Subversion Repositories Kolibri OS

/*

    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

*/

#include 

#include 

#include 

#include "SDL_endian.h"

#include "SDL_image.h"

#ifdef LOAD_TGA

/*

 * A TGA loader for the SDL library

 * Supports: Reading 8, 15, 16, 24 and 32bpp images, with alpha or colourkey,

 *           uncompressed or RLE encoded.

 *

 * 2000-06-10 Mattias Engdegård : initial version

 * 2000-06-26 Mattias Engdegård : read greyscale TGAs

 * 2000-08-09 Mattias Engdegård : alpha inversion removed

 */

struct TGAheader {

    Uint8 infolen;		/* length of info field */

    Uint8 has_cmap;		/* 1 if image has colormap, 0 otherwise */

    Uint8 type;

    Uint8 cmap_start[2];	/* index of first colormap entry */

    Uint8 cmap_len[2];		/* number of entries in colormap */

    Uint8 cmap_bits;		/* bits per colormap entry */

    Uint8 yorigin[2];		/* image origin (ignored here) */

    Uint8 xorigin[2];

    Uint8 width[2];		/* image size */

    Uint8 height[2];

    Uint8 pixel_bits;		/* bits/pixel */

    Uint8 flags;

};

enum tga_type {

    TGA_TYPE_INDEXED = 1,

    TGA_TYPE_RGB = 2,

    TGA_TYPE_BW = 3,

    TGA_TYPE_RLE_INDEXED = 9,

    TGA_TYPE_RLE_RGB = 10,

    TGA_TYPE_RLE_BW = 11

};

#define TGA_INTERLEAVE_MASK	0xc0

#define TGA_INTERLEAVE_NONE	0x00

#define TGA_INTERLEAVE_2WAY	0x40

#define TGA_INTERLEAVE_4WAY	0x80

#define TGA_ORIGIN_MASK		0x30

#define TGA_ORIGIN_LEFT		0x00

#define TGA_ORIGIN_RIGHT	0x10

#define TGA_ORIGIN_LOWER	0x00

#define TGA_ORIGIN_UPPER	0x20

/* read/write unaligned little-endian 16-bit ints */

#define LE16(p) ((p)[0] + ((p)[1] << 8))

#define SETLE16(p, v) ((p)[0] = (v), (p)[1] = (v) >> 8)

static void unsupported(void)

{

    IMG_SetError("unsupported TGA format");

}

/* Load a TGA type image from an SDL datasource */

SDL_Surface *IMG_LoadTGA_RW(SDL_RWops *src)

{

    struct TGAheader hdr;

    int rle = 0;

    int alpha = 0;

    int indexed = 0;

    int grey = 0;

    int ckey = -1;

    int ncols, w, h;

    SDL_Surface *img;

    Uint32 rmask, gmask, bmask, amask;

    Uint8 *dst;

    int i;

    int bpp;

    int lstep;

    Uint32 pixel;

    int count, rep;

    if(!SDL_RWread(src, &hdr, sizeof(hdr), 1))

	goto error;

    ncols = LE16(hdr.cmap_len);

    switch(hdr.type) {

    case TGA_TYPE_RLE_INDEXED:

	rle = 1;

	/* fallthrough */

    case TGA_TYPE_INDEXED:

	if(!hdr.has_cmap || hdr.pixel_bits != 8 || ncols > 256)

	    goto error;

	indexed = 1;

	break;

    case TGA_TYPE_RLE_RGB:

	rle = 1;

	/* fallthrough */

    case TGA_TYPE_RGB:

	indexed = 0;

	break;

    case TGA_TYPE_RLE_BW:

	rle = 1;

	/* fallthrough */

    case TGA_TYPE_BW:

	if(hdr.pixel_bits != 8)

	    goto error;

	/* Treat greyscale as 8bpp indexed images */

	indexed = grey = 1;

	break;

    default:

        unsupported();

	return NULL;

    }

    bpp = (hdr.pixel_bits + 7) >> 3;

    rmask = gmask = bmask = amask = 0;

    switch(hdr.pixel_bits) {

    case 8:

	if(!indexed) {

	    unsupported();

	    return NULL;

	}

	break;

    case 15:

    case 16:

	/* 15 and 16bpp both seem to use 5 bits/plane. The extra alpha bit

	   is ignored for now. */

	rmask = 0x7c00;

	gmask = 0x03e0;

	bmask = 0x001f;

	break;

    case 32:

	alpha = 1;

