Stream.h

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

#ifndef STREAM_H
#define STREAM_H

#ifdef __GNUC__
#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,
  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);

  // 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();
  virtual int lookChar();
  virtual int getRawChar();
  virtual GString *getPSFilter(char *indent);
  virtual GBool isBinary(GBool last = gTrue);

private:

  StreamPredictor *pred;        // predictor
  int early;                    // early parameter
  FILE *zPipe;                  // uncompress pipe
  GString *zName;               // .Z file name
  int inputBuf;                 // input buffer
  int inputBits;                // number of bits in input buffer
  int inCodeBits;               // size of input code
  char buf[256];                // buffer
  char *bufPtr;                 // next char to read
  char *bufEnd;                 // end of buffer

  void dumpFile(FILE *f);
  int getCode();
  GBool fillBuf();
};

//------------------------------------------------------------------------
// RunLengthStream
//------------------------------------------------------------------------

class RunLengthStream: public FilterStream {
public:

  RunLengthStream(Stream *strA);
  virtual ~RunLengthStream();
  virtual StreamKind getKind() { return strRunLength; }
  virtual void reset();
  virtual int getChar()
    { return (bufPtr >= bufEnd && !fillBuf()) ? EOF : (*bufPtr++ & 0xff); }
  virtual int lookChar()
    { return (bufPtr >= bufEnd && !fillBuf()) ? EOF : (*bufPtr & 0xff); }
  virtual GString *getPSFilter(char *indent);
  virtual GBool isBinary(GBool last = gTrue);

private:

  char buf[128];                // buffer
  char *bufPtr;                 // next char to read
  char *bufEnd;                 // end of buffer
  GBool eof;

  GBool fillBuf();
};

//------------------------------------------------------------------------
// CCITTFaxStream
//------------------------------------------------------------------------

struct CCITTCodeTable;

class CCITTFaxStream: public FilterStream {
public:

  CCITTFaxStream(Stream *strA, int encodingA, GBool endOfLineA,
                 GBool byteAlignA, int columnsA, int rowsA,
                 GBool endOfBlockA, GBool blackA);
  virtual ~CCITTFaxStream();
  virtual StreamKind getKind() { return strCCITTFax; }
  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 encoding;                 // 'K' parameter
  GBool endOfLine;              // 'EndOfLine' parameter
  GBool byteAlign;              // 'EncodedByteAlign' parameter
  int columns;                  // 'Columns' parameter
  int rows;                     // 'Rows' parameter
  GBool endOfBlock;             // 'EndOfBlock' parameter
  GBool black;                  // 'BlackIs1' parameter
  GBool eof;                    // true if at eof
  GBool nextLine2D;             // true if next line uses 2D encoding
  int row;                      // current row
  int inputBuf;                 // input buffer
  int inputBits;                // number of bits in input buffer
  short *refLine;               // reference line changing elements
  int b1;                       // index into refLine
  short *codingLine;            // coding line changing elements
  int a0;                       // index into codingLine
  int outputBits;               // remaining ouput bits
  int buf;                      // character buffer

  short getTwoDimCode();
  short getWhiteCode();
  short getBlackCode();
  short lookBits(int n);
  void eatBits(int n) { inputBits -= n; }
};

//------------------------------------------------------------------------
// DCTStream
//------------------------------------------------------------------------

// DCT component info
struct DCTCompInfo {
  int id;                       // component ID
  GBool inScan;                 // is this component in the current scan?
  int hSample, vSample;         // horiz/vert sampling resolutions
  int quantTable;               // quantization table number
  int dcHuffTable, acHuffTable; // Huffman table numbers
  int prevDC;                   // DC coefficient accumulator
};

// DCT Huffman decoding table
struct DCTHuffTable {
  Guchar firstSym[17];          // first symbol for this bit length
  Gushort firstCode[17];        // first code for this bit length
  Gushort numCodes[17];         // number of codes of this bit length
  Guchar sym[256];              // symbols
};

class DCTStream: public FilterStream {
public:

