tif_tile.c

一个国人自己实现图像库的程序（有参考价值）

/* $Header: /cvsroot/osrs/libtiff/libtiff/tif_tile.c,v 1.1.1.1 1999/07/27 21:50:27 mike Exp $ */

/*
 * Copyright (c) 1991-1997 Sam Leffler
 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */

/*
 * TIFF Library.
 *
 * Tiled Image Support Routines.
 */
#include "tiffiop.h"

/*
 * Compute which tile an (x,y,z,s) value is in.
 */
ttile_t
TIFFComputeTile(TIFF* tif, uint32 x, uint32 y, uint32 z, tsample_t s)
{
	TIFFDirectory *td = &tif->tif_dir;
	uint32 dx = td->td_tilewidth;
	uint32 dy = td->td_tilelength;
	uint32 dz = td->td_tiledepth;
	ttile_t tile = 1;

	if (td->td_imagedepth == 1)
		z = 0;
	if (dx == (uint32) -1)
		dx = td->td_imagewidth;
	if (dy == (uint32) -1)
		dy = td->td_imagelength;
	if (dz == (uint32) -1)
		dz = td->td_imagedepth;
	if (dx != 0 && dy != 0 && dz != 0) {
		uint32 xpt = TIFFhowmany(td->td_imagewidth, dx); 
		uint32 ypt = TIFFhowmany(td->td_imagelength, dy); 
		uint32 zpt = TIFFhowmany(td->td_imagedepth, dz); 

		if (td->td_planarconfig == PLANARCONFIG_SEPARATE) 
			tile = (xpt*ypt*zpt)*s +
			     (xpt*ypt)*(z/dz) +
			     xpt*(y/dy) +
			     x/dx;
		else
			tile = (xpt*ypt)*(z/dz) + xpt*(y/dy) + x/dx + s;
	}
	return (tile);
}

/*
 * Check an (x,y,z,s) coordinate
 * against the image bounds.
 */
int
TIFFCheckTile(TIFF* tif, uint32 x, uint32 y, uint32 z, tsample_t s)
{
	TIFFDirectory *td = &tif->tif_dir;

	if (x >= td->td_imagewidth) {
		TIFFError(tif->tif_name, "Col %ld out of range, max %lu",
		    (long) x, (u_long) td->td_imagewidth);
		return (0);
	}
	if (y >= td->td_imagelength) {
		TIFFError(tif->tif_name, "Row %ld out of range, max %lu",
		    (long) y, (u_long) td->td_imagelength);
		return (0);
	}
	if (z >= td->td_imagedepth) {
		TIFFError(tif->tif_name, "Depth %ld out of range, max %lu",
		    (long) z, (u_long) td->td_imagedepth);
		return (0);
	}
	if (td->td_planarconfig == PLANARCONFIG_SEPARATE &&
	    s >= td->td_samplesperpixel) {
		TIFFError(tif->tif_name, "Sample %d out of range, max %u",
		    (int) s, td->td_samplesperpixel);
		return (0);
	}
	return (1);
}

/*
 * Compute how many tiles are in an image.
 */
ttile_t
TIFFNumberOfTiles(TIFF* tif)
{
	TIFFDirectory *td = &tif->tif_dir;
	uint32 dx = td->td_tilewidth;
	uint32 dy = td->td_tilelength;
	uint32 dz = td->td_tiledepth;
	ttile_t ntiles;

	if (dx == (uint32) -1)
		dx = td->td_imagewidth;
	if (dy == (uint32) -1)
		dy = td->td_imagelength;
	if (dz == (uint32) -1)
		dz = td->td_imagedepth;
	ntiles = (dx == 0 || dy == 0 || dz == 0) ? 0 :
	    (TIFFhowmany(td->td_imagewidth, dx) *
	     TIFFhowmany(td->td_imagelength, dy) *
	     TIFFhowmany(td->td_imagedepth, dz));
	if (td->td_planarconfig == PLANARCONFIG_SEPARATE)
		ntiles *= td->td_samplesperpixel;
	return (ntiles);
}

/*
 * Compute the # bytes in each row of a tile.
 */
tsize_t
TIFFTileRowSize(TIFF* tif)
{
	TIFFDirectory *td = &tif->tif_dir;
	tsize_t rowsize;
	
	if (td->td_tilelength == 0 || td->td_tilewidth == 0)
		return ((tsize_t) 0);
	rowsize = td->td_bitspersample * td->td_tilewidth;
	if (td->td_planarconfig == PLANARCONFIG_CONTIG)
		rowsize *= td->td_samplesperpixel;
	return ((tsize_t) TIFFhowmany(rowsize, 8));
}

/*
 * Compute the # bytes in a variable length, row-aligned tile.
 */
tsize_t
TIFFVTileSize(TIFF* tif, uint32 nrows)
{
	TIFFDirectory *td = &tif->tif_dir;
	tsize_t tilesize;

	if (td->td_tilelength == 0 || td->td_tilewidth == 0 ||
	    td->td_tiledepth == 0)
		return ((tsize_t) 0);
#ifdef YCBCR_SUPPORT
	if (td->td_planarconfig == PLANARCONFIG_CONTIG &&
	    td->td_photometric == PHOTOMETRIC_YCBCR &&
	    !isUpSampled(tif)) {
		/*
		 * Packed YCbCr data contain one Cb+Cr for every
		 * HorizontalSampling*VerticalSampling Y values.
		 * Must also roundup width and height when calculating
		 * since images that are not a multiple of the
		 * horizontal/vertical subsampling area include
		 * YCbCr data for the extended image.
		 */
		tsize_t w =
		    TIFFroundup(td->td_tilewidth, td->td_ycbcrsubsampling[0]);
		tsize_t rowsize = TIFFhowmany(w*td->td_bitspersample, 8);
		tsize_t samplingarea =
		    td->td_ycbcrsubsampling[0]*td->td_ycbcrsubsampling[1];
		nrows = TIFFroundup(nrows, td->td_ycbcrsubsampling[1]);
		/* NB: don't need TIFFhowmany here 'cuz everything is rounded */
		tilesize = nrows*rowsize + 2*(nrows*rowsize / samplingarea);
	} else
#endif
		tilesize = nrows * TIFFTileRowSize(tif);
	return ((tsize_t)(tilesize * td->td_tiledepth));
}

/*
 * Compute the # bytes in a row-aligned tile.
 */
tsize_t
TIFFTileSize(TIFF* tif)
{
	return (TIFFVTileSize(tif, tif->tif_dir.td_tilelength));
}

/*
 * Compute a default tile size based on the image
 * characteristics and a requested value.  If a
 * request is <1 then we choose a size according
 * to certain heuristics.
 */
void
TIFFDefaultTileSize(TIFF* tif, uint32* tw, uint32* th)
{
	(*tif->tif_deftilesize)(tif, tw, th);
}

void
_TIFFDefaultTileSize(TIFF* tif, uint32* tw, uint32* th)
{
	(void) tif;
	if (*(int32*) tw < 1)
		*tw = 256;
	if (*(int32*) th < 1)
		*th = 256;
	/* roundup to a multiple of 16 per the spec */
	if (*tw & 0xf)
		*tw = TIFFroundup(*tw, 16);
	if (*th & 0xf)
		*th = TIFFroundup(*th, 16);
}