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.Environment;
24import android.os.ParcelFileDescriptor;
25import android.os.UserHandle;
26import android.util.Slog;
27import android.view.Display;
28import android.view.WindowManager;
29
30import java.io.File;
31
32/**
33 * Helper for backing up / restoring wallpapers.  Basically an AbsoluteFileBackupHelper,
34 * but with logic for deciding what to do with restored wallpaper images.
35 *
36 * @hide
37 */
38public class WallpaperBackupHelper extends FileBackupHelperBase implements BackupHelper {
39    private static final String TAG = "WallpaperBackupHelper";
40    private static final boolean DEBUG = false;
41
42    // If 'true', then apply an acceptable-size heuristic at restore time, dropping back
43    // to the factory default wallpaper if the restored one differs "too much" from the
44    // device's preferred wallpaper image dimensions.
45    private static final boolean REJECT_OUTSIZED_RESTORE = true;
46
47    // When outsized restore rejection is enabled, this is the maximum ratio between the
48    // source and target image heights that will be permitted.  The ratio is checked both
49    // ways (i.e. >= MAX, or <= 1/MAX) to validate restores from both largeer-than-target
50    // and smaller-than-target sources.
51    private static final double MAX_HEIGHT_RATIO = 1.35;
52
53    // The height ratio check when applying larger images on smaller screens is separate;
54    // in current policy we accept any such restore regardless of the relative dimensions.
55    private static final double MIN_HEIGHT_RATIO = 0;
56
57    // This path must match what the WallpaperManagerService uses
58    // TODO: Will need to change if backing up non-primary user's wallpaper
59    // http://b/22388012
60    public static final String WALLPAPER_IMAGE =
61            new File(Environment.getUserSystemDirectory(UserHandle.USER_SYSTEM),
62                    "wallpaper").getAbsolutePath();
63    public static final String WALLPAPER_INFO =
64            new File(Environment.getUserSystemDirectory(UserHandle.USER_SYSTEM),
65                    "wallpaper_info.xml").getAbsolutePath();
66    // Use old keys to keep legacy data compatibility and avoid writing two wallpapers
67    public static final String WALLPAPER_IMAGE_KEY =
68            "/data/data/com.android.settings/files/wallpaper";
69    public static final String WALLPAPER_INFO_KEY = "/data/system/wallpaper_info.xml";
70
71    // Stage file - should be adjacent to the WALLPAPER_IMAGE location.  The wallpapers
72    // will be saved to this file from the restore stream, then renamed to the proper
73    // location if it's deemed suitable.
74    // TODO: Will need to change if backing up non-primary user's wallpaper
75    // http://b/22388012
76    private static final String STAGE_FILE =
77            new File(Environment.getUserSystemDirectory(UserHandle.USER_SYSTEM),
78                    "wallpaper-tmp").getAbsolutePath();
79
80    Context mContext;
81    String[] mFiles;
82    String[] mKeys;
83    double mDesiredMinWidth;
84    double mDesiredMinHeight;
85
86    /**
87     * Construct a helper for backing up / restoring the files at the given absolute locations
88     * within the file system.
89     *
90     * @param context
91     * @param files
92     */
93    public WallpaperBackupHelper(Context context, String[] files, String[] keys) {
94        super(context);
95
96        mContext = context;
97        mFiles = files;
98        mKeys = keys;
99
100        final WindowManager wm =
101                (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
102        final WallpaperManager wpm =
103                (WallpaperManager) context.getSystemService(Context.WALLPAPER_SERVICE);
104        final Display d = wm.getDefaultDisplay();
105        final Point size = new Point();
106        d.getSize(size);
107        mDesiredMinWidth = Math.min(size.x, size.y);
108        mDesiredMinHeight = (double) wpm.getDesiredMinimumHeight();
109        if (mDesiredMinHeight <= 0) {
110            mDesiredMinHeight = size.y;
111        }
112
113        if (DEBUG) {
114            Slog.d(TAG, "dmW=" + mDesiredMinWidth + " dmH=" + mDesiredMinHeight);
115        }
116    }
117
118    /**
119     * Based on oldState, determine which of the files from the application's data directory
120     * need to be backed up, write them to the data stream, and fill in newState with the
121     * state as it exists now.
