tif_dirwrite.c

一个国人自己实现图像库的程序（有参考价值）

	status = TIFFWriteData(tif, dir, (char *)t);
	_TIFFfree((char*) t);
	return (status);
}

static int
TIFFWriteFloatArray(TIFF* tif,
    TIFFDataType type, ttag_t tag, TIFFDirEntry* dir, uint32 n, float* v)
{
	dir->tdir_tag = (uint16) tag;
	dir->tdir_type = (short) type;
	dir->tdir_count = n;
	TIFFCvtNativeToIEEEFloat(tif, n, v);
	if (n == 1) {
		dir->tdir_offset = *(uint32*) &v[0];
		return (1);
	} else
		return (TIFFWriteData(tif, dir, (char*) v));
}

static int
TIFFWriteDoubleArray(TIFF* tif,
    TIFFDataType type, ttag_t tag, TIFFDirEntry* dir, uint32 n, double* v)
{
	dir->tdir_tag = (uint16) tag;
	dir->tdir_type = (short) type;
	dir->tdir_count = n;
	TIFFCvtNativeToIEEEDouble(tif, n, v);
	return (TIFFWriteData(tif, dir, (char*) v));
}

/*
 * Write an array of ``type'' values for a specified tag (i.e. this is a tag
 * which is allowed to have different types, e.g. SMaxSampleType).
 * Internally the data values are represented as double since a double can
 * hold any of the TIFF tag types (yes, this should really be an abstract
 * type tany_t for portability).  The data is converted into the specified
 * type in a temporary buffer and then handed off to the appropriate array
 * writer.
 */
static int
TIFFWriteAnyArray(TIFF* tif,
    TIFFDataType type, ttag_t tag, TIFFDirEntry* dir, uint32 n, double* v)
{
	char buf[10 * sizeof(double)];
	char* w = buf;
	int i, status = 0;

	if (n * tiffDataWidth[type] > sizeof buf)
		w = (char*) _TIFFmalloc(n * tiffDataWidth[type]);
	switch (type) {
	case TIFF_BYTE:
		{ uint8* bp = (uint8*) w;
		  for (i = 0; i < (int) n; i++)
			bp[i] = (uint8) v[i];
		  dir->tdir_tag = (uint16) tag;
		  dir->tdir_type = (short) type;
		  dir->tdir_count = n;
		  if (!TIFFWriteByteArray(tif, dir, (char*) bp))
			goto out;
		}
		break;
	case TIFF_SBYTE:
		{ int8* bp = (int8*) w;
		  for (i = 0; i < (int) n; i++)
			bp[i] = (int8) v[i];
		  dir->tdir_tag = (uint16) tag;
		  dir->tdir_type = (short) type;
		  dir->tdir_count = n;
		  if (!TIFFWriteByteArray(tif, dir, (char*) bp))
			goto out;
		}
		break;
	case TIFF_SHORT:
		{ uint16* bp = (uint16*) w;
		  for (i = 0; i < (int) n; i++)
			bp[i] = (uint16) v[i];
		  if (!TIFFWriteShortArray(tif, type, tag, dir, n, (uint16*)bp))
				goto out;
		}
		break;
	case TIFF_SSHORT:
		{ int16* bp = (int16*) w;
		  for (i = 0; i < (int) n; i++)
			bp[i] = (int16) v[i];
		  if (!TIFFWriteShortArray(tif, type, tag, dir, n, (uint16*)bp))
			goto out;
		}
		break;
	case TIFF_LONG:
		{ uint32* bp = (uint32*) w;
		  for (i = 0; i < (int) n; i++)
			bp[i] = (uint32) v[i];
		  if (!TIFFWriteLongArray(tif, type, tag, dir, n, bp))
			goto out;
		}
		break;
	case TIFF_SLONG:
		{ int32* bp = (int32*) w;
		  for (i = 0; i < (int) n; i++)
			bp[i] = (int32) v[i];
		  if (!TIFFWriteLongArray(tif, type, tag, dir, n, (uint32*) bp))
			goto out;
		}
		break;
	case TIFF_FLOAT:
		{ float* bp = (float*) w;
		  for (i = 0; i < (int) n; i++)
			bp[i] = (float) v[i];
		  if (!TIFFWriteFloatArray(tif, type, tag, dir, n, bp))
			goto out;
		}
		break;
	case TIFF_DOUBLE:
		return (TIFFWriteDoubleArray(tif, type, tag, dir, n, v));
	default:
		/* TIFF_NOTYPE */
		/* TIFF_ASCII */
		/* TIFF_UNDEFINED */
		/* TIFF_RATIONAL */
		/* TIFF_SRATIONAL */
		goto out;
	}
	status = 1;
 out:
	if (w != buf)
		_TIFFfree(w);
	return (status);
}

