Android 切换壁纸代码流程追踪

1.长按home页，会弹出切换界面

点击Wallpaper?进入应用中?这里的应用为??com.android.wallpaperpicker/.WallpaperPickerActivity

packages\apps\WallpaperPicker\src\com\android\wallpaperpicker\WallpaperPickerActivity.java

public class WallpaperPickerActivity extends WallpaperCropActivity
        implements OnClickListener, OnLongClickListener, ActionMode.Callback {

如果选中了具体的?wallpaper?set按钮会显示出来

@Override
    public void onClick(View v) {
        if (mActionMode != null) {
            // When CAB is up, clicking toggles the item instead
            if (v.isLongClickable()) {
                onLongClick(v);
            }
            return;
        }
        WallpaperTileInfo info = (WallpaperTileInfo) v.getTag();
        if (info.isSelectable() && v.getVisibility() == View.VISIBLE) {
            selectTile(v);
            setWallpaperButtonEnabled(true);
        }
        info.onClick(this);
    }

public void setWallpaperButtonEnabled(boolean enabled) {
        mSetWallpaperButton.setEnabled(enabled);
    }

mSetWallpaperButton在?WallpaperCropActivity里定义?点击事件为

packages\apps\WallpaperPicker\src\com\android\wallpaperpicker\WallpaperCropActivity.java

final ActionBar actionBar = getActionBar();
        actionBar.setCustomView(R.layout.actionbar_set_wallpaper);
        actionBar.getCustomView().setOnClickListener(
                new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        actionBar.hide();
                        // Never fade on finish because we return to the app that started us (e.g.
                        // Photos), not the home screen.
                        cropImageAndSetWallpaper(imageUri, null, false /* shouldFadeOutOnFinish */);
                    }
                });

@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR1)
    public void cropImageAndSetWallpaper(Uri uri,
            CropAndSetWallpaperTask.OnBitmapCroppedHandler onBitmapCroppedHandler,
            boolean shouldFadeOutOnFinish) {
        // Get the crop
        boolean ltr = mCropView.getLayoutDirection() == View.LAYOUT_DIRECTION_LTR;

        Display d = getWindowManager().getDefaultDisplay();

        Point displaySize = new Point();
        d.getSize(displaySize);
        boolean isPortrait = displaySize.x < displaySize.y;

        Point defaultWallpaperSize = WallpaperUtils.getDefaultWallpaperSize(getResources(),
                getWindowManager());
        // Get the crop
        RectF cropRect = mCropView.getCrop();

        Point inSize = mCropView.getSourceDimensions();

        int cropRotation = mCropView.getImageRotation();
        float cropScale = mCropView.getWidth() / (float) cropRect.width();

        Matrix rotateMatrix = new Matrix();
        rotateMatrix.setRotate(cropRotation);
        float[] rotatedInSize = new float[] { inSize.x, inSize.y };
        rotateMatrix.mapPoints(rotatedInSize);
        rotatedInSize[0] = Math.abs(rotatedInSize[0]);
        rotatedInSize[1] = Math.abs(rotatedInSize[1]);

        // due to rounding errors in the cropview renderer the edges can be slightly offset
        // therefore we ensure that the boundaries are sanely defined
        cropRect.left = Math.max(0, cropRect.left);
        cropRect.right = Math.min(rotatedInSize[0], cropRect.right);
        cropRect.top = Math.max(0, cropRect.top);
        cropRect.bottom = Math.min(rotatedInSize[1], cropRect.bottom);

        // ADJUST CROP WIDTH
        // Extend the crop all the way to the right, for parallax
        // (or all the way to the left, in RTL)
        float extraSpace = ltr ? rotatedInSize[0] - cropRect.right : cropRect.left;
        // Cap the amount of extra width
        float maxExtraSpace = defaultWallpaperSize.x / cropScale - cropRect.width();
        extraSpace = Math.min(extraSpace, maxExtraSpace);

        if (ltr) {
            cropRect.right += extraSpace;
        } else {
            cropRect.left -= extraSpace;
        }

