDesiredMinWidth = (double) wpm.getDesiredMinimumWidth();
69        mDesiredMinHeight = (double) wpm.getDesiredMinimumHeight();
70
71        if (mDesiredMinWidth <= 0 || mDesiredMinHeight <= 0) {
72            WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
73            Display d = wm.getDefaultDisplay();
74            Point size = new Point();
75            d.getSize(size);
76            mDesiredMinWidth = size.x;
77            mDesiredMinHeight = size.y;
78        }
79
80        if (DEBUG) {
81            Slog.d(TAG, "dmW=" + mDesiredMinWidth + " dmH=" + mDesiredMinHeight);
82        }
83    }
84
85    /**
86     * Based on oldState, determine which of the files from the application's data directory
87     * need to be backed up, write them to the data stream, and fill in newState with the
88     * state as it exists now.
89     */
90    public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
91            ParcelFileDescriptor newState) {
92        performBackup_checked(oldState, data, newState, mFiles, mFiles);
93    }
94
95    /**
96     * Restore one absolute file entity from the restore stream.  If we're restoring the
97     * magic wallpaper file, take specific action to determine whether it is suitable for
98     * the current device.
99     */
100    public void restoreEntity(BackupDataInputStream data) {
101        final String key = data.getKey();
102        if (isKeyInList(key, mFiles)) {
103            if (key.equals(WALLPAPER_IMAGE)) {
104                // restore the file to the stage for inspection
105                File f = new File(STAGE_FILE);
106                if (writeFile(f, data)) {
107
108                    // Preflight the restored image's dimensions without loading it
109                    BitmapFactory.Options options = new BitmapFactory.Options();
110                    options.inJustDecodeBounds = true;
111                    BitmapFactory.decodeFile(STAGE_FILE, options);
112
113                    if (DEBUG) Slog.d(TAG, "Restoring wallpaper image w=" + options.outWidth
114                            + " h=" + options.outHeight);
115
116                    // How much does the image differ from our preference?  The threshold
117                    // here is set to accept any image larger than our target, because
118                    // scaling down is acceptable; but to reject images that are deemed
119                    // "too small" to scale up attractively.  The value 1.33 is just barely
120                    // too low to pass Nexus 1 or Droid wallpapers for use on a Xoom, but
121                    // will pass anything relatively larger.
122                    double widthRatio = mDesiredMinWidth / options.outWidth;
123                    double heightRatio = mDesiredMinHeight / options.outHeight;
124                    if (widthRatio > 0 && widthRatio < 1.33
125                            && heightRatio > 0 && heightRatio < 1.33) {
126                        // sufficiently close to our resolution; go ahead and use it
127                        if (DEBUG) Slog.d(TAG, "wallpaper dimension match; using");
128                        f.renameTo(new File(WALLPAPER_IMAGE));
129                        // TODO: spin a service to copy the restored image to sd/usb storage,
130                        // since it does not exist anywhere other than the private wallpaper
131                        // file.
132                    } else {
133                        if (DEBUG) Slog.d(TAG, "dimensions too far off: wr=" + widthRatio
134                                + " hr=" + heightRatio);
135                        f.delete();
136                    }
137                }
138            } else {
139                // Some other normal file; just decode it to its destination
140                File f = new File(key);
141                writeFile(f, data);
142            }
143        }
144    }
145}
146