inflaterinputstream.cs

用C#實現能產生PDF格式文件的源碼

// InflaterInputStream.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using System;
using System.IO;

using PdfSharp.SharpZipLib.Zip.Compression;
using PdfSharp.SharpZipLib.Checksums;

namespace PdfSharp.SharpZipLib.Zip.Compression.Streams 
{
	
	/// <summary>
	/// This filter stream is used to decompress data compressed using the "deflate"
	/// format. The "deflate" format is described in RFC 1951.
	///
	/// Author of the original java version : John Leuner.
	/// </summary>
	internal class InflaterInputStream : Stream
	{
		/// <summary>
		/// Decompressor for this stream
		/// </summary>
		protected Inflater inf;
		
		/// <summary>
		/// Byte array used for buffering input.
		/// </summary>
		protected byte[] buf;

		/// <summary>
		/// Size of buffer <see cref="buf"></see>
		/// </summary>
		protected int len;
		
		// Used for reading single bytes the ReadByte() call
		private byte[] onebytebuffer = new byte[1];
		
		/// <summary>
		/// Base stream the inflater reads from.
		/// </summary>
		protected Stream baseInputStream;
		
    ////		/// <summary>
    ////		/// The compressed size
    ////		/// </summary>
    ////		protected long csize;
		
		bool isStreamOwner = true;
		
		/// <summary>
		/// Get/set flag indicating ownership of underlying stream.
		/// When the flag is true <see cref="Close"/> will close the underlying stream also.
		/// </summary>
		/// <remarks>
		/// The default value is true.
		/// </remarks>
		public bool IsStreamOwner
		{
			get { return isStreamOwner; }
			set { isStreamOwner = value; }
		}
		
		/// <summary>
		/// Gets a value indicating whether the current stream supports reading
		/// </summary>
		public override bool CanRead {
			get {
				return baseInputStream.CanRead;
			}
		}
		
		/// <summary>
		/// Gets a value of false indicating seeking is not supported for this stream.
		/// </summary>
		public override bool CanSeek {
			get {
				return false;
			}
		}
		
		/// <summary>
		/// Gets a value of false indicating that this stream is not writeable.
		/// </summary>
		public override bool CanWrite {
			get {
				return false;
			}
		}
		
		/// <summary>
		/// A value representing the length of the stream in bytes.
		/// </summary>
		public override long Length {
			get {
				return len;
			}
		}
		
		/// <summary>
		/// The current position within the stream.
		/// Throws a NotSupportedException when attempting to set the position
		/// </summary>
		/// <exception cref="NotSupportedException">Attempting to set the position</exception>
		public override long Position {
			get {
				return baseInputStream.Position;
			}
			set {
				throw new NotSupportedException("InflaterInputStream Position not supported");
			}
		}
		
		/// <summary>
		/// Flushes the baseInputStream
		/// </summary>
		public override void Flush()
		{
			baseInputStream.Flush();
		}
		
		/// <summary>
		/// Sets the position within the current stream
		/// Always throws a NotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override long Seek(long offset, SeekOrigin origin)
		{
			throw new NotSupportedException("Seek not supported");
		}
		
		/// <summary>
		/// Set the length of the current stream
		/// Always throws a NotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override void SetLength(long val)
		{
			throw new NotSupportedException("InflaterInputStream SetLength not supported");
		}
		
		/// <summary>
		/// Writes a sequence of bytes to stream and advances the current position
		/// This method always throws a NotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override void Write(byte[] array, int offset, int count)
		{
			throw new NotSupportedException("InflaterInputStream Write not supported");
		}
		
		/// <summary>
		/// Writes one byte to the current stream and advances the current position
		/// Always throws a NotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override void WriteByte(byte val)
		{
			throw new NotSupportedException("InflaterInputStream WriteByte not supported");
		}
		
		/// <summary>
		/// Entry point to begin an asynchronous write.  Always throws a NotSupportedException.
		/// </summary>
		/// <param name="buffer">The buffer to write data from</param>
		/// <param name="offset">Offset of first byte to write</param>
		/// <param name="count">The maximum number of bytes to write</param>
		/// <param name="callback">The method to be called when the asynchronous write operation is completed</param>
		/// <param name="state">A user-provided object that distinguishes this particular asynchronous write request from other requests</param>
		/// <returns>An <see cref="System.IAsyncResult">IAsyncResult</see> that references the asynchronous write</returns>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
		{
			throw new NotSupportedException("InflaterInputStream BeginWrite not supported");
		}
		
		/// <summary>
		/// Create an InflaterInputStream with the default decompressor
		/// and a default buffer size of 4KB.
		/// </summary>
		/// <param name = "baseInputStream">
		/// The InputStream to read bytes from
		/// </param>
		public InflaterInputStream(Stream baseInputStream) : this(baseInputStream, new Inflater(), 4096)
		{
		}
		
		/// <summary>
		/// Create an InflaterInputStream with the specified decompressor
		/// and a default buffer size of 4KB.
		/// </summary>
		/// <param name = "baseInputStream">
		/// The source of input data
		/// </param>
		/// <param name = "inf">
		/// The decompressor used to decompress data read from baseInputStream
		/// </param>
		public InflaterInputStream(Stream baseInputStream, Inflater inf) : this(baseInputStream, inf, 4096)
		{
		}
		
		/// <summary>
		/// Create an InflaterInputStream with the specified decompressor
		/// and the specified buffer size.
		/// </summary>
		/// <param name = "baseInputStream">
		/// The InputStream to read bytes from
		/// </param>
		/// <param name = "inflater">
		/// The decompressor to use
		/// </param>
		/// <param name = "bufferSize">
		/// Size of the buffer to use
		/// </param>
		public InflaterInputStream(Stream baseInputStream, Inflater inflater, int bufferSize)
		{
			if (baseInputStream == null) {
				throw new ArgumentNullException("InflaterInputStream baseInputStream is null");
			}
			
			if (inflater == null) {
				throw new ArgumentNullException("InflaterInputStream Inflater is null");
			}
			
			if (bufferSize <= 0) {
				throw new ArgumentOutOfRangeException("bufferSize");
			}
			
			this.baseInputStream = baseInputStream;
			this.inf = inflater;
			buf = new byte[bufferSize];
			
			if (baseInputStream.CanSeek) {