        // ADJUST CROP HEIGHT
        if (isPortrait) {
            cropRect.bottom = cropRect.top + defaultWallpaperSize.y / cropScale;
        } else { // LANDSCAPE
            float extraPortraitHeight =
                    defaultWallpaperSize.y / cropScale - cropRect.height();
            float expandHeight =
                    Math.min(Math.min(rotatedInSize[1] - cropRect.bottom, cropRect.top),
                            extraPortraitHeight / 2);
            cropRect.top -= expandHeight;
            cropRect.bottom += expandHeight;
        }

        final int outWidth = (int) Math.round(cropRect.width() * cropScale);
        final int outHeight = (int) Math.round(cropRect.height() * cropScale);
        CropAndFinishHandler onEndCrop = new CropAndFinishHandler(new Point(outWidth, outHeight),
                shouldFadeOutOnFinish);

        CropAndSetWallpaperTask cropTask = new CropAndSetWallpaperTask(
                InputStreamProvider.fromUri(this, uri), this,
                cropRect, cropRotation, outWidth, outHeight, onEndCrop) {
            @Override
            protected void onPreExecute() {
                // Give some feedback so user knows something is happening.
                mProgressView.setVisibility(View.VISIBLE);
            }
        };
        if (onBitmapCroppedHandler != null) {
            cropTask.setOnBitmapCropped(onBitmapCroppedHandler);
        }
        DialogUtils.executeCropTaskAfterPrompt(this, cropTask, getOnDialogCancelListener());
    }

执行?DialogUtils.executeCropTaskAfterPrompt?设置要设置的范围

packages\apps\WallpaperPicker\src\com\android\wallpaperpicker\common\DialogUtils.java

public static void executeCropTaskAfterPrompt(
            Context context, final AsyncTask<Integer, ?, ?> cropTask,
            DialogInterface.OnCancelListener onCancelListener) {
        if (Utilities.isAtLeastN()) {
            new AlertDialog.Builder(context)
                    .setTitle(R.string.wallpaper_instructions)
                    .setItems(R.array.which_wallpaper_options, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int selectedItemIndex) {
                        int whichWallpaper;
                        if (selectedItemIndex == 0) {
                            whichWallpaper = WallpaperManagerCompat.FLAG_SET_SYSTEM;
                        } else if (selectedItemIndex == 1) {
                            whichWallpaper = WallpaperManagerCompat.FLAG_SET_LOCK;
                        } else {
                            whichWallpaper = WallpaperManagerCompat.FLAG_SET_SYSTEM
                                    | WallpaperManagerCompat.FLAG_SET_LOCK;
                        }
                        cropTask.execute(whichWallpaper);
                    }
                })
                .setOnCancelListener(onCancelListener)
                .show();
        } else {
            cropTask.execute(WallpaperManagerCompat.FLAG_SET_SYSTEM);
        }
    }

packages\apps\WallpaperPicker\src\com\android\wallpaperpicker\common\CropAndSetWallpaperTask.java

public boolean cropBitmap(int whichWallpaper) {
        Bitmap crop = mStreamProvider.readCroppedBitmap(
                mCropBounds, mOutWidth, mOutHeight, mRotation);
        if (crop == null) {
            return false;
        }

        boolean failure = false;
        // Compress to byte array
        ByteArrayOutputStream tmpOut = new ByteArrayOutputStream(2048);
        if (crop.compress(CompressFormat.JPEG, DEFAULT_COMPRESS_QUALITY, tmpOut)) {
            // Set the wallpaper
            try {
                byte[] outByteArray = tmpOut.toByteArray();
                WallpaperManagerCompat.getInstance(mContext).setStream(
                        new ByteArrayInputStream(outByteArray),
                        null, true, whichWallpaper);
                if (mOnBitmapCroppedHandler != null) {
                    mOnBitmapCroppedHandler.onBitmapCropped(outByteArray);
                }
            } catch (IOException e) {
                Log.w(TAG, "cannot write stream to wallpaper", e);
                failure = true;
            }
        } else {
            Log.w(TAG, "cannot compress bitmap");
            failure = true;
        }
        return !failure; // True if any of the operations failed
    }

    @Override
    protected Boolean doInBackground(Integer... whichWallpaper) {
        return cropBitmap(whichWallpaper[0]);
    }

