jbig2stream.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

      if (bufLen <= 12) {
	code = buf << (12 - bufLen);
      } else {
	code = buf >> (bufLen - 12);
      }
      p = &whiteTab1[code & 0x1f];
    } else {
      if (bufLen <= 9) {
	code = buf << (9 - bufLen);
      } else {
	code = buf >> (bufLen - 9);
      }
      p = &whiteTab2[code & 0x1ff];
    }
    if (p->bits > 0 && p->bits <= (int)bufLen) {
      bufLen -= p->bits;
      return p->n;
    }
    if (bufLen >= 12) {
      break;
    }
    buf = (buf << 8) | (str->getChar() & 0xff);
    bufLen += 8;
    ++nBytesRead;
  }
  error(str->getPos(), "Bad white code in JBIG2 MMR stream");
  // eat a bit and return a positive number so that the caller doesn't
  // go into an infinite loop
  --bufLen;
  return 1;
}

int JBIG2MMRDecoder::getBlackCode() {
  CCITTCode *p;
  Guint code;

  if (bufLen == 0) {
    buf = str->getChar() & 0xff;
    bufLen = 8;
    ++nBytesRead;
  }
  while (1) {
    if (bufLen >= 6 && ((buf >> (bufLen - 6)) & 0x3f) == 0) {
      if (bufLen <= 13) {
	code = buf << (13 - bufLen);
      } else {
	code = buf >> (bufLen - 13);
      }
      p = &blackTab1[code & 0x7f];
    } else if (bufLen >= 4 && ((buf >> (bufLen - 4)) & 0x0f) == 0) {
      if (bufLen <= 12) {
	code = buf << (12 - bufLen);
      } else {
	code = buf >> (bufLen - 12);
      }
      p = &blackTab2[(code & 0xff) - 64];
    } else {
      if (bufLen <= 6) {
	code = buf << (6 - bufLen);
      } else {
	code = buf >> (bufLen - 6);
      }
      p = &blackTab3[code & 0x3f];
    }
    if (p->bits > 0 && p->bits <= (int)bufLen) {
      bufLen -= p->bits;
      return p->n;
    }
    if (bufLen >= 13) {
      break;
    }
    buf = (buf << 8) | (str->getChar() & 0xff);
    bufLen += 8;
    ++nBytesRead;
  }
  error(str->getPos(), "Bad black code in JBIG2 MMR stream");
  // eat a bit and return a positive number so that the caller doesn't
  // go into an infinite loop
  --bufLen;
  return 1;
}

Guint JBIG2MMRDecoder::get24Bits() {
  while (bufLen < 24) {
    buf = (buf << 8) | (str->getChar() & 0xff);
    bufLen += 8;
    ++nBytesRead;
  }
  return (buf >> (bufLen - 24)) & 0xffffff;
}

void JBIG2MMRDecoder::skipTo(Guint length) {
  while (nBytesRead < length) {
    str->getChar();
    ++nBytesRead;
  }
}

//------------------------------------------------------------------------
// JBIG2Segment
//------------------------------------------------------------------------

enum JBIG2SegmentType {
  jbig2SegBitmap,
  jbig2SegSymbolDict,
  jbig2SegPatternDict,
  jbig2SegCodeTable
};

class JBIG2Segment {
public:

  JBIG2Segment(Guint segNumA) { segNum = segNumA; }
  virtual ~JBIG2Segment() {}
  void setSegNum(Guint segNumA) { segNum = segNumA; }
  Guint getSegNum() { return segNum; }
  virtual JBIG2SegmentType getType() = 0;

private:

  Guint segNum;
};

//------------------------------------------------------------------------
// JBIG2Bitmap
//------------------------------------------------------------------------

struct JBIG2BitmapPtr {
  Guchar *p;
  int shift;
  int x;
};

class JBIG2Bitmap: public JBIG2Segment {
public:

