// // © Copyright Henrik Ravn 2004 // // Use, modification and distribution are subject to the Boost Software License, Version 1.0. // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) // using System; using System.Diagnostics; using System.Runtime.InteropServices; namespace DotZLib { /// <summary> /// Implements a data compressor, using the deflate algorithm in the ZLib dll /// </summary> public sealed class Deflater : CodecBase { #region Dll imports [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)] private static extern int deflateInit_(ref ZStream sz, int level, string vs, int size); [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)] private static extern int deflate(ref ZStream sz, int flush); [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)] private static extern int deflateReset(ref ZStream sz); [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)] private static extern int deflateEnd(ref ZStream sz); #endregion /// <summary> /// Constructs an new instance of the <c>Deflater</c> /// </summary> /// <param name="level">The compression level to use for this <c>Deflater</c></param> public Deflater(CompressLevel level) : base() { int retval = deflateInit_(ref _ztream, (int)level, Info.Version, Marshal.SizeOf(_ztream)); if (retval != 0) throw new ZLibException(retval, "Could not initialize deflater"); resetOutput(); } /// <summary> /// Adds more data to the codec to be processed. /// </summary> /// <param name="data">Byte array containing the data to be added to the codec</param> /// <param name="offset">The index of the first byte to add from <c>data</c></param> /// <param name="count">The number of bytes to add</param> /// <remarks>Adding data may, or may not, raise the <c>DataAvailable</c> event</remarks> public override void Add(byte[] data, int offset, int count) { if (data == null) throw new ArgumentNullException(); if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException(); if ((offset+count) > data.Length) throw new ArgumentException(); int total = count; int inputIndex = offset; int err = 0; while (err >= 0 && inputIndex < total) { copyInput(data, inputIndex, Math.Min(total - inputIndex, kBufferSize)); while (err >= 0 && _ztream.avail_in > 0) { err = deflate(ref _ztream, (int)FlushTypes.None); if (err == 0) while (_ztream.avail_out == 0) { OnDataAvailable(); err = deflate(ref _ztream, (int)FlushTypes.None); } inputIndex += (int)_ztream.total_in; } } setChecksum( _ztream.adler ); } /// <summary> /// Finishes up any pending data that needs to be processed and handled. /// </summary> public override void Finish() { int err; do { err = deflate(ref _ztream, (int)FlushTypes.Finish); OnDataAvailable(); } while (err == 0); setChecksum( _ztream.adler ); deflateReset(ref _ztream); resetOutput(); } /// <summary> /// Closes the internal zlib deflate stream /// </summary> protected override void CleanUp() { deflateEnd(ref _ztream); } } }