public void InsertMessage(string message)
{
Stopwatch watch = new Stopwatch();
watch.Start();
var dataToEncode = Encoding.ASCII.GetBytes(message);
byte[] dataWithMeta = new byte[dataToEncode.Length + MessageLength + MessageLengthPadding];
//four bytes for message length; 2 bytes for padding
var messageLengthInfo = BitConverter.GetBytes(message.Length);
Array.Copy(messageLengthInfo, dataWithMeta, MessageLength);
Array.Copy(dataToEncode, 0, dataWithMeta, MessageLength + MessageLengthPadding, dataToEncode.Length);
BitArray bits = new BitArray(dataWithMeta);
var e = bits.GetEnumerator();
var bmpPixelEnumerator = new BitmapPixelEnumerator(_img);
foreach (Pixel pixel in bmpPixelEnumerator)
{
byte oldBlue = pixel.Blue;
byte oldGreen = pixel.Green;
byte oldRed = pixel.Red;
byte newBlue;
if (InsertData(e, oldBlue, out newBlue))
{
return;
}
_copy.SetPixel(pixel.X, pixel.Y, Color.FromArgb(newBlue, oldGreen, oldRed));
byte newGreen;
if (InsertData(e, oldGreen, out newGreen))
{
return;
}
_copy.SetPixel(pixel.X, pixel.Y, Color.FromArgb(newBlue, newGreen, oldRed));
byte newRed;
if (InsertData(e, oldRed, out newRed))
{
return;
}
_copy.SetPixel(pixel.X, pixel.Y, Color.FromArgb(newBlue, newGreen, newRed));
}
watch.Stop();
Debug.WriteLine(watch.Elapsed);
}
/// <summary>
/// Expected 471 length
/// </summary>
/// <returns></returns>
public string ReadMessage()
{
var bmpPixelEnumerator = new BitmapPixelEnumerator(_img);
var encodedLength = bmpPixelEnumerator.Take(PixelsWithMessageLengthAndPadding).ToArray();
int indexLengthBit = 0;
var ba = new BitArray(BitsWithMessageLengthAndPadding);
foreach (var pixel in encodedLength)
{
indexLengthBit = ReadTwoBits(pixel.Blue, ba, indexLengthBit);
indexLengthBit = ReadTwoBits(pixel.Green, ba, indexLengthBit);
indexLengthBit = ReadTwoBits(pixel.Red, ba, indexLengthBit);
}
var messageLength = ba.ConvertBitsToWord();
int indexMessageBit = 0;
var messageBitArray = new BitArray(messageLength * PixelsWithMessageLengthAndPadding);
bmpPixelEnumerator.Reset();
var encodedPixels = bmpPixelEnumerator.Skip(PixelsWithMessageLengthAndPadding).Take((int)Math.Ceiling(messageLength * (double)PixelsWithMessageLengthAndPadding / (double)BitsPerPixel));
foreach (var pixel in encodedPixels)
{
indexMessageBit = ReadTwoBits(pixel.Blue, messageBitArray, indexMessageBit);
if (indexMessageBit >= messageBitArray.Count)
{
break;
}
indexMessageBit = ReadTwoBits(pixel.Green, messageBitArray, indexMessageBit);
if (indexMessageBit >= messageBitArray.Count)
{
break;
}
indexMessageBit = ReadTwoBits(pixel.Red, messageBitArray, indexMessageBit);
if (indexMessageBit >= messageBitArray.Count)
{
break;
}
}
byte[] messageBytes = new byte[messageLength];
messageBitArray.CopyTo(messageBytes, 0);
var message = Encoding.ASCII.GetString(messageBytes);
return(message);
}
