tif_compress.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_compress.c,v 1.4 1999/12/21 17:03:03 mwelles Exp $ */

/*
 * Copyright (c) 1988-1997 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
 *
 * Compression Scheme Configuration Support.
 */
#include "tiffiop.h"

static int
TIFFNoEncode(TIFF* tif, char* method)
{
	const TIFFCodec* c = TIFFFindCODEC(tif->tif_dir.td_compression);

	if (c) { 
	  if (! strncmp(c->name, "LZW", 3) ){ 
	    TIFFError(tif->tif_name, 
		      "%s %s encoding is no longer implemented due to Unisys patent enforcement", 
		      c->name, method); 
	  } else { 
	    TIFFError(tif->tif_name, "%s %s encoding is not implemented",
		      c->name, method);
	  }
	}
	else { 
		TIFFError(tif->tif_name,
			  "Compression scheme %u %s encoding is not implemented",
		    tif->tif_dir.td_compression, method);
	}
	return (-1);
}

int
_TIFFNoRowEncode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
	(void) pp; (void) cc; (void) s;
	return (TIFFNoEncode(tif, "scanline"));
}

int
_TIFFNoStripEncode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
	(void) pp; (void) cc; (void) s;
	return (TIFFNoEncode(tif, "strip"));
}

int
_TIFFNoTileEncode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
	(void) pp; (void) cc; (void) s;
	return (TIFFNoEncode(tif, "tile"));
}

static int
TIFFNoDecode(TIFF* tif, char* method)
{
	const TIFFCodec* c = TIFFFindCODEC(tif->tif_dir.td_compression);

	if (c)
		TIFFError(tif->tif_name, "%s %s decoding is not implemented",
		    c->name, method);
	else
		TIFFError(tif->tif_name,
		    "Compression scheme %u %s decoding is not implemented",
		    tif->tif_dir.td_compression, method);
	return (-1);
}

int
_TIFFNoRowDecode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
	(void) pp; (void) cc; (void) s;
	return (TIFFNoDecode(tif, "scanline"));
}

int
_TIFFNoStripDecode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
	(void) pp; (void) cc; (void) s;
	return (TIFFNoDecode(tif, "strip"));
}

int
_TIFFNoTileDecode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
	(void) pp; (void) cc; (void) s;
	return (TIFFNoDecode(tif, "tile"));
}

int
_TIFFNoSeek(TIFF* tif, uint32 off)
{
	(void) off;
	TIFFError(tif->tif_name,
	    "Compression algorithm does not support random access");
	return (0);
}

int
_TIFFNoPreCode(TIFF* tif, tsample_t s)
{
	(void) tif; (void) s;
	return (1);
}

static int _TIFFtrue(TIFF* tif) { (void) tif; return (1); }
static void _TIFFvoid(TIFF* tif) { (void) tif; }

void
_TIFFSetDefaultCompressionState(TIFF* tif)
{
	tif->tif_setupdecode = _TIFFtrue;
	tif->tif_predecode = _TIFFNoPreCode;
	tif->tif_decoderow = _TIFFNoRowDecode;
	tif->tif_decodestrip = _TIFFNoStripDecode;
	tif->tif_decodetile = _TIFFNoTileDecode;
	tif->tif_setupencode = _TIFFtrue;
	tif->tif_preencode = _TIFFNoPreCode;
	tif->tif_postencode = _TIFFtrue;
	tif->tif_encoderow = _TIFFNoRowEncode;
	tif->tif_encodestrip = _TIFFNoStripEncode;
	tif->tif_encodetile = _TIFFNoTileEncode;
	tif->tif_close = _TIFFvoid;
	tif->tif_seek = _TIFFNoSeek;
	tif->tif_cleanup = _TIFFvoid;
	tif->tif_defstripsize = _TIFFDefaultStripSize;
	tif->tif_deftilesize = _TIFFDefaultTileSize;
	tif->tif_flags &= ~TIFF_NOBITREV;
}

int
TIFFSetCompressionScheme(TIFF* tif, int scheme)
{
	const TIFFCodec *c = TIFFFindCODEC((uint16) scheme);

	_TIFFSetDefaultCompressionState(tif);
	/*
	 * Don't treat an unknown compression scheme as an error.
	 * This permits applications to open files with data that
	 * the library does not have builtin support for, but which
	 * may still be meaningful.
	 */
	return (c ? (*c->init)(tif, scheme) : 1);
}

/*
 * Other compression schemes may be registered.  Registered
 * schemes can also override the builtin versions provided
 * by this library.
 */
typedef struct _codec {
	struct _codec*	next;
	TIFFCodec*	info;
} codec_t;
static	codec_t* registeredCODECS = NULL;

const TIFFCodec*
TIFFFindCODEC(uint16 scheme)
{
	const TIFFCodec* c;
	codec_t* cd;

	for (cd = registeredCODECS; cd; cd = cd->next)
		if (cd->info->scheme == scheme)
			return ((const TIFFCodec*) cd->info);
	for (c = _TIFFBuiltinCODECS; c->name; c++)
		if (c->scheme == scheme)
			return (c);
	return ((const TIFFCodec*) 0);
}

TIFFCodec*
TIFFRegisterCODEC(uint16 scheme, const char* name, TIFFInitMethod init)
{
	codec_t* cd = (codec_t*)
	    _TIFFmalloc(sizeof (codec_t) + sizeof (TIFFCodec) + strlen(name)+1);

	if (cd != NULL) {
		cd->info = (TIFFCodec*) ((tidata_t) cd + sizeof (codec_t));
		cd->info->name = (char*)
		    ((tidata_t) cd->info + sizeof (TIFFCodec));
		strcpy(cd->info->name, name);
		cd->info->scheme = scheme;
		cd->info->init = init;
		cd->next = registeredCODECS;
		registeredCODECS = cd;
	} else
		TIFFError("TIFFRegisterCODEC",
		    "No space to register compression scheme %s", name);
	return (cd->info);
}

void
TIFFUnRegisterCODEC(TIFFCodec* c)
{
	codec_t* cd;
	codec_t** pcd;

	for (pcd = &registeredCODECS; (cd = *pcd); pcd = &cd->next)
		if (cd->info == c) {
			*pcd = cd->next;
			_TIFFfree(cd);
			return;
		}
	TIFFError("TIFFUnRegisterCODEC",
	    "Cannot remove compression scheme %s; not registered", c->name);
}