imgs.cpp

一个google的OCR源码

                               inT32 ystart,
                               inT32 xext,          //extent to copy
                               inT32 yext,
                               IMAGE *dest,         //destination image
                               inT32 xdest,         //destination coords
                               inT32 ydest,
                               BOOL8 preserve_grey  //shift to new bpp
                              ) {
  IMAGELINE copyline;            //copy of line
  uinT8 *copy;                   //source pointer
  inT8 shift4;                   //shift factor
  inT8 shift6;                   //shift factor
  inT8 colour_shift;             //shift of colours
  uinT8 white_level;             //dest white value
  inT32 pixel;                   //pixel index
  inT32 y;                       //line index
  inT32 yoffset;                 //current adjusted offset
  inT8 srcppb;                   //pixels per byte

  if (xstart < 0 || ystart < 0 || xdest < 0 || ydest < 0)
    return;
  if (xext <= 0)
    xext = source->get_xsize (); //default to all
  if (xext > source->get_xsize () - xstart)
                                 //clip to smallest
    xext = source->get_xsize () - xstart;
  if (xext > dest->get_xsize () - xdest)
    xext = dest->get_xsize () - xdest;
  if (yext <= 0)
    yext = source->get_ysize (); //default to all
  if (yext > source->get_ysize () - ystart)
                                 //clip to smallest
    yext = source->get_ysize () - ystart;
  if (yext > dest->get_ysize () - ydest)
    yext = dest->get_ysize () - ydest;
  if (xext <= 0 || yext <= 0)
    return;                      //nothing to do

                                 //pixels per byte
  srcppb = 8 / source->get_bpp ();
  shift4 = 4 - dest->get_bpp (); //for different bpps
  shift6 = 6 - dest->get_bpp ();
                                 //for grey preserve
  colour_shift = 8 - dest->get_bpp ();
  white_level = dest->get_white_level ();
  for (y = 0; y < yext; y++) {
    if (ystart >= ydest)
      yoffset = y;               //top down
    else
      yoffset = yext - y - 1;    //bottom up
    source->check_legal_access (xstart, ystart + yoffset, xext);
    dest->check_legal_access (xdest, ydest + yoffset, xext);
    source->get_line (xstart, ystart + yoffset, xext, &copyline, 0);
    for (pixel = 0, copy = copyline.pixels; pixel < xext; pixel++) {
      if (*copy < FIXED_COLOURS && preserve_grey)
        *copy = grey_scales[*copy] >> colour_shift;
      else if (*copy < FIXED_COLOURS) {
        if (*copy == BLACK_PIX)
          *copy = white_level;   //black->white
        else
          *copy = 0;             //others->black
      }
      else if (*copy >= MIN_4BIT && *copy < MAX_4BIT) {
        if (shift4 < 0)
          *copy = (*copy - MIN_4BIT) << (-shift4);
        else
          *copy = (*copy - MIN_4BIT) >> shift4;
      }
      else if (*copy >= MIN_6BIT && *copy < MAX_6BIT) {
        if (shift6 < 0)
          *copy = (*copy - MIN_6BIT) << (-shift6);
        else
          *copy = (*copy - MIN_6BIT) >> shift6;
      }
      else {
        *copy = white_level;     //white the rest
      }
      copy++;
    }
    dest->put_line (xdest, ydest + yoffset, xext, &copyline, 0);
  }
}


/**********************************************************************
 * fast_get_line
 *
 * Get a line of image into the supplied image line buffer.
 * The image is converted to 8bpp by simple assignment.
 * If the image is aleady 8 or 6bpp, no copy is done and a pointer
 * to the correct image section is put in the line buffer.
 **********************************************************************/

void IMAGE::fast_get_line(                    //get image line
                          inT32 x,            //coord to start at
                          inT32 y,            //line to get
                          inT32 width,        //no of pixels to get
                          IMAGELINE *linebuf  //line to copy to
                         ) {
  if (width > 0 && bpp > 4) {
    check_legal_access(x, y, width);
                                 //get pointer only
    linebuf->pixels = image + xdim * (ymax - 1 - y) + x * bytespp;
  }
  else
                                 //just copy it
    this->get_line (x, y, width, linebuf, 0);
  linebuf->bpp = bpp;
}


/**********************************************************************
 * get_line
 *
 * Get a line of image into the supplied image line buffer.
 * The image is converted to 8bpp by simple assignment.
 **********************************************************************/

void IMAGE::get_line(                     //get image line
                     inT32 x,             //coord to start at
                     inT32 y,             //line to get
                     inT32 width,         //no of pixels to get
                     IMAGELINE *linebuf,  //line to copy to
                     inT32 margins        //size of margins
                    ) {
  uinT8 *src;                    //source pointer
  uinT8 *dest;                   //destination pointer
  uinT8 *unpacksrc;              //unpacking pointer
  inT8 bit;                      //bit index
  inT8 pixperbyte;               //pixels per byte
  uinT8 white;                   //white colour
  inT32 pixel;                   //pixel index

