tif_dirread.c

一个国人自己实现图像库的程序（有参考价值）

	case TIFF_SBYTE:
		if (!TIFFFetchByteArray(tif, dir, (uint16*) v))
			return (0);
		if (dir->tdir_type == TIFF_BYTE) {
			uint16* vp = (uint16*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		} else {
			int16* vp = (int16*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		}
		break;
	case TIFF_SHORT:
	case TIFF_SSHORT:
		if (!TIFFFetchShortArray(tif, dir, (uint16*) v))
			return (0);
		if (dir->tdir_type == TIFF_SHORT) {
			uint16* vp = (uint16*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		} else {
			int16* vp = (int16*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		}
		break;
	case TIFF_LONG:
	case TIFF_SLONG:
		if (!TIFFFetchLongArray(tif, dir, (uint32*) v))
			return (0);
		if (dir->tdir_type == TIFF_LONG) {
			uint32* vp = (uint32*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		} else {
			int32* vp = (int32*) v;
			for (i = dir->tdir_count-1; i >= 0; i--)
				v[i] = vp[i];
		}
		break;
	case TIFF_RATIONAL:
	case TIFF_SRATIONAL:
		if (!TIFFFetchRationalArray(tif, dir, (float*) v))
			return (0);
		{ float* vp = (float*) v;
		  for (i = dir->tdir_count-1; i >= 0; i--)
			v[i] = vp[i];
		}
		break;
	case TIFF_FLOAT:
		if (!TIFFFetchFloatArray(tif, dir, (float*) v))
			return (0);
		{ float* vp = (float*) v;
		  for (i = dir->tdir_count-1; i >= 0; i--)
			v[i] = vp[i];
		}
		break;
	case TIFF_DOUBLE:
		return (TIFFFetchDoubleArray(tif, dir, (double*) v));
	default:
		/* TIFF_NOTYPE */
		/* TIFF_ASCII */
		/* TIFF_UNDEFINED */
		TIFFError(tif->tif_name,
		    "Cannot read TIFF_ANY type %d for field \"%s\"",
		    _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
		return (0);
	}
	return (1);
}

/*
 * Fetch a tag that is not handled by special case code.
 */
static int
TIFFFetchNormalTag(TIFF* tif, TIFFDirEntry* dp)
{
	static const char mesg[] = "to fetch tag value";
	int ok = 0;
	const TIFFFieldInfo* fip = _TIFFFieldWithTag(tif, dp->tdir_tag);

	if (dp->tdir_count > 1) {		/* array of values */
		char* cp = NULL;

