private void InputFileChoose_OnFilenameChanged(object sender, EventArgs e)
{
if (InputImage?.Source == null)
{
return;
}
var w = new WriteableBitmap((BitmapSource)InputImage.Source);
unsafe {
uint * pixel = (uint *)w.BackBuffer;
MessageHeader header = new MessageHeader {
ChecksumType = new XorChecksumCalculator()
};
var headerData = new byte[header.Length];
for (int i = 0; i < headerData.Length; i++)
{
headerData[i] = ByteHider.RecoverByte(*pixel);
pixel++;
}
try {
header = MessageHeader.FromBytes(headerData);
}
catch (FormatException) {
ShowImageInvalidMessage();
return;
}
pixel++;
int startIndex = FillStartUtility.GetFillStartIndex(header.Fill, w.PixelWidth, w.PixelHeight, header.DataLength * (header.DataSpacing + 1));
pixel += startIndex - header.Length - 1;
var dataBuffer = new byte[header.DataLength];
for (int i = 0; i < dataBuffer.Length; i++)
{
dataBuffer[i] = ByteHider.RecoverByte(*pixel);
pixel++;
// skip spacing pixels
for (int j = 0; j < header.DataSpacing; j++)
{
pixel++;
}
}
// check the checksum
var checksumMatches = header.Checksum.SequenceEqual(_checksumCalculator.GetChecksum(dataBuffer));
if (!checksumMatches)
{
ShowImageInvalidMessage();
}
else
{
OutputTextBox.Text = Encoding.UTF8.GetString(dataBuffer);
}
}
}
private void MessageTextChanged(object sender, TextChangedEventArgs e)
{
if (OutputImage?.Source == null)
{
return;
}
var w = (WriteableBitmap)OutputImage.Source;
var textBox = sender as TextBox;
IsOverCapacity = false;
var data = Encoding.UTF8.GetBytes(textBox.Text);
var header = new MessageHeader {
Fill = (FillStart)FillComboBox.SelectedIndex,
ChecksumType = new XorChecksumCalculator(),
DataLength = checked ((ushort)data.Length)
};
try {
header.DataSpacing = byte.Parse(SpaceTextBox.Text);
if (header.DataSpacing > 254)
{
throw new Exception();
}
}
catch {
MessageBox.Show("Invalid spacing, allowed range is 0-254");
return;
}
var capacity = Math.Min(ushort.MaxValue,
(w.PixelWidth * w.PixelHeight - header.Length) / (header.DataSpacing + 1));
ProgressBar.Maximum = capacity;
var textDataLength = Encoding.UTF8.GetByteCount(textBox.Text);
ProgressBar.Value = textDataLength;
if (textDataLength > capacity)
{
IsOverCapacity = true;
return;
}
header.SetChecksumFromData(data);
int dataStartPixelIndex =
FillStartUtility.GetFillStartIndex(header.Fill, w.PixelWidth, w.PixelHeight, data.Length * (header.DataSpacing + 1));
var original = new WriteableBitmap((BitmapSource)InputImage.Source);
w.Lock();
long counter = 0;
unsafe {
uint *originalPixel = (uint *)original.BackBuffer;
uint *pixel = (uint *)w.BackBuffer;
var headerBytes = header.GetBytes();
// place header bytes
foreach (byte b in headerBytes)
{
*pixel = ByteHider.HideByte(*originalPixel, b);
pixel++;
originalPixel++;
counter++;
}
// copy unmodified bytes
while (counter < dataStartPixelIndex)
{
*pixel = *originalPixel;
pixel++;
originalPixel++;
counter++;
}
// place data
foreach (byte b in data)
{
*pixel = ByteHider.HideByte(*originalPixel, b);
pixel++;
originalPixel++;
counter++;
// copy spacing pixels
for (int i = 0; i < header.DataSpacing; i++)
{
*pixel = *originalPixel;
pixel++;
originalPixel++;
counter++;
}
}
// copy unmodified bytes
while (counter < w.PixelWidth * w.PixelHeight)
{
*pixel = *originalPixel;
pixel++;
originalPixel++;
counter++;
}
}
w.AddDirtyRect(new Int32Rect(0, 0, w.PixelWidth, w.PixelHeight));
w.Unlock();
}
