+++ /dev/null
-/*
- * rdjpgcom.c
- *
- * Copyright (C) 1994-1997, Thomas G. Lane.
- * This file is part of the Independent JPEG Group's software.
- * For conditions of distribution and use, see the accompanying README file.
- *
- * This file contains a very simple stand-alone application that displays
- * the text in COM (comment) markers in a JFIF file.
- * This may be useful as an example of the minimum logic needed to parse
- * JPEG markers.
- */
-
-#define JPEG_CJPEG_DJPEG /* to get the command-line config symbols */
-#include "jinclude.h" /* get auto-config symbols, <stdio.h> */
-
-#include <ctype.h> /* to declare isupper(), tolower() */
-#ifdef USE_SETMODE
-#include <fcntl.h> /* to declare setmode()'s parameter macros */
-/* If you have setmode() but not <io.h>, just delete this line: */
-#include <io.h> /* to declare setmode() */
-#endif
-
-#ifdef USE_CCOMMAND /* command-line reader for Macintosh */
-#ifdef __MWERKS__
-#include <SIOUX.h> /* Metrowerks needs this */
-#include <console.h> /* ... and this */
-#endif
-#ifdef THINK_C
-#include <console.h> /* Think declares it here */
-#endif
-#endif
-
-#ifdef DONT_USE_B_MODE /* define mode parameters for fopen() */
-#define READ_BINARY "r"
-#else
-#ifdef VMS /* VMS is very nonstandard */
-#define READ_BINARY "rb", "ctx=stm"
-#else /* standard ANSI-compliant case */
-#define READ_BINARY "rb"
-#endif
-#endif
-
-#ifndef EXIT_FAILURE /* define exit() codes if not provided */
-#define EXIT_FAILURE 1
-#endif
-#ifndef EXIT_SUCCESS
-#ifdef VMS
-#define EXIT_SUCCESS 1 /* VMS is very nonstandard */
-#else
-#define EXIT_SUCCESS 0
-#endif
-#endif
-
-
-/*
- * These macros are used to read the input file.
- * To reuse this code in another application, you might need to change these.
- */
-
-static FILE * infile; /* input JPEG file */
-
-/* Return next input byte, or EOF if no more */
-#define NEXTBYTE() getc(infile)
-
-
-/* Error exit handler */
-#define ERREXIT(msg) (fprintf(stderr, "%s\n", msg), exit(EXIT_FAILURE))
-
-
-/* Read one byte, testing for EOF */
-static int
-read_1_byte (void)
-{
- int c;
-
- c = NEXTBYTE();
- if (c == EOF)
- ERREXIT("Premature EOF in JPEG file");
- return c;
-}
-
-/* Read 2 bytes, convert to unsigned int */
-/* All 2-byte quantities in JPEG markers are MSB first */
-static unsigned int
-read_2_bytes (void)
-{
- int c1, c2;
-
- c1 = NEXTBYTE();
- if (c1 == EOF)
- ERREXIT("Premature EOF in JPEG file");
- c2 = NEXTBYTE();
- if (c2 == EOF)
- ERREXIT("Premature EOF in JPEG file");
- return (((unsigned int) c1) << 8) + ((unsigned int) c2);
-}
-
-
-/*
- * JPEG markers consist of one or more 0xFF bytes, followed by a marker
- * code byte (which is not an FF). Here are the marker codes of interest
- * in this program. (See jdmarker.c for a more complete list.)
- */
-
-#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 */
-
-
-/*
- * Find the next JPEG marker and return its marker code.
- * We expect at least one FF byte, possibly more if the compressor used FFs
- * to pad the file.
- * There could also be non-FF garbage between markers. The treatment of such
- * garbage is unspecified; we choose to skip over it but emit a warning msg.
- * NB: this routine must not be used after seeing SOS marker, since it will
- * not deal correctly with FF/00 sequences in the compressed image data...
- */
-
-static int
-next_marker (void)
-{
- int c;
- int discarded_bytes = 0;
-
- /* Find 0xFF byte; count and skip any non-FFs. */
- c = read_1_byte();
- while (c != 0xFF) {
- discarded_bytes++;
- c = read_1_byte();
- }
- /* 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 {
- c = read_1_byte();
- } while (c == 0xFF);
-
- if (discarded_bytes != 0) {
- fprintf(stderr, "Warning: garbage data found in JPEG file\n");
- }
-
- return c;
-}
-
-
-/*
- * Read the initial marker, which should be SOI.
- * For a JFIF file, the first two bytes of the file should be literally
- * 0xFF M_SOI. To be more general, we could use next_marker, but if the
- * input file weren't actually JPEG at all, next_marker might read the whole
- * file and then return a misleading error message...
