/*

SDL_image: An example image loading library for use with SDL

Copyright (C) 1997-2006 Sam Lantinga

This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Lesser General Public

License as published by the Free Software Foundation; either

version 2.1 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

Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public

License along with this library; if not, write to the Free Software

Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

Sam Lantinga

slouken@libsdl.org

*/

/* This is a ILBM image file loading framework

Load IFF pictures, PBM & ILBM packing methods, with or without stencil

Written by Daniel Morais ( Daniel AT Morais DOT com ) in September 2001.

24 bits ILBM files support added by Marc Le Douarain (http://www.multimania.com/mavati)

in December 2002.

EHB and HAM (specific Amiga graphic chip modes) support added by Marc Le Douarain

(http://www.multimania.com/mavati) in December 2003.

Stencil and colorkey fixes by David Raulo (david.raulo AT free DOT fr) in February 2004.

*/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "SDL_endian.h"

#include "SDL_image.h"

#ifdef LOAD_LBM

#define MAXCOLORS 256

/* Structure for an IFF picture ( BMHD = Bitmap Header ) */

typedef struct

{

Uint16 w, h; /* width & height of the bitmap in pixels */

Sint16 x, y; /* screen coordinates of the bitmap */

Uint8 planes; /* number of planes of the bitmap */

Uint8 mask; /* mask type ( 0 => no mask ) */

Uint8 tcomp; /* compression type */

Uint8 pad1; /* dummy value, for padding */

Uint16 tcolor; /* transparent color */

Uint8 xAspect, /* pixel aspect ratio */

yAspect;

Sint16 Lpage; /* width of the screen in pixels */

Sint16 Hpage; /* height of the screen in pixels */

} BMHD;

int IMG_isLBM( SDL_RWops *src )

{

int start;

int is_LBM;

Uint8 magic[4+4+4];

start = SDL_RWtell(src);

is_LBM = 0;

if ( SDL_RWread( src, magic, sizeof(magic), 1 ) )

{

if ( !memcmp( magic, "FORM", 4 ) &&

( !memcmp( magic + 8, "PBM ", 4 ) ||

!memcmp( magic + 8, "ILBM", 4 ) ) )

{

is_LBM = 1;

}

}

SDL_RWseek(src, start, SEEK_SET);

return( is_LBM );

}

SDL_Surface *IMG_LoadLBM_RW( SDL_RWops *src )

{

int start;

SDL_Surface *Image;

Uint8 id[4], pbm, colormap[MAXCOLORS*3], *MiniBuf, *ptr, count, color, msk;

Uint32 size, bytesloaded, nbcolors;

Uint32 i, j, bytesperline, nbplanes, plane, h;

Uint32 remainingbytes;

Uint32 width;

BMHD bmhd;

char *error;

Uint8 flagHAM,flagEHB;

Image = NULL;

error = NULL;

MiniBuf = NULL;

if ( !src ) {

/* The error message has been set in SDL_RWFromFile */

return NULL;

}

start = SDL_RWtell(src);

if ( !SDL_RWread( src, id, 4, 1 ) )

{

error="error reading IFF chunk";

goto done;

}

/* Should be the size of the file minus 4+4 ( 'FORM'+size ) */

if ( !SDL_RWread( src, &size, 4, 1 ) )

{

error="error reading IFF chunk size";

goto done;

}

/* As size is not used here, no need to swap it */

if ( memcmp( id, "FORM", 4 ) != 0 )

{

error="not a IFF file";

goto done;

}

if ( !SDL_RWread( src, id, 4, 1 ) )

{

error="error reading IFF chunk";

goto done;

}

pbm = 0;

/* File format : PBM=Packed Bitmap, ILBM=Interleaved Bitmap */

if ( !memcmp( id, "PBM ", 4 ) ) pbm = 1;

else if ( memcmp( id, "ILBM", 4 ) )

{

error="not a IFF picture";

goto done;

}

nbcolors = 0;

memset( &bmhd, 0, sizeof( BMHD ) );

flagHAM = 0;

flagEHB = 0;

while ( memcmp( id, "BODY", 4 ) != 0 )

{

if ( !SDL_RWread( src, id, 4, 1 ) )

{

error="error reading IFF chunk";

goto done;

}

if ( !SDL_RWread( src, &size, 4, 1 ) )

{

error="error reading IFF chunk size";

goto done;

}

bytesloaded = 0;

size = SDL_SwapBE32( size );

if ( !memcmp( id, "BMHD", 4 ) ) /* Bitmap header */

{

if ( !SDL_RWread( src, &bmhd, sizeof( BMHD ), 1 ) )

{

error="error reading BMHD chunk";

goto done;

}

bytesloaded = sizeof( BMHD );

bmhd.w = SDL_SwapBE16( bmhd.w );

bmhd.h = SDL_SwapBE16( bmhd.h );

bmhd.x = SDL_SwapBE16( bmhd.x );

bmhd.y = SDL_SwapBE16( bmhd.y );

bmhd.tcolor = SDL_SwapBE16( bmhd.tcolor );

bmhd.Lpage = SDL_SwapBE16( bmhd.Lpage );

bmhd.Hpage = SDL_SwapBE16( bmhd.Hpage );

}

if ( !memcmp( id, "CMAP", 4 ) ) /* palette ( Color Map ) */

{

if ( !SDL_RWread( src, &colormap, size, 1 ) )

