tif_jpeg.c

一个国人自己实现图像库的程序（有参考价值）

			return (0);
		}
	}

	/* Create a JPEGTables field if appropriate */
	if (sp->jpegtablesmode & (JPEGTABLESMODE_QUANT|JPEGTABLESMODE_HUFF)) {
		if (!prepare_JPEGTables(tif))
			return (0);
		/* Mark the field present */
		/* Can't use TIFFSetField since BEENWRITING is already set! */
		TIFFSetFieldBit(tif, FIELD_JPEGTABLES);
		tif->tif_flags |= TIFF_DIRTYDIRECT;
	} else {
		/* We do not support application-supplied JPEGTables, */
		/* so mark the field not present */
		TIFFClrFieldBit(tif, FIELD_JPEGTABLES);
	}

	/* Direct libjpeg output to libtiff's output buffer */
	TIFFjpeg_data_dest(sp, tif);

	return (1);
}

/*
 * Set encoding state at the start of a strip or tile.
 */
static int
JPEGPreEncode(TIFF* tif, tsample_t s)
{
	JPEGState *sp = JState(tif);
	TIFFDirectory *td = &tif->tif_dir;
	static const char module[] = "JPEGPreEncode";
	uint32 segment_width, segment_height;
	int downsampled_input;

	assert(sp != NULL);
	assert(!sp->cinfo.comm.is_decompressor);
	/*
	 * Set encoding parameters for this strip/tile.
	 */
	if (isTiled(tif)) {
		segment_width = td->td_tilewidth;
		segment_height = td->td_tilelength;
		sp->bytesperline = TIFFTileRowSize(tif);
	} else {
		segment_width = td->td_imagewidth;
		segment_height = td->td_imagelength - tif->tif_row;
		if (segment_height > td->td_rowsperstrip)
			segment_height = td->td_rowsperstrip;
		sp->bytesperline = TIFFScanlineSize(tif);
	}
	if (td->td_planarconfig == PLANARCONFIG_SEPARATE && s > 0) {
		/* for PC 2, scale down the strip/tile size
		 * to match a downsampled component
		 */
		segment_width = TIFFhowmany(segment_width, sp->h_sampling);
		segment_height = TIFFhowmany(segment_height, sp->v_sampling);
	}
	if (segment_width > 65535 || segment_height > 65535) {
		TIFFError(module, "Strip/tile too large for JPEG");
		return (0);
	}
	sp->cinfo.c.image_width = segment_width;
	sp->cinfo.c.image_height = segment_height;
	downsampled_input = FALSE;
	if (td->td_planarconfig == PLANARCONFIG_CONTIG) {
		sp->cinfo.c.input_components = td->td_samplesperpixel;
		if (sp->photometric == PHOTOMETRIC_YCBCR) {
			if (sp->jpegcolormode == JPEGCOLORMODE_RGB) {
				sp->cinfo.c.in_color_space = JCS_RGB;
			} else {
				sp->cinfo.c.in_color_space = JCS_YCbCr;
				if (sp->h_sampling != 1 || sp->v_sampling != 1)
					downsampled_input = TRUE;
			}
			if (!TIFFjpeg_set_colorspace(sp, JCS_YCbCr))
				return (0);
			/*
			 * Set Y sampling factors;
			 * we assume jpeg_set_colorspace() set the rest to 1
			 */
			sp->cinfo.c.comp_info[0].h_samp_factor = sp->h_sampling;
			sp->cinfo.c.comp_info[0].v_samp_factor = sp->v_sampling;
		} else {
			sp->cinfo.c.in_color_space = JCS_UNKNOWN;
			if (!TIFFjpeg_set_colorspace(sp, JCS_UNKNOWN))
				return (0);
			/* jpeg_set_colorspace set all sampling factors to 1 */
		}
	} else {
		sp->cinfo.c.input_components = 1;
		sp->cinfo.c.in_color_space = JCS_UNKNOWN;
		if (!TIFFjpeg_set_colorspace(sp, JCS_UNKNOWN))
			return (0);
		sp->cinfo.c.comp_info[0].component_id = s;
		/* jpeg_set_colorspace() set sampling factors to 1 */
		if (sp->photometric == PHOTOMETRIC_YCBCR && s > 0) {
			sp->cinfo.c.comp_info[0].quant_tbl_no = 1;
			sp->cinfo.c.comp_info[0].dc_tbl_no = 1;
			sp->cinfo.c.comp_info[0].ac_tbl_no = 1;
		}
	}
	/* ensure libjpeg won't write any extraneous markers */
	sp->cinfo.c.write_JFIF_header = FALSE;
	sp->cinfo.c.write_Adobe_marker = FALSE;
	/* set up table handling correctly */
	if (! (sp->jpegtablesmode & JPEGTABLESMODE_QUANT)) {
		if (!TIFFjpeg_set_quality(sp, sp->jpegquality, FALSE))
			return (0);
		unsuppress_quant_table(sp, 0);
		unsuppress_quant_table(sp, 1);
	}
	if (sp->jpegtablesmode & JPEGTABLESMODE_HUFF)
		sp->cinfo.c.optimize_coding = FALSE;
	else
		sp->cinfo.c.optimize_coding = TRUE;
	if (downsampled_input) {
		/* Need to use raw-data interface to libjpeg */
		sp->cinfo.c.raw_data_in = TRUE;
		tif->tif_encoderow = JPEGEncodeRaw;
		tif->tif_encodestrip = JPEGEncodeRaw;
		tif->tif_encodetile = JPEGEncodeRaw;
	} else {
		/* Use normal interface to libjpeg */
		sp->cinfo.c.raw_data_in = FALSE;
		tif->tif_encoderow = JPEGEncode;
		tif->tif_encodestrip = JPEGEncode;
		tif->tif_encodetile = JPEGEncode;
	}
	/* Start JPEG compressor */
	if (!TIFFjpeg_start_compress(sp, FALSE))
		return (0);
	/* Allocate downsampled-data buffers if needed */
	if (downsampled_input) {
		if (!alloc_downsampled_buffers(tif, sp->cinfo.c.comp_info,
					       sp->cinfo.c.num_components))
			return (0);
	}
	sp->scancount = 0;