调用了WallpaperManagerCompat.getInstance(mContext).setStream(
? ? ? ? ? ? ? ? ? ? ? ? new ByteArrayInputStream(outByteArray),
? ? ? ? ? ? ? ? ? ? ? ? null, true, whichWallpaper);

packages\apps\WallpaperPicker\src\com\android\wallpaperpicker\common\WallpaperManagerCompat.java

public static WallpaperManagerCompat getInstance(Context context) {
        synchronized (sInstanceLock) {
            if (sInstance == null) {
                if (Utilities.isAtLeastN()) {
                    sInstance = new WallpaperManagerCompatVN(context.getApplicationContext());
                } else {
                    sInstance = new WallpaperManagerCompatV16(context.getApplicationContext());
                }
            }
            return sInstance;
        }
    }

    public abstract void setStream(InputStream stream, Rect visibleCropHint, boolean allowBackup,
            int whichWallpaper) throws IOException;

public static boolean isAtLeastN() {
        // TODO: replace this with a more final implementation.
        try {
            WallpaperManager.class.getMethod("getWallpaperFile", int.class);
            return true;
        } catch (NoSuchMethodException e) {
            return false;
        }
    }

frameworks\base\core\java\android\app\WallpaperManager.java

  @RequiresPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE)
    public ParcelFileDescriptor getWallpaperFile(@SetWallpaperFlags int which) {
        return getWallpaperFile(which, mContext.getUserId());
    }

所以实例化的是WallpaperManagerCompatVN

@Override
    public void setStream(final InputStream data, Rect visibleCropHint, boolean allowBackup,
            int whichWallpaper) throws IOException {
        try {
            // TODO: use mWallpaperManager.setStream(data, visibleCropHint, allowBackup, which)
            // without needing reflection.
            Method setStream = WallpaperManager.class.getMethod("setStream", InputStream.class,
                    Rect.class, boolean.class, int.class);
            setStream.invoke(mWallpaperManager, data, visibleCropHint, allowBackup, whichWallpaper);
        } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
            // Fall back to previous implementation (set both)
            super.setStream(data, visibleCropHint, allowBackup, whichWallpaper);
        }
    }

frameworks\base\core\java\android\app\WallpaperManager.java

    @RequiresPermission(android.Manifest.permission.SET_WALLPAPER)
    public int setStream(InputStream bitmapData, Rect visibleCropHint,
            boolean allowBackup, @SetWallpaperFlags int which)
                    throws IOException {
        validateRect(visibleCropHint);
        if (sGlobals.mService == null) {
            Log.w(TAG, "WallpaperService not running");
            throw new RuntimeException(new DeadSystemException());
        }
        final Bundle result = new Bundle();
        final WallpaperSetCompletion completion = new WallpaperSetCompletion();
        try {
            ParcelFileDescriptor fd = sGlobals.mService.setWallpaper(null,
                    mContext.getOpPackageName(), visibleCropHint, allowBackup,
                    result, which, completion, mContext.getUserId());
            if (fd != null) {
                FileOutputStream fos = null;
                try {
                    fos = new ParcelFileDescriptor.AutoCloseOutputStream(fd);
                    copyStreamToWallpaperFile(bitmapData, fos);
                    fos.close();
                    completion.waitForCompletion();
                } finally {
                    IoUtils.closeQuietly(fos);
                }
            }
        } catch (RemoteException e) {
            throw e.rethrowFromSystemServer();
        }

        return result.getInt(EXTRA_NEW_WALLPAPER_ID, 0);
    }

调用sGlobals.mService.setWallpaper

private static class Globals extends IWallpaperManagerCallback.Stub {
        private final IWallpaperManager mService;

转入WallpaperManagerService frameworks\base\services\core\java\com\android\server\wallpaper\WallpaperManagerService.java