		switch (dp->tdir_type) {
		case TIFF_BYTE:
		case TIFF_SBYTE:
			/* NB: always expand BYTE values to shorts */
			cp = CheckMalloc(tif,
			    dp->tdir_count * sizeof (uint16), mesg);
			ok = cp && TIFFFetchByteArray(tif, dp, (uint16*) cp);
			break;
		case TIFF_SHORT:
		case TIFF_SSHORT:
			cp = CheckMalloc(tif,
			    dp->tdir_count * sizeof (uint16), mesg);
			ok = cp && TIFFFetchShortArray(tif, dp, (uint16*) cp);
			break;
		case TIFF_LONG:
		case TIFF_SLONG:
			cp = CheckMalloc(tif,
			    dp->tdir_count * sizeof (uint32), mesg);
			ok = cp && TIFFFetchLongArray(tif, dp, (uint32*) cp);
			break;
		case TIFF_RATIONAL:
		case TIFF_SRATIONAL:
			cp = CheckMalloc(tif,
			    dp->tdir_count * sizeof (float), mesg);
			ok = cp && TIFFFetchRationalArray(tif, dp, (float*) cp);
			break;
		case TIFF_FLOAT:
			cp = CheckMalloc(tif,
			    dp->tdir_count * sizeof (float), mesg);
			ok = cp && TIFFFetchFloatArray(tif, dp, (float*) cp);
			break;
		case TIFF_DOUBLE:
			cp = CheckMalloc(tif,
			    dp->tdir_count * sizeof (double), mesg);
			ok = cp && TIFFFetchDoubleArray(tif, dp, (double*) cp);
			break;
		case TIFF_ASCII:
		case TIFF_UNDEFINED:		/* bit of a cheat... */
			/*
			 * Some vendors write strings w/o the trailing
			 * NULL byte, so always append one just in case.
			 */
			cp = CheckMalloc(tif, dp->tdir_count+1, mesg);
			if( (ok = (cp && TIFFFetchString(tif, dp, cp))) != 0 )
				cp[dp->tdir_count] = '\0';	/* XXX */
			break;
		}
		if (ok) {
			ok = (fip->field_passcount ?
			    TIFFSetField(tif, dp->tdir_tag, dp->tdir_count, cp)
			  : TIFFSetField(tif, dp->tdir_tag, cp));
		}
		if (cp != NULL)
			_TIFFfree(cp);
	} else if (CheckDirCount(tif, dp, 1)) {	/* singleton value */
		switch (dp->tdir_type) {
		case TIFF_BYTE:
		case TIFF_SBYTE:
		case TIFF_SHORT:
		case TIFF_SSHORT:
			/*
			 * If the tag is also acceptable as a LONG or SLONG
			 * then TIFFSetField will expect an uint32 parameter
			 * passed to it (through varargs).  Thus, for machines
			 * where sizeof (int) != sizeof (uint32) we must do
			 * a careful check here.  It's hard to say if this
			 * is worth optimizing.
			 *
			 * NB: We use TIFFFieldWithTag here knowing that
			 *     it returns us the first entry in the table
			 *     for the tag and that that entry is for the
			 *     widest potential data type the tag may have.
			 */
			{ TIFFDataType type = fip->field_type;
			  if (type != TIFF_LONG && type != TIFF_SLONG) {
				uint16 v = (uint16)
			   TIFFExtractData(tif, dp->tdir_type, dp->tdir_offset);
				ok = (fip->field_passcount ?
				    TIFFSetField(tif, dp->tdir_tag, 1, &v)
				  : TIFFSetField(tif, dp->tdir_tag, v));
				break;
			  }
			}
			/* fall thru... */
		case TIFF_LONG:
		case TIFF_SLONG:
			{ uint32 v32 =
		    TIFFExtractData(tif, dp->tdir_type, dp->tdir_offset);
			  ok = (fip->field_passcount ? 
			      TIFFSetField(tif, dp->tdir_tag, 1, &v32)
			    : TIFFSetField(tif, dp->tdir_tag, v32));
			}
			break;
		case TIFF_RATIONAL:
		case TIFF_SRATIONAL:
		case TIFF_FLOAT:
			{ float v = (dp->tdir_type == TIFF_FLOAT ? 
			      TIFFFetchFloat(tif, dp)
			    : TIFFFetchRational(tif, dp));
			  ok = (fip->field_passcount ?
			      TIFFSetField(tif, dp->tdir_tag, 1, &v)
			    : TIFFSetField(tif, dp->tdir_tag, v));
			}
			break;
		case TIFF_DOUBLE:
			{ double v;
			  ok = (TIFFFetchDoubleArray(tif, dp, &v) &&
			    (fip->field_passcount ?
			      TIFFSetField(tif, dp->tdir_tag, 1, &v)
			    : TIFFSetField(tif, dp->tdir_tag, v))
			  );
			}
			break;
		case TIFF_ASCII:
		case TIFF_UNDEFINED:		/* bit of a cheat... */
			{ char c[2];
			  if( (ok = (TIFFFetchString(tif, dp, c) != 0)) != 0 ){
				c[1] = '\0';		/* XXX paranoid */
				ok = TIFFSetField(tif, dp->tdir_tag, c);
			  }
			}
			break;
		}
	}
	return (ok);
}

