Go to the source code of this file.
Defines | |
| #define | NEXTBYTE() getc(infile) |
| #define | M_SOF0 0xC0 |
| #define | M_SOF1 0xC1 |
| #define | M_SOF2 0xC2 |
| #define | M_SOF3 0xC3 |
| #define | M_SOF5 0xC5 |
| #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 |
| #define | M_EOI 0xD9 |
| #define | M_SOS 0xDA |
| #define | M_APP0 0xE0 |
| #define | M_APP12 0xEC |
| #define | M_COM 0xFE |
| #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 |
Define Documentation
| #define M_APP0 0xE0 |
Definition at line 42 of file jpegSize.cpp.
| #define M_APP12 0xEC |
Definition at line 43 of file jpegSize.cpp.
| #define M_COM 0xFE |
Definition at line 44 of file jpegSize.cpp.
| #define M_EOI 0xD9 |
Definition at line 40 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF0 0xC0 |
Definition at line 26 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF1 0xC1 |
Definition at line 27 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF10 0xCA |
Definition at line 34 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF11 0xCB |
Definition at line 35 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF13 0xCD |
Definition at line 36 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF14 0xCE |
Definition at line 37 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF15 0xCF |
Definition at line 38 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF2 0xC2 |
Definition at line 28 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF3 0xC3 |
Definition at line 29 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF5 0xC5 |
Definition at line 30 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF6 0xC6 |
Definition at line 31 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF7 0xC7 |
Definition at line 32 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOF9 0xC9 |
Definition at line 33 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define M_SOI 0xD8 |
Definition at line 39 of file jpegSize.cpp.
Referenced by first_marker().
| #define M_SOS 0xDA |
Definition at line 41 of file jpegSize.cpp.
Referenced by getJPEGSize().
| #define NEXTBYTE | ( | ) | getc(infile) |
Definition at line 18 of file jpegSize.cpp.
Referenced by first_marker(), read_1_byte(), and read_2_bytes().
| #define READ_BINARY "rb" |
Definition at line 52 of file jpegSize.cpp.
Referenced by getJPEGSize().
Function Documentation
| bool first_marker | ( | int * | res | ) |
Definition at line 149 of file jpegSize.cpp.
References M_SOI, and NEXTBYTE.
Referenced by getJPEGSize().
| bool getJPEGSize | ( | const char * | filename, |
| int & | width, | ||
| int & | height | ||
| ) |
Definition at line 65 of file jpegSize.cpp.
References first_marker(), 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, and skip_variable().
Referenced by getImageSize(), and isJpeg().
{
//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;
}
| bool next_marker | ( | int * | res | ) |
Definition at line 172 of file jpegSize.cpp.
References read_1_byte().
Referenced by getJPEGSize().
{
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;
}
| bool process_SOFn | ( | int & | width, |
| int & | height | ||
| ) |
Definition at line 261 of file jpegSize.cpp.
References read_1_byte(), and read_2_bytes().
Referenced by getJPEGSize().
{
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;
}
| bool read_1_byte | ( | int * | res | ) |
Definition at line 202 of file jpegSize.cpp.
References NEXTBYTE.
Referenced by next_marker(), process_SOFn(), and skip_variable().
{
int c = NEXTBYTE();
if (c == EOF)
return false;
else
{
*res = c;
return true;
}
}
| bool read_2_bytes | ( | unsigned int * | res | ) |
Definition at line 216 of file jpegSize.cpp.
References NEXTBYTE.
Referenced by process_SOFn(), and skip_variable().
| bool skip_variable | ( | ) |
Definition at line 237 of file jpegSize.cpp.
References read_1_byte(), and read_2_bytes().
Referenced by getJPEGSize().
{
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;
}
Variable Documentation
| FILE* infile |
Definition at line 56 of file jpegSize.cpp.
Referenced by getJPEGSize().