    @Override
    public ParcelFileDescriptor setWallpaper(String name, String callingPackage,
            Rect cropHint, boolean allowBackup, Bundle extras, int which,
            IWallpaperManagerCallback completion, int userId) {
        userId = ActivityManager.handleIncomingUser(getCallingPid(), getCallingUid(), userId,
                false /* all */, true /* full */, "changing wallpaper", null /* pkg */);
        checkPermission(android.Manifest.permission.SET_WALLPAPER);

        if ((which & (FLAG_LOCK|FLAG_SYSTEM)) == 0) {
            final String msg = "Must specify a valid wallpaper category to set";
            Slog.e(TAG, msg);
            throw new IllegalArgumentException(msg);
        }

        if (!isWallpaperSupported(callingPackage) || !isSetWallpaperAllowed(callingPackage)) {
            return null;
        }

        // "null" means the no-op crop, preserving the full input image
        if (cropHint == null) {
            cropHint = new Rect(0, 0, 0, 0);
        } else {
            if (cropHint.isEmpty()
                    || cropHint.left < 0
                    || cropHint.top < 0) {
                throw new IllegalArgumentException("Invalid crop rect supplied: " + cropHint);
            }
        }

        synchronized (mLock) {
            if (DEBUG) Slog.v(TAG, "setWallpaper which=0x" + Integer.toHexString(which));
            WallpaperData wallpaper;

            /* If we're setting system but not lock, and lock is currently sharing the system
             * wallpaper, we need to migrate that image over to being lock-only before
             * the caller here writes new bitmap data.
             */
            if (which == FLAG_SYSTEM && mLockWallpaperMap.get(userId) == null) {
                if (DEBUG) {
                    Slog.i(TAG, "Migrating system->lock to preserve");
                }
                migrateSystemToLockWallpaperLocked(userId);
            }

            wallpaper = getWallpaperSafeLocked(userId, which);
            final long ident = Binder.clearCallingIdentity();
            try {
                ParcelFileDescriptor pfd = updateWallpaperBitmapLocked(name, wallpaper, extras);
                if (pfd != null) {
                    wallpaper.imageWallpaperPending = true;
                    wallpaper.whichPending = which;
                    wallpaper.setComplete = completion;
                    wallpaper.cropHint.set(cropHint);
                    wallpaper.allowBackup = allowBackup;
                }
                return pfd;
            } finally {
                Binder.restoreCallingIdentity(ident);
            }
        }
    }

wallpaper = getWallpaperSafeLocked(userId, which);

    /**
     * Sometimes it is expected the wallpaper map may not have a user's data.  E.g. This could
     * happen during user switch.  The async user switch observer may not have received
     * the event yet.  We use this safe method when we don't care about this ordering and just
     * want to update the data.  The data is going to be applied when the user switch observer
     * is eventually executed.
     *
     * Important: this method loads settings to initialize the given user's wallpaper data if
     * there is no current in-memory state.
     */
    private WallpaperData getWallpaperSafeLocked(int userId, int which) {
        // We're setting either just system (work with the system wallpaper),
        // both (also work with the system wallpaper), or just the lock
        // wallpaper (update against the existing lock wallpaper if any).
        // Combined or just-system operations use the 'system' WallpaperData
        // for this use; lock-only operations use the dedicated one.
        final SparseArray<WallpaperData> whichSet =
                (which == FLAG_LOCK) ? mLockWallpaperMap : mWallpaperMap;
        WallpaperData wallpaper = whichSet.get(userId);
        if (wallpaper == null) {
            // common case, this is the first lookup post-boot of the system or
            // unified lock, so we bring up the saved state lazily now and recheck.
            loadSettingsLocked(userId, false);
            wallpaper = whichSet.get(userId);
            // if it's still null here, this is a lock-only operation and there is not
            // yet a lock-only wallpaper set for this user, so we need to establish
            // it now.
            if (wallpaper == null) {
                if (which == FLAG_LOCK) {
                    wallpaper = new WallpaperData(userId,
                            WALLPAPER_LOCK_ORIG, WALLPAPER_LOCK_CROP);
                    mLockWallpaperMap.put(userId, wallpaper);
                    ensureSaneWallpaperData(wallpaper);
                } else {
                    // sanity fallback: we're in bad shape, but establishing a known
                    // valid system+lock WallpaperData will keep us from dying.
                    Slog.wtf(TAG, "Didn't find wallpaper in non-lock case!");
                    wallpaper = new WallpaperData(userId, WALLPAPER, WALLPAPER_CROP);
                    mWallpaperMap.put(userId, wallpaper);
                    ensureSaneWallpaperData(wallpaper);
                }
            }
        }
        return wallpaper;
    }