  JBIG2Bitmap(Guint segNumA, int wA, int hA);
  virtual ~JBIG2Bitmap();
  virtual JBIG2SegmentType getType() { return jbig2SegBitmap; }
  JBIG2Bitmap *copy() { return new JBIG2Bitmap(0, this); }
  JBIG2Bitmap *getSlice(Guint x, Guint y, Guint wA, Guint hA);
  void expand(int newH, Guint pixel);
  void clearToZero();
  void clearToOne();
  int getWidth() { return w; }
  int getHeight() { return h; }
  int getPixel(int x, int y)
    { return (x < 0 || x >= w || y < 0 || y >= h) ? 0 :
             (data[y * line + (x >> 3)] >> (7 - (x & 7))) & 1; }
  void setPixel(int x, int y)
    { data[y * line + (x >> 3)] |= 1 << (7 - (x & 7)); }
  void clearPixel(int x, int y)
    { data[y * line + (x >> 3)] &= 0x7f7f >> (x & 7); }
  void getPixelPtr(int x, int y, JBIG2BitmapPtr *ptr);
  int nextPixel(JBIG2BitmapPtr *ptr);
  void duplicateRow(int yDest, int ySrc);
  void combine(JBIG2Bitmap *bitmap, int x, int y, Guint combOp);
  Guchar *getDataPtr() { return data; }
  int getDataSize() { return h * line; }

private:

  JBIG2Bitmap(Guint segNumA, JBIG2Bitmap *bitmap);

  int w, h, line;
  Guchar *data;
};

JBIG2Bitmap::JBIG2Bitmap(Guint segNumA, int wA, int hA):
  JBIG2Segment(segNumA)
{
  w = wA;
  h = hA;
  line = (wA + 7) >> 3;
  if (w <= 0 || h <= 0 || line <= 0 || h >= (INT_MAX - 1) / line) {
    data = NULL;
    return;
  }
  // need to allocate one extra guard byte for use in combine()
  data = (Guchar *)gmalloc(h * line + 1);
  data[h * line] = 0;
}

JBIG2Bitmap::JBIG2Bitmap(Guint segNumA, JBIG2Bitmap *bitmap):
  JBIG2Segment(segNumA)
{
  w = bitmap->w;
  h = bitmap->h;
  line = bitmap->line;
  if (w <= 0 || h <= 0 || line <= 0 || h >= (INT_MAX - 1) / line) {
    data = NULL;
    return;
  }
  // need to allocate one extra guard byte for use in combine()
  data = (Guchar *)gmalloc(h * line + 1);
  memcpy(data, bitmap->data, h * line);
  data[h * line] = 0;
}

JBIG2Bitmap::~JBIG2Bitmap() {
  gfree(data);
}

//~ optimize this
JBIG2Bitmap *JBIG2Bitmap::getSlice(Guint x, Guint y, Guint wA, Guint hA) {
  JBIG2Bitmap *slice;
  Guint xx, yy;

  slice = new JBIG2Bitmap(0, wA, hA);
  slice->clearToZero();
  for (yy = 0; yy < hA; ++yy) {
    for (xx = 0; xx < wA; ++xx) {
      if (getPixel(x + xx, y + yy)) {
	slice->setPixel(xx, yy);
      }
    }
  }
  return slice;
}

void JBIG2Bitmap::expand(int newH, Guint pixel) {
  if (newH <= h || line <= 0 || newH >= (INT_MAX - 1) / line) {
    return;
  }
  // need to allocate one extra guard byte for use in combine()
  data = (Guchar *)grealloc(data, newH * line + 1);
  if (pixel) {
    memset(data + h * line, 0xff, (newH - h) * line);
  } else {
    memset(data + h * line, 0x00, (newH - h) * line);
  }
  h = newH;
  data[h * line] = 0;
}

