mif_cod.c

用C语言实现的JPEG编码

		jas_image_destroy(tmpimage);
	}
	if (data) {
		jas_seq2d_destroy(data);
	}
	return -1;
}

/******************************************************************************\
* Code for validate operation.
\******************************************************************************/

int mif_validate(jas_stream_t *in)
{
	uchar buf[MIF_MAGICLEN];
	uint_fast32_t magic;
	int i;
	int n;

	assert(JAS_STREAM_MAXPUTBACK >= MIF_MAGICLEN);

	/* Read the validation data (i.e., the data used for detecting
	  the format). */
	if ((n = jas_stream_read(in, buf, MIF_MAGICLEN)) < 0) {
		return -1;
	}

	/* Put the validation data back onto the stream, so that the
	  stream position will not be changed. */
	for (i = n - 1; i >= 0; --i) {
		if (jas_stream_ungetc(in, buf[i]) == EOF) {
			return -1;
		}
	}

	/* Was enough data read? */
	if (n < MIF_MAGICLEN) {
		return -1;
	}

	/* Compute the signature value. */
	magic = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];

	/* Ensure that the signature is correct for this format. */
	if (magic != MIF_MAGIC) {
		return -1;
	}

	return 0;
}

/******************************************************************************\
* Code for MIF header class.
\******************************************************************************/

static mif_hdr_t *mif_hdr_create(int maxcmpts)
{
	mif_hdr_t *hdr;
	if (!(hdr = jas_malloc(sizeof(mif_hdr_t)))) {
		return 0;
	}
	hdr->numcmpts = 0;
	hdr->maxcmpts = 0;
	hdr->cmpts = 0;
	if (mif_hdr_growcmpts(hdr, maxcmpts)) {
		mif_hdr_destroy(hdr);
		return 0;
	}
	return hdr;
}

static void mif_hdr_destroy(mif_hdr_t *hdr)
{
	int cmptno;
	if (hdr->cmpts) {
		for (cmptno = 0; cmptno < hdr->numcmpts; ++cmptno) {
			mif_cmpt_destroy(hdr->cmpts[cmptno]);
		}
		jas_free(hdr->cmpts);
	}
	jas_free(hdr);
}

static int mif_hdr_growcmpts(mif_hdr_t *hdr, int maxcmpts)
{
	int cmptno;
	mif_cmpt_t **newcmpts;
	assert(maxcmpts >= hdr->numcmpts);
	newcmpts = (!hdr->cmpts) ? jas_malloc(maxcmpts * sizeof(mif_cmpt_t *)) :
	  jas_realloc(hdr->cmpts, maxcmpts * sizeof(mif_cmpt_t *));
	if (!newcmpts) {
		return -1;
	}
	hdr->maxcmpts = maxcmpts;
	hdr->cmpts = newcmpts;
	for (cmptno = hdr->numcmpts; cmptno < hdr->maxcmpts; ++cmptno) {
		hdr->cmpts[cmptno] = 0;
	}
	return 0;
}

static mif_hdr_t *mif_hdr_get(jas_stream_t *in)
{
	uchar magicbuf[MIF_MAGICLEN];
	char buf[4096];
	mif_hdr_t *hdr;
	bool done;
	jas_tvparser_t *tvp;
	int id;

	hdr = 0;

	if (jas_stream_read(in, magicbuf, MIF_MAGICLEN) != MIF_MAGICLEN) {
		goto error;
	}
	if (magicbuf[0] != (MIF_MAGIC >> 24) || magicbuf[1] != ((MIF_MAGIC >> 16) &
	  0xff) || magicbuf[2] != ((MIF_MAGIC >> 8) & 0xff) || magicbuf[3] !=
	  (MIF_MAGIC & 0xff)) {
		fprintf(stderr, "error: bad signature\n");
		goto error;
	}

