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 IGIFBlock ReadGraphicControlBlock(BinaryReader aReader)
{
byte blockSize = aReader.ReadByte();
if (blockSize != 4)
{
throw new Exception("GIF: GraphicControl extension block size wrong: " + blockSize + " != 4");
}
var res = new GIFGraphicControlExt();
res.flags = (EGraphicControlFlags)aReader.ReadByte();
res.delay = aReader.ReadUInt16();
res.transparentColorIndex = aReader.ReadByte();
byte nullByte = aReader.ReadByte();
if (nullByte != 0)
{
throw new Exception("GIF: GraphicControl extension block not terminated with '0x00' (found:0x" + nullByte.ToString("xx") + ")");
}
lastGrCtrl = res;
return(res);
}
private IGIFBlock ReadPlainTextBlock(BinaryReader aReader)
{
byte blockSize = aReader.ReadByte();
if (blockSize != 12)
{
throw new Exception("GIF: PlainText extension block size wrong: " + blockSize + " != 12");
}
var res = new GIFTextBlock();
res.xPos = aReader.ReadUInt16();
res.yPos = aReader.ReadUInt16();
res.width = aReader.ReadUInt16();
res.height = aReader.ReadUInt16();
res.charWidth = aReader.ReadByte();
res.charHeight = aReader.ReadByte();
res.colorIndex = aReader.ReadByte();
res.bgColorIndex = aReader.ReadByte();
using (MemoryStream ms = new MemoryStream())
using (BinaryWriter bw = new BinaryWriter(ms))
{
byte size = aReader.ReadByte();
while (size > 0)
{
int read = aReader.Read(buf, 0, size);
bw.Write(buf, 0, read);
size = aReader.ReadByte();
}
bw.Flush();
res.text = System.Text.Encoding.ASCII.GetString(ms.ToArray());
}
if (lastGrCtrl != null)
{
res.graphicControl = lastGrCtrl;
lastGrCtrl = null;
}
return(res);
}
