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IMG_tif.c
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IMG_tif.c
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/*
IMGLIB: An example image loading library for use with SDL
Copyright (C) 1999 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
5635-34 Springhouse Dr.
Pleasanton, CA 94588 (USA)
slouken@devolution.com
5/29/2000: TIFF loader written. Mark Baker (mbaker@0x7a69.net)
*/
/* 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;
Uint32 x, y;
Uint32 half;
Uint32 tl_coord, bl_coord;
Uint32 tl_pixel, bl_pixel;
/* 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);
if (SDL_BYTEORDER == SDL_LIL_ENDIAN)
{
Rmask = 0x000000FF;
Gmask = 0x0000FF00;
Bmask = 0x00FF0000;
Amask = 0xFF000000;
}
else
{
Rmask = 0xFF000000;
Gmask = 0x00FF0000;
Bmask = 0x0000FF00;
Amask = 0x000000FF;
}
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;
/*
* For this to make any sense, a little information is needed.
* Firstly, SDL uses more or less the opposite value for alpha as
* libtiff, so we need to invert the alpha channel of each pixel.
* To do this, I'm just xor it with the alpha mask.
*
* Secondly, libtiff loads the image more or less inverted.
* So the top left of the image ends up being the bottom left.
* To correct for this, we swap the pixels as we're inverting the
* alpha channel
*/
// We only need to loop 1/2 the height, because we're swapping values.
half = img_height / 2;
for(y = 0; y <= half; y++)
{
for(x = 0; x < img_width; x++)
{
tl_coord = y * img_width + x;
bl_coord = (img_height - y - 1) * img_width + x;
/* Invert the value of the alpha channel, while copying the pixel */
tl_pixel = *((Uint32*)surface->pixels + tl_coord) ^ Amask;
bl_pixel = *((Uint32*)surface->pixels + bl_coord) ^ Amask;
/* Now invert the location of the pixel relative to the image */
*((Uint32*)surface->pixels + bl_coord) = tl_pixel;
*((Uint32*)surface->pixels + tl_coord) = bl_pixel;
}
}
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 */