img_tif.c

sdl的image开发包

/*
    SDL_image:  An example image loading library for use with SDL
    Copyright (C) 1999, 2000, 2001  Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    [e-mail]
*/

/* $Id: IMG_tif.c,v 1.3 2001/12/14 13:02:16 slouken Exp $ */



/* This is a TIFF image file loading framework */

#include <stdio.h>

#include "SDL_image.h"

#ifdef LOAD_TIF

#include <tiffio.h>

/*
 * These are the thunking routine to use the SDL_RWops* routines from
 * libtiff's internals.
*/

static tsize_t tiff_read(thandle_t fd, tdata_t buf, tsize_t size)
{
	return SDL_RWread((SDL_RWops*)fd, buf, 1, size);
}

static toff_t tiff_seek(thandle_t fd, toff_t offset, int origin)
{
	return SDL_RWseek((SDL_RWops*)fd, offset, origin);
}

static tsize_t tiff_write(thandle_t fd, tdata_t buf, tsize_t size)
{
	return SDL_RWwrite((SDL_RWops*)fd, buf, 1, size);
}

static int tiff_close(thandle_t fd)
{
	/*
	 * We don't want libtiff closing our SDL_RWops*, but if it's not given
         * a routine to try, and if the image isn't a TIFF, it'll segfault.
	 */
	return 0;
}

static toff_t tiff_size(thandle_t fd)
{
	Uint32 save_pos;
	toff_t size;

	save_pos = SDL_RWtell((SDL_RWops*)fd);
	SDL_RWseek((SDL_RWops*)fd, 0, SEEK_END);
        size = SDL_RWtell((SDL_RWops*)fd);
	SDL_RWseek((SDL_RWops*)fd, save_pos, SEEK_SET);
	return size;
}

int IMG_isTIF(SDL_RWops* src)
{
	TIFF* tiff;
	TIFFErrorHandler prev_handler;

	/* Suppress output from libtiff */
	prev_handler = TIFFSetErrorHandler(NULL);
	
	/* Attempt to process the given file data */
	/* turn off memory mapped access with the m flag */
	tiff = TIFFClientOpen("SDL_image", "rm", (thandle_t)src, 
		tiff_read, tiff_write, tiff_seek, tiff_close, tiff_size, NULL, NULL);

	/* Reset the default error handler, since it can be useful for info */
	TIFFSetErrorHandler(prev_handler);

	/* If it's not a TIFF, then tiff will be NULL. */
	if(!tiff)
		return 0;

	/* Free up any dynamically allocated memory libtiff uses */
	TIFFClose(tiff);
	
	return 1;
}

SDL_Surface* IMG_LoadTIF_RW(SDL_RWops* src)
{
	TIFF* tiff;
	SDL_Surface* surface = NULL;
	Uint32 img_width, img_height;
	Uint32 Rmask, Gmask, Bmask, Amask, mask;
	Uint32 x, y;
	Uint32 half;


	/* turn off memory mapped access with the m flag */
	tiff = TIFFClientOpen("SDL_image", "rm", (thandle_t)src, 
		tiff_read, tiff_write, tiff_seek, tiff_close, tiff_size, NULL, NULL);
	if(!tiff)
		return NULL;

	/* Retrieve the dimensions of the image from the TIFF tags */
	TIFFGetField(tiff, TIFFTAG_IMAGEWIDTH, &img_width);
	TIFFGetField(tiff, TIFFTAG_IMAGELENGTH, &img_height);

	Rmask = 0x000000FF;
	Gmask = 0x0000FF00;
	Bmask = 0x00FF0000;
	Amask = 0xFF000000;
	surface = SDL_AllocSurface(SDL_SWSURFACE, img_width, img_height, 32,
		Rmask, Gmask, Bmask, Amask);
	if(!surface)
		return NULL;
	
	if(!TIFFReadRGBAImage(tiff, img_width, img_height, surface->pixels, 0))
		return NULL;

	/* libtiff loads the image upside-down, flip it back */
	half = img_height / 2;
	for(y = 0; y < half; y++)
	{
	        Uint32 *top = (Uint32 *)surface->pixels + y * surface->pitch/4;
	        Uint32 *bot = (Uint32 *)surface->pixels
		              + (img_height - y - 1) * surface->pitch/4;
		for(x = 0; x < img_width; x++)
		{
		        Uint32 tmp = top[x];
			top[x] = bot[x];
			bot[x] = tmp;
		}
	}
	TIFFClose(tiff);
	
	return surface;
}

#else

/* See if an image is contained in a data source */
int IMG_isTIF(SDL_RWops *src)
{
	return(0);
}

/* Load a TIFF type image from an SDL datasource */
SDL_Surface *IMG_LoadTIF_RW(SDL_RWops *src)
{
	return(NULL);
}

#endif /* LOAD_TIF */