?

    private void loadSettingsLocked(int userId, boolean keepDimensionHints) {
        JournaledFile journal = makeJournaledFile(userId);
        FileInputStream stream = null;
        File file = journal.chooseForRead();

        WallpaperData wallpaper = mWallpaperMap.get(userId);
        if (wallpaper == null) {
            // Do this once per boot
            migrateFromOld();

            wallpaper = new WallpaperData(userId, WALLPAPER, WALLPAPER_CROP);
            wallpaper.allowBackup = true;
            mWallpaperMap.put(userId, wallpaper);
            if (!wallpaper.cropExists()) {
                if (wallpaper.sourceExists()) {
                    generateCrop(wallpaper);
                } else {
                    Slog.i(TAG, "No static wallpaper imagery; defaults will be shown");
                }
            }
        }
        boolean success = false;
        try {
            stream = new FileInputStream(file);
            XmlPullParser parser = Xml.newPullParser();
            parser.setInput(stream, StandardCharsets.UTF_8.name());

            int type;
            do {
                type = parser.next();
                if (type == XmlPullParser.START_TAG) {
                    String tag = parser.getName();
                    if ("wp".equals(tag)) {
                        // Common to system + lock wallpapers
                        parseWallpaperAttributes(parser, wallpaper, keepDimensionHints);

                        // A system wallpaper might also be a live wallpaper
                        String comp = parser.getAttributeValue(null, "component");
                        wallpaper.nextWallpaperComponent = comp != null
                                ? ComponentName.unflattenFromString(comp)
                                : null;
                        if (wallpaper.nextWallpaperComponent == null
                                || "android".equals(wallpaper.nextWallpaperComponent
                                        .getPackageName())) {
                            wallpaper.nextWallpaperComponent = mImageWallpaper;
                        }

                        if (DEBUG) {
                            Slog.v(TAG, "mWidth:" + wallpaper.width);
                            Slog.v(TAG, "mHeight:" + wallpaper.height);
                            Slog.v(TAG, "cropRect:" + wallpaper.cropHint);
                            Slog.v(TAG, "primaryColors:" + wallpaper.primaryColors);
                            Slog.v(TAG, "mName:" + wallpaper.name);
                            Slog.v(TAG, "mNextWallpaperComponent:"
                                    + wallpaper.nextWallpaperComponent);
                        }
                    } else if ("kwp".equals(tag)) {
                        // keyguard-specific wallpaper for this user
                        WallpaperData lockWallpaper = mLockWallpaperMap.get(userId);
                        if (lockWallpaper == null) {
                            lockWallpaper = new WallpaperData(userId,
                                    WALLPAPER_LOCK_ORIG, WALLPAPER_LOCK_CROP);
                            mLockWallpaperMap.put(userId, lockWallpaper);
                        }
                        parseWallpaperAttributes(parser, lockWallpaper, false);
                    }
                }
            } while (type != XmlPullParser.END_DOCUMENT);
            success = true;
        } catch (FileNotFoundException e) {
            Slog.w(TAG, "no current wallpaper -- first boot?");
        } catch (NullPointerException e) {
            Slog.w(TAG, "failed parsing " + file + " " + e);
        } catch (NumberFormatException e) {
            Slog.w(TAG, "failed parsing " + file + " " + e);
        } catch (XmlPullParserException e) {
            Slog.w(TAG, "failed parsing " + file + " " + e);
        } catch (IOException e) {
            Slog.w(TAG, "failed parsing " + file + " " + e);
        } catch (IndexOutOfBoundsException e) {
            Slog.w(TAG, "failed parsing " + file + " " + e);
        }
        IoUtils.closeQuietly(stream);

        if (!success) {
            wallpaper.width = -1;
            wallpaper.height = -1;
            wallpaper.cropHint.set(0, 0, 0, 0);
            wallpaper.padding.set(0, 0, 0, 0);
            wallpaper.name = "";

            mLockWallpaperMap.remove(userId);
        } else {
            if (wallpaper.wallpaperId <= 0) {
                wallpaper.wallpaperId = makeWallpaperIdLocked();
                if (DEBUG) {
                    Slog.w(TAG, "Didn't set wallpaper id in loadSettingsLocked(" + userId
                            + "); now " + wallpaper.wallpaperId);
                }
            }
        }

        ensureSaneWallpaperData(wallpaper);
        WallpaperData lockWallpaper = mLockWallpaperMap.get(userId);
        if (lockWallpaper != null) {
            ensureSaneWallpaperData(lockWallpaper);
        }
    }