	return (1);
}

/*
 * Encode a chunk of pixels.
 * "Standard" case: incoming data is not downsampled.
 */
static int
JPEGEncode(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
	JPEGState *sp = JState(tif);
	tsize_t nrows;
	JSAMPROW bufptr[1];

	(void) s;
	assert(sp != NULL);
	/* data is expected to be supplied in multiples of a scanline */
	nrows = cc / sp->bytesperline;
	if (cc % sp->bytesperline)
		TIFFWarning(tif->tif_name, "fractional scanline discarded");

	while (nrows-- > 0) {
		bufptr[0] = (JSAMPROW) buf;
		if (TIFFjpeg_write_scanlines(sp, bufptr, 1) != 1)
			return (0);
		if (nrows > 0)
			tif->tif_row++;
		buf += sp->bytesperline;
	}
	return (1);
}

/*
 * Encode a chunk of pixels.
 * Incoming data is expected to be downsampled per sampling factors.
 */
static int
JPEGEncodeRaw(TIFF* tif, tidata_t buf, tsize_t cc, tsample_t s)
{
	JPEGState *sp = JState(tif);
	JSAMPLE* inptr;
	JSAMPLE* outptr;
	tsize_t nrows;
	JDIMENSION clumps_per_line, nclump;
	int clumpoffset, ci, xpos, ypos;
	jpeg_component_info* compptr;
	int samples_per_clump = sp->samplesperclump;

	(void) s;
	assert(sp != NULL);
	/* data is expected to be supplied in multiples of a scanline */
	nrows = cc / sp->bytesperline;
	if (cc % sp->bytesperline)
		TIFFWarning(tif->tif_name, "fractional scanline discarded");

	/* Cb,Cr both have sampling factors 1, so this is correct */
	clumps_per_line = sp->cinfo.c.comp_info[1].downsampled_width;

	while (nrows-- > 0) {
		/*
		 * Fastest way to separate the data is to make one pass
		 * over the scanline for each row of each component.
		 */
		clumpoffset = 0;		/* first sample in clump */
		for (ci = 0, compptr = sp->cinfo.c.comp_info;
		     ci < sp->cinfo.c.num_components;
		     ci++, compptr++) {
		    int hsamp = compptr->h_samp_factor;
		    int vsamp = compptr->v_samp_factor;
		    int padding = (int) (compptr->width_in_blocks * DCTSIZE -
					 clumps_per_line * hsamp);
		    for (ypos = 0; ypos < vsamp; ypos++) {
			inptr = ((JSAMPLE*) buf) + clumpoffset;
			outptr = sp->ds_buffer[ci][sp->scancount*vsamp + ypos];
			if (hsamp == 1) {
			    /* fast path for at least Cb and Cr */
			    for (nclump = clumps_per_line; nclump-- > 0; ) {
				*outptr++ = inptr[0];
				inptr += samples_per_clump;
			    }
			} else {
			    /* general case */
			    for (nclump = clumps_per_line; nclump-- > 0; ) {
				for (xpos = 0; xpos < hsamp; xpos++)
				    *outptr++ = inptr[xpos];
				inptr += samples_per_clump;
			    }
			}
			/* pad each scanline as needed */
			for (xpos = 0; xpos < padding; xpos++) {
			    *outptr = outptr[-1];
			    outptr++;
			}
			clumpoffset += hsamp;
		    }
		}
		sp->scancount++;
		if (sp->scancount >= DCTSIZE) {
			int n = sp->cinfo.c.max_v_samp_factor * DCTSIZE;
			if (TIFFjpeg_write_raw_data(sp, sp->ds_buffer, n) != n)
				return (0);
			sp->scancount = 0;
		}
		if (nrows > 0)
			tif->tif_row++;
		buf += sp->bytesperline;
	}
	return (1);
}