#ifdef COLORIMETRY_SUPPORT
static int
TIFFWriteTransferFunction(TIFF* tif, TIFFDirEntry* dir)
{
	TIFFDirectory* td = &tif->tif_dir;
	tsize_t n = (1L<<td->td_bitspersample) * sizeof (uint16);
	uint16** tf = td->td_transferfunction;
	int ncols;

	/*
	 * Check if the table can be written as a single column,
	 * or if it must be written as 3 columns.  Note that we
	 * write a 3-column tag if there are 2 samples/pixel and
	 * a single column of data won't suffice--hmm.
	 */
	switch (td->td_samplesperpixel - td->td_extrasamples) {
	default:	if (_TIFFmemcmp(tf[0], tf[2], n)) { ncols = 3; break; }
	case 2:		if (_TIFFmemcmp(tf[0], tf[1], n)) { ncols = 3; break; }
	case 1: case 0:	ncols = 1;
	}
	return (TIFFWriteShortTable(tif,
	    TIFFTAG_TRANSFERFUNCTION, dir, ncols, tf));
}
#endif

#ifdef CMYK_SUPPORT
static int
TIFFWriteInkNames(TIFF* tif, TIFFDirEntry* dir)
{
	TIFFDirectory* td = &tif->tif_dir;

	dir->tdir_tag = TIFFTAG_INKNAMES;
	dir->tdir_type = (short) TIFF_ASCII;
	dir->tdir_count = td->td_inknameslen;
	return (TIFFWriteByteArray(tif, dir, td->td_inknames));
}
#endif

/*
 * Write a contiguous directory item.
 */
static int
TIFFWriteData(TIFF* tif, TIFFDirEntry* dir, char* cp)
{
	tsize_t cc;

	if (tif->tif_flags & TIFF_SWAB) {
		switch (dir->tdir_type) {
		case TIFF_SHORT:
		case TIFF_SSHORT:
			TIFFSwabArrayOfShort((uint16*) cp, dir->tdir_count);
			break;
		case TIFF_LONG:
		case TIFF_SLONG:
		case TIFF_FLOAT:
			TIFFSwabArrayOfLong((uint32*) cp, dir->tdir_count);
			break;
		case TIFF_RATIONAL:
		case TIFF_SRATIONAL:
			TIFFSwabArrayOfLong((uint32*) cp, 2*dir->tdir_count);
			break;
		case TIFF_DOUBLE:
			TIFFSwabArrayOfDouble((double*) cp, dir->tdir_count);
			break;
		}
	}
	dir->tdir_offset = tif->tif_dataoff;
	cc = dir->tdir_count * tiffDataWidth[dir->tdir_type];
	if (SeekOK(tif, dir->tdir_offset) &&
	    WriteOK(tif, cp, cc)) {
		tif->tif_dataoff += (cc + 1) & ~1;
		return (1);
	}
	TIFFError(tif->tif_name, "Error writing data for field \"%s\"",
	    _TIFFFieldWithTag(tif, dir->tdir_tag)->field_name);
	return (0);
}

/*
 * Similar to TIFFWriteDirectory(), but if the directory has already
 * been written once, it is relocated to the end of the file, in case it
 * has changed in size.  Note that this will result in the loss of the 
 * previously used directory space. 
 */ 

int 
TIFFRewriteDirectory( TIFF *tif )
{
    static const char module[] = "TIFFRewriteDirectory";

    /* We don't need to do anything special if it hasn't been written. */
    if( tif->tif_diroff == 0 )
        return TIFFWriteDirectory( tif );

    /*
    ** Find and zero the pointer to this directory, so that TIFFLinkDirectory
    ** will cause it to be added after this directories current pre-link.
    */
    
    /* Is it the first directory in the file? */
    if (tif->tif_header.tiff_diroff == tif->tif_diroff) 
    {
        tif->tif_header.tiff_diroff = 0;
        tif->tif_diroff = 0;

