public void LzwEncodingIsReversible(LzwGifToolsTestCase testCase) // and decoding
{
LzwCompressor compressor = new LzwCompressor(testCase.LzwMinimumCodeSize);
LzwDecompressor decompressor = new LzwDecompressor(testCase.LzwMinimumCodeSize);
List <int> lzwCompressedStream = compressor.Compress(testCase.CodeStream);
List <int> lzwDecompressedStream = decompressor.Decompress(lzwCompressedStream);
CollectionAssert.AreEqual(testCase.CodeStream, lzwDecompressedStream);
}
public void AllMethodsWork(LzwGifToolsTestCase testCase)
{
LzwCompressor compressor = new LzwCompressor(testCase.LzwMinimumCodeSize);
StreamPacker packer = new StreamPacker(testCase.LzwMinimumCodeSize);
StreamUnpacker unpacker = new StreamUnpacker(testCase.LzwMinimumCodeSize);
LzwDecompressor decompressor = new LzwDecompressor(testCase.LzwMinimumCodeSize);
List <int> lzwEncodedCodeStream = compressor.Compress(testCase.CodeStream);
List <byte> packedBytes = packer.Pack(lzwEncodedCodeStream);
List <int> lzwEncodedCodeStream2 = unpacker.Unpack(packedBytes);
List <int> codeStream = decompressor.Decompress(lzwEncodedCodeStream2);
CollectionAssert.AreEqual(testCase.CodeStream, codeStream);
}
public void ExportLzwCompressedCodeStreamToTextFile(LzwGifToolsTestCase testCase)
{
LzwCompressor compressor = new LzwCompressor(testCase.LzwMinimumCodeSize);
List <int> lzwCompressedStream = compressor.Compress(testCase.CodeStream);
using (StreamWriter sw = File.CreateText(Config.WorkingDirectory + @"/" + "lzw-compressed-code-stream.txt"))
{
int index = 0;
foreach (int i in lzwCompressedStream)
{
index++;
sw.Write(string.Format("{0} ", i));
if (index % 8 == 0)
{
sw.WriteLine("");
}
}
}
}
public void Write(string path, Image image)
{
Color[,] colors = GetColors(image.Bitmap);
Color[] table = GetTable(colors);
int tableSize = AlignToPowerOfTwo(table.Length);
byte power = (byte)((byte)Math.Log2(tableSize) - 1);
string stringPower = Convert.ToString(power, 2).PadLeft(3, '0');
List <int> codes = LzwCompressor.Compress(colors, table, tableSize);
byte minCodeSize = (byte)(power + 1 < 2 ? 2 : power + 1);
List <byte> bytes = LzwBytePacker.PackBytes(codes, minCodeSize);
byte fullBlock = 255;
int fullBlockQuantity = bytes.Count / fullBlock;
byte partialBlockCount = (byte)(bytes.Count % fullBlock);
short height = (short)image.Header.Height;
short width = (short)image.Header.Width;
BinaryWriter writer;
try
{
writer = new BinaryWriter(File.Open(path + ".gif", FileMode.Create));
}
catch (Exception e)
{
throw new InvalidOperationException(e.Message);
}
WriteHeader();
WriteLogicalScreen();
WriteColorTable();
WriteImageDescriptor();
WriteImageData();
WriteTrailer();
writer.Close();
void WriteHeader()
{
foreach (var ch in _header)
{
writer.Write(ch);
}
}
void WriteLogicalScreen()
{
writer.Write(width);
writer.Write(height);
byte packedField = Convert.ToByte(GlobalTableBit + stringPower + SortBit + stringPower, 2);
writer.Write(packedField);
writer.Write(BgColorIndex);
writer.Write(PixelAspectRatio);
}
void WriteColorTable()
{
for (int i = 0; i < tableSize; i++)
{
if (i < table.Length)
{
writer.Write((byte)table[i].R);
writer.Write((byte)table[i].G);
writer.Write((byte)table[i].B);
}
else
{
for (int j = 0; j < ColorBytes; j++)
{
writer.Write(EmptyColorByte);
}
}
}
}
void WriteImageDescriptor()
{
writer.Write(ImageSeparator);
writer.Write(ImageLeft);
writer.Write(ImageRight);
writer.Write(width);
writer.Write(height);
writer.Write(ImagePackedField);
}
void WriteImageData()
{
writer.Write(minCodeSize);
for (int i = 0; i < fullBlockQuantity; i++)
{
writer.Write(fullBlock);
for (int j = 0; j < fullBlock; j++)
{
writer.Write(bytes[i * fullBlock + j]);
}
}
if (partialBlockCount != 0)
{
writer.Write(partialBlockCount);
for (int i = 0; i < partialBlockCount; i++)
{
writer.Write(bytes[fullBlockQuantity * fullBlock + i]);
}
}
writer.Write(BlockTerminator);
}
void WriteTrailer()
{
writer.Write(Trailer);
}
}
