public ShpReader(Stream stream)
{
imageCount = stream.ReadUInt16();
stream.Position += 4;
var width = stream.ReadUInt16();
var height = stream.ReadUInt16();
Size = new Size(width, height);
stream.Position += 4;
var headers = new ImageHeader[imageCount];
Frames = headers.AsReadOnly();
for (var i = 0; i < headers.Length; i++)
headers[i] = new ImageHeader(stream, this);
// Skip eof and zero headers
stream.Position += 16;
var offsets = headers.ToDictionary(h => h.FileOffset, h => h);
for (var i = 0; i < imageCount; i++)
{
var h = headers[i];
if (h.Format == Format.Format20)
h.RefImage = headers[i - 1];
else if (h.Format == Format.Format40 && !offsets.TryGetValue(h.RefOffset, out h.RefImage))
throw new InvalidDataException("Reference doesnt point to image data {0}->{1}".F(h.FileOffset, h.RefOffset));
}
shpBytesFileOffset = stream.Position;
shpBytes = stream.ReadBytes((int)(stream.Length - stream.Position));
foreach (var h in headers)
Decompress(h);
}
void Decompress(Stream stream, ImageHeader h)
{
if (recurseDepth > ImageCount)
throw new InvalidDataException("Format20/40 headers contain infinite loop");
switch(h.Format)
{
case Format.Format20:
case Format.Format40:
{
if (h.RefImage.Image == null)
{
++recurseDepth;
Decompress(stream, h.RefImage);
--recurseDepth;
}
h.Image = CopyImageData(h.RefImage.Image);
Format40.DecodeInto(ReadCompressedData(stream, h), h.Image);
break;
}
case Format.Format80:
{
var imageBytes = new byte[Width * Height];
Format80.DecodeInto(ReadCompressedData(stream, h), imageBytes);
h.Image = imageBytes;
break;
}
default:
throw new InvalidDataException();
}
}
static byte[] ReadCompressedData(Stream stream, ImageHeader h)
{
stream.Position = h.Offset;
// TODO: Actually, far too big. There's no length field with the correct length though :(
var compressedLength = (int)(stream.Length - stream.Position);
var compressedBytes = new byte[ compressedLength ];
stream.Read( compressedBytes, 0, compressedLength );
return compressedBytes;
}
public static void Write(Stream s, Size size, IEnumerable<byte[]> frames)
{
var compressedFrames = frames.Select(f => Format80.Encode(f)).ToList();
// note: end-of-file and all-zeroes headers
var dataOffset = 14 + (compressedFrames.Count + 2) * 8;
using (var bw = new BinaryWriter(s))
{
bw.Write((ushort)compressedFrames.Count);
bw.Write((ushort)0);
bw.Write((ushort)0);
bw.Write((ushort)size.Width);
bw.Write((ushort)size.Height);
bw.Write((uint)0);
foreach (var f in compressedFrames)
{
var ih = new ImageHeader { Format = Format.Format80, FileOffset = (uint)dataOffset };
dataOffset += f.Length;
ih.WriteTo(bw);
}
var eof = new ImageHeader { FileOffset = (uint)dataOffset };
eof.WriteTo(bw);
var allZeroes = new ImageHeader { };
allZeroes.WriteTo(bw);
foreach (var f in compressedFrames)
bw.Write(f);
}
}
void Decompress(ImageHeader h)
{
// No extra work is required for empty frames
if (h.Size.Width == 0 || h.Size.Height == 0)
return;
if (recurseDepth > imageCount)
throw new InvalidDataException("Format20/40 headers contain infinite loop");
switch (h.Format)
{
case Format.Format20:
case Format.Format40:
{
if (h.RefImage.Data == null)
{
++recurseDepth;
Decompress(h.RefImage);
--recurseDepth;
}
h.Data = CopyImageData(h.RefImage.Data);
Format40.DecodeInto(shpBytes, h.Data, (int)(h.FileOffset - shpBytesFileOffset));
break;
}
case Format.Format80:
{
var imageBytes = new byte[Size.Width * Size.Height];
Format80.DecodeInto(shpBytes, imageBytes, (int)(h.FileOffset - shpBytesFileOffset));
h.Data = imageBytes;
break;
}
default:
throw new InvalidDataException();
}
}