  DCTStream(Stream *strA);
  virtual ~DCTStream();
  virtual StreamKind getKind() { return strDCT; }
  virtual void reset();
  virtual int getChar();
  virtual int lookChar();
  virtual GString *getPSFilter(char *indent);
  virtual GBool isBinary(GBool last = gTrue);
  Stream *getRawStream() { return str; }

private:

  int width, height;            // image size
  int mcuWidth, mcuHeight;      // size of min coding unit, in data units
  DCTCompInfo compInfo[4];      // info for each component
  int numComps;                 // number of components in image
  int colorXform;               // need YCbCr-to-RGB transform?
  GBool gotAdobeMarker;         // set if APP14 Adobe marker was present
  int restartInterval;          // restart interval, in MCUs
  Guchar quantTables[4][64];    // quantization tables
  int numQuantTables;           // number of quantization tables
  DCTHuffTable dcHuffTables[4]; // DC Huffman tables
  DCTHuffTable acHuffTables[4]; // AC Huffman tables
  int numDCHuffTables;          // number of DC Huffman tables
  int numACHuffTables;          // number of AC Huffman tables
  Guchar *rowBuf[4][32];        // buffer for one MCU
  int comp, x, y, dy;           // current position within image/MCU
  int restartCtr;               // MCUs left until restart
  int restartMarker;            // next restart marker
  int inputBuf;                 // input buffer for variable length codes
  int inputBits;                // number of valid bits in input buffer

  void restart();
  GBool readMCURow();
  GBool readDataUnit(DCTHuffTable *dcHuffTable, DCTHuffTable *acHuffTable,
                     Guchar quantTable[64], int *prevDC, Guchar data[64]);
  int readHuffSym(DCTHuffTable *table);
  int readAmp(int size);
  int readBit();
  GBool readHeader();
  GBool readFrameInfo();
  GBool readScanInfo();
  GBool readQuantTables();
  GBool readHuffmanTables();
  GBool readRestartInterval();
  GBool readAdobeMarker();
  GBool readTrailer();
  int readMarker();
  int read16();
};

//------------------------------------------------------------------------
// FlateStream
//------------------------------------------------------------------------

#define flateWindow          32768    // buffer size
#define flateMask            (flateWindow-1)
#define flateMaxHuffman         15    // max Huffman code length
#define flateMaxCodeLenCodes    19    // max # code length codes
#define flateMaxLitCodes       288    // max # literal codes
#define flateMaxDistCodes       30    // max # distance codes

// Huffman code table entry
struct FlateCode {
  int len;                      // code length in bits
  int code;                     // code word
  int val;                      // value represented by this code
};

// Huffman code table
struct FlateHuffmanTab {
  int start[flateMaxHuffman+2]; // indexes of first code of each length
  FlateCode *codes;             // codes, sorted by length and code word
};

// Decoding info for length and distance code words
struct FlateDecode {
  int bits;                     // # extra bits
  int first;                    // first length/distance
};

class FlateStream: public FilterStream {
public:

  FlateStream(Stream *strA, int predictor, int columns,
              int colors, int bits);
  virtual ~FlateStream();
  virtual StreamKind getKind() { return strFlate; }
  virtual void reset();
  virtual int getChar();
  virtual int lookChar();
  virtual int getRawChar();
  virtual GString *getPSFilter(char *indent);
  virtual GBool isBinary(GBool last = gTrue);

private:

  StreamPredictor *pred;        // predictor
  Guchar buf[flateWindow];      // output data buffer
  int index;                    // current index into output buffer
  int remain;                   // number valid bytes in output buffer
  int codeBuf;                  // input buffer
  int codeSize;                 // number of bits in input buffer
  FlateCode                     // literal and distance codes
    allCodes[flateMaxLitCodes + flateMaxDistCodes];
  FlateHuffmanTab litCodeTab;   // literal code table
  FlateHuffmanTab distCodeTab;  // distance code table
  GBool compressedBlock;        // set if reading a compressed block
  int blockLen;                 // remaining length of uncompressed block
  GBool endOfBlock;             // set when end of block is reached
  GBool eof;                    // set when end of stream is reached

  static int                    // code length code reordering
    codeLenCodeMap[flateMaxCodeLenCodes];
  static FlateDecode            // length decoding info
    lengthDecode[flateMaxLitCodes-257];
  static FlateDecode            // distance decoding info
    distDecode[flateMaxDistCodes];

  void readSome();
  GBool startBlock();
  void loadFixedCodes();
  GBool readDynamicCodes();
  void compHuffmanCodes(FlateHuffmanTab *tab, int n);
  int getHuffmanCodeWord(FlateHuffmanTab *tab);
  int getCodeWord(int bits);
};

//------------------------------------------------------------------------
// EOFStream
//------------------------------------------------------------------------

class EOFStream: public FilterStream {
public:

  EOFStream(Stream *strA);
  virtual ~EOFStream();
  virtual StreamKind getKind() { return strWeird; }
  virtual void reset() {}
  virtual int getChar() { return EOF; }
  virtual int lookChar() { return EOF; }
  virtual GString *getPSFilter(char *indent)  { return NULL; }
  virtual GBool isBinary(GBool last = gTrue) { return gFalse; }
};

//------------------------------------------------------------------------
// FixedLengthEncoder
//------------------------------------------------------------------------

class FixedLengthEncoder: public FilterStream {
public:

  FixedLengthEncoder(Stream *strA, int lengthA);
  ~FixedLengthEncoder();
  virtual StreamKind getKind() { return strWeird; }
  virtual void reset();
  virtual void close();
  virtual int getChar();
  virtual int lookChar();
  virtual GString *getPSFilter(char *indent) { return NULL; }
  virtual GBool isBinary(GBool last = gTrue) { return gFalse; }
  virtual GBool isEncoder() { return gTrue; }

private:

  int length;
  int count;
};

//------------------------------------------------------------------------
// ASCIIHexEncoder
//------------------------------------------------------------------------

class ASCIIHexEncoder: public FilterStream {
public:

  ASCIIHexEncoder(Stream *strA);
  virtual ~ASCIIHexEncoder();
  virtual StreamKind getKind() { return strWeird; }
  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 GString *getPSFilter(char *indent) { return NULL; }
  virtual GBool isBinary(GBool last = gTrue) { return gFalse; }
  virtual GBool isEncoder() { return gTrue; }

private:

  char buf[4];
  char *bufPtr;
  char *bufEnd;
  int lineLen;
  GBool eof;

  GBool fillBuf();
};

//------------------------------------------------------------------------
// ASCII85Encoder
//------------------------------------------------------------------------

class ASCII85Encoder: public FilterStream {
public:

  ASCII85Encoder(Stream *strA);
  virtual ~ASCII85Encoder();
  virtual StreamKind getKind() { return strWeird; }
  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 GString *getPSFilter(char *indent) { return NULL; }
  virtual GBool isBinary(GBool last = gTrue) { return gFalse; }
  virtual GBool isEncoder() { return gTrue; }

private:

  char buf[8];
  char *bufPtr;
  char *bufEnd;
  int lineLen;
  GBool eof;

  GBool fillBuf();
};

//------------------------------------------------------------------------
// RunLengthEncoder
//------------------------------------------------------------------------

class RunLengthEncoder: public FilterStream {
public:

  RunLengthEncoder(Stream *strA);
  virtual ~RunLengthEncoder();
  virtual StreamKind getKind() { return strWeird; }
  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 GString *getPSFilter(char *indent) { return NULL; }
  virtual GBool isBinary(GBool last = gTrue) { return gFalse; }
  virtual GBool isEncoder() { return gTrue; }

private:

  char buf[131];
  char *bufPtr;
  char *bufEnd;
  char *nextEnd;
  GBool eof;

  GBool fillBuf();
};

#endif

---