private void Perform_LWZ_Compression_Button_Click(object sender, RoutedEventArgs e)
{
this.ToggleComponents(false, true);
this.CompressionStatus.Visibility = Visibility.Visible;
this.PerformActionButton.IsEnabled = false;
this.model = new LZWCompressionDataModel
{
DataToCompress = this.PlainText.Text
};
this.worker.RunWorkerAsync();
}
public static LZWCompressionResultModel PerformLZWCompression(LZWCompressionDataModel model)
{
int indexSeed = 256;
byte[] dataBytes = Encoding.Default.GetBytes(model.DataToCompress);
List <Pair <byte[], int> > indexDictionary = new List <Pair <byte[], int> >(
dataBytes.Distinct().OrderBy(x => x).Select(x => new Pair <byte[], int>(new byte[] { x }, (int)x)));
List <int> output = new List <int>();
List <byte> current = new List <byte>();
byte? next;
for (int i = 0, len = dataBytes.Length; i < len; i++)
{
current.Add(dataBytes[i]);
next = null;
next = (i < len - 1) ? dataBytes[i + 1] : next;
var combined = new List <byte>(current.ToArray());
if (next.HasValue)
{
combined.Add(next.Value);
}
bool isInDictionary = false;
int currentIndex = -1;
for (int j = 0, lenj = indexDictionary.Count; j < lenj; j++)
{
if (indexDictionary[j].Key.SequenceEqual(combined))
{
isInDictionary = true;
if (!next.HasValue)
{
currentIndex = j;
}
break;
}
if (indexDictionary[j].Key.SequenceEqual(current))
{
currentIndex = j;
}
}
if (!isInDictionary)
{
if (currentIndex != -1)
{
output.Add(indexDictionary[currentIndex].Value);
}
indexDictionary.Add(new Pair <byte[], int>(combined.ToArray(), indexSeed++));
current.Clear();
}
else
{
if (!next.HasValue && currentIndex != -1)
{
output.Add(indexDictionary[currentIndex].Value);
}
}
}
return(new LZWCompressionResultModel(dataBytes, output, indexDictionary));
}
