gt: 			float left = (newWidth - scaledWidth) / 2;
context: package eu.siacs.conversations.persistance;
  
  import java.io.ByteArrayOutputStream;
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.security.DigestOutputStream;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.text.SimpleDateFormat;
  import java.util.Date;
  import java.util.Locale;
  
  import android.database.Cursor;
  import android.graphics.Bitmap;
  import android.graphics.BitmapFactory;
  import android.graphics.Canvas;
  import android.graphics.Matrix;
  import android.graphics.RectF;
  import android.net.Uri;
  import android.os.Environment;
  import android.provider.MediaStore;
  import android.util.Base64;
  import android.util.Base64OutputStream;
  import android.util.Log;
  import eu.siacs.conversations.Config;
  import eu.siacs.conversations.R;
  import eu.siacs.conversations.entities.DownloadableFile;
  import eu.siacs.conversations.entities.Message;
  import eu.siacs.conversations.services.XmppConnectionService;
  import eu.siacs.conversations.utils.CryptoHelper;
  import eu.siacs.conversations.utils.ExifHelper;
  import eu.siacs.conversations.xmpp.pep.Avatar;
  
  public class FileBackend {
  
  	private static int IMAGE_SIZE = 1920;
  
  	private SimpleDateFormat imageDateFormat = new SimpleDateFormat(
  			"yyyyMMdd_HHmmssSSS", Locale.US);
  
  	private XmppConnectionService mXmppConnectionService;
  
  	public FileBackend(XmppConnectionService service) {
  		this.mXmppConnectionService = service;
  	}
  
  	public DownloadableFile getFile(Message message) {
  		return getFile(message, true);
  	}
  
  	public DownloadableFile getFile(Message message, boolean decrypted) {
  		StringBuilder filename = new StringBuilder();
  		filename.append(getConversationsDirectory());
  		filename.append(message.getUuid());
  		if ((decrypted) || (message.getEncryption() == Message.ENCRYPTION_NONE)) {
  			filename.append(".webp");
  		} else {
  			if (message.getEncryption() == Message.ENCRYPTION_OTR) {
  				filename.append(".webp");
  			} else {
  				filename.append(".webp.pgp");
  			}
  		}
  		return new DownloadableFile(filename.toString());
  	}
  
  	public static String getConversationsDirectory() {
  		return Environment.getExternalStoragePublicDirectory(
  				Environment.DIRECTORY_PICTURES).getAbsolutePath()
  				+ "/Conversations/";
  	}
  
  	public Bitmap resize(Bitmap originalBitmap, int size) {
  		int w = originalBitmap.getWidth();
  		int h = originalBitmap.getHeight();
  		if (Math.max(w, h) > size) {
  			int scalledW;
  			int scalledH;
  			if (w <= h) {
  				scalledW = (int) (w / ((double) h / size));
  				scalledH = size;
  			} else {
  				scalledW = size;
  				scalledH = (int) (h / ((double) w / size));
  			}
  			Bitmap scalledBitmap = Bitmap.createScaledBitmap(originalBitmap,
  					scalledW, scalledH, true);
  			return scalledBitmap;
  		} else {
  			return originalBitmap;
  		}
  	}
  
  	public Bitmap rotate(Bitmap bitmap, int degree) {
  		int w = bitmap.getWidth();
  		int h = bitmap.getHeight();
  		Matrix mtx = new Matrix();
  		mtx.postRotate(degree);
  		return Bitmap.createBitmap(bitmap, 0, 0, w, h, mtx, true);
  	}
  
  	public DownloadableFile copyImageToPrivateStorage(Message message, Uri image)
  			throws ImageCopyException {
  		return this.copyImageToPrivateStorage(message, image, 0);
  	}
  