#define	NITEMS(x)	(sizeof (x) / sizeof (x[0]))
/*
 * Fetch samples/pixel short values for 
 * the specified tag and verify that
 * all values are the same.
 */
static int
TIFFFetchPerSampleShorts(TIFF* tif, TIFFDirEntry* dir, int* pl)
{
	int samples = tif->tif_dir.td_samplesperpixel;
	int status = 0;

	if (CheckDirCount(tif, dir, (uint32) samples)) {
		uint16 buf[10];
		uint16* v = buf;

		if (samples > NITEMS(buf))
			v = (uint16*) _TIFFmalloc(samples * sizeof (uint16));
		if (TIFFFetchShortArray(tif, dir, v)) {
			int i;
			for (i = 1; i < samples; i++)
				if (v[i] != v[0]) {
					TIFFError(tif->tif_name,
		"Cannot handle different per-sample values for field \"%s\"",
			   _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
					goto bad;
				}
			*pl = v[0];
			status = 1;
		}
	bad:
		if (v != buf)
			_TIFFfree((char*) v);
	}
	return (status);
}

/*
 * Fetch samples/pixel ANY values for 
 * the specified tag and verify that
 * all values are the same.
 */
static int
TIFFFetchPerSampleAnys(TIFF* tif, TIFFDirEntry* dir, double* pl)
{
	int samples = (int) tif->tif_dir.td_samplesperpixel;
	int status = 0;

	if (CheckDirCount(tif, dir, (uint32) samples)) {
		double buf[10];
		double* v = buf;

		if (samples > NITEMS(buf))
			v = (double*) _TIFFmalloc(samples * sizeof (double));
		if (TIFFFetchAnyArray(tif, dir, v)) {
			int i;
			for (i = 1; i < samples; i++)
				if (v[i] != v[0]) {
					TIFFError(tif->tif_name,
		"Cannot handle different per-sample values for field \"%s\"",
			   _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
					goto bad;
				}
			*pl = v[0];
			status = 1;
		}
	bad:
		if (v != buf)
			_TIFFfree(v);
	}
	return (status);
}
#undef NITEMS

/*
 * Fetch a set of offsets or lengths.
 * While this routine says "strips",
 * in fact it's also used for tiles.
 */
static int
TIFFFetchStripThing(TIFF* tif, TIFFDirEntry* dir, long nstrips, uint32** lpp)
{
	register uint32* lp;
	int status;

	if (!CheckDirCount(tif, dir, (uint32) nstrips))
		return (0);
	/*
	 * Allocate space for strip information.
	 */
	if (*lpp == NULL &&
	    (*lpp = (uint32 *)CheckMalloc(tif,
	      nstrips * sizeof (uint32), "for strip array")) == NULL)
		return (0);
	lp = *lpp;
	if (dir->tdir_type == (int)TIFF_SHORT) {
		/*
		 * Handle uint16->uint32 expansion.
		 */
		uint16* dp = (uint16*) CheckMalloc(tif,
		    dir->tdir_count* sizeof (uint16), "to fetch strip tag");
		if (dp == NULL)
			return (0);
		if( (status = TIFFFetchShortArray(tif, dir, dp)) != 0 ) {
			register uint16* wp = dp;
			while (nstrips-- > 0)
				*lp++ = *wp++;
		}
		_TIFFfree((char*) dp);
	} else
		status = TIFFFetchLongArray(tif, dir, lp);
	return (status);
}

#define	NITEMS(x)	(sizeof (x) / sizeof (x[0]))
/*
 * Fetch and set the ExtraSamples tag.
 */
static int
TIFFFetchExtraSamples(TIFF* tif, TIFFDirEntry* dir)
{
	uint16 buf[10];
	uint16* v = buf;
	int status;

	if (dir->tdir_count > NITEMS(buf))
		v = (uint16*) _TIFFmalloc(dir->tdir_count * sizeof (uint16));
	if (dir->tdir_type == TIFF_BYTE)
		status = TIFFFetchByteArray(tif, dir, v);
	else
		status = TIFFFetchShortArray(tif, dir, v);
	if (status)
		status = TIFFSetField(tif, dir->tdir_tag, dir->tdir_count, v);
	if (v != buf)
		_TIFFfree((char*) v);
	return (status);
}
#undef NITEMS

