stream.cc

这是一个做pdf阅读器的源代码文件,是大家学习阅读器资料的很好参考

  bufPtr = bufEnd = buf;
  bufPos = start;
  savePos = 0;
  saved = gFalse;
}

FileStream::~FileStream() {
  close();
}

Stream *FileStream::makeSubStream(Guint startA, GBool limitedA,
				  Guint lengthA, Object *dictA) {
  return new FileStream(f, startA, limitedA, lengthA, dictA);
}

void FileStream::reset() {
#if HAVE_FSEEKO
  savePos = (Guint)ftello(f);
  fseeko(f, start, SEEK_SET);
#elif HAVE_FSEEK64
  savePos = (Guint)ftell64(f);
  fseek64(f, start, SEEK_SET);
#else
  savePos = (Guint)ftell(f);
  fseek(f, start, SEEK_SET);
#endif
  saved = gTrue;
  bufPtr = bufEnd = buf;
  bufPos = start;
}

void FileStream::close() {
  if (saved) {
#if HAVE_FSEEKO
    fseeko(f, savePos, SEEK_SET);
#elif HAVE_FSEEK64
    fseek64(f, savePos, SEEK_SET);
#else
    fseek(f, savePos, SEEK_SET);
#endif
    saved = gFalse;
  }
}

GBool FileStream::fillBuf() {
  int n;

  bufPos += bufEnd - buf;
  bufPtr = bufEnd = buf;
  if (limited && bufPos >= start + length) {
    return gFalse;
  }
  if (limited && bufPos + fileStreamBufSize > start + length) {
    n = start + length - bufPos;
  } else {
    n = fileStreamBufSize;
  }
  n = fread(buf, 1, n, f);
  bufEnd = buf + n;
  if (bufPtr >= bufEnd) {
    return gFalse;
  }
  return gTrue;
}

void FileStream::setPos(Guint pos, int dir) {
  Guint size;

  if (dir >= 0) {
#if HAVE_FSEEKO
    fseeko(f, pos, SEEK_SET);
#elif HAVE_FSEEK64
    fseek64(f, pos, SEEK_SET);
#else
    fseek(f, pos, SEEK_SET);
#endif
    bufPos = pos;
  } else {
#if HAVE_FSEEKO
    fseeko(f, 0, SEEK_END);
    size = (Guint)ftello(f);
#elif HAVE_FSEEK64
    fseek64(f, 0, SEEK_END);
    size = (Guint)ftell64(f);
#else
    fseek(f, 0, SEEK_END);
    size = (Guint)ftell(f);
#endif
    if (pos > size)
      pos = (Guint)size;
#ifdef __CYGWIN32__
    //~ work around a bug in cygwin's implementation of fseek
    rewind(f);
#endif
#if HAVE_FSEEKO
    fseeko(f, -(int)pos, SEEK_END);
    bufPos = (Guint)ftello(f);
#elif HAVE_FSEEK64
    fseek64(f, -(int)pos, SEEK_END);
    bufPos = (Guint)ftell64(f);
#else
    fseek(f, -(int)pos, SEEK_END);
    bufPos = (Guint)ftell(f);
#endif
  }
  bufPtr = bufEnd = buf;
}

void FileStream::moveStart(int delta) {
  start += delta;
  bufPtr = bufEnd = buf;
  bufPos = start;
}

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

MemStream::MemStream(char *bufA, Guint startA, Guint lengthA, Object *dictA):
    BaseStream(dictA) {
  buf = bufA;
  start = startA;
  length = lengthA;
  bufEnd = buf + start + length;
  bufPtr = buf + start;
  needFree = gFalse;
}

MemStream::~MemStream() {
  if (needFree) {
    gfree(buf);
  }
}

Stream *MemStream::makeSubStream(Guint startA, GBool limited,
				 Guint lengthA, Object *dictA) {
  MemStream *subStr;
  Guint newLength;

  if (!limited || startA + lengthA > start + length) {
    newLength = start + length - startA;
  } else {
    newLength = lengthA;
  }
  subStr = new MemStream(buf, startA, newLength, dictA);
  return subStr;
}

void MemStream::reset() {
  bufPtr = buf + start;
}

void MemStream::close() {
}

void MemStream::setPos(Guint pos, int dir) {
  Guint i;

  if (dir >= 0) {
    i = pos;
  } else {
    i = start + length - pos;
  }
  if (i < start) {
    i = start;
  } else if (i > start + length) {
    i = start + length;
  }
  bufPtr = buf + i;
}

void MemStream::moveStart(int delta) {
  start += delta;
  length -= delta;
  bufPtr = buf + start;
}

//------------------------------------------------------------------------
// EmbedStream
//------------------------------------------------------------------------