  	private DownloadableFile copyImageToPrivateStorage(Message message,
  			Uri image, int sampleSize) throws ImageCopyException {
  		try {
  			InputStream is = mXmppConnectionService.getContentResolver()
  					.openInputStream(image);
  			DownloadableFile file = getFile(message);
  			file.getParentFile().mkdirs();
  			file.createNewFile();
  			Bitmap originalBitmap;
  			BitmapFactory.Options options = new BitmapFactory.Options();
  			int inSampleSize = (int) Math.pow(2, sampleSize);
  			Log.d(Config.LOGTAG, "reading bitmap with sample size "
  					+ inSampleSize);
  			options.inSampleSize = inSampleSize;
  			originalBitmap = BitmapFactory.decodeStream(is, null, options);
  			is.close();
  			if (originalBitmap == null) {
  				throw new ImageCopyException(R.string.error_not_an_image_file);
  			}
  			Bitmap scalledBitmap = resize(originalBitmap, IMAGE_SIZE);
  			originalBitmap = null;
  			int rotation = getRotation(image);
  			if (rotation > 0) {
  				scalledBitmap = rotate(scalledBitmap, rotation);
  			}
  			OutputStream os = new FileOutputStream(file);
  			boolean success = scalledBitmap.compress(
  					Bitmap.CompressFormat.WEBP, 75, os);
  			if (!success) {
  				throw new ImageCopyException(R.string.error_compressing_image);
  			}
  			os.flush();
  			os.close();
  			long size = file.getSize();
  			int width = scalledBitmap.getWidth();
  			int height = scalledBitmap.getHeight();
  			message.setBody(Long.toString(size) + ',' + width + ',' + height);
  			return file;
  		} catch (FileNotFoundException e) {
  			throw new ImageCopyException(R.string.error_file_not_found);
  		} catch (IOException e) {
  			throw new ImageCopyException(R.string.error_io_exception);
  		} catch (SecurityException e) {
  			throw new ImageCopyException(
  					R.string.error_security_exception_during_image_copy);
  		} catch (OutOfMemoryError e) {
  			++sampleSize;
  			if (sampleSize <= 3) {
  				return copyImageToPrivateStorage(message, image, sampleSize);
  			} else {
  				throw new ImageCopyException(R.string.error_out_of_memory);
  			}
  		}
  	}
  
  	private int getRotation(Uri image) {
  		try {
  			InputStream is = mXmppConnectionService.getContentResolver()
  					.openInputStream(image);
  			return ExifHelper.getOrientation(is);
  		} catch (FileNotFoundException e) {
  			return 0;
  		}
  	}
  
  	public Bitmap getImageFromMessage(Message message) {
  		return BitmapFactory.decodeFile(getFile(message).getAbsolutePath());
  	}
  
  	public Bitmap getThumbnail(Message message, int size, boolean cacheOnly)
  			throws FileNotFoundException {
  		Bitmap thumbnail = mXmppConnectionService.getBitmapCache().get(
  				message.getUuid());
  		if ((thumbnail == null) && (!cacheOnly)) {
  			File file = getFile(message);
  			BitmapFactory.Options options = new BitmapFactory.Options();
  			options.inSampleSize = calcSampleSize(file, size);
  			Bitmap fullsize = BitmapFactory.decodeFile(file.getAbsolutePath(),
  					options);
  			if (fullsize == null) {
  				throw new FileNotFoundException();
  			}
  			thumbnail = resize(fullsize, size);
  			this.mXmppConnectionService.getBitmapCache().put(message.getUuid(),
  					thumbnail);
  		}
  		return thumbnail;
  	}
  
  	public Uri getTakePhotoUri() {
  		StringBuilder pathBuilder = new StringBuilder();
  		pathBuilder.append(Environment
  				.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM));
  		pathBuilder.append('/');
  		pathBuilder.append("Camera");
  		pathBuilder.append('/');
  		pathBuilder.append("IMG_" + this.imageDateFormat.format(new Date())
  				+ ".jpg");
  		Uri uri = Uri.parse("file://" + pathBuilder.toString());
  		File file = new File(uri.toString());
  		file.getParentFile().mkdirs();
  		return uri;
  	}
  
