jpegSize.h File Reference

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Functions
bool	getJPEGSize (const char *filename, int &width, int &height)

Function Documentation

getJPEGSize()

bool getJPEGSize	(	const char *	filename,
		int &	width,
		int &	height )

Definition at line 65 of file jpegSize.cpp.

{
  //open file
  if ((infile = fopen(filename, READ_BINARY)) == NULL)
    return false;
 
  //this is scan_JPEG_header (int verbose)
  //Parse the marker stream until SOFn is seen;
  int marker;
  
  //Expect SOI at start of file
  if (!first_marker(&marker))
  {
    fclose(infile);
    return false;
  }
    
    /* Scan miscellaneous markers until we reach SOFn. */
  for (;;) 
  {
    if(!next_marker(&marker))
    {
      fclose(infile);
      return false;
    }
 
    switch (marker) 
    {
      /* Note that marker codes 0xC4, 0xC8, 0xCC are not, and must not be,
       * treated as SOFn.  C4 in particular is actually DHT.
       */
    case M_SOF0:    /* Baseline */
    case M_SOF1:    /* Extended sequential, Huffman */
    case M_SOF2:    /* Progressive, Huffman */
    case M_SOF3:    /* Lossless, Huffman */
    case M_SOF5:    /* Differential sequential, Huffman */
    case M_SOF6:    /* Differential progressive, Huffman */
    case M_SOF7:    /* Differential lossless, Huffman */
    case M_SOF9:    /* Extended sequential, arithmetic */
    case M_SOF10:   /* Progressive, arithmetic */
    case M_SOF11:   /* Lossless, arithmetic */
    case M_SOF13:   /* Differential sequential, arithmetic */
    case M_SOF14:   /* Differential progressive, arithmetic */
    case M_SOF15:   /* Differential lossless, arithmetic */      
      if(!process_SOFn(width, height))
      {
        fclose(infile);
        return false;
      }
      else
      {
        fclose(infile);
        return true;
      }
    case M_SOS:     /* stop before hitting compressed data */
    {
      fclose(infile);
      return false;
    }
    case M_EOI:     /* in case it's a tables-only JPEG stream */
    {
      fclose(infile);
      return false;
    }
    default:      /* Anything else just gets skipped */
      skip_variable();    /* we assume it has a parameter count... */
      break;
    }
  } /* end loop */
 
 
//cout << "ERROR!\n";
return false;
 
}

References first_marker(), height, infile, M_EOI, M_SOF0, M_SOF1, M_SOF10, M_SOF11, M_SOF13, M_SOF14, M_SOF15, M_SOF2, M_SOF3, M_SOF5, M_SOF6, M_SOF7, M_SOF9, M_SOS, next_marker(), process_SOFn(), READ_BINARY, skip_variable(), and width.

Referenced by getImageSize(), and isJpeg().