    ParcelFileDescriptor updateWallpaperBitmapLocked(String name, WallpaperData wallpaper,
            Bundle extras) {
        if (name == null) name = "";
        try {
            File dir = getWallpaperDir(wallpaper.userId);
            if (!dir.exists()) {
                dir.mkdir();
                FileUtils.setPermissions(
                        dir.getPath(),
                        FileUtils.S_IRWXU|FileUtils.S_IRWXG|FileUtils.S_IXOTH,
                        -1, -1);
            }
            ParcelFileDescriptor fd = ParcelFileDescriptor.open(wallpaper.wallpaperFile,
                    MODE_CREATE|MODE_READ_WRITE|MODE_TRUNCATE);
            if (!SELinux.restorecon(wallpaper.wallpaperFile)) {
                return null;
            }
            wallpaper.name = name;
            wallpaper.wallpaperId = makeWallpaperIdLocked();
            if (extras != null) {
                extras.putInt(WallpaperManager.EXTRA_NEW_WALLPAPER_ID, wallpaper.wallpaperId);
            }
            // Nullify field to require new computation
            wallpaper.primaryColors = null;
            if (DEBUG) {
                Slog.v(TAG, "updateWallpaperBitmapLocked() : id=" + wallpaper.wallpaperId
                        + " name=" + name + " file=" + wallpaper.wallpaperFile.getName());
            }
            return fd;
        } catch (FileNotFoundException e) {
            Slog.w(TAG, "Error setting wallpaper", e);
        }
        return null;
    }

    /**
     * Once a new wallpaper has been written via setWallpaper(...), it needs to be cropped
     * for display.
     */
    private void generateCrop(WallpaperData wallpaper) {
        boolean success = false;

        Rect cropHint = new Rect(wallpaper.cropHint);

        if (DEBUG) {
            Slog.v(TAG, "Generating crop for new wallpaper(s): 0x"
                    + Integer.toHexString(wallpaper.whichPending)
                    + " to " + wallpaper.cropFile.getName()
                    + " crop=(" + cropHint.width() + 'x' + cropHint.height()
                    + ") dim=(" + wallpaper.width + 'x' + wallpaper.height + ')');
        }

        // Analyse the source; needed in multiple cases
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(wallpaper.wallpaperFile.getAbsolutePath(), options);
        if (options.outWidth <= 0 || options.outHeight <= 0) {
            Slog.w(TAG, "Invalid wallpaper data");
            success = false;
        } else {
            boolean needCrop = false;
            boolean needScale = false;

            // Empty crop means use the full image
            if (cropHint.isEmpty()) {
                cropHint.left = cropHint.top = 0;
                cropHint.right = options.outWidth;
                cropHint.bottom = options.outHeight;
            } else {
                // force the crop rect to lie within the measured bounds
                cropHint.offset(
                        (cropHint.right > options.outWidth ? options.outWidth - cropHint.right : 0),
                        (cropHint.bottom > options.outHeight ? options.outHeight - cropHint.bottom : 0));

                // If the crop hint was larger than the image we just overshot. Patch things up.
                if (cropHint.left < 0) {
                    cropHint.left = 0;
                }
                if (cropHint.top < 0) {
                    cropHint.top = 0;
                }

                // Don't bother cropping if what we're left with is identity
                needCrop = (options.outHeight > cropHint.height()
                        || options.outWidth > cropHint.width());
            }

