/// <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);
}
