#include "jpegSize.h"
#include <stdio.h>

Include dependency graph for jpegSize.cpp:

Macros
#define	NEXTBYTE()

#define	M_SOF0 0xC0 /* Start Of Frame N */

#define	M_SOF1 0xC1 /* N indicates which compression process */

#define	M_SOF2 0xC2 /* Only SOF0-SOF2 are now in common use */

#define	M_SOF3 0xC3

#define	M_SOF5 0xC5 /* NB: codes C4 and CC are NOT SOF markers */

#define	M_SOF6 0xC6

#define	M_SOF7 0xC7

#define	M_SOF9 0xC9

#define	M_SOF10 0xCA

#define	M_SOF11 0xCB

#define	M_SOF13 0xCD

#define	M_SOF14 0xCE

#define	M_SOF15 0xCF

#define	M_SOI 0xD8 /* Start Of Image (beginning of datastream) */

#define	M_EOI 0xD9 /* End Of Image (end of datastream) */

#define	M_SOS 0xDA /* Start Of Scan (begins compressed data) */

#define	M_APP0 0xE0 /* Application-specific marker, type N */

#define	M_APP12 0xEC /* (we don't bother to list all 16 APPn's) */

#define	M_COM 0xFE /* COMment */

#define	READ_BINARY "rb"

Functions
bool	process_SOFn (int &width, int &height)

bool	skip_variable ()

bool	read_1_byte (int *res)

bool	read_2_bytes (unsigned int *res)

bool	first_marker (int *res)

bool	next_marker (int *res)

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

Variables
FILE *	infile

Macro Definition Documentation

◆ M_APP0

#define M_APP0 0xE0 /* Application-specific marker, type N */

Definition at line 42 of file jpegSize.cpp.

◆ M_APP12

#define M_APP12 0xEC /* (we don't bother to list all 16 APPn's) */

Definition at line 43 of file jpegSize.cpp.

◆ M_COM

#define M_COM 0xFE /* COMment */

Definition at line 44 of file jpegSize.cpp.

◆ M_EOI

#define M_EOI 0xD9 /* End Of Image (end of datastream) */

Definition at line 40 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF0

#define M_SOF0 0xC0 /* Start Of Frame N */

Definition at line 26 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF1

#define M_SOF1 0xC1 /* N indicates which compression process */

Definition at line 27 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF10

#define M_SOF10 0xCA

Definition at line 34 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF11

#define M_SOF11 0xCB

Definition at line 35 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF13

#define M_SOF13 0xCD

Definition at line 36 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF14

#define M_SOF14 0xCE

Definition at line 37 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF15

#define M_SOF15 0xCF

Definition at line 38 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF2

#define M_SOF2 0xC2 /* Only SOF0-SOF2 are now in common use */

Definition at line 28 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF3

#define M_SOF3 0xC3

Definition at line 29 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF5

#define M_SOF5 0xC5 /* NB: codes C4 and CC are NOT SOF markers */

Definition at line 30 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF6

#define M_SOF6 0xC6

Definition at line 31 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF7

#define M_SOF7 0xC7

Definition at line 32 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOF9

#define M_SOF9 0xC9

Definition at line 33 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ M_SOI

#define M_SOI 0xD8 /* Start Of Image (beginning of datastream) */

Definition at line 39 of file jpegSize.cpp.

Referenced by first_marker().

◆ M_SOS

#define M_SOS 0xDA /* Start Of Scan (begins compressed data) */

Definition at line 41 of file jpegSize.cpp.

Referenced by getJPEGSize().

◆ NEXTBYTE

#define NEXTBYTE ( )

Value:

getc(infile)

infile

FILE * infile

Definition jpegSize.cpp:56

Definition at line 18 of file jpegSize.cpp.

Referenced by first_marker(), read_1_byte(), and read_2_bytes().

◆ READ_BINARY

#define READ_BINARY "rb"

Definition at line 52 of file jpegSize.cpp.

Referenced by getJPEGSize().