void JBIG2Bitmap::clearToZero() {
  memset(data, 0, h * line);
}

void JBIG2Bitmap::clearToOne() {
  memset(data, 0xff, h * line);
}

inline void JBIG2Bitmap::getPixelPtr(int x, int y, JBIG2BitmapPtr *ptr) {
  if (y < 0 || y >= h || x >= w) {
    ptr->p = NULL;
  } else if (x < 0) {
    ptr->p = &data[y * line];
    ptr->shift = 7;
    ptr->x = x;
  } else {
    ptr->p = &data[y * line + (x >> 3)];
    ptr->shift = 7 - (x & 7);
    ptr->x = x;
  }
}

inline int JBIG2Bitmap::nextPixel(JBIG2BitmapPtr *ptr) {
  int pix;

  if (!ptr->p) {
    pix = 0;
  } else if (ptr->x < 0) {
    ++ptr->x;
    pix = 0;
  } else {
    pix = (*ptr->p >> ptr->shift) & 1;
    if (++ptr->x == w) {
      ptr->p = NULL;
    } else if (ptr->shift == 0) {
      ++ptr->p;
      ptr->shift = 7;
    } else {
      --ptr->shift;
    }
  }
  return pix;
}

void JBIG2Bitmap::duplicateRow(int yDest, int ySrc) {
  memcpy(data + yDest * line, data + ySrc * line, line);
}

void JBIG2Bitmap::combine(JBIG2Bitmap *bitmap, int x, int y,
			  Guint combOp) {
  int x0, x1, y0, y1, xx, yy;
  Guchar *srcPtr, *destPtr;
  Guint src0, src1, src, dest, s1, s2, m1, m2, m3;
  GBool oneByte;

  if (y < 0) {
    y0 = -y;
  } else {
    y0 = 0;
  }
  if (y + bitmap->h > h) {
    y1 = h - y;
  } else {
    y1 = bitmap->h;
  }
  if (y0 >= y1) {
    return;
  }

  if (x >= 0) {
    x0 = x & ~7;
  } else {
    x0 = 0;
  }
  x1 = x + bitmap->w;
  if (x1 > w) {
    x1 = w;
  }
  if (x0 >= x1) {
    return;
  }

  s1 = x & 7;
  s2 = 8 - s1;
  m1 = 0xff >> (x1 & 7);
  m2 = 0xff << (((x1 & 7) == 0) ? 0 : 8 - (x1 & 7));
  m3 = (0xff >> s1) & m2;

  oneByte = x0 == ((x1 - 1) & ~7);

  for (yy = y0; yy < y1; ++yy) {

    // one byte per line -- need to mask both left and right side
    if (oneByte) {
      if (x >= 0) {
	destPtr = data + (y + yy) * line + (x >> 3);
	srcPtr = bitmap->data + yy * bitmap->line;
	dest = *destPtr;
	src1 = *srcPtr;
	switch (combOp) {
	case 0: // or
	  dest |= (src1 >> s1) & m2;
	  break;
	case 1: // and
	  dest &= ((0xff00 | src1) >> s1) | m1;
	  break;
	case 2: // xor
	  dest ^= (src1 >> s1) & m2;
	  break;
	case 3: // xnor
	  dest ^= ((src1 ^ 0xff) >> s1) & m2;
	  break;
	case 4: // replace
	  dest = (dest & ~m3) | ((src1 >> s1) & m3);
	  break;
	}
	*destPtr = dest;
      } else {
	destPtr = data + (y + yy) * line;
	srcPtr = bitmap->data + yy * bitmap->line + (-x >> 3);
	dest = *destPtr;
	src1 = *srcPtr;
	switch (combOp) {
	case 0: // or
	  dest |= src1 & m2;
	  break;
	case 1: // and
	  dest &= src1 | m1;
	  break;
	case 2: // xor
	  dest ^= src1 & m2;
	  break;
	case 3: // xnor
	  dest ^= (src1 ^ 0xff) & m2;
	  break;
	case 4: // replace
	  dest = (src1 & m2) | (dest & m1);
	  break;
	}
	*destPtr = dest;
      }

    // multiple bytes per line -- need to mask left side of left-most
    // byte and right side of right-most byte
    } else {