                                 //test coords
  this->check_legal_access (x, y, width);
  if (width > xsize - x)
    width = xsize - x;           //clip to image
  width *= bytespp;
  linebuf->init (width + margins * bytespp * 2);
  linebuf->bpp = bpp;
                                 //start of line
  src = image + xdim * (ymax - 1 - y);
  dest = linebuf->line;          //destination line
  linebuf->pixels = dest;
  white = (1 << bpp) - 1;        //max value of pixel
  for (pixel = margins * bytespp; pixel > 0; pixel--) {
    *dest++ = white;             //margins are white
  }
  if (width > 0) {
    if (bpp > 4) {
      src += x;                  //offset
                                 //easy way
      memmove (dest, src, (unsigned) width);
    }
    else if (bpp == 4) {
      src += x / 2;              //offset on line
      if (x & 1) {
                                 //get coded nibble
        *dest++ = bpp4table[*src++][1];
        width--;
      }
      while (width >= 2) {
                                 //get coded bits
        unpacksrc = bpp4table[*src++];
        *dest++ = *unpacksrc++;
        *dest++ = *unpacksrc++;  //copy nibbles
        width -= 2;
      }
      if (width) {
                                 //get coded nibble
        *dest++ = bpp4table[*src++][0];
      }
    }
    else if (bpp == 2) {
      pixperbyte = 4;
      src += x / 4;              //offset on line
      bit = (inT8) (x % 4);      //offset in byte
      width += bit;
      while (width > 0) {        //until all done
        if (width < pixperbyte)
                                 //less on last byte
          pixperbyte = (inT8) width;
                                 //get coded bits
        unpacksrc = &bpp2table[*src++][bit];
        for (; bit < pixperbyte; bit++)
          *dest++ = *unpacksrc++;//copy bytes
        width -= pixperbyte;
        bit = 0;
      }
    }
    else {
      pixperbyte = 8;
      src += x / 8;              //offset on line
      bit = (inT8) (x % 8);      //offset in byte
      width += bit;
      while (width > 0) {        //until all done
        if (width < pixperbyte)
                                 //less on last byte
          pixperbyte = (inT8) width;
                                 //get coded bits
        unpacksrc = &bpp1table[*src++][bit];
        for (; bit < pixperbyte; bit++)
          *dest++ = *unpacksrc++;//copy bytes
        width -= pixperbyte;
        bit = 0;
      }
    }
  }
  for (pixel = margins * bytespp; pixel > 0; pixel--) {
    *dest++ = white;             //margins are white
  }
}


/**********************************************************************
 * get_column
 *
 * Get a column of image into the supplied image line buffer.
 * The image is converted to 8bpp by simple assignment.
 **********************************************************************/

void IMAGE::get_column(                     //get image column
                       inT32 x,             //coord to start at
                       inT32 y,             //line to get
                       inT32 height,        //no of pixels to get
                       IMAGELINE *linebuf,  //line to copy to
                       inT32 margins        //size of margins
                      ) {
  uinT8 *src;                    //source pointer
  uinT8 *dest;                   //destination pointer
  inT8 bit;                      //bit index
  inT8 pixperbyte;               //pixels per byte
  uinT8 white;                   //white colour
  inT32 pixel;                   //pixel index

                                 //test coords
  this->check_legal_access (x, y, 1);
                                 //test coords
  this->check_legal_access (x, y + height - 1, 1);
  if (height > ysize - y)
    height = ysize - y;          //clip to image
  linebuf->init (height * bytespp + margins * bytespp * 2);
                                 //start of line
  src = image + xdim * (ymax - 1 - y);
  dest = linebuf->line;          //destination line
  linebuf->pixels = dest;
  white = (1 << bpp) - 1;        //max value of pixel
  for (pixel = margins * bytespp; pixel > 0; pixel--) {
    *dest++ = white;             //margins are white
  }
  if (height > 0) {
    if (bpp == 24) {
      src += x * bytespp;        //offset
      for (; height > 0; --height) {
        *dest++ = *src;          //copy bytes
        *dest++ = *(src + 1);
        *dest++ = *(src + 2);
        src -= xdim;
      }
    }
    else if (bpp > 4) {
      src += x;
      for (; height > 0; --height) {
        *dest++ = *src;          //copy bytes
        src -= xdim;
      }
    }
    else if (bpp == 4) {
      src += x / 2;              //offset on line
      if (x & 1) {
        for (; height > 0; --height) {
                                 //get coded nibble
          *dest++ = bpp4table[*src][1];
          src -= xdim;
        }
      }
      else {
        for (; height > 0; --height) {
                                 //get coded nibble
          *dest++ = bpp4table[*src][0];
          src -= xdim;
        }
      }
    }
    else if (bpp == 2) {
      pixperbyte = 4;
      src += x / 4;              //offset on line
      bit = (inT8) (x % 4);      //offset in byte
      for (; height > 0; --height) {
                                 //get coded bits
        *dest++ = bpp2table[*src][bit];
        src -= xdim;
      }
    }
    else {
      pixperbyte = 8;
      src += x / 8;              //offset on line
      bit = (inT8) (x % 8);      //offset in byte
      for (; height > 0; --height) {
                                 //get coded bits
        *dest++ = bpp1table[*src][bit];
        src -= xdim;
      }
    }
  }
  for (pixel = margins * bytespp; pixel > 0; pixel--) {
    *dest++ = white;             //margins are white
  }
}