	/* fallthrough */

    case 24:

	if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {

	    int s = alpha ? 0 : 8;

	    amask = 0x000000ff >> s;

	    rmask = 0x0000ff00 >> s;

	    gmask = 0x00ff0000 >> s;

	    bmask = 0xff000000 >> s;

	} else {

	    amask = alpha ? 0xff000000 : 0;

	    rmask = 0x00ff0000;

	    gmask = 0x0000ff00;

	    bmask = 0x000000ff;

	}

	break;

    default:

	unsupported();

	return NULL;

    }

    if((hdr.flags & TGA_INTERLEAVE_MASK) != TGA_INTERLEAVE_NONE

       || hdr.flags & TGA_ORIGIN_RIGHT) {

	unsupported();

	return NULL;

    }

    SDL_RWseek(src, hdr.infolen, SEEK_CUR); /* skip info field */

    w = LE16(hdr.width);

    h = LE16(hdr.height);

    img = SDL_CreateRGBSurface(SDL_SWSURFACE, w, h,

			       bpp * 8,

			       rmask, gmask, bmask, amask);

    if(hdr.has_cmap) {

	int palsiz = ncols * ((hdr.cmap_bits + 7) >> 3);

	if(indexed && !grey) {

	    Uint8 *pal = malloc(palsiz), *p = pal;

	    SDL_Color *colors = img->format->palette->colors;

	    img->format->palette->ncolors = ncols;

	    SDL_RWread(src, pal, palsiz, 1);

	    for(i = 0; i < ncols; i++) {

		switch(hdr.cmap_bits) {

		case 15:

		case 16:

		    {

			Uint16 c = p[0] + (p[1] << 8);

			p += 2;

			colors[i].r = (c >> 7) & 0xf8;

			colors[i].g = (c >> 2) & 0xf8;

			colors[i].b = c << 3;

		    }

		    break;

		case 24:

		case 32:

		    colors[i].b = *p++;

		    colors[i].g = *p++;

		    colors[i].r = *p++;

		    if(hdr.cmap_bits == 32 && *p++ < 128)

			ckey = i;

		    break;

		}

	    }

	    free(pal);

	    if(ckey >= 0)

		SDL_SetColorKey(img, SDL_SRCCOLORKEY, ckey);

	} else {

	    /* skip unneeded colormap */

	    SDL_RWseek(src, palsiz, SEEK_CUR);

	}

    }

    if(grey) {

	SDL_Color *colors = img->format->palette->colors;

	for(i = 0; i < 256; i++)

	    colors[i].r = colors[i].g = colors[i].b = i;

	img->format->palette->ncolors = 256;

    }

    if(hdr.flags & TGA_ORIGIN_UPPER) {

	lstep = img->pitch;

	dst = img->pixels;

    } else {

	lstep = -img->pitch;

	dst = (Uint8 *)img->pixels + (h - 1) * img->pitch;

    }

    /* The RLE decoding code is slightly convoluted since we can't rely on

       spans not to wrap across scan lines */

    count = rep = 0;

    for(i = 0; i < h; i++) {

	if(rle) {

	    int x = 0;

	    for(;;) {

		Uint8 c;

		if(count) {

		    int n = count;

		    if(n > w - x)

			n = w - x;

		    SDL_RWread(src, dst + x * bpp, n * bpp, 1);

		    count -= n;

		    x += n;

		    if(x == w)

			break;

		} else if(rep) {

		    int n = rep;

		    if(n > w - x)

			n = w - x;

		    rep -= n;

		    while(n--) {

			memcpy(dst + x * bpp, &pixel, bpp);

			x++;

		    }

		    if(x == w)

			break;

		}

		SDL_RWread(src, &c, 1, 1);

		if(c & 0x80) {

		    SDL_RWread(src, &pixel, bpp, 1);

		    rep = (c & 0x7f) + 1;

		} else {

		    count = c + 1;

		}

	    }

	} else {

	    SDL_RWread(src, dst, w * bpp, 1);

	}

	if(SDL_BYTEORDER == SDL_BIG_ENDIAN && bpp == 2) {

	    /* swap byte order */

	    int x;

	    Uint16 *p = (Uint16 *)dst;

	    for(x = 0; x < w; x++)

		p[x] = SDL_Swap16(p[x]);

	}

	dst += lstep;

    }

    return img;

error:

    IMG_SetError("Error reading TGA data");

    return NULL;

}

#else

/* dummy TGA load routine */

SDL_Surface *IMG_LoadTGA_RW(SDL_RWops *src)

{

	return(NULL);

}

#endif /* LOAD_TGA */