	if (!(hdr = mif_hdr_create(0))) {
		goto error;
	}

	done = false;
	do {
		if (!mif_getline(in, buf, sizeof(buf))) {
			goto error;
		}
		if (buf[0] == '\0') {
			continue;
		}
		if (!(tvp = jas_tvparser_create(buf))) {
			goto error;
		}
		if (jas_tvparser_next(tvp)) {
			abort();
		}
		id = jas_taginfo_nonull(jas_taginfos_lookup(mif_tags2, jas_tvparser_gettag(tvp)))->id;
		jas_tvparser_destroy(tvp);
		switch (id) {
		case MIF_CMPT:
			mif_process_cmpt(hdr, buf);
			break;
		case MIF_END:
			done = 1;
			break;
		}
	} while (!done);

	return hdr;

error:
	if (hdr) {
		mif_hdr_destroy(hdr);
	}
	return 0;
}

static int mif_process_cmpt(mif_hdr_t *hdr, char *buf)
{
	jas_tvparser_t *tvp;
	mif_cmpt_t *cmpt;
	int id;

	cmpt = 0;
	tvp = 0;

	if (!(cmpt = mif_cmpt_create())) {
		goto error;
	}
	cmpt->tlx = 0;
	cmpt->tly = 0;
	cmpt->sampperx = 0;
	cmpt->samppery = 0;
	cmpt->width = 0;
	cmpt->height = 0;
	cmpt->prec = 0;
	cmpt->sgnd = -1;
	cmpt->data = 0;

	if (!(tvp = jas_tvparser_create(buf))) {
		goto error;
	}
	while (!(id = jas_tvparser_next(tvp))) {
		switch (jas_taginfo_nonull(jas_taginfos_lookup(mif_tags,
		  jas_tvparser_gettag(tvp)))->id) {
		case MIF_TLX:
			cmpt->tlx = atoi(jas_tvparser_getval(tvp));
			break;
		case MIF_TLY:
			cmpt->tly = atoi(jas_tvparser_getval(tvp));
			break;
		case MIF_WIDTH:
			cmpt->width = atoi(jas_tvparser_getval(tvp));
			break;
		case MIF_HEIGHT:
			cmpt->height = atoi(jas_tvparser_getval(tvp));
			break;
		case MIF_HSAMP:
			cmpt->sampperx = atoi(jas_tvparser_getval(tvp));
			break;
		case MIF_VSAMP:
			cmpt->samppery = atoi(jas_tvparser_getval(tvp));
			break;
		case MIF_PREC:
			cmpt->prec = atoi(jas_tvparser_getval(tvp));
			break;
		case MIF_SGND:
			cmpt->sgnd = atoi(jas_tvparser_getval(tvp));
			break;
		case MIF_DATA:
			if (!(cmpt->data = jas_strdup(jas_tvparser_getval(tvp)))) {
				return -1;
			}
			break;
		}
	}
	jas_tvparser_destroy(tvp);
	if (!cmpt->sampperx || !cmpt->samppery) {
		goto error;
	}
	if (mif_hdr_addcmpt(hdr, hdr->numcmpts, cmpt)) {
		goto error;
	}
	return 0;

error:
	if (cmpt) {
		mif_cmpt_destroy(cmpt);
	}
	if (tvp) {
		jas_tvparser_destroy(tvp);
	}
	return -1;
}

static int mif_hdr_put(mif_hdr_t *hdr, jas_stream_t *out)
{
	int cmptno;
	mif_cmpt_t *cmpt;

	/* Output signature. */
	jas_stream_putc(out, (MIF_MAGIC >> 24) & 0xff);
	jas_stream_putc(out, (MIF_MAGIC >> 16) & 0xff);
	jas_stream_putc(out, (MIF_MAGIC >> 8) & 0xff);
	jas_stream_putc(out, MIF_MAGIC & 0xff);

	/* Output component information. */
	for (cmptno = 0; cmptno < hdr->numcmpts; ++cmptno) {
		cmpt = hdr->cmpts[cmptno];
		jas_stream_printf(out, "component tlx=%ld tly=%ld "
		  "sampperx=%ld samppery=%ld width=%ld height=%ld prec=%d sgnd=%d",
		  cmpt->tlx, cmpt->tly, cmpt->sampperx, cmpt->samppery, cmpt->width,
		  cmpt->height, cmpt->prec, cmpt->sgnd);
		if (cmpt->data) {
			jas_stream_printf(out, " data=%s", cmpt->data);
		}
		jas_stream_printf(out, "\n");
	}