/**********************************************************************
 * fast_put_line
 *
 * Put a line buffer back into the image.
 * If the line buffer merely points back into the image, nothing is done.
 * Otherwise, put_line is used to copy the line back.
 **********************************************************************/

void IMAGE::fast_put_line(                    //put image line
                          inT32 x,            //coord to start at
                          inT32 y,            //line to get
                          inT32 width,        //no of pixels to put
                          IMAGELINE *linebuf  //line to copy to
                         ) {
  if (width > 0 && (bpp <= 4 || linebuf->pixels == linebuf->line))
                                 //just copy it
    put_line (x, y, width, linebuf, 0);
}


/**********************************************************************
 * put_line
 *
 * Put the supplied line buffer into the image.
 * The image is converted from 8bpp by simple assignment.
 **********************************************************************/

void IMAGE::put_line(                     //put image line
                     inT32 x,             //coord to start at
                     inT32 y,             //line to get
                     inT32 width,         //no of pixels to get
                     IMAGELINE *linebuf,  //line to copy to
                     inT32 margins        //margins in buffer
                    ) {
  uinT8 *src;                    //source pointer
  uinT8 *dest;                   //destination pointer
  inT8 bit;                      //bit index
  uinT8 pixel;                   //collected bits
  inT8 pixperbyte;               //pixels in a byte
  inT8 bytesperpix;              //in source

  this->check_legal_access (x, y, width);
  if (width > xsize - x)
    width = xsize - x;           //clip to image
  if (width <= 0)
    return;                      //nothing to do
                                 //source line
  src = linebuf->pixels + margins;
                                 //start of line
  dest = image + xdim * (ymax - 1 - y);

  if (linebuf->bpp == 24) {
    src++;
    bytesperpix = 3;
  }
  else
    bytesperpix = 1;
  if (bpp == 24 && linebuf->bpp == 24) {
    dest += x * bytespp;
    width *= bytespp;
    memmove (dest, src - 1, (unsigned) width);
  }
  else if (bpp == 24) {
    src--;
    dest += x * bytespp;
    while (width > 0) {
      pixel = *src++;
      *dest++ = pixel;
      *dest++ = pixel;
      *dest++ = pixel;
      width--;
    }
  }
  else if (bpp > 4) {
    dest += x;                   //offset
    if (linebuf->bpp == 24) {
      while (width > 0) {
        *dest++ = *src;
        src += 3;
        width--;
      }
    }
    else
                                 //easy way
      memmove (dest, src, (unsigned) width);
  }
  else if (bpp == 4) {
    dest += x / 2;               //offset on line
    if (x & 1) {
      *dest &= 0xf0;             //clean odd byte
      *dest++ |= *src & 0x0f;    //and copy it
      src += bytesperpix;
      width--;
    }
    while (width >= 2) {
      pixel = *src << 4;         //left pixel
      src += bytesperpix;
      pixel |= *src & 0x0f;      //right pixel
      src += bytesperpix;
      *dest++ = pixel;
      width -= 2;
    }
    if (width) {
      *dest &= 0x0f;             //clean odd byte
      *dest |= *src << 4;
    }
  }
  else if (bpp == 2) {
    pixperbyte = 4;
    dest += x / 4;               //offset on line
    bit = (inT8) (x % 4);        //offset in byte
    width += bit;
    pixel = *dest >> (8 - bit - bit);
    while (width >= 4) {         //until all done
      for (; bit < 4; bit++) {
        pixel <<= 2;             //make space for new one
        pixel |= *src & 3;
        src += bytesperpix;
      }
      *dest++ = pixel;           //new pixel
      width -= 4;
      bit = 0;
    }
    if (width > 0) {             //until all done
      for (bit = 0; bit < width; bit++) {
        pixel <<= 2;             //make space for new one
        pixel |= *src & 3;
        src += bytesperpix;
      }
      pixel <<= (8 - bit - bit); //shift rest
                                 //keep trainling bits