/// <summary>
/// Constructor which creates a new <see cref="ZLibStream" /> object and initializes it as a compression or a decompression one depending on the <paramref name="dir"/> parameter.
/// </summary>
/// <param name="stream">The stream containing compressed data for decompression or the stream to store compressed data for compression.</param>
/// <param name="dir">One of the <see cref="CompressionDirection" /> values that indicates the action to take (compression or decompression).</param>
/// <param name="leaveOpen">Whether we need to leave the underlying stream open when <see cref="ZLibStream.Close">closing</see> the current stream.</param>
public ZLibStream(Stream stream, CompressionDirection dir, bool leaveOpen)
{
if (stream == null)
{
throw new ArgumentNullException("Stream to decompression cannot be null", "stream");
}
this.compressionDirection = dir;
this._stream = stream;
this.leaveOpen = leaveOpen;
if (dir == CompressionDirection.Compression)
{
if (!this._stream.CanWrite)
{
throw new ArgumentException("The stream is not writable", "stream");
}
this.compressionStream = new ZOutputStream(this._stream, this.compLevel);
}
else
{
if (!this._stream.CanRead)
{
throw new ArgumentException("The stream is not readable", "stream");
}
this.decompressionStream = new ZInputStream(this._stream);
}
}
/// <summary>
/// Decompresses (inflates) bytes from input stream.
/// </summary>
/// <remarks>
/// Stream marker is being set at +<code>numOfBytes</code> position of the stream.
/// </remarks>
/// <param name="buf">Input byte buffer stream.</param>
/// <param name="numOfBytes">The number of bytes to be read.</param>
/// <returns>new <c>ByteBuffer</c> with the inflated block of data.</returns>
/// <exception cref="IOException">When an error occurs while reading or inflating the buffer.</exception>
private Stream Inflate(Stream buf, int numOfBytes)
{
if (buf.Length - buf.Position < numOfBytes)
{
throw new MatlabIOException("Compressed buffer length miscalculated!");
}
#if false
// test code!
byte[] byteBuffer = new byte[numOfBytes];
long pos = buf.Position;
int n = buf.Read(byteBuffer, 0, numOfBytes);
buf.Position = pos;
File.WriteAllBytes("DeflatedMatlabData.bin", byteBuffer);
#endif
try
{
#if NET20
MemoryStream inflatedStream = new MemoryStream(numOfBytes);
// copy all the compressed bytes to a new stream.
byte[] compressedBytes = new byte[numOfBytes];
int numBytesRead = buf.Read(compressedBytes, 0, numOfBytes);
if (numBytesRead != numOfBytes)
{
throw new IOException("numBytesRead != numOfBytes");
}
// now use zlib on the compressedBytes
MemoryStream compressedStream = new MemoryStream(compressedBytes);
zlib.ZInputStream zis = new zlib.ZInputStream(compressedStream);
Helpers.CopyStream(zis, inflatedStream);
zis.Close();
inflatedStream.Position = 0;
return(inflatedStream);
#endif
#if NET40 || NET45
// skip CRC (at end) and zip format (0x789C at begin)
buf.Position += 2;
numOfBytes -= 6;
MemoryStream compressedStream = new MemoryStream();
int data;
do
{
data = buf.ReadByte();
if (data != -1)
{
compressedStream.WriteByte((byte)(data & 0x000000FF));
}
}while (data != -1 && compressedStream.Length < numOfBytes);
// skip CRC
buf.Position += 4;
compressedStream.Position = 0;
MemoryStream decompressedStream = new MemoryStream();
using (DeflateStream df = new DeflateStream(compressedStream, CompressionMode.Decompress))
{
do
{
data = df.ReadByte();
if (data != -1)
{
decompressedStream.WriteByte((byte)(data & 0x000000FF));
}
}while (data != -1);
}
decompressedStream.Position = 0;
return(decompressedStream);
#endif
}
catch (IOException e)
{
throw new MatlabIOException("Could not decompress data: " + e);
}
}