/* ------------------------- readjpeg.c ------------------------- */
#include <stdio.h>
#include <string.h>
#ifndef DOS
#include <unistd.h>
#endif
#include "psimage.h"
/* The following enum is stolen from the IJG JPEG library
* Comments added by tm
* This table contains far too many names since jpeg2ps
* is rather simple-minded about markers
*/
extern BOOL quiet;
typedef enum { /* JPEG marker codes */
M_SOF0 = 0xc0, /* baseline DCT */
M_SOF1 = 0xc1, /* extended sequential DCT */
M_SOF2 = 0xc2, /* progressive DCT */
M_SOF3 = 0xc3, /* lossless (sequential) */
M_SOF5 = 0xc5, /* differential sequential DCT */
M_SOF6 = 0xc6, /* differential progressive DCT */
M_SOF7 = 0xc7, /* differential lossless */
M_JPG = 0xc8, /* JPEG extensions */
M_SOF9 = 0xc9, /* extended sequential DCT */
M_SOF10 = 0xca, /* progressive DCT */
M_SOF11 = 0xcb, /* lossless (sequential) */
M_SOF13 = 0xcd, /* differential sequential DCT */
M_SOF14 = 0xce, /* differential progressive DCT */
M_SOF15 = 0xcf, /* differential lossless */
M_DHT = 0xc4, /* define Huffman tables */
M_DAC = 0xcc, /* define arithmetic conditioning table */
M_RST0 = 0xd0, /* restart */
M_RST1 = 0xd1, /* restart */
M_RST2 = 0xd2, /* restart */
M_RST3 = 0xd3, /* restart */
M_RST4 = 0xd4, /* restart */
M_RST5 = 0xd5, /* restart */
M_RST6 = 0xd6, /* restart */
M_RST7 = 0xd7, /* restart */
M_SOI = 0xd8, /* start of image */
M_EOI = 0xd9, /* end of image */
M_SOS = 0xda, /* start of scan */
M_DQT = 0xdb, /* define quantization tables */
M_DNL = 0xdc, /* define number of lines */
M_DRI = 0xdd, /* define restart interval */
M_DHP = 0xde, /* define hierarchical progression */
M_EXP = 0xdf, /* expand reference image(s) */
M_APP0 = 0xe0, /* application marker, used for JFIF */
M_APP1 = 0xe1, /* application marker */
M_APP2 = 0xe2, /* application marker */
M_APP3 = 0xe3, /* application marker */
M_APP4 = 0xe4, /* application marker */
M_APP5 = 0xe5, /* application marker */
M_APP6 = 0xe6, /* application marker */
M_APP7 = 0xe7, /* application marker */
M_APP8 = 0xe8, /* application marker */
M_APP9 = 0xe9, /* application marker */
M_APP10 = 0xea, /* application marker */
M_APP11 = 0xeb, /* application marker */
M_APP12 = 0xec, /* application marker */
M_APP13 = 0xed, /* application marker */
M_APP14 = 0xee, /* application marker, used by Adobe */
M_APP15 = 0xef, /* application marker */
M_JPG0 = 0xf0, /* reserved for JPEG extensions */
M_JPG13 = 0xfd, /* reserved for JPEG extensions */
M_COM = 0xfe, /* comment */
M_TEM = 0x01, /* temporary use */
M_ERROR = 0x100 /* dummy marker, internal use only */
} JPEG_MARKER;
/*
* The following routine used to be a macro in its first incarnation:
* #define get_2bytes(fp) ((unsigned int) (getc(fp) << 8) + getc(fp))
* However, this is bad programming since C doesn't guarantee
* the evaluation order of the getc() calls! As suggested by
* Murphy's law, there are indeed compilers which produce the wrong
* order of the getc() calls, e.g. the Metrowerks C compilers for BeOS
* and Macintosh.
* Since there are only few calls we don't care about the performance
* penalty and use a simplistic C function.
