private static void Decode(Stream stream, ShpOffset[] offsets, int width, int height,
byte[][] frames, byte[] src, ref int recdepth)
{
if (recdepth > frames.Length)
{
throw new NotImplementedException("Format 40/20 frames contain infinite loop!");
}
for (uint i = 0; i < frames.Length; i++)
{
byte[] frame = new byte[width * height];
byte[] refframe = null;
ShpOffset curoff = offsets[i + 0];
ShpOffset nxtoff = offsets[i + 1];
int srclen = (int)(nxtoff.Offset - curoff.Offset);
stream.Read(src, 0, srclen);
switch (curoff.OffsetFormat)
{
// Format 20
case 0x20:
refframe = frames[i - 1];
goto do_format40;
// Format 40
case 0x40:
int j = Array.FindIndex(offsets, o => o.Offset == curoff.Ref);
if (j < 0)
{
throw new IndexOutOfRangeException("Invalid frame reference!");
}
refframe = frames[j];
do_format40:
if (refframe == null)
{
recdepth++;
Decode(stream, offsets, width, height, frames, src, ref recdepth);
recdepth--;
}
Format40.Decode(src, srclen, frame, refframe);
break;
// Format 80
case 0x80:
Format80.Decode(src, 0, frame, 0, srclen);
break;
// Invalid format
default:
throw new NotImplementedException("Invalid format!");
}
frames[i] = frame;
}
}
public static Sprite Read(Stream stream)
{
ShpHeader header = stream.ReadStruct <ShpHeader>();
ShpOffset[] offsets = new ShpOffset[2 + header.nframes];
for (uint i = 0; i < offsets.Length; i++)
{
offsets[i] = stream.ReadStruct <ShpOffset>();
}
int frame_w = header.width;
int frame_h = header.height;
byte[][] frames = Decode(stream, offsets, frame_w, frame_h, header.nframes);
return(new Sprite(frames, frame_w, frame_h));
}