      // left-most byte
      if (x >= 0) {
	destPtr = data + (y + yy) * line + (x >> 3);
	srcPtr = bitmap->data + yy * bitmap->line;
	src1 = *srcPtr++;
	dest = *destPtr;
	switch (combOp) {
	case 0: // or
	  dest |= src1 >> s1;
	  break;
	case 1: // and
	  dest &= (0xff00 | src1) >> s1;
	  break;
	case 2: // xor
	  dest ^= src1 >> s1;
	  break;
	case 3: // xnor
	  dest ^= (src1 ^ 0xff) >> s1;
	  break;
	case 4: // replace
	  dest = (dest & (0xff << s2)) | (src1 >> s1);
	  break;
	}
	*destPtr++ = dest;
	xx = x0 + 8;
      } else {
	destPtr = data + (y + yy) * line;
	srcPtr = bitmap->data + yy * bitmap->line + (-x >> 3);
	src1 = *srcPtr++;
	xx = x0;
      }

      // middle bytes
      for (; xx < x1 - 8; xx += 8) {
	dest = *destPtr;
	src0 = src1;
	src1 = *srcPtr++;
	src = (((src0 << 8) | src1) >> s1) & 0xff;
	switch (combOp) {
	case 0: // or
	  dest |= src;
	  break;
	case 1: // and
	  dest &= src;
	  break;
	case 2: // xor
	  dest ^= src;
	  break;
	case 3: // xnor
	  dest ^= src ^ 0xff;
	  break;
	case 4: // replace
	  dest = src;
	  break;
	}
	*destPtr++ = dest;
      }

      // right-most byte
      // note: this last byte (src1) may not actually be used, depending
      // on the values of s1, m1, and m2 - and in fact, it may be off
      // the edge of the source bitmap, which means we need to allocate
      // one extra guard byte at the end of each bitmap
      dest = *destPtr;
      src0 = src1;
      src1 = *srcPtr++;
      src = (((src0 << 8) | src1) >> s1) & 0xff;
      switch (combOp) {
      case 0: // or
	dest |= src & m2;
	break;
      case 1: // and
	dest &= src | m1;
	break;
      case 2: // xor
	dest ^= src & m2;
	break;
      case 3: // xnor
	dest ^= (src ^ 0xff) & m2;
	break;
      case 4: // replace
	dest = (src & m2) | (dest & m1);
	break;
      }
      *destPtr = dest;
    }
  }
}

//------------------------------------------------------------------------
// JBIG2SymbolDict
//------------------------------------------------------------------------

class JBIG2SymbolDict: public JBIG2Segment {
public:

  JBIG2SymbolDict(Guint segNumA, Guint sizeA);
  virtual ~JBIG2SymbolDict();
  virtual JBIG2SegmentType getType() { return jbig2SegSymbolDict; }
  Guint getSize() { return size; }
  void setBitmap(Guint idx, JBIG2Bitmap *bitmap) { bitmaps[idx] = bitmap; }
  JBIG2Bitmap *getBitmap(Guint idx) { return bitmaps[idx]; }
  void setGenericRegionStats(JArithmeticDecoderStats *stats)
    { genericRegionStats = stats; }
  void setRefinementRegionStats(JArithmeticDecoderStats *stats)
    { refinementRegionStats = stats; }
  JArithmeticDecoderStats *getGenericRegionStats()
    { return genericRegionStats; }
  JArithmeticDecoderStats *getRefinementRegionStats()
    { return refinementRegionStats; }

private:

  Guint size;
  JBIG2Bitmap **bitmaps;
  JArithmeticDecoderStats *genericRegionStats;
  JArithmeticDecoderStats *refinementRegionStats;
};

JBIG2SymbolDict::JBIG2SymbolDict(Guint segNumA, Guint sizeA):
  JBIG2Segment(segNumA)
{
  size = sizeA;
  bitmaps = (JBIG2Bitmap **)gmallocn(size, sizeof(JBIG2Bitmap *));
  genericRegionStats = NULL;
  refinementRegionStats = NULL;
}

JBIG2SymbolDict::~JBIG2SymbolDict() {