/// <summary>
/// Compress a byte array into a new byte array using DEFLATE.
/// </summary>
///
/// <remarks>
/// Uncompress it with <see cref="DeflateStream.UncompressBuffer(byte[])"/>.
/// </remarks>
///
/// <seealso cref="DeflateStream.CompressString(string)">DeflateStream.CompressString(string)</seealso>
/// <seealso cref="DeflateStream.UncompressBuffer(byte[])">DeflateStream.UncompressBuffer(byte[])</seealso>
/// <seealso cref="GZipStream.CompressBuffer(byte[])">GZipStream.CompressBuffer(byte[])</seealso>
/// <seealso cref="ZlibStream.CompressBuffer(byte[])">ZlibStream.CompressBuffer(byte[])</seealso>
///
/// <param name="b">
/// A buffer to compress.
/// </param>
///
/// <returns>The data in compressed form</returns>
public static byte[] CompressBuffer(byte[] b)
{
using (var ms = new System.IO.MemoryStream())
{
System.IO.Stream compressor =
new DeflateStream( ms, CompressionMode.Compress, CompressionLevel.BestCompression );
ZlibBaseStream.CompressBuffer(b, compressor);
return ms.ToArray();
}
}
/// <summary>
/// Uncompress a DEFLATE'd byte array into a byte array.
/// </summary>
///
/// <seealso cref="DeflateStream.CompressBuffer(byte[])">DeflateStream.CompressBuffer(byte[])</seealso>
/// <seealso cref="DeflateStream.UncompressString(byte[])">DeflateStream.UncompressString(byte[])</seealso>
/// <seealso cref="GZipStream.UncompressBuffer(byte[])">GZipStream.UncompressBuffer(byte[])</seealso>
/// <seealso cref="ZlibStream.UncompressBuffer(byte[])">ZlibStream.UncompressBuffer(byte[])</seealso>
///
/// <param name="compressed">
/// A buffer containing data that has been compressed with DEFLATE.
/// </param>
///
/// <returns>The data in uncompressed form</returns>
public static byte[] UncompressBuffer(byte[] compressed)
{
using (var input = new System.IO.MemoryStream(compressed))
{
System.IO.Stream decompressor =
new DeflateStream( input, CompressionMode.Decompress );
return ZlibBaseStream.UncompressBuffer(compressed, decompressor);
}
}
private Stream MaybeApplyCompression(Stream s, long streamLength)
{
if (_CompressionMethod == 0x08 && CompressionLevel != Ionic.Zlib.CompressionLevel.None)
{
#if !NETCF
// ParallelDeflateThreshold == 0 means ALWAYS use parallel deflate
// ParallelDeflateThreshold == -1L means NEVER use parallel deflate
// Other values specify the actual threshold.
if (_container.ParallelDeflateThreshold == 0L ||
(streamLength > _container.ParallelDeflateThreshold &&
_container.ParallelDeflateThreshold > 0L))
{
// This is sort of hacky.
//
// It's expensive to create a ParallelDeflateOutputStream, because
// of the large memory buffers. But the class is unlike most Stream
// classes in that it can be re-used, so the caller can compress
// multiple files with it, one file at a time. The key is to call
// Reset() on it, in between uses.
//
// The ParallelDeflateOutputStream is attached to the container
// itself - there is just one for the entire ZipFile or
// ZipOutputStream. So it gets created once, per save, and then
// re-used many times.
//
// This approach will break when we go to a "parallel save"
// approach, where multiple entries within the zip file are being
// compressed and saved at the same time. But for now it's ok.
//
// instantiate the ParallelDeflateOutputStream
if (_container.ParallelDeflater == null)
{
_container.ParallelDeflater =
new ParallelDeflateOutputStream(s,
CompressionLevel,
_container.Strategy,
true);
// can set the codec buffer size only before the first call to Write().
if (_container.CodecBufferSize > 0)
_container.ParallelDeflater.BufferSize = _container.CodecBufferSize;
if (_container.ParallelDeflateMaxBufferPairs > 0)
_container.ParallelDeflater.MaxBufferPairs =
_container.ParallelDeflateMaxBufferPairs;
}
// reset it with the new stream
Ionic.Zlib.ParallelDeflateOutputStream o1 = _container.ParallelDeflater;
o1.Reset(s);
return o1;
}
#endif
var o = new DeflateStream(s, OfficeOpenXml.Packaging.Ionic.Zlib.CompressionMode.Compress,
CompressionLevel,
true);
if (_container.CodecBufferSize > 0)
o.BufferSize = _container.CodecBufferSize;
o.Strategy = _container.Strategy;
return o;
}
#if BZIP
if (_CompressionMethod == 0x0c)
{
#if !NETCF
if (_container.ParallelDeflateThreshold == 0L ||
(streamLength > _container.ParallelDeflateThreshold &&
_container.ParallelDeflateThreshold > 0L))
{
var o1 = new Ionic.BZip2.ParallelBZip2OutputStream(s, true);
return o1;
}
#endif
var o = new Ionic.BZip2.BZip2OutputStream(s, true);
return o;
}
#endif
return s;
}
