private Color embedMonochromeImage(int currX, uint messageImageWidth, int currY, uint messageImageHeight,
byte[] messagePixels, Color sourcePixelColor)
{
if (currX < messageImageWidth && currY < messageImageHeight)
{
if (this.isEncrypted)
{
currY = swapYQuadrant(currY, messageImageHeight);
}
var messagePixelColor = PixelColorInfo.GetPixelBgra8(messagePixels, currY,
currX, messageImageWidth);
if (isBlackPixel(messagePixelColor))
{
sourcePixelColor.B &= 0xfe;
}
else if (isWhitePixel(messagePixelColor))
{
sourcePixelColor.B |= 1;
}
}
return(sourcePixelColor);
}
/// <summary>
/// Embeds the text message in image.
/// </summary>
/// @Precondition none
/// @Postcondition the message is embedded into the image
/// <param name="messageData">The message data.</param>
/// <param name="messageLength">Length of the message.</param>
/// <param name="messageImageHeight">Height of the message image.</param>
/// <param name="sourceImageWidth">Width of the source image.</param>
/// <param name="sourceImageHeight">Height of the source image.</param>
/// <param name="encryptionIsChecked">if set to <c>true</c> [encryption is selected].</param>
/// <param name="bpcc">The BPCC.</param>
/// <returns>Task</returns>
/// <exception cref="NotImplementedException"></exception>
public override async Task EmbedMessageInImage(byte[] messageData, uint messageLength, uint messageImageHeight,
uint sourceImageWidth, uint sourceImageHeight, bool encryptionIsChecked, int bpcc)
{
var totalAvailableSourcePixels = sourceImageWidth * sourceImageHeight - 2;
this.currentByteIndex = 0;
var numberOfBits = messageData.Length * this.numberOfBitsInByte;
if (numberOfBits / bpcc > totalAvailableSourcePixels * PixelConstants.NumberOfColorChannels)
{
var requiredBpcc = this.calculateBpccRequiredToEmbedText(numberOfBits, totalAvailableSourcePixels);
if (requiredBpcc > this.numberOfBitsInByte)
{
await Dialogs.ShowNotPossibleToEmbedTextDialog();
}
else
{
await Dialogs.ShowRequiredBpccToEmbedTextDialog(requiredBpcc);
}
MessageTooLarge = true;
return;
}
var currentIndex = 0;
for (var currY = 0; currY < sourceImageHeight; currY++)
{
for (var currX = 0; currX < sourceImageWidth; currX++)
{
var sourcePixelColor =
PixelColorInfo.GetPixelBgra8(SourceImagePixels, currY, currX, sourceImageWidth);
if (IsFirstPixel(currX, currY))
{
sourcePixelColor = HeaderPixelFormatter.FormatFirstHeaderPixel(sourcePixelColor);
}
else if (IsSecondPixel(currX, currY))
{
sourcePixelColor = HeaderPixelFormatter.FormatSecondHeaderPixel(FileTypes.Text,
sourcePixelColor, encryptionIsChecked, bpcc);
}
else
{
sourcePixelColor = this.embedTextMessage(messageData, sourcePixelColor, currentIndex, bpcc);
currentIndex += PixelConstants.NumberOfColorChannels * bpcc;
}
PixelColorInfo.SetPixelBgra8(SourceImagePixels, currY, currX, sourcePixelColor, sourceImageWidth);
}
}
await SetEmbeddedImage(sourceImageHeight, sourceImageWidth);
}
/// <summary>
/// Extracts the message from image.
/// </summary>
/// <param name="embeddedPixels">The embedded pixels.</param>
/// <param name="embeddedImageWidth">Width of the embedded image.</param>
/// <param name="embeddedImageHeight">Height of the embedded image.</param>
/// @Precondition none
/// @Postcondition message is extracted from the image
public override async Task ExtractMessageFromImage(byte[] embeddedPixels, uint embeddedImageWidth,
uint embeddedImageHeight)
{
var encryptionPassword = new StringBuilder();
var count = 0;
for (var currY = 0; currY < embeddedImageHeight; currY++)
{
for (var currX = 0; currX < embeddedImageWidth; currX++)
{
var embeddedPixelColor = PixelColorInfo.GetPixelBgra8(embeddedPixels, currY, currX,
embeddedImageWidth);
if (isFirstPixel(currY, currX))
{
if (embeddedPixelColor.R == 212 && embeddedPixelColor.B == 212 &&
embeddedPixelColor.G == 212)
{
continue;
}
await Dialogs.ShowNoMessageDialog();
return;
}
if (isSecondPixel(currY, currX))
{
EncryptionUsed = (embeddedPixelColor.R & 1) != 0;
this.endOfEncryptionKeyReached = !EncryptionUsed;
this.bpcc = BinaryDecimalConverter.CalculateBpccFromBinary(embeddedPixelColor.G);
var numberOfBits = (embeddedImageWidth * embeddedImageHeight - 2) *
PixelConstants.NumberOfColorChannels * this.bpcc;
this.embeddedBits = new BitArray((int)numberOfBits);
}
else
{
if (this.endOfMessageReached)
{
this.handleReachedEndOfMessage(encryptionPassword);
return;
}
this.extractMessageBitsFromPixel(embeddedPixelColor, count);
count += PixelConstants.NumberOfColorChannels * this.bpcc;
}
}
}
}
/// <summary>
/// Extracts the message from image.
