public void DecodeTest()
{
MockEncoder encoder = new MockEncoder();
encoder.values.Add(42);
encoder.values.Add(43);
encoder.values.Add(256);
LZW lzw = new LZW(encoder);
Assert.AreEqual(42, lzw.Decode());
Assert.AreEqual(43, lzw.Decode());
Assert.AreEqual(42, lzw.Decode());
Assert.AreEqual(43, lzw.Decode());
}
private byte[] DecodePicture(ref int index, uint length)
{
byte bits = _bytes[index++];
byte[] img = new byte[length - 5];
Array.Copy(_bytes, index, img, 0, (int)(length - 5));
index += (int)(length - 5);
return(RLE.Decode(LZW.Decode(img)));
}
public void EncodeDecodeTest()
{
MockEncoder encoder = new MockEncoder();
LZW lzw = new LZW(encoder);
foreach (byte character in "Lorem ipsum dolor sit amet consectetur adepiscig nullam")
{
lzw.Encode(character);
}
lzw.EncoderFinalize();
LZW lzwDecoder = new LZW(encoder);
String output = "";
foreach (byte character in "Lorem ipsum dolor sit amet consectetur adepiscig nullam")
{
byte actual = lzwDecoder.Decode();
output += (char)actual;
Assert.AreEqual(character, actual);
}
}
private void Decode(object sender, RoutedEventArgs e)
{
resultDecode.Text = LZW.Decode(alphabet, encodeList);
}
public GifFile(byte[] buffer)
{
// Check for valid GIF-file header
if (Encoding.UTF8.GetString(buffer, 0, 6) != "GIF87a" && Encoding.UTF8.GetString(buffer, 0, 6) != "GIF89a")
{
return;
}
int width = BitConverter.ToUInt16(buffer, 6);
int height = BitConverter.ToUInt16(buffer, 8);
// GCT Descriptor
bool hasGct = ((buffer[10] >> 7) & 1) == 1;
byte colourResolution = (byte)(((buffer[10] >> 4) & 7) + 1);
bool sorted = ((buffer[10] >> 3) * 1) == 1;
int colourCount = (int)Math.Pow(2, (buffer[10] & 7) + 1);
byte backgroundIndex = buffer[11];
byte aspectRatio = buffer[12];
if (aspectRatio != 0)
{
return; // Can not handle this file
}
if (!hasGct)
{
return; // Can not handle this file
}
//if (colourResolution != 8) return; // Can not handle this file
int index = 13;
Colour[] palette = new Colour[256];
for (int i = 0; i < colourCount; i++)
{
byte r = buffer[index++], g = buffer[index++], b = buffer[index++];
palette[i] = new Colour(r, g, b);
}
while (index < buffer.Length)
{
switch (buffer[index])
{
case 0x2C:
// Image descriptor
if (buffer[index++] != 0x2C)
{
return; // Unexpected byte
}
if (BitConverter.ToUInt16(buffer, index) != 0)
{
return; // Can not handle this file
}
if (BitConverter.ToUInt16(buffer, index + 2) != 0)
{
return; // Can not handle this file
}
if (BitConverter.ToUInt16(buffer, index + 4) != width)
{
return; // Can not handle this file
}
if (BitConverter.ToUInt16(buffer, index + 6) != height)
{
return; // Can not handle this file
}
index += 8;
if (buffer[index++] != 0)
{
return; // Can not handle this file
}
break;
case 0x21:
// Graphics Control Extension/Comment Extension Block
index++;
switch (buffer[index++])
{
case 0xF9:
// Graphics Control Extension
{
int size = buffer[index++];
if (size == 4)
{
byte packed = buffer[index++];
ushort delayTime = BitConverter.ToUInt16(buffer, index);
index += 2;
byte transparentColour = buffer[index++];
if ((packed & 1) == 1)
{
palette[transparentColour] = Colour.Transparent;
}
index++;
}
else
{
index += size + 1;
}
}
break;
case 0xFE:
// Comment Extension Block
{
int size = buffer[index++];
index += size + 1;
}
break;
default:
// Unexpected byte
return;
}
break;
case 0x3B:
// Trailer (end of file)
index = buffer.Length;
break;
default:
int minCode = buffer[index++];
List <byte> lzwData = new List <byte>();
foreach (byte[] data in InputBlock(buffer, index))
{
index += (data.Length + 2);
lzwData.AddRange(data);
}
try
{
byte[] pixels = LZW.Decode(lzwData.ToArray(), true, false, minCode, 12);
_pixels = new Bytemap(width, height).FromByteArray(pixels);
_palette = palette;
}
catch
{
RuntimeHandler.Runtime.Log("Could not decode GIF file.");
}
return;
}
}
}
