/*=========================================================================

  Program:   Visualization Toolkit
  Module:    vtkBase64InputStream.h

  Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notice for more information.

=========================================================================*/
// .NAME vtkBase64InputStream - Reads base64-encoded input from a stream.
// .SECTION Description
// vtkBase64InputStream implements base64 decoding with the
// vtkInputStream interface.

#ifndef __vtkBase64InputStream_h
#define __vtkBase64InputStream_h

#include "vtkInputStream.h"

class VTK_IO_EXPORT vtkBase64InputStream : public vtkInputStream
{
public:
  vtkTypeRevisionMacro(vtkBase64InputStream,vtkInputStream);
  static vtkBase64InputStream *New();
  void PrintSelf(ostream& os, vtkIndent indent);
  
  // Description:
  // Called after the stream position has been set by the caller, but
  // before any Seek or Read calls.  The stream position should not be
  // adjusted by the caller until after an EndReading call.
  void StartReading();
  
  // Description:
  // Seek to the given offset in the input data.  Returns 1 for
  // success, 0 for failure.
  int Seek(unsigned long offset);
  
  // Description:
  // Read input data of the given length.  Returns amount actually
  // read.
  unsigned long Read(unsigned char* data, unsigned long length);
  
  // Description:
  // Called after all desired calls to Seek and Read have been made.
  // After this call, the caller is free to change the position of the
  // stream.  Additional reads should not be done until after another
  // call to StartReading.
  void EndReading();
protected:
  vtkBase64InputStream();
  ~vtkBase64InputStream();  
  
  // Number of decoded bytes left in Buffer from last call to Read.
  int BufferLength;
  unsigned char Buffer[2];
  
  // Reads 4 bytes from the input stream and decodes them into 3 bytes.
  int DecodeTriplet(unsigned char& c0, unsigned char& c1, unsigned char& c2);

private:
  vtkBase64InputStream(const vtkBase64InputStream&);  // Not implemented.
  void operator=(const vtkBase64InputStream&);  // Not implemented.
};

#endif