	/* Output end of header indicator. */
	jas_stream_printf(out, "end\n");

	return 0;
}

static int mif_hdr_addcmpt(mif_hdr_t *hdr, int cmptno, mif_cmpt_t *cmpt)
{
	assert(cmptno >= hdr->numcmpts);
	if (hdr->numcmpts >= hdr->maxcmpts) {
		if (mif_hdr_growcmpts(hdr, hdr->numcmpts + 128)) {
			return -1;
		}
	}
	hdr->cmpts[hdr->numcmpts] = cmpt;
	++hdr->numcmpts;
	return 0;
}

/******************************************************************************\
* Code for MIF component class.
\******************************************************************************/

static mif_cmpt_t *mif_cmpt_create()
{
	mif_cmpt_t *cmpt;
	if (!(cmpt = jas_malloc(sizeof(mif_cmpt_t)))) {
		return 0;
	}
	memset(cmpt, 0, sizeof(mif_cmpt_t));
	return cmpt;
}

static void mif_cmpt_destroy(mif_cmpt_t *cmpt)
{
	if (cmpt->data) {
		jas_free(cmpt->data);
	}
	jas_free(cmpt);
}

/******************************************************************************\
* MIF parsing code.
\******************************************************************************/

static char *mif_getline(jas_stream_t *stream, char *buf, int bufsize)
{
	int c;
	char *bufptr;
	assert(bufsize > 0);

	bufptr = buf;
	while (bufsize > 1) {
		if ((c = mif_getc(stream)) == EOF) {
			break;
		}
		*bufptr++ = c;
		--bufsize;
		if (c == '\n') {
			break;
		}
	}
	*bufptr = '\0';
	if (!(bufptr = strchr(buf, '\n'))) {
		return 0;
	}
	*bufptr = '\0';
	return buf;
}

static int mif_getc(jas_stream_t *in)
{
	int c;
	bool done;

	done = false;
	do {
		switch (c = jas_stream_getc(in)) {
		case EOF:
			done = 1;
			break;
		case '#':
			for (;;) {
				if ((c = jas_stream_getc(in)) == EOF) {
					done = 1;
					break;
				}	
				if (c == '\n') {
					break;
				}
			}
			break;
		case '\\':
			if (jas_stream_peekc(in) == '\n') {
				jas_stream_getc(in);
			}
			break;
		default:
			done = 1;
			break;
		}
	} while (!done);

	return c;
}

/******************************************************************************\
* Miscellaneous functions.
\******************************************************************************/

static mif_hdr_t *mif_makehdrfromimage(jas_image_t *image)
{
	mif_hdr_t *hdr;
	int cmptno;
	mif_cmpt_t *cmpt;

	if (!(hdr = mif_hdr_create(jas_image_numcmpts(image)))) {
		return 0;
	}
	hdr->magic = MIF_MAGIC;
	hdr->numcmpts = jas_image_numcmpts(image);
	for (cmptno = 0; cmptno < hdr->numcmpts; ++cmptno) {
		hdr->cmpts[cmptno] = jas_malloc(sizeof(mif_cmpt_t));
		cmpt = hdr->cmpts[cmptno];
		cmpt->tlx = jas_image_cmpttlx(image, cmptno);
		cmpt->tly = jas_image_cmpttly(image, cmptno);
		cmpt->width = jas_image_cmptwidth(image, cmptno);
		cmpt->height = jas_image_cmptheight(image, cmptno);
		cmpt->sampperx = jas_image_cmpthstep(image, cmptno);
		cmpt->samppery = jas_image_cmptvstep(image, cmptno);
		cmpt->prec = jas_image_cmptprec(image, cmptno);
		cmpt->sgnd = jas_image_cmptsgnd(image, cmptno);
		cmpt->data = 0;
	}
	return hdr;
}