/// Takes an input string and the frequency list generated earlier to
/// create a Huffman Tree to be used for the compression and
/// decompression. It then encodes the provided text string and outputs
/// it to the user in a compressed format, which can later be used
/// to decompress to verify the result.
private void BtnCompressClick(object sender, RoutedEventArgs e)
{
if (txtPlain.Text.Count() == 0)
{
MessageBox.Show("Cannot compress a message that doesn't"
+ " exist!\nPlease enter (1) or more "
+ "alphanumeric characters");
}
else if (nodeList.Count == 0)
{
MessageBox.Show("Cannot compress text without a frequency"
+ " table!\nPlease generate a frequency "
+ "table before compression");
}
else
{
HuffmanGenerator hg = new HuffmanGenerator(nodeList);
huffmanTree = hg.CreateTree();
encodeDict = hg.BuildEncodingMap(huffmanTree);
HuffmanEncoder he = new HuffmanEncoder();
txtCompressed.Text = he.Encode(txtPlain.Text.ToCharArray(), encodeDict);
txtPlain.Text = "";
txtFreqTbl.Text = "";
}
}
/// <summary>
/// Generates a canonical depth-limited Huffman tree using the provided <paramref name="symbolFrequencies"/>.
/// </summary>
public static HuffmanTree <T> FromSymbols(FrequencyList <T> symbolFrequencies, byte maxDepth)
{
if (symbolFrequencies.Count == 0)
{
throw new ArgumentOutOfRangeException(nameof(symbolFrequencies), "Cannot generate a tree with no symbols.");
}
else if (symbolFrequencies.Count == 1)
{
return(new HuffmanTree <T>(new HuffmanNode <T> .Leaf(symbolFrequencies.First())));
}
else
{
return(new HuffmanTree <T>(HuffmanGenerator <T> .FromFrequenciesCanonical(symbolFrequencies.HuffmanFreq.ToArray(), maxDepth)));
}
}
void AddMarkedSymbol(HuffmanGenerator <T> .Entry entry)
{
symbolEntries.Add(entry);
reader.MarkStart();
reader.MarkEndValue("entry", entry);
}