EmbedStream::EmbedStream(Stream *strA, Object *dictA,
			 GBool limitedA, Guint lengthA):
    BaseStream(dictA) {
  str = strA;
  limited = limitedA;
  length = lengthA;
}

EmbedStream::~EmbedStream() {
}

Stream *EmbedStream::makeSubStream(Guint start, GBool limitedA,
				   Guint lengthA, Object *dictA) {
  error(-1, "Internal: called makeSubStream() on EmbedStream");
  return NULL;
}

int EmbedStream::getChar() {
  if (limited && !length) {
    return EOF;
  }
  --length;
  return str->getChar();
}

int EmbedStream::lookChar() {
  if (limited && !length) {
    return EOF;
  }
  return str->lookChar();
}

void EmbedStream::setPos(Guint pos, int dir) {
  error(-1, "Internal: called setPos() on EmbedStream");
}

Guint EmbedStream::getStart() {
  error(-1, "Internal: called getStart() on EmbedStream");
  return 0;
}

void EmbedStream::moveStart(int delta) {
  error(-1, "Internal: called moveStart() on EmbedStream");
}

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

ASCIIHexStream::ASCIIHexStream(Stream *strA):
    FilterStream(strA) {
  buf = EOF;
  eof = gFalse;
}

ASCIIHexStream::~ASCIIHexStream() {
  delete str;
}

void ASCIIHexStream::reset() {
  str->reset();
  buf = EOF;
  eof = gFalse;
}

int ASCIIHexStream::lookChar() {
  int c1, c2, x;

  if (buf != EOF)
    return buf;
  if (eof) {
    buf = EOF;
    return EOF;
  }
  do {
    c1 = str->getChar();
  } while (isspace(c1));
  if (c1 == '>') {
    eof = gTrue;
    buf = EOF;
    return buf;
  }
  do {
    c2 = str->getChar();
  } while (isspace(c2));
  if (c2 == '>') {
    eof = gTrue;
    c2 = '0';
  }
  if (c1 >= '0' && c1 <= '9') {
    x = (c1 - '0') << 4;
  } else if (c1 >= 'A' && c1 <= 'F') {
    x = (c1 - 'A' + 10) << 4;
  } else if (c1 >= 'a' && c1 <= 'f') {
    x = (c1 - 'a' + 10) << 4;
  } else if (c1 == EOF) {
    eof = gTrue;
    x = 0;
  } else {
    error(getPos(), "Illegal character <%02x> in ASCIIHex stream", c1);
    x = 0;
  }
  if (c2 >= '0' && c2 <= '9') {
    x += c2 - '0';
  } else if (c2 >= 'A' && c2 <= 'F') {
    x += c2 - 'A' + 10;
  } else if (c2 >= 'a' && c2 <= 'f') {
    x += c2 - 'a' + 10;
  } else if (c2 == EOF) {
    eof = gTrue;
    x = 0;
  } else {
    error(getPos(), "Illegal character <%02x> in ASCIIHex stream", c2);
  }
  buf = x & 0xff;
  return buf;
}

GString *ASCIIHexStream::getPSFilter(int psLevel, char *indent) {
  GString *s;

  if (psLevel < 2) {
    return NULL;
  }
  if (!(s = str->getPSFilter(psLevel, indent))) {
    return NULL;
  }
  s->append(indent)->append("/ASCIIHexDecode filter\n");
  return s;
}

GBool ASCIIHexStream::isBinary(GBool last) {
  return str->isBinary(gFalse);
}

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

ASCII85Stream::ASCII85Stream(Stream *strA):
    FilterStream(strA) {
  index = n = 0;
  eof = gFalse;
}

ASCII85Stream::~ASCII85Stream() {
  delete str;
}

void ASCII85Stream::reset() {
  str->reset();
  index = n = 0;
  eof = gFalse;
}

int ASCII85Stream::lookChar() {
  int k;
  Gulong t;

  if (index >= n) {
    if (eof)
      return EOF;
    index = 0;
    do {
      c[0] = str->getChar();
    } while (Lexer::isSpace(c[0]));
    if (c[0] == '~' || c[0] == EOF) {
      eof = gTrue;
      n = 0;
      return EOF;
    } else if (c[0] == 'z') {
      b[0] = b[1] = b[2] = b[3] = 0;
      n = 4;
    } else {
      for (k = 1; k < 5; ++k) {
	do {
	  c[k] = str->getChar();
	} while (Lexer::isSpace(c[k]));
	if (c[k] == '~' || c[k] == EOF)
	  break;
      }
      n = k - 1;
      if (k < 5 && (c[k] == '~' || c[k] == EOF)) {
	for (++k; k < 5; ++k)
	  c[k] = 0x21 + 84;
	eof = gTrue;
      }
      t = 0;
      for (k = 0; k < 5; ++k)
	t = t * 85 + (c[k] - 0x21);
      for (k = 3; k >= 0; --k) {
	b[k] = (int)(t & 0xff);
	t >>= 8;
      }
    }
  }
  return b[index];
}