122     */
123    @Override
124    public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
125            ParcelFileDescriptor newState) {
126        performBackup_checked(oldState, data, newState, mFiles, mKeys);
127    }
128
129    /**
130     * Restore one absolute file entity from the restore stream.  If we're restoring the
131     * magic wallpaper file, take specific action to determine whether it is suitable for
132     * the current device.
133     */
134    @Override
135    public void restoreEntity(BackupDataInputStream data) {
136        final String key = data.getKey();
137        if (isKeyInList(key, mKeys)) {
138            if (key.equals(WALLPAPER_IMAGE_KEY)) {
139                // restore the file to the stage for inspection
140                File f = new File(STAGE_FILE);
141                if (writeFile(f, data)) {
142
143                    // Preflight the restored image's dimensions without loading it
144                    BitmapFactory.Options options = new BitmapFactory.Options();
145                    options.inJustDecodeBounds = true;
146                    BitmapFactory.decodeFile(STAGE_FILE, options);
147
148                    if (DEBUG) Slog.d(TAG, "Restoring wallpaper image w=" + options.outWidth
149                            + " h=" + options.outHeight);
150
151                    if (REJECT_OUTSIZED_RESTORE) {
152                        // We accept any wallpaper that is at least as wide as our preference
153                        // (i.e. wide enough to fill the screen), and is within a comfortable
154                        // factor of the target height, to avoid significant clipping/scaling/
155                        // letterboxing.  At this point we know that mDesiredMinWidth is the
156                        // smallest dimension, regardless of current orientation, so we can
157                        // safely require that the candidate's width and height both exceed
158                        // that hard minimum.
159                        final double heightRatio = mDesiredMinHeight / options.outHeight;
160                        if (options.outWidth < mDesiredMinWidth
161                                || options.outHeight < mDesiredMinWidth
162                                || heightRatio >= MAX_HEIGHT_RATIO
163                                || heightRatio <= MIN_HEIGHT_RATIO) {
164                            // Not wide enough for the screen, or too short/tall to be a good fit
165                            // for the height of the screen, broken image file, or the system's
166                            // desires for wallpaper size are in a bad state.  Probably one of the
167                            // first two.
168                            Slog.i(TAG, "Restored image dimensions (w="
169                                    + options.outWidth + ", h=" + options.outHeight
170                                    + ") too far off target (tw="
171                                    + mDesiredMinWidth + ", th=" + mDesiredMinHeight
172                                    + "); falling back to default wallpaper.");
173                            f.delete();
174                            return;
175                        }
176                    }
177
178                    // We passed the acceptable-dimensions test (if any), so we're going to
179                    // use the restored image.  That comes last, when we are done restoring
180                    // both the pixels and the metadata.
181                }
182            } else if (key.equals(WALLPAPER_INFO_KEY)) {
183                // XML file containing wallpaper info
184                File f = new File(WALLPAPER_INFO);
185                writeFile(f, data);
186            }
187        }
188    }
189
190    /**
191     * Hook for the agent to call this helper upon completion of the restore.  We do this
192     * upon completion so that we know both the imagery and the wallpaper info have
193     * been emplaced without requiring either or relying on ordering.
194     */
195    public void onRestoreFinished() {
196        final File f = new File(STAGE_FILE);
197        if (f.exists()) {
198            // TODO: spin a service to copy the restored image to sd/usb storage,
199            // since it does not exist anywhere other than the private wallpaper
200            // file.
201            Slog.d(TAG, "Applying restored wallpaper image.");
202            f.renameTo(new File(WALLPAPER_IMAGE));
203        }
204    }
205}
206