  	public Avatar getPepAvatar(Uri image, int size, Bitmap.CompressFormat format) {
  		try {
  			Avatar avatar = new Avatar();
  			Bitmap bm = cropCenterSquare(image, size);
  			if (bm == null) {
  				return null;
  			}
  			ByteArrayOutputStream mByteArrayOutputStream = new ByteArrayOutputStream();
  			Base64OutputStream mBase64OutputSttream = new Base64OutputStream(
  					mByteArrayOutputStream, Base64.DEFAULT);
  			MessageDigest digest = MessageDigest.getInstance("SHA-1");
  			DigestOutputStream mDigestOutputStream = new DigestOutputStream(
  					mBase64OutputSttream, digest);
  			if (!bm.compress(format, 75, mDigestOutputStream)) {
  				return null;
  			}
  			mDigestOutputStream.flush();
  			mDigestOutputStream.close();
  			avatar.sha1sum = CryptoHelper.bytesToHex(digest.digest());
  			avatar.image = new String(mByteArrayOutputStream.toByteArray());
  			return avatar;
  		} catch (NoSuchAlgorithmException e) {
  			return null;
  		} catch (IOException e) {
  			return null;
  		}
  	}
  
  	public boolean isAvatarCached(Avatar avatar) {
  		File file = new File(getAvatarPath(avatar.getFilename()));
  		return file.exists();
  	}
  
  	public boolean save(Avatar avatar) {
  		if (isAvatarCached(avatar)) {
  			return true;
  		}
  		String filename = getAvatarPath(avatar.getFilename());
  		File file = new File(filename + ".tmp");
  		file.getParentFile().mkdirs();
  		try {
  			file.createNewFile();
  			FileOutputStream mFileOutputStream = new FileOutputStream(file);
  			MessageDigest digest = MessageDigest.getInstance("SHA-1");
  			digest.reset();
  			DigestOutputStream mDigestOutputStream = new DigestOutputStream(
  					mFileOutputStream, digest);
  			mDigestOutputStream.write(avatar.getImageAsBytes());
  			mDigestOutputStream.flush();
  			mDigestOutputStream.close();
  			avatar.size = file.length();
  			String sha1sum = CryptoHelper.bytesToHex(digest.digest());
  			if (sha1sum.equals(avatar.sha1sum)) {
  				file.renameTo(new File(filename));
  				return true;
  			} else {
  				Log.d(Config.LOGTAG, "sha1sum mismatch for " + avatar.owner);
  				file.delete();
  				return false;
  			}
  		} catch (FileNotFoundException e) {
  			return false;
  		} catch (IOException e) {
  			return false;
  		} catch (NoSuchAlgorithmException e) {
  			return false;
  		}
  	}
  
  	public String getAvatarPath(String avatar) {
  		return mXmppConnectionService.getFilesDir().getAbsolutePath()
  				+ "/avatars/" + avatar;
  	}
  
  	public Uri getAvatarUri(String avatar) {
  		return Uri.parse("file:" + getAvatarPath(avatar));
  	}
  
  	public Bitmap cropCenterSquare(Uri image, int size) {
  		try {
  			BitmapFactory.Options options = new BitmapFactory.Options();
  			options.inSampleSize = calcSampleSize(image, size);
  			InputStream is = mXmppConnectionService.getContentResolver()
  					.openInputStream(image);
  			Bitmap input = BitmapFactory.decodeStream(is, null, options);
  			if (input == null) {
  				return null;
  			} else {
  				int rotation = getRotation(image);
  				if (rotation > 0) {
  					input = rotate(input, rotation);
  				}
  				return cropCenterSquare(input, size);
  			}
  		} catch (FileNotFoundException e) {
  			return null;
  		}
  	}
  
  	public Bitmap cropCenter(Uri image, int newHeight, int newWidth) {
  		try {
  			BitmapFactory.Options options = new BitmapFactory.Options();
  			options.inSampleSize = calcSampleSize(image,
  					Math.max(newHeight, newWidth));
  			InputStream is = mXmppConnectionService.getContentResolver()
  					.openInputStream(image);
  			Bitmap source = BitmapFactory.decodeStream(is, null, options);
  
  			int sourceWidth = source.getWidth();
  			int sourceHeight = source.getHeight();
  			float xScale = (float) newWidth / sourceWidth;
  			float yScale = (float) newHeight / sourceHeight;
  			float scale = Math.max(xScale, yScale);
  			float scaledWidth = scale * sourceWidth;
  			float scaledHeight = scale * sourceHeight;
  