stream.h

source code: Covert TXT to PDF

//========================================================================
//
// Stream.h
//
// Copyright 1996-2002 Glyph & Cog, LLC
//
//========================================================================

#ifndef STREAM_H
#define STREAM_H

#include <aconf.h>

#ifdef USE_GCC_PRAGMAS
#pragma interface
#endif

#include <stdio.h>
#include "gtypes.h"
#include "Object.h"

#ifndef NO_DECRYPTION
class Decrypt;
#endif
class BaseStream;

//------------------------------------------------------------------------

enum StreamKind {
  strFile,
  strASCIIHex,
  strASCII85,
  strLZW,
  strRunLength,
  strCCITTFax,
  strDCT,
  strFlate,
  strJBIG2,
  strWeird			// internal-use stream types
};

//------------------------------------------------------------------------
// Stream (base class)
//------------------------------------------------------------------------

class Stream {
public:

  // Constructor.
  Stream();

  // Destructor.
  virtual ~Stream();

  // Reference counting.
  int incRef() { return ++ref; }
  int decRef() { return --ref; }

  // Get kind of stream.
  virtual StreamKind getKind() = 0;

  // Reset stream to beginning.
  virtual void reset() = 0;

  // Close down the stream.
  virtual void close();

  // Get next char from stream.
  virtual int getChar() = 0;

  // Peek at next char in stream.
  virtual int lookChar() = 0;

  // Get next char from stream without using the predictor.
  // This is only used by StreamPredictor.
  virtual int getRawChar();

  // Get next line from stream.
  virtual char *getLine(char *buf, int size);

  // Get current position in file.
  virtual int getPos() = 0;

  // Go to a position in the stream.  If <dir> is negative, the
  // position is from the end of the file; otherwise the position is
  // from the start of the file.
  virtual void setPos(Guint pos, int dir = 0) = 0;

  // Get PostScript command for the filter(s).
  virtual GString *getPSFilter(char *indent);

  // Does this stream type potentially contain non-printable chars?
  virtual GBool isBinary(GBool last = gTrue) = 0;

  // Get the BaseStream or EmbedStream of this stream.
  virtual BaseStream *getBaseStream() = 0;

  // Get the dictionary associated with this stream.
  virtual Dict *getDict() = 0;

  // Is this an encoding filter?
  virtual GBool isEncoder() { return gFalse; }

  // Add filters to this stream according to the parameters in <dict>.
  // Returns the new stream.
  Stream *addFilters(Object *dict);

private:

  Stream *makeFilter(char *name, Stream *str, Object *params);

  int ref;			// reference count
};

//------------------------------------------------------------------------
// BaseStream
//
// This is the base class for all streams that read directly from a file.
//------------------------------------------------------------------------

class BaseStream: public Stream {
public:

  BaseStream(Object *dictA);
  virtual ~BaseStream();
  virtual Stream *makeSubStream(Guint start, GBool limited,
				Guint length, Object *dict) = 0;
  virtual void setPos(Guint pos, int dir = 0) = 0;
  virtual BaseStream *getBaseStream() { return this; }
  virtual Dict *getDict() { return dict.getDict(); }

  // Get/set position of first byte of stream within the file.
  virtual Guint getStart() = 0;
  virtual void moveStart(int delta) = 0;

#ifndef NO_DECRYPTION
  // Set decryption for this stream.
  virtual void doDecryption(Guchar *fileKey, int keyLength,
			    int objNum, int objGen);
#endif

#ifndef NO_DECRYPTION
protected:

  Decrypt *decrypt;
#endif

private:

  Object dict;
};

//------------------------------------------------------------------------
// FilterStream
//
// This is the base class for all streams that filter another stream.
//------------------------------------------------------------------------

class FilterStream: public Stream {
public:

  FilterStream(Stream *strA);
  virtual ~FilterStream();
  virtual void close();
  virtual int getPos() { return str->getPos(); }
  virtual void setPos(Guint pos, int dir = 0);
  virtual BaseStream *getBaseStream() { return str->getBaseStream(); }
  virtual Dict *getDict() { return str->getDict(); }

protected:

  Stream *str;
};

//------------------------------------------------------------------------
// ImageStream
//------------------------------------------------------------------------

class ImageStream {
public:

  // Create an image stream object for an image with the specified
  // parameters.  Note that these are the actual image parameters,
  // which may be different from the predictor parameters.
  ImageStream(Stream *strA, int widthA, int nCompsA, int nBitsA);

  ~ImageStream();

  // Reset the stream.
  void reset();

  // Gets the next pixel from the stream.  <pix> should be able to hold
  // at least nComps elements.  Returns false at end of file.
  GBool getPixel(Guchar *pix);

  // Returns a pointer to the next line of pixels.  Returns NULL at
  // end of file.
  Guchar *getLine();

  // Skip an entire line from the image.
  void skipLine();

private:

  Stream *str;			// base stream
  int width;			// pixels per line
  int nComps;			// components per pixel
  int nBits;			// bits per component
  int nVals;			// components per line
  Guchar *imgLine;		// line buffer
  int imgIdx;			// current index in imgLine
};

//------------------------------------------------------------------------
// StreamPredictor
//------------------------------------------------------------------------

class StreamPredictor {
public:

  // Create a predictor object.  Note that the parameters are for the
  // predictor, and may not match the actual image parameters.
  StreamPredictor(Stream *strA, int predictorA,
		  int widthA, int nCompsA, int nBitsA);

  ~StreamPredictor();

  int lookChar();
  int getChar();

private:

  GBool getNextLine();