#ifdef COLORIMETRY_SUPPORT
/*
 * Fetch and set the RefBlackWhite tag.
 */
static int
TIFFFetchRefBlackWhite(TIFF* tif, TIFFDirEntry* dir)
{
	static const char mesg[] = "for \"ReferenceBlackWhite\" array";
	char* cp;
	int ok;

	if (dir->tdir_type == TIFF_RATIONAL)
		return (TIFFFetchNormalTag(tif, dir));
	/*
	 * Handle LONG's for backward compatibility.
	 */
	cp = CheckMalloc(tif, dir->tdir_count * sizeof (uint32), mesg);
	if( (ok = (cp && TIFFFetchLongArray(tif, dir, (uint32*) cp))) != 0) {
		float* fp = (float*)
		    CheckMalloc(tif, dir->tdir_count * sizeof (float), mesg);
		if( (ok = (fp != NULL)) != 0 ) {
			uint32 i;
			for (i = 0; i < dir->tdir_count; i++)
				fp[i] = (float)((uint32*) cp)[i];
			ok = TIFFSetField(tif, dir->tdir_tag, fp);
			_TIFFfree((char*) fp);
		}
	}
	if (cp)
		_TIFFfree(cp);
	return (ok);
}
#endif

/*
 * Replace a single strip (tile) of uncompressed data by
 * multiple strips (tiles), each approximately 8Kbytes.
 * This is useful for dealing with large images or
 * for dealing with machines with a limited amount
 * memory.
 */
static void
ChopUpSingleUncompressedStrip(TIFF* tif)
{
	register TIFFDirectory *td = &tif->tif_dir;
	uint32 bytecount = td->td_stripbytecount[0];
	uint32 offset = td->td_stripoffset[0];
	tsize_t rowbytes = TIFFVTileSize(tif, 1), stripbytes;
	tstrip_t strip, nstrips, rowsperstrip;
	uint32* newcounts;
	uint32* newoffsets;

	/*
	 * Make the rows hold at least one
	 * scanline, but fill 8k if possible.
	 */
	if (rowbytes > 8192) {
		stripbytes = rowbytes;
		rowsperstrip = 1;
	} else {
		rowsperstrip = 8192 / rowbytes;
		stripbytes = rowbytes * rowsperstrip;
	}
	/* never increase the number of strips in an image */
	if (rowsperstrip >= td->td_rowsperstrip)
		return;
	nstrips = (tstrip_t) TIFFhowmany(bytecount, stripbytes);
	newcounts = (uint32*) CheckMalloc(tif, nstrips * sizeof (uint32),
				"for chopped \"StripByteCounts\" array");
	newoffsets = (uint32*) CheckMalloc(tif, nstrips * sizeof (uint32),
				"for chopped \"StripOffsets\" array");
	if (newcounts == NULL || newoffsets == NULL) {
	        /*
		 * Unable to allocate new strip information, give
		 * up and use the original one strip information.
		 */
		if (newcounts != NULL)
			_TIFFfree(newcounts);
		if (newoffsets != NULL)
			_TIFFfree(newoffsets);
		return;
	}
	/*
	 * Fill the strip information arrays with
	 * new bytecounts and offsets that reflect
	 * the broken-up format.
	 */
	for (strip = 0; strip < nstrips; strip++) {
		if (stripbytes > (tsize_t) bytecount)
			stripbytes = bytecount;
		newcounts[strip] = stripbytes;
		newoffsets[strip] = offset;
		offset += stripbytes;
		bytecount -= stripbytes;
	}
	/*
	 * Replace old single strip info with multi-strip info.
	 */
	td->td_stripsperimage = td->td_nstrips = nstrips;
	TIFFSetField(tif, TIFFTAG_ROWSPERSTRIP, rowsperstrip);

	_TIFFfree(td->td_stripbytecount);
	_TIFFfree(td->td_stripoffset);
	td->td_stripbytecount = newcounts;
	td->td_stripoffset = newoffsets;
}