- */
-
-static int
-first_marker (void)
-{
- int c1, c2;
-
- c1 = NEXTBYTE();
- c2 = NEXTBYTE();
- if (c1 != 0xFF || c2 != M_SOI)
- ERREXIT("Not a JPEG file");
- return c2;
-}
-
-
-/*
- * Most types of marker are followed by a variable-length parameter segment.
- * This routine skips over the parameters for any marker we don't otherwise
- * want to process.
- * Note that we MUST skip the parameter segment explicitly in order not to
- * be fooled by 0xFF bytes that might appear within the parameter segment;
- * such bytes do NOT introduce new markers.
- */
-
-static void
-skip_variable (void)
-/* Skip over an unknown or uninteresting variable-length marker */
-{
- unsigned int length;
-
- /* Get the marker parameter length count */
- length = read_2_bytes();
- /* Length includes itself, so must be at least 2 */
- if (length < 2)
- ERREXIT("Erroneous JPEG marker length");
- length -= 2;
- /* Skip over the remaining bytes */
- while (length > 0) {
- (void) read_1_byte();
- length--;
- }
-}
-
-
-/*
- * Process a COM marker.
- * We want to print out the marker contents as legible text;
- * we must guard against non-text junk and varying newline representations.
- */
-
-static void
-process_COM (void)
-{
- unsigned int length;
- int ch;
- int lastch = 0;
-
- /* Get the marker parameter length count */
- length = read_2_bytes();
- /* Length includes itself, so must be at least 2 */
- if (length < 2)
- ERREXIT("Erroneous JPEG marker length");
- length -= 2;
-
- while (length > 0) {
- ch = read_1_byte();
- /* Emit the character in a readable form.
- * Nonprintables are converted to \nnn form,
- * while \ is converted to \\.
- * Newlines in CR, CR/LF, or LF form will be printed as one newline.
- */
- if (ch == '\r') {
- printf("\n");
- } else if (ch == '\n') {
- if (lastch != '\r')
- printf("\n");
- } else if (ch == '\\') {
- printf("\\\\");
- } else if (isprint(ch)) {
- putc(ch, stdout);
- } else {
- printf("\\%03o", ch);
- }
- lastch = ch;
- length--;
- }
- printf("\n");
-}
-
-
-/*
- * Process a SOFn marker.
- * This code is only needed if you want to know the image dimensions...
- */
-
-static void
-process_SOFn (int marker)
-{
- unsigned int length;
- unsigned int image_height, image_width;
- int data_precision, num_components;
- const char * process;
- int ci;
-
- length = read_2_bytes(); /* usual parameter length count */
-
- data_precision = read_1_byte();
- image_height = read_2_bytes();
- image_width = read_2_bytes();
- num_components = read_1_byte();
-
- switch (marker) {
- case M_SOF0: process = "Baseline"; break;
- case M_SOF1: process = "Extended sequential"; break;
- case M_SOF2: process = "Progressive"; break;
- case M_SOF3: process = "Lossless"; break;
- case M_SOF5: process = "Differential sequential"; break;
- case M_SOF6: process = "Differential progressive"; break;
- case M_SOF7: process = "Differential lossless"; break;
- case M_SOF9: process = "Extended sequential, arithmetic coding"; break;
- case M_SOF10: process = "Progressive, arithmetic coding"; break;
- case M_SOF11: process = "Lossless, arithmetic coding"; break;
- case M_SOF13: process = "Differential sequential, arithmetic coding"; break;
- case M_SOF14: process = "Differential progressive, arithmetic coding"; break;
- case M_SOF15: process = "Differential lossless, arithmetic coding"; break;
- default: process = "Unknown"; break;
- }
-
- printf("JPEG image is %uw * %uh, %d color components, %d bits per sample\n",
- image_width, image_height, num_components, data_precision);
- printf("JPEG process: %s\n", process);
-
- if (length != (unsigned int) (8 + num_components * 3))
- ERREXIT("Bogus SOF marker length");
-
- for (ci = 0; ci < num_components; ci++) {
- (void) read_1_byte(); /* Component ID code */
- (void) read_1_byte(); /* H, V sampling factors */
- (void) read_1_byte(); /* Quantization table number */
- }
-}
-
-
-/*
- * Parse the marker stream until SOS or EOI is seen;
- * display any COM markers.
- * While the companion program wrjpgcom will always insert COM markers before
- * SOFn, other implementations might not, so we scan to SOS before stopping.
- * If we were only interested in the image dimensions, we would stop at SOFn.