  Stream *str;			// base stream
  int predictor;		// predictor
  int width;			// pixels per line
  int nComps;			// components per pixel
  int nBits;			// bits per component
  int nVals;			// components per line
  int pixBytes;			// bytes per pixel
  int rowBytes;			// bytes per line
  Guchar *predLine;		// line buffer
  int predIdx;			// current index in predLine
};

//------------------------------------------------------------------------
// FileStream
//------------------------------------------------------------------------

#define fileStreamBufSize 256

class FileStream: public BaseStream {
public:

  FileStream(FILE *fA, Guint startA, GBool limitedA,
	     Guint lengthA, Object *dictA);
  virtual ~FileStream();
  virtual Stream *makeSubStream(Guint startA, GBool limitedA,
				Guint lengthA, Object *dictA);
  virtual StreamKind getKind() { return strFile; }
  virtual void reset();
  virtual void close();
  virtual int getChar()
    { return (bufPtr >= bufEnd && !fillBuf()) ? EOF : (*bufPtr++ & 0xff); }
  virtual int lookChar()
    { return (bufPtr >= bufEnd && !fillBuf()) ? EOF : (*bufPtr & 0xff); }
  virtual int getPos() { return bufPos + (bufPtr - buf); }
  virtual void setPos(Guint pos, int dir = 0);
  virtual GBool isBinary(GBool last = gTrue) { return last; }
  virtual Guint getStart() { return start; }
  virtual void moveStart(int delta);

private:

  GBool fillBuf();

  FILE *f;
  Guint start;
  GBool limited;
  Guint length;
  char buf[fileStreamBufSize];
  char *bufPtr;
  char *bufEnd;
  Guint bufPos;
  int savePos;
  GBool saved;
};

//------------------------------------------------------------------------
// MemStream
//------------------------------------------------------------------------

class MemStream: public BaseStream {
public:

  MemStream(char *bufA, Guint lengthA, Object *dictA);
  virtual ~MemStream();
  virtual Stream *makeSubStream(Guint start, GBool limited,
				Guint lengthA, Object *dictA);
  virtual StreamKind getKind() { return strWeird; }
  virtual void reset();
  virtual void close();
  virtual int getChar()
    { return (bufPtr < bufEnd) ? (*bufPtr++ & 0xff) : EOF; }
  virtual int lookChar()
    { return (bufPtr < bufEnd) ? (*bufPtr & 0xff) : EOF; }
  virtual int getPos() { return bufPtr - buf; }
  virtual void setPos(Guint pos, int dir = 0);
  virtual GBool isBinary(GBool last = gTrue) { return last; }
  virtual Guint getStart() { return 0; }
  virtual void moveStart(int delta);
#ifndef NO_DECRYPTION
  virtual void doDecryption(Guchar *fileKey, int keyLength,
			    int objNum, int objGen);
#endif

private:

  char *buf;
  Guint length;
  GBool needFree;
  char *bufEnd;
  char *bufPtr;
};

//------------------------------------------------------------------------
// EmbedStream
//
// This is a special stream type used for embedded streams (inline
// images).  It reads directly from the base stream -- after the
// EmbedStream is deleted, reads from the base stream will proceed where
// the BaseStream left off.  Note that this is very different behavior
// that creating a new FileStream (using makeSubStream).
//------------------------------------------------------------------------

class EmbedStream: public BaseStream {
public:

  EmbedStream(Stream *strA, Object *dictA);
  virtual ~EmbedStream();
  virtual Stream *makeSubStream(Guint start, GBool limited,
				Guint length, Object *dictA);
  virtual StreamKind getKind() { return str->getKind(); }
  virtual void reset() {}
  virtual int getChar() { return str->getChar(); }
  virtual int lookChar() { return str->lookChar(); }
  virtual int getPos() { return str->getPos(); }
  virtual void setPos(Guint pos, int dir = 0);
  virtual GBool isBinary(GBool last = gTrue) { return last; }
  virtual Guint getStart();
  virtual void moveStart(int delta);

private:

  Stream *str;
};

//------------------------------------------------------------------------
// ASCIIHexStream
//------------------------------------------------------------------------

class ASCIIHexStream: public FilterStream {
public:

  ASCIIHexStream(Stream *strA);
  virtual ~ASCIIHexStream();
  virtual StreamKind getKind() { return strASCIIHex; }
  virtual void reset();
  virtual int getChar()
    { int c = lookChar(); buf = EOF; return c; }
  virtual int lookChar();
  virtual GString *getPSFilter(char *indent);
  virtual GBool isBinary(GBool last = gTrue);

private:

  int buf;
  GBool eof;
};

//------------------------------------------------------------------------
// ASCII85Stream
//------------------------------------------------------------------------

class ASCII85Stream: public FilterStream {
public:

  ASCII85Stream(Stream *strA);
  virtual ~ASCII85Stream();
  virtual StreamKind getKind() { return strASCII85; }
  virtual void reset();
  virtual int getChar()
    { int ch = lookChar(); ++index; return ch; }
  virtual int lookChar();
  virtual GString *getPSFilter(char *indent);
  virtual GBool isBinary(GBool last = gTrue);

private:

  int c[5];
  int b[4];
  int index, n;
  GBool eof;
};

//------------------------------------------------------------------------
// LZWStream
//------------------------------------------------------------------------

class LZWStream: public FilterStream {
public:

  LZWStream(Stream *strA, int predictor, int columns, int colors,
	    int bits, int earlyA);
  virtual ~LZWStream();
  virtual StreamKind getKind() { return strLZW; }
  virtual void reset();
  virtual int getChar();