private IGIFBlock ReadImage(BinaryReader aReader, GIFImage aImage)
{
var res = new GIFImageBlock();
res.xPos = aReader.ReadUInt16();
res.yPos = aReader.ReadUInt16();
res.width = aReader.ReadUInt16();
res.height = aReader.ReadUInt16();
res.flags = (EImageDescriptorFlags)aReader.ReadByte();
if (res.HasLocalColorTable)
{
Log("Read local color table: " + res.SizeOfLocalColorTable);
res.usedColorTable =
res.colorTable = ReadColorTable(aReader, res.SizeOfLocalColorTable);
}
else
{
res.colorTable = null;
res.usedColorTable = aImage.screen.globalColorTable;
}
if (lastGrCtrl != null)
{
res.graphicControl = lastGrCtrl;
lastGrCtrl = null;
}
Log("Start LZW");
ReadLZWImage(aReader, res);
return(res);
}
private void ReadLZWImage(BinaryReader aReader, GIFImageBlock res)
{
byte initialCodeSize = aReader.ReadByte();
var bitReader = new BitStreamReader(aReader);
var output = new List <byte>();
var dict = new Dict(initialCodeSize);
long startPos = aReader.BaseStream.Position;
while (!bitReader.EndOfData)
{
int code = (int)bitReader.ReadBits(dict.bits);
if (bitReader.EndOfData)
{
break;
}
if (code == dict.ClearCode)
{
dict.Clear();
}
else if (code == dict.EODCode)
{
break;
}
else
{
int pre = dict.Expand(code, output);
if (pre != -1 && dict.lastCode != -1)
{
dict.AddPair(dict.lastCode, (byte)pre);
}
dict.lastCode = code;
}
}
if (!bitReader.EndOfData)
{
byte tmp = 1;
while (tmp != 0 && aReader.BaseStream.Position < aReader.BaseStream.Length)
{
tmp = aReader.ReadByte();
}
}
res.packedSize = (int)(aReader.BaseStream.Position - startPos);
res.data = output;
GIFLoader.Log("Image Data:" + output.Count + " (packed: " + res.packedSize + ")");
GIFLoader.Log("X: " + res.xPos + " Y: " + res.yPos);
GIFLoader.Log("W: " + res.width + " H: " + res.height);
GIFLoader.Log("Winterlaced: " + res.IsInterlaced);
GIFLoader.Log("---");
}