/// </summary>
/// @Precondition none
/// @postcondition message is extracted from the image
/// <param name="embeddedPixels">The embedded pixels.</param>
/// <param name="embeddedImageWidth">Width of the embedded image.</param>
/// <param name="embeddedImageHeight">Height of the embedded image.</param>
public override async Task ExtractMessageFromImage(byte[] embeddedPixels, uint embeddedImageWidth,
uint embeddedImageHeight)
{
for (var currY = 0; currY < embeddedImageHeight; currY++)
{
for (var currX = 0; currX < embeddedImageWidth; currX++)
{
var embeddedPixelColor = PixelColorInfo.GetPixelBgra8(embeddedPixels, currY, currX,
embeddedImageWidth);
if (isFirstPixel(currY, currX))
{
if (!(embeddedPixelColor.R == 212 && embeddedPixelColor.B == 212 &&
embeddedPixelColor.G == 212))
{
await Dialogs.ShowNoMessageDialog();
return;
}
}
else if (isSecondPixel(currY, currX))
{
EncryptionUsed = (embeddedPixelColor.R & 1) == 0;
}
else
{
var currentBlueColorByte = embeddedPixelColor.B;
if (isBitSet(currentBlueColorByte, 0))
{
embeddedPixelColor = this.whitePixel;
}
else
{
embeddedPixelColor = this.blackPixel;
}
}
PixelColorInfo.SetPixelBgra8(embeddedPixels, currY, currX, embeddedPixelColor, embeddedImageWidth);
}
}
ExtractedImage =
new WriteableBitmap((int)embeddedImageWidth, (int)embeddedImageHeight);
using (var writeStream = ExtractedImage.PixelBuffer.AsStream())
{
await writeStream.WriteAsync(embeddedPixels, 0, embeddedPixels.Length);
}
}
/// <summary>
/// Embeds the message in image.
/// </summary>
/// @Precondition none
/// @Postcondition the message is embedded into the image
/// <param name="messagePixels">The message pixels.</param>
/// <param name="messageImageWidth">Width of the message image.</param>
/// <param name="messageImageHeight">Height of the message image.</param>
/// <param name="sourceImageWidth">Width of the source image.</param>
/// <param name="sourceImageHeight">Height of the source image.</param>
/// <param name="encryptionIsChecked">if set to <c>true</c> [encryption is checked].</param>
/// <param name="bpcc">The BPCC.</param>
public override async Task EmbedMessageInImage(byte[] messagePixels, uint messageImageWidth,
uint messageImageHeight, uint sourceImageWidth, uint sourceImageHeight, bool encryptionIsChecked, int bpcc)
{
this.isEncrypted = encryptionIsChecked;
if (messageImageWidth > sourceImageWidth || messageImageHeight > sourceImageHeight)
{
await Dialogs.ShowMessageFileTooLargeDialog();
MessageTooLarge = true;
return;
}
for (var currY = 0; currY < sourceImageHeight; currY++)
{
for (var currX = 0; currX < sourceImageWidth; currX++)
{
var sourcePixelColor =
PixelColorInfo.GetPixelBgra8(SourceImagePixels, currY, currX, sourceImageWidth);
if (IsFirstPixel(currX, currY))
{
sourcePixelColor = HeaderPixelFormatter.FormatFirstHeaderPixel(sourcePixelColor);
}
else if (IsSecondPixel(currX, currY))
{
sourcePixelColor = HeaderPixelFormatter.FormatSecondHeaderPixel(FileTypes.Bitmap,
sourcePixelColor, encryptionIsChecked, bpcc);
}
else
{
sourcePixelColor = this.embedMonochromeImage(currX, messageImageWidth, currY,
messageImageHeight, messagePixels, sourcePixelColor);
}
PixelColorInfo.SetPixelBgra8(SourceImagePixels, currY, currX, sourcePixelColor, sourceImageWidth);
}
}
await SetEmbeddedImage(sourceImageHeight, sourceImageWidth);
}