GString *ASCII85Stream::getPSFilter(int psLevel, char *indent) {
  GString *s;

  if (psLevel < 2) {
    return NULL;
  }
  if (!(s = str->getPSFilter(psLevel, indent))) {
    return NULL;
  }
  s->append(indent)->append("/ASCII85Decode filter\n");
  return s;
}

GBool ASCII85Stream::isBinary(GBool last) {
  return str->isBinary(gFalse);
}

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

LZWStream::LZWStream(Stream *strA, int predictor, int columns, int colors,
		     int bits, int earlyA):
    FilterStream(strA) {
  if (predictor != 1) {
    pred = new StreamPredictor(this, predictor, columns, colors, bits);
    if (!pred->isOk()) {
      delete pred;
      pred = NULL;
    }
  } else {
    pred = NULL;
  }
  early = earlyA;
  eof = gFalse;
  inputBits = 0;
  clearTable();
}

LZWStream::~LZWStream() {
  if (pred) {
    delete pred;
  }
  delete str;
}

int LZWStream::getChar() {
  if (pred) {
    return pred->getChar();
  }
  if (eof) {
    return EOF;
  }
  if (seqIndex >= seqLength) {
    if (!processNextCode()) {
      return EOF;
    }
  }
  return seqBuf[seqIndex++];
}

int LZWStream::lookChar() {
  if (pred) {
    return pred->lookChar();
  }
  if (eof) {
    return EOF;
  }
  if (seqIndex >= seqLength) {
    if (!processNextCode()) {
      return EOF;
    }
  }
  return seqBuf[seqIndex];
}

int LZWStream::getRawChar() {
  if (eof) {
    return EOF;
  }
  if (seqIndex >= seqLength) {
    if (!processNextCode()) {
      return EOF;
    }
  }
  return seqBuf[seqIndex++];
}

void LZWStream::reset() {
  str->reset();
  eof = gFalse;
  inputBits = 0;
  clearTable();
}

GBool LZWStream::processNextCode() {
  int code;
  int nextLength;
  int i, j;

  // check for EOF
  if (eof) {
    return gFalse;
  }

  // check for eod and clear-table codes
 start:
  code = getCode();
  if (code == EOF || code == 257) {
    eof = gTrue;
    return gFalse;
  }
  if (code == 256) {
    clearTable();
    goto start;
  }
  if (nextCode >= 4097) {
    error(getPos(), "Bad LZW stream - expected clear-table code");
    clearTable();
  }

  // process the next code
  nextLength = seqLength + 1;
  if (code < 256) {
    seqBuf[0] = code;
    seqLength = 1;
  } else if (code < nextCode) {
    seqLength = table[code].length;
    for (i = seqLength - 1, j = code; i > 0; --i) {
      seqBuf[i] = table[j].tail;
      j = table[j].head;
    }
    seqBuf[0] = j;
  } else if (code == nextCode) {
    seqBuf[seqLength] = newChar;
    ++seqLength;
  } else {
    error(getPos(), "Bad LZW stream - unexpected code");
    eof = gTrue;
    return gFalse;
  }
  newChar = seqBuf[0];
  if (first) {
    first = gFalse;
  } else {
    table[nextCode].length = nextLength;
    table[nextCode].head = prevCode;
    table[nextCode].tail = newChar;
    ++nextCode;
    if (nextCode + early == 512)
      nextBits = 10;
    else if (nextCode + early == 1024)
      nextBits = 11;
    else if (nextCode + early == 2048)
      nextBits = 12;
  }
  prevCode = code;

  // reset buffer
  seqIndex = 0;

  return gTrue;
}

void LZWStream::clearTable() {
  nextCode = 258;
  nextBits = 9;
  seqIndex = seqLength = 0;
  first = gTrue;
}

int LZWStream::getCode() {
  int c;
  int code;

  while (inputBits < nextBits) {
    if ((c = str->getChar()) == EOF)
      return EOF;
    inputBuf = (inputBuf << 8) | (c & 0xff);
    inputBits += 8;
  }
  code = (inputBuf >> (inputBits - nextBits)) & ((1 << nextBits) - 1);
  inputBits -= nextBits;
  return code;
}

GString *LZWStream::getPSFilter(int psLevel, char *indent) {
  GString *s;

  if (psLevel < 2 || pred) {
    return NULL;
  }
  if (!(s = str->getPSFilter(psLevel, indent))) {
    return NULL;
  }
  s->append(indent)->append("<< ");
  if (!early) {
    s->append("/EarlyChange 0 ");
  }
  s->append(">> /LZWDecode filter\n");
  return s;
}