/*
 * Finish up at the end of a strip or tile.
 */
static int
JPEGPostEncode(TIFF* tif)
{
	JPEGState *sp = JState(tif);

	if (sp->scancount > 0) {
		/*
		 * Need to emit a partial bufferload of downsampled data.
		 * Pad the data vertically.
		 */
		int ci, ypos, n;
		jpeg_component_info* compptr;

		for (ci = 0, compptr = sp->cinfo.c.comp_info;
		     ci < sp->cinfo.c.num_components;
		     ci++, compptr++) {
			int vsamp = compptr->v_samp_factor;
			tsize_t row_width = compptr->width_in_blocks * DCTSIZE
				* sizeof(JSAMPLE);
			for (ypos = sp->scancount * vsamp;
			     ypos < DCTSIZE * vsamp; ypos++) {
				_TIFFmemcpy((tdata_t)sp->ds_buffer[ci][ypos],
					    (tdata_t)sp->ds_buffer[ci][ypos-1],
					    row_width);

			}
		}
		n = sp->cinfo.c.max_v_samp_factor * DCTSIZE;
		if (TIFFjpeg_write_raw_data(sp, sp->ds_buffer, n) != n)
			return (0);
	}

	return (TIFFjpeg_finish_compress(JState(tif)));
}

static void
JPEGCleanup(TIFF* tif)
{
	if (tif->tif_data) {
		JPEGState *sp = JState(tif);
		TIFFjpeg_destroy(sp);		/* release libjpeg resources */
		if (sp->jpegtables)		/* tag value */
			_TIFFfree(sp->jpegtables);
		_TIFFfree(tif->tif_data);	/* release local state */
		tif->tif_data = NULL;
	}
}

static int
JPEGVSetField(TIFF* tif, ttag_t tag, va_list ap)
{
	JPEGState* sp = JState(tif);
	TIFFDirectory* td = &tif->tif_dir;
	uint32 v32;

	switch (tag) {
	case TIFFTAG_JPEGTABLES:
		v32 = va_arg(ap, uint32);
		if (v32 == 0) {
			/* XXX */
			return (0);
		}
		_TIFFsetByteArray(&sp->jpegtables, va_arg(ap, void*),
		    (long) v32);
		sp->jpegtables_length = v32;
		TIFFSetFieldBit(tif, FIELD_JPEGTABLES);
		break;
	case TIFFTAG_JPEGQUALITY:
		sp->jpegquality = va_arg(ap, int);
		return (1);			/* pseudo tag */
	case TIFFTAG_JPEGCOLORMODE:
		sp->jpegcolormode = va_arg(ap, int);
		/*
		 * Mark whether returned data is up-sampled or not
		 * so TIFFStripSize and TIFFTileSize return values
		 * that reflect the true amount of data.
		 */
		tif->tif_flags &= ~TIFF_UPSAMPLED;
		if (td->td_planarconfig == PLANARCONFIG_CONTIG) {
		    if (td->td_photometric == PHOTOMETRIC_YCBCR &&
		      sp->jpegcolormode == JPEGCOLORMODE_RGB) {
			tif->tif_flags |= TIFF_UPSAMPLED;
		    } else {
			if (td->td_ycbcrsubsampling[0] != 1 ||
			    td->td_ycbcrsubsampling[1] != 1)
			    ; /* XXX what about up-sampling? */
		    }
		}
		/*
		 * Must recalculate cached tile size
		 * in case sampling state changed.
		 */
		tif->tif_tilesize = TIFFTileSize(tif);
		return (1);			/* pseudo tag */
	case TIFFTAG_JPEGTABLESMODE:
		sp->jpegtablesmode = va_arg(ap, int);
		return (1);			/* pseudo tag */
	default:
		return (*sp->vsetparent)(tif, tag, ap);
	}
	tif->tif_flags |= TIFF_DIRTYDIRECT;
	return (1);
}

static int
JPEGVGetField(TIFF* tif, ttag_t tag, va_list ap)
{
	JPEGState* sp = JState(tif);