#define	HDROFF(f)	((toff_t) &(((TIFFHeader*) 0)->f))
        TIFFSeekFile(tif, HDROFF(tiff_diroff), SEEK_SET);
        if (!WriteOK(tif, &(tif->tif_header.tiff_diroff), 
                     sizeof (tif->tif_diroff))) 
        {
            TIFFError(tif->tif_name, "Error updating TIFF header");
            return (0);
        }
    }
    else
    {
        toff_t  nextdir, off;

	nextdir = tif->tif_header.tiff_diroff;
	do {
		uint16 dircount;

		if (!SeekOK(tif, nextdir) ||
		    !ReadOK(tif, &dircount, sizeof (dircount))) {
			TIFFError(module, "Error fetching directory count");
			return (0);
		}
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabShort(&dircount);
		(void) TIFFSeekFile(tif,
		    dircount * sizeof (TIFFDirEntry), SEEK_CUR);
		if (!ReadOK(tif, &nextdir, sizeof (nextdir))) {
			TIFFError(module, "Error fetching directory link");
			return (0);
		}
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabLong(&nextdir);
	} while (nextdir != tif->tif_diroff && nextdir != 0);
        off = TIFFSeekFile(tif, 0, SEEK_CUR); /* get current offset */
        (void) TIFFSeekFile(tif, off - (toff_t)sizeof(nextdir), SEEK_SET);
        tif->tif_diroff = 0;
	if (!WriteOK(tif, &(tif->tif_diroff), sizeof (nextdir))) {
		TIFFError(module, "Error writing directory link");
		return (0);
	}
    }

    /*
    ** Now use TIFFWriteDirectory() normally.
    */

    return TIFFWriteDirectory( tif );
}


/*
 * Link the current directory into the
 * directory chain for the file.
 */
static int
TIFFLinkDirectory(TIFF* tif)
{
	static const char module[] = "TIFFLinkDirectory";
	toff_t nextdir;
	toff_t diroff, off;

	tif->tif_diroff = (TIFFSeekFile(tif, (toff_t) 0, SEEK_END)+1) &~ 1;
	diroff = tif->tif_diroff;
	if (tif->tif_flags & TIFF_SWAB)
		TIFFSwabLong(&diroff);
#if SUBIFD_SUPPORT
	if (tif->tif_flags & TIFF_INSUBIFD) {
		(void) TIFFSeekFile(tif, tif->tif_subifdoff, SEEK_SET);
		if (!WriteOK(tif, &diroff, sizeof (diroff))) {
			TIFFError(module,
			    "%s: Error writing SubIFD directory link",
			    tif->tif_name);
			return (0);
		}
		/*
		 * Advance to the next SubIFD or, if this is
		 * the last one configured, revert back to the
		 * normal directory linkage.
		 */
		if (--tif->tif_nsubifd)
			tif->tif_subifdoff += sizeof (diroff);
		else
			tif->tif_flags &= ~TIFF_INSUBIFD;
		return (1);
	}
#endif
	if (tif->tif_header.tiff_diroff == 0) {
		/*
		 * First directory, overwrite offset in header.
		 */
		tif->tif_header.tiff_diroff = tif->tif_diroff;
#define	HDROFF(f)	((toff_t) &(((TIFFHeader*) 0)->f))
		(void) TIFFSeekFile(tif, HDROFF(tiff_diroff), SEEK_SET);
		if (!WriteOK(tif, &diroff, sizeof (diroff))) {
			TIFFError(tif->tif_name, "Error writing TIFF header");
			return (0);
		}
		return (1);
	}
	/*
	 * Not the first directory, search to the last and append.
	 */
	nextdir = tif->tif_header.tiff_diroff;
	do {
		uint16 dircount;

		if (!SeekOK(tif, nextdir) ||
		    !ReadOK(tif, &dircount, sizeof (dircount))) {
			TIFFError(module, "Error fetching directory count");
			return (0);
		}
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabShort(&dircount);
		(void) TIFFSeekFile(tif,
		    dircount * sizeof (TIFFDirEntry), SEEK_CUR);
		if (!ReadOK(tif, &nextdir, sizeof (nextdir))) {
			TIFFError(module, "Error fetching directory link");
			return (0);
		}
		if (tif->tif_flags & TIFF_SWAB)
			TIFFSwabLong(&nextdir);
	} while (nextdir != 0);
        off = TIFFSeekFile(tif, 0, SEEK_CUR); /* get current offset */
        (void) TIFFSeekFile(tif, off - (toff_t)sizeof(nextdir), SEEK_SET);
	if (!WriteOK(tif, &diroff, sizeof (diroff))) {
		TIFFError(module, "Error writing directory link");
		return (0);
	}
	return (1);
}