*/
/* read two byte parameter, MSB first */
static unsigned int
get_2bytes(FILE *fp)
{
unsigned int val;
val = getc(fp) << 8;
val += getc(fp);
return val;
}
static int
next_marker P1(FILE *, fp)
{ /* look for next JPEG Marker */
int c, nbytes = 0;
if (feof(fp))
return M_ERROR; /* dummy marker */
do {
do { /* skip to FF */
nbytes++;
c = getc(fp);
} while (c != 0xFF);
do { /* skip repeated FFs */
c = getc(fp);
} while (c == 0xFF);
} while (c == 0); /* repeat if FF/00 */
return c;
}
/* analyze JPEG marker */
BOOL AnalyzeJPEG P1(imagedata *, image) {
int b, c, unit;
unsigned long i, length = 0;
#define APP_MAX 255
unsigned char appstring[APP_MAX];
BOOL SOF_done = FALSE;
/* Tommy's special trick for Macintosh JPEGs: simply skip some */
/* hundred bytes at the beginning of the file! */
do {
do { /* skip if not FF */
c = getc(image->fp);
} while (!feof(image->fp) && c != 0xFF);
do { /* skip repeated FFs */
c = getc(image->fp);
} while (c == 0xFF);
/* remember start position */
if ((image->startpos = ftell(image->fp)) < 0L) {
fprintf(stderr, "Error: internal error in ftell()!\n");
return FALSE;
}
image->startpos -= 2; /* subtract marker length */
if (c == M_SOI) {
fseek(image->fp, image->startpos, SEEK_SET);
break;
}
} while (!feof(image->fp));
if (feof(image->fp)) {
fprintf(stderr, "Error: SOI marker not found!\n");
return FALSE;
}
if (image->startpos > 0L && !quiet) {
fprintf(stderr, "Note: skipped %ld bytes ", image->startpos);
fprintf(stderr, "Probably Macintosh JPEG file?\n");
}
/* process JPEG markers */
while (!SOF_done && (c = next_marker(image->fp)) != M_EOI) {
switch (c) {
case M_ERROR:
fprintf(stderr, "Error: unexpected end of JPEG file!\n");
return FALSE;
/* The following are not officially supported in PostScript level 2 */
case M_SOF2:
case M_SOF3:
case M_SOF5:
case M_SOF6:
case M_SOF7:
case M_SOF9:
case M_SOF10:
case M_SOF11:
case M_SOF13:
case M_SOF14:
case M_SOF15:
fprintf(stderr,
"Warning: JPEG file uses compression method %X - proceeding anyway.\n",
c);
fprintf(stderr,
"PostScript output does not work on all PS interpreters!\n");
/* FALLTHROUGH */
case M_SOF0:
case M_SOF1:
length = get_2bytes(image->fp); /* read segment length */
image->bits_per_component = getc(image->fp);
image->height = get_2bytes(image->fp);
image->width = get_2bytes(image->fp);
image->components = getc(image->fp);
SOF_done = TRUE;
break;
case M_APP0: /* check for JFIF marker with resolution */
length = get_2bytes(image->fp);
for (i = 0; i < length-2; i++) { /* get contents of marker */
b = getc(image->fp);
if (i < APP_MAX) /* store marker in appstring */
appstring[i] = b;
}
/* Check for JFIF application marker and read density values
* per JFIF spec version 1.02.
* We only check X resolution, assuming X and Y resolution are equal.
* Use values only if resolution not preset by user or to be ignored.
*/
#define ASPECT_RATIO 0 /* JFIF unit byte: aspect ratio only */
#define DOTS_PER_INCH 1 /* JFIF unit byte: dots per inch */
#define DOTS_PER_CM 2 /* JFIF unit byte: dots per cm */
if (image->dpi == DPI_USE_FILE && length >= 14 &&
!strncmp((const char *)appstring, "JFIF", 4)) {
unit = appstring[7]; /* resolution unit */
/* resolution value */
image->dpi = (float) ((appstring[8]<<8) + appstring[9]);
if (image->dpi == 0.0) {
image->dpi = DPI_USE_FILE;
break;
}
switch (unit) {
/* tell the caller we didn't find a resolution value */
case ASPECT_RATIO:
image->dpi = DPI_USE_FILE;
break;
case DOTS_PER_INCH:
break;
case DOTS_PER_CM:
image->dpi *= (float) 2.54;
break;
default: /* unknown ==> ignore */
fprintf(stderr,
"Warning: JPEG file contains unknown JFIF resolution unit - ignored!\n");
image->dpi = DPI_IGNORE;
break;
}
}
break;
case M_APP14: /* check for Adobe marker */
length = get_2bytes(image->fp);
for (i = 0; i < length-2; i++) { /* get contents of marker */
b = getc(image->fp);
if (i < APP_MAX) /* store marker in appstring */
appstring[i] = b;
}
/* Check for Adobe application marker. It is known (per Adobe's TN5116)
* to contain the string "Adobe" at the start of the APP14 marker.
*/
if (length >= 12 && !strncmp((const char *) appstring, "Adobe", 5))
image->adobe = TRUE; /* set Adobe flag */
break;
case M_SOI: /* ignore markers without parameters */
case M_EOI:
case M_TEM:
case M_RST0:
case M_RST1:
case M_RST2:
case M_RST3:
case M_RST4:
case M_RST5:
case M_RST6:
case M_RST7:
break;
default: /* skip variable length markers */
length = get_2bytes(image->fp);
for (length -= 2; length > 0; length--)
(void) getc(image->fp);
break;
}
}
/* do some sanity checks with the parameters */
if (image->height <= 0 || image->width <= 0 || image->components <= 0) {
fprintf(stderr, "Error: DNL marker not supported in PostScript Level 2!\n");
return FALSE;
}
/* some broken JPEG files have this but they print anyway... */
if (length != (unsigned int) (image->components * 3 + 8))
fprintf(stderr, "Warning: SOF marker has incorrect length - ignored!\n");
if (image->bits_per_component != 8) {
fprintf(stderr, "Error: %d bits per color component ",
image->bits_per_component);
fprintf(stderr, "not supported in PostScript level 2!\n");
return FALSE;
}
if (image->components!=1 && image->components!=3 && image->components!=4) {
fprintf(stderr, "Error: unknown color space (%d components)!\n",
image->components);
return FALSE;
}
return TRUE;
}