	switch (tag) {
	case TIFFTAG_JPEGTABLES:
		/* u_short is bogus --- should be uint32 ??? */
		/* TIFFWriteNormalTag needs fixed  XXX */
		*va_arg(ap, u_short*) = (u_short) sp->jpegtables_length;
		*va_arg(ap, void**) = sp->jpegtables;
		break;
	case TIFFTAG_JPEGQUALITY:
		*va_arg(ap, int*) = sp->jpegquality;
		break;
	case TIFFTAG_JPEGCOLORMODE:
		*va_arg(ap, int*) = sp->jpegcolormode;
		break;
	case TIFFTAG_JPEGTABLESMODE:
		*va_arg(ap, int*) = sp->jpegtablesmode;
		break;
	default:
		return (*sp->vgetparent)(tif, tag, ap);
	}
	return (1);
}

static void
JPEGPrintDir(TIFF* tif, FILE* fd, long flags)
{
	JPEGState* sp = JState(tif);

	(void) flags;
	if (TIFFFieldSet(tif,FIELD_JPEGTABLES))
		fprintf(fd, "  JPEG Tables: (%lu bytes)\n",
			(u_long) sp->jpegtables_length);
}

static uint32
JPEGDefaultStripSize(TIFF* tif, uint32 s)
{
	JPEGState* sp = JState(tif);
	TIFFDirectory *td = &tif->tif_dir;

	s = (*sp->defsparent)(tif, s);
	if (s < td->td_imagelength)
		s = TIFFroundup(s, td->td_ycbcrsubsampling[1] * DCTSIZE);
	return (s);
}

static void
JPEGDefaultTileSize(TIFF* tif, uint32* tw, uint32* th)
{
	JPEGState* sp = JState(tif);
	TIFFDirectory *td = &tif->tif_dir;

	(*sp->deftparent)(tif, tw, th);
	*tw = TIFFroundup(*tw, td->td_ycbcrsubsampling[0] * DCTSIZE);
	*th = TIFFroundup(*th, td->td_ycbcrsubsampling[1] * DCTSIZE);
}

int
TIFFInitJPEG(TIFF* tif, int scheme)
{
	JPEGState* sp;

	assert(scheme == COMPRESSION_JPEG);

	/*
	 * Allocate state block so tag methods have storage to record values.
	 */
	tif->tif_data = (tidata_t) _TIFFmalloc(sizeof (JPEGState));
	if (tif->tif_data == NULL) {
		TIFFError("TIFFInitJPEG", "No space for JPEG state block");
		return (0);
	}
	sp = JState(tif);
	sp->tif = tif;				/* back link */

	/*
	 * Merge codec-specific tag information and
	 * override parent get/set field methods.
	 */
	_TIFFMergeFieldInfo(tif, jpegFieldInfo, N(jpegFieldInfo));
	sp->vgetparent = tif->tif_vgetfield;
	tif->tif_vgetfield = JPEGVGetField;	/* hook for codec tags */
	sp->vsetparent = tif->tif_vsetfield;
	tif->tif_vsetfield = JPEGVSetField;	/* hook for codec tags */
	tif->tif_printdir = JPEGPrintDir;	/* hook for codec tags */

	/* Default values for codec-specific fields */
	sp->jpegtables = NULL;
	sp->jpegtables_length = 0;
	sp->jpegquality = 75;			/* Default IJG quality */
	sp->jpegcolormode = JPEGCOLORMODE_RAW;
	sp->jpegtablesmode = JPEGTABLESMODE_QUANT | JPEGTABLESMODE_HUFF;

	/*
	 * Install codec methods.
	 */
	tif->tif_setupdecode = JPEGSetupDecode;
	tif->tif_predecode = JPEGPreDecode;
	tif->tif_decoderow = JPEGDecode;
	tif->tif_decodestrip = JPEGDecode;
	tif->tif_decodetile = JPEGDecode;
	tif->tif_setupencode = JPEGSetupEncode;
	tif->tif_preencode = JPEGPreEncode;
	tif->tif_postencode = JPEGPostEncode;
	tif->tif_encoderow = JPEGEncode;
	tif->tif_encodestrip = JPEGEncode;
	tif->tif_encodetile = JPEGEncode;
	tif->tif_cleanup = JPEGCleanup;
	sp->defsparent = tif->tif_defstripsize;
	tif->tif_defstripsize = JPEGDefaultStripSize;
	sp->deftparent = tif->tif_deftilesize;
	tif->tif_deftilesize = JPEGDefaultTileSize;
	tif->tif_flags |= TIFF_NOBITREV;	/* no bit reversal, please */

	/*
	 * Initialize libjpeg.
	 */
	if (tif->tif_mode == O_RDONLY) {
		if (!TIFFjpeg_create_decompress(sp))
			return (0);
	} else {
		if (!TIFFjpeg_create_compress(sp))
			return (0);
	}

	return (1);
}
#endif /* JPEG_SUPPORT */