Function Documentation

◆ first_marker()

bool first_marker ( int * res )

Definition at line 149 of file jpegSize.cpp.

{
  int c1, c2;
  c1 = NEXTBYTE();
  c2 = NEXTBYTE();
  if (c1 != 0xFF || c2 != M_SOI)
    return false;
  else
  {
    *res = c2;
    return true;
  }
}

References M_SOI, and NEXTBYTE.

Referenced by getJPEGSize().

◆ 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().

◆ next_marker()

bool next_marker ( int * res )

Definition at line 172 of file jpegSize.cpp.

{
  int c;
  int discarded_bytes = 0;
 
  /* Find 0xFF byte; count and skip any non-FFs. */
  if(!read_1_byte(&c))
    return false;
  while (c != 0xFF) 
  {
    discarded_bytes++;
    if(!read_1_byte(&c))
      return false;
  }
  /* Get marker code byte, swallowing any duplicate FF bytes.  Extra FFs
   * are legal as pad bytes, so don't count them in discarded_bytes.
   */
  do 
  {
    if(!read_1_byte(&c))
      return false;
  } while (c == 0xFF);
 
//  if (discarded_bytes != 0) { cout << "Warning: garbage data found in JPEG file\n"; }
 
  *res = c;
  return true;
}

References read_1_byte().

Referenced by getJPEGSize().

◆ process_SOFn()

bool process_SOFn	(	int &	width,
		int &	height )

Definition at line 261 of file jpegSize.cpp.

{
  unsigned int length;
  unsigned int image_height, image_width;
  int data_precision;
  
  if(!read_2_bytes(&length) ||
      !read_1_byte(&data_precision) ||
      !read_2_bytes(&image_height) ||
      !read_2_bytes(&image_width) )
      return false;
 
  width = (int) image_width;
  height = (int) image_height;
  return true;   
}

References height, read_1_byte(), read_2_bytes(), and width.

Referenced by getJPEGSize().

◆ read_1_byte()

bool read_1_byte ( int * res )

Definition at line 202 of file jpegSize.cpp.

{
  int c = NEXTBYTE();
  if (c == EOF)
    return false;
  else
  {
    *res = c;
    return true;
  }
}

References NEXTBYTE.

Referenced by next_marker(), process_SOFn(), and skip_variable().

◆ read_2_bytes()

bool read_2_bytes ( unsigned int * res )

Definition at line 216 of file jpegSize.cpp.

{
  int c1, c2;
  c1 = NEXTBYTE();
  if (c1 == EOF)
    return false;
  c2 = NEXTBYTE();
  if (c2 == EOF)
    return false;
  *res = (((unsigned int) c1) << 8) + ((unsigned int) c2);
  return true;
}

References NEXTBYTE.

Referenced by process_SOFn(), and skip_variable().

◆ skip_variable()

bool skip_variable ( )

Definition at line 237 of file jpegSize.cpp.

{
  unsigned int length;
 
  /* Get the marker parameter length count */
  if(!read_2_bytes(&length))
    return false;
  /* Length includes itself, so must be at least 2 */
  if (length < 2)
    return false;
  length -= 2;
  /* Skip over the remaining bytes */
  while (length > 0) 
  {
    int tmp;
    if(!read_1_byte(&tmp))
      return false;
    length--;
  }
  return false;
}

References read_1_byte(), and read_2_bytes().

Referenced by getJPEGSize().

Variable Documentation

◆ infile

FILE* infile

Definition at line 56 of file jpegSize.cpp.

Referenced by getJPEGSize().

Macros

Functions

Variables

Macro Definition Documentation

◆ M_APP0

◆ M_APP12

◆ M_COM

◆ 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_SOI

◆ M_SOS

◆ NEXTBYTE

◆ READ_BINARY

Function Documentation

◆ first_marker()

◆ getJPEGSize()

◆ next_marker()

◆ process_SOFn()

◆ read_1_byte()

◆ read_2_bytes()

◆ skip_variable()

Variable Documentation

◆ infile