public static HuffmanNode MakeTree(byte[] data)
{
// First get the frequencies and create the leafs
var leafs = new Dictionary <byte, HuffmanNode>();
foreach (var d in data)
{
if (!leafs.ContainsKey(d))
{
leafs.Add(d, new HuffmanNode(d));
}
leafs[d].Frequency++;
}
// Now create the tree
var nodes = new SortedSet <HuffmanNode>(leafs.Values, new FrequencyComparer());
while (nodes.Count > 1)
{
// Take the two elements with lower frequency
var lowest1 = nodes.Last();
nodes.Remove(lowest1);
var lowest2 = nodes.Last();
nodes.Remove(lowest2);
// Create a new node that contains both of them
var parent = new HuffmanNode(0);
parent.Frequency = lowest1.Frequency + lowest2.Frequency;
parent.LeftLeaf = lowest1;
parent.RightLeaf = lowest2;
// Add the node to the list
nodes.Add(parent);
}
return(nodes.First());
}
/// <summary>
/// Convert the specified font into binary format..
/// </summary>
/// <returns>Binary representation of the font.</returns>
/// <param name="source">Font to convert.</param>
public BinaryFormat Convert(GameFont source)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
var stream = new DataStream(new MemoryStream(), 0, 0);
var writer = new DataWriter(stream);
int numGlyphs = source.Glyphs.Count;
int pixGlyph = source.CharWidth * source.CharHeight;
// Main header
// Hard-coded: 4 bpp with flags 0x010101
writer.Write(0x20);
writer.Write(0x00); // will set later
writer.Write(0x010101);
writer.Write((ushort)0x00);
writer.Write((ushort)numGlyphs);
writer.Write((ushort)source.CharWidth);
writer.Write((ushort)source.CharHeight);
writer.Write((ushort)(pixGlyph / 2));
writer.Write((ushort)0x01);
stream.WriteTimes(0x00, 8);
// Palette
foreach (var color in source.GetPalette())
{
writer.Write((byte)color.Red);
writer.Write((byte)color.Green);
writer.Write((byte)color.Blue);
if (color.Red > 0 && color.Green > 0 && color.Blue > 0)
{
writer.Write((byte)0x80);
}
else
{
writer.Write((byte)0x00);
}
}
// Variable Width Table (VWT)
int vwtSize = numGlyphs * 2;
writer.Write(vwtSize);
foreach (var glyph in source.Glyphs)
{
writer.Write((byte)glyph.BearingX);
writer.Write((byte)glyph.Advance);
}
// Reserved space
stream.WriteTimes(0x00, 4 + (4 * numGlyphs));
// Glyphs
long glyphSection = stream.RelativePosition;
stream.WriteTimes(0x00, 0x20); // header
// Flatten the glyph bytes
var rawData = new byte[numGlyphs * pixGlyph / 2];
int rawDataIdx = 0;
foreach (var glyph in source.Glyphs)
{
int[,] glyphImg = glyph.GetImage();
for (int h = 0; h < source.CharHeight; h++)
{
for (int w = 0; w < source.CharWidth; w++)
{
if (rawDataIdx % 2 == 0)
{
rawData[rawDataIdx / 2] = (byte)glyphImg[w, h];
}
else
{
rawData[rawDataIdx / 2] |= (byte)(glyphImg[w, h] << 4);
}
rawDataIdx++;
}
}
}
// Get Huffman tree
HuffmanNode huffmanTree = Huffman.MakeTree(rawData);
int huffmanTreeSize = Huffman.WriteTree(huffmanTree, stream);
var codewords = Huffman.GetCodewords(huffmanTree);
// Write empty position table
long positionTableSection = stream.RelativePosition;
stream.WriteTimes(0x00, numGlyphs * 4L);
var compressed = new DataStream(stream, stream.RelativePosition, 0);
int compressedPos = 0;
rawDataIdx = 0;
for (int i = 0; i < numGlyphs; i++)
{
stream.Seek(positionTableSection + (i * 4L), SeekMode.Origin);
writer.Write(compressedPos);
Huffman.Compress(codewords, rawData, rawDataIdx, pixGlyph, compressed, ref compressedPos);
rawDataIdx += pixGlyph;
}
// ..Header
stream.Seek(glyphSection, SeekMode.Origin);
writer.Write(0x20);
writer.Write(huffmanTreeSize);
writer.Write((uint)compressed.Length);
writer.Write(compressedPos);
writer.Write(pixGlyph / 2);
writer.Write(numGlyphs + 1);
writer.Write((numGlyphs + 1) * 4);
writer.Write(rawData.Length);
compressed.Dispose();
// Set the unknown field size
stream.Seek(0x04, SeekMode.Origin);
writer.Write((uint)(stream.Length - vwtSize - 7));
return(new BinaryFormat(stream));
}
public static int WriteTree(HuffmanNode tree, DataStream stream)
{
throw new NotImplementedException();
}