- * (Conversely, if we only cared about COM markers, there would be no need
- * for special code to handle SOFn; we could treat it like other markers.)
- */
-
-static int
-scan_JPEG_header (int verbose)
-{
- int marker;
-
- /* Expect SOI at start of file */
- if (first_marker() != M_SOI)
- ERREXIT("Expected SOI marker first");
-
- /* Scan miscellaneous markers until we reach SOS. */
- for (;;) {
- marker = next_marker();
- 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 (verbose)
- process_SOFn(marker);
- else
- skip_variable();
- break;
-
- case M_SOS: /* stop before hitting compressed data */
- return marker;
-
- case M_EOI: /* in case it's a tables-only JPEG stream */
- return marker;
-
- case M_COM:
- process_COM();
- break;
-
- case M_APP12:
- /* Some digital camera makers put useful textual information into
- * APP12 markers, so we print those out too when in -verbose mode.
- */
- if (verbose) {
- printf("APP12 contains:\n");
- process_COM();
- } else
- skip_variable();
- break;
-
- default: /* Anything else just gets skipped */
- skip_variable(); /* we assume it has a parameter count... */
- break;
- }
- } /* end loop */
-}
-
-
-/* Command line parsing code */
-
-static const char * progname; /* program name for error messages */
-
-
-static void
-usage (void)
-/* complain about bad command line */
-{
- fprintf(stderr, "rdjpgcom displays any textual comments in a JPEG file.\n");
-
- fprintf(stderr, "Usage: %s [switches] [inputfile]\n", progname);
-
- fprintf(stderr, "Switches (names may be abbreviated):\n");
- fprintf(stderr, " -verbose Also display dimensions of JPEG image\n");
-
- exit(EXIT_FAILURE);
-}
-
-
-static int
-keymatch (char * arg, const char * keyword, int minchars)
-/* Case-insensitive matching of (possibly abbreviated) keyword switches. */
-/* keyword is the constant keyword (must be lower case already), */
-/* minchars is length of minimum legal abbreviation. */
-{
- register int ca, ck;
- register int nmatched = 0;
-
- while ((ca = *arg++) != '\0') {
- if ((ck = *keyword++) == '\0')
- return 0; /* arg longer than keyword, no good */
- if (isupper(ca)) /* force arg to lcase (assume ck is already) */
- ca = tolower(ca);
- if (ca != ck)
- return 0; /* no good */
- nmatched++; /* count matched characters */
- }
- /* reached end of argument; fail if it's too short for unique abbrev */
- if (nmatched < minchars)
- return 0;
- return 1; /* A-OK */
-}
-
-
-/*
- * The main program.
- */
-
-int
-main (int argc, char **argv)
-{
- int argn;
- char * arg;
- int verbose = 0;
-
- /* On Mac, fetch a command line. */
-#ifdef USE_CCOMMAND
- argc = ccommand(&argv);
-#endif
-
- progname = argv[0];
- if (progname == NULL || progname[0] == 0)
- progname = "rdjpgcom"; /* in case C library doesn't provide it */
-
- /* Parse switches, if any */
- for (argn = 1; argn < argc; argn++) {
- arg = argv[argn];
- if (arg[0] != '-')
- break; /* not switch, must be file name */
- arg++; /* advance over '-' */
- if (keymatch(arg, "verbose", 1)) {
- verbose++;
- } else
- usage();
- }
-
- /* Open the input file. */
- /* Unix style: expect zero or one file name */
- if (argn < argc-1) {
- fprintf(stderr, "%s: only one input file\n", progname);
- usage();
- }
- if (argn < argc) {
- if ((infile = fopen(argv[argn], READ_BINARY)) == NULL) {
- fprintf(stderr, "%s: can't open %s\n", progname, argv[argn]);
- exit(EXIT_FAILURE);
- }
- } else {
- /* default input file is stdin */
-#ifdef USE_SETMODE /* need to hack file mode? */
- setmode(fileno(stdin), O_BINARY);
-#endif
-#ifdef USE_FDOPEN /* need to re-open in binary mode? */
- if ((infile = fdopen(fileno(stdin), READ_BINARY)) == NULL) {
- fprintf(stderr, "%s: can't open stdin\n", progname);
- exit(EXIT_FAILURE);
- }
-#else
- infile = stdin;
-#endif
- }
-
- /* Scan the JPEG headers. */
- (void) scan_JPEG_header(verbose);
-
- /* All done. */
- exit(EXIT_SUCCESS);
- return 0; /* suppress no-return-value warnings */
-}
projects / synfig.git / blobdiff