            // scale if the crop height winds up not matching the recommended metrics
            //needScale = (wallpaper.height != cropHint.height());
            needScale = false;
            if (DEBUG) {
                Slog.v(TAG, "crop: w=" + cropHint.width() + " h=" + cropHint.height());
                Slog.v(TAG, "dims: w=" + wallpaper.width + " h=" + wallpaper.height);
                Slog.v(TAG, "meas: w=" + options.outWidth + " h=" + options.outHeight);
                Slog.v(TAG, "crop?=" + needCrop + " scale?=" + needScale);
            }

            if (!needCrop && !needScale) {
                // Simple case:  the nominal crop fits what we want, so we take
                // the whole thing and just copy the image file directly.
                if (DEBUG) {
                    Slog.v(TAG, "Null crop of new wallpaper; copying");
                }
                success = FileUtils.copyFile(wallpaper.wallpaperFile, wallpaper.cropFile);
                if (!success) {
                    wallpaper.cropFile.delete();
                    // TODO: fall back to default wallpaper in this case
                }
            } else {
                // Fancy case: crop and scale.  First, we decode and scale down if appropriate.
                FileOutputStream f = null;
                BufferedOutputStream bos = null;
                try {
                    BitmapRegionDecoder decoder = BitmapRegionDecoder.newInstance(
                            wallpaper.wallpaperFile.getAbsolutePath(), false);

                    // This actually downsamples only by powers of two, but that's okay; we do
                    // a proper scaling blit later.  This is to minimize transient RAM use.
                    // We calculate the largest power-of-two under the actual ratio rather than
                    // just let the decode take care of it because we also want to remap where the
                    // cropHint rectangle lies in the decoded [super]rect.
                    final BitmapFactory.Options scaler;
                    final int actualScale = cropHint.height() / wallpaper.height;
                    int scale = 1;
                    while (2*scale < actualScale) {
                        scale *= 2;
                    }
                    if (scale > 1) {
                        scaler = new BitmapFactory.Options();
                        scaler.inSampleSize = scale;
                        if (DEBUG) {
                            Slog.v(TAG, "Downsampling cropped rect with scale " + scale);
                        }
                    } else {
                        scaler = null;
                    }
                    Bitmap cropped = decoder.decodeRegion(cropHint, scaler);
                    decoder.recycle();

                    if (cropped == null) {
                        Slog.e(TAG, "Could not decode new wallpaper");
                    } else {
                        // We've got the extracted crop; now we want to scale it properly to
                        // the desired rectangle.  That's a height-biased operation: make it
                        // fit the hinted height, and accept whatever width we end up with.
                        cropHint.offsetTo(0, 0);
                        cropHint.right /= scale;    // adjust by downsampling factor
                        cropHint.bottom /= scale;
                        final float heightR = ((float)wallpaper.height) / ((float)cropHint.height());
                        if (DEBUG) {
                            Slog.v(TAG, "scale " + heightR + ", extracting " + cropHint);
                        }
                        final int destWidth = (int)(cropHint.width() * heightR);
                        final Bitmap finalCrop = Bitmap.createScaledBitmap(cropped,
                                destWidth, wallpaper.height, true);
                        if (DEBUG) {
                            Slog.v(TAG, "Final extract:");
                            Slog.v(TAG, "  dims: w=" + wallpaper.width
                                    + " h=" + wallpaper.height);
                            Slog.v(TAG, "   out: w=" + finalCrop.getWidth()
                                    + " h=" + finalCrop.getHeight());
                        }

                        f = new FileOutputStream(wallpaper.cropFile);
                        bos = new BufferedOutputStream(f, 32*1024);
                        finalCrop.compress(Bitmap.CompressFormat.JPEG, 100, bos);
                        bos.flush();  // don't rely on the implicit flush-at-close when noting success
                        success = true;
                    }
                } catch (Exception e) {
                    if (DEBUG) {
                        Slog.e(TAG, "Error decoding crop", e);
                    }
                } finally {
                    IoUtils.closeQuietly(bos);
                    IoUtils.closeQuietly(f);
                }
            }
        }

        if (!success) {
            Slog.e(TAG, "Unable to apply new wallpaper");
            wallpaper.cropFile.delete();
        }

        if (wallpaper.cropFile.exists()) {
            boolean didRestorecon = SELinux.restorecon(wallpaper.cropFile.getAbsoluteFile());
            if (DEBUG) {
                Slog.v(TAG, "restorecon() of crop file returned " + didRestorecon);
            }
        }
    }