public static async Task <Bitmap> Encode(Bitmap carrierImage, byte[] message, string password, Func <double, bool> checkCancel = null)
{
var shuffleSeed = FisherYates.GetSeed(password);
var messageAsBitArray = message.ConvertToBitArray();
var userCancelled = false;
var stopwatch = new Stopwatch();
stopwatch.Start();
await Task.Run(() => // move away from the calling thread while working
{
var bitsWritten = 0;
IterateBitmap(carrierImage, shuffleSeed, (x, y) => {
EncodePixel(carrierImage, messageAsBitArray, ref bitsWritten, x, y);
var percentComplete = ((double)bitsWritten / messageAsBitArray.Length);
userCancelled = checkCancel == null ? false : CheckCancelAndUpdate(stopwatch, percentComplete, checkCancel);
bool encodeComplete = bitsWritten >= messageAsBitArray.Length;
return(userCancelled || encodeComplete);
});
});
return(userCancelled ? null : carrierImage);
}
private static void IterateBitmap(Bitmap bitmap, int shuffleSeed, Func <int, int, bool> onPixel)
{
var shuffledIndices = FisherYates.Shuffle(shuffleSeed, bitmap.Height * bitmap.Width);
for (var i = 0; i < shuffledIndices.Length; i++)
{
var(x, y) = bitmap.Get2DCoordinate(shuffledIndices[i]);
var done = onPixel(x, y);
if (done)
{
break;
}
}
}
public static async Task <byte[]> Take(Bitmap carrierImage, string password, int startingByteIndex, Int64 bytesToTake, Func <double, bool> checkCancel = null)
{
var shuffleSeed = FisherYates.GetSeed(password);
bool userCancelled = false;
List <bool> messageBuilder = new List <bool>();
int startingIndexInBits = startingByteIndex * 8;
int bitsToTake = (int)bytesToTake * 8;
var userUpdateStopwatch = new Stopwatch();
var eofStopwatch = new Stopwatch();
userUpdateStopwatch.Start();
eofStopwatch.Start();
await Task.Run(() => // move away from the calling thread while working
{
IterateBitmap(carrierImage, shuffleSeed, (x, y) =>
{
var pixelBits = DecodePixel(carrierImage, x, y);
messageBuilder.AddRange(pixelBits);
var recoveredAllBits = messageBuilder.Count >= startingIndexInBits + bitsToTake;
var percentComplete = (double)messageBuilder.Count / carrierImage.BitCapacity;
userCancelled = checkCancel == null ? false : CheckCancelAndUpdate(userUpdateStopwatch, percentComplete, checkCancel);
return(recoveredAllBits || userCancelled);
});
});
messageBuilder.RemoveRange(0, startingIndexInBits);
messageBuilder = messageBuilder.Take(bitsToTake).ToList(); // TODO: does this ever blow up if the image is ..small? or something. ...on encode it can check. here we could get an error?
return(messageBuilder.ConvertToByteArray());
}