{

error="error reading CMAP chunk";

goto done;

}

bytesloaded = size;

nbcolors = size / 3;

}

if ( !memcmp( id, "CAMG", 4 ) ) /* Amiga ViewMode */

{

Uint32 viewmodes;

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

{

error="error reading CAMG chunk";

goto done;

}

bytesloaded = size;

viewmodes = SDL_SwapBE32( viewmodes );

if ( viewmodes & 0x0800 )

flagHAM = 1;

if ( viewmodes & 0x0080 )

flagEHB = 1;

}

if ( memcmp( id, "BODY", 4 ) )

{

if ( size & 1 ) ++size; /* padding ! */

size -= bytesloaded;

/* skip the remaining bytes of this chunk */

if ( size ) SDL_RWseek( src, size, SEEK_CUR );

}

}

/* compute some usefull values, based on the bitmap header */

width = ( bmhd.w + 15 ) & 0xFFFFFFF0; /* Width in pixels modulo 16 */

bytesperline = ( ( bmhd.w + 15 ) / 16 ) * 2;

nbplanes = bmhd.planes;

if ( pbm ) /* File format : 'Packed Bitmap' */

{

bytesperline *= 8;

nbplanes = 1;

}

if ( bmhd.mask & 1 ) ++nbplanes; /* There is a mask ( 'stencil' ) */

/* Allocate memory for a temporary buffer ( used for

decompression/deinterleaving ) */

if ( ( MiniBuf = (void *)malloc( bytesperline * nbplanes ) ) == NULL )

{

error="no enough memory for temporary buffer";

goto done;

}

if ( ( Image = SDL_CreateRGBSurface( SDL_SWSURFACE, width, bmhd.h, (bmhd.planes==24 || flagHAM==1)?24:8, 0, 0, 0, 0 ) ) == NULL )

goto done;

if ( bmhd.mask & 2 ) /* There is a transparent color */

SDL_SetColorKey( Image, SDL_SRCCOLORKEY, bmhd.tcolor );

/* Update palette informations */

/* There is no palette in 24 bits ILBM file */

if ( nbcolors>0 && flagHAM==0 )

{

int nbrcolorsfinal = 1 << nbplanes;

ptr = &colormap[0];

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

{

Image->format->palette->colors[i].r = *ptr++;

Image->format->palette->colors[i].g = *ptr++;

Image->format->palette->colors[i].b = *ptr++;

}

/* Amiga EHB mode (Extra-Half-Bright) */

/* 6 bitplanes mode with a 32 colors palette */

/* The 32 last colors are the same but divided by 2 */

/* Some Amiga pictures save 64 colors with 32 last wrong colors, */

/* they shouldn't !, and here we overwrite these 32 bad colors. */

if ( (nbcolors==32 || flagEHB ) && (1<<bmhd.planes)==64 )

{

nbcolors = 64;

ptr = &colormap[0];

for ( i=32; i<64; i++ )

{

Image->format->palette->colors[i].r = (*ptr++)/2;

Image->format->palette->colors[i].g = (*ptr++)/2;

Image->format->palette->colors[i].b = (*ptr++)/2;

}

}

/* If nbcolors < 2^nbplanes, repeat the colormap */

/* This happens when pictures have a stencil mask */

if ( nbrcolorsfinal > (1<<bmhd.planes) ) {

nbrcolorsfinal = (1<<bmhd.planes);

}

for ( i=nbcolors; i < (Uint32)nbrcolorsfinal; i++ )

{

Image->format->palette->colors[i].r = Image->format->palette->colors[i%nbcolors].r;

Image->format->palette->colors[i].g = Image->format->palette->colors[i%nbcolors].g;

Image->format->palette->colors[i].b = Image->format->palette->colors[i%nbcolors].b;

}

Image->format->palette->ncolors = nbrcolorsfinal;

}

/* Get the bitmap */

for ( h=0; h < bmhd.h; h++ )

{

/* uncompress the datas of each planes */

for ( plane=0; plane < nbplanes; plane++ )

{

ptr = MiniBuf + ( plane * bytesperline );

remainingbytes = bytesperline;

if ( bmhd.tcomp == 1 ) /* Datas are compressed */

{

do

{

if ( !SDL_RWread( src, &count, 1, 1 ) )

{

error="error reading BODY chunk";

goto done;

}

if ( count & 0x80 )

{

count ^= 0xFF;

count += 2; /* now it */

if ( !SDL_RWread( src, &color, 1, 1 ) )

{

error="error reading BODY chunk";

goto done;

}

memset( ptr, color, count );

}

else

{

++count;

if ( !SDL_RWread( src, ptr, count, 1 ) )

{

error="error reading BODY chunk";

goto done;

}

}

ptr += count;

remainingbytes -= count;

} while ( remainingbytes > 0 );

}

else

{

if ( !SDL_RWread( src, ptr, bytesperline, 1 ) )

{

error="error reading BODY chunk";

goto done;

}

}

}

/* One line has been read, store it ! */

ptr = Image->pixels;

if ( nbplanes==24 || flagHAM==1 )

ptr += h * width * 3;

else

ptr += h * width;

if ( pbm ) /* File format : 'Packed Bitmap' */

{

memcpy( ptr, MiniBuf, width );

}

else /* We have to un-interlace the bits ! */

{

if ( nbplanes!=24 && flagHAM==0 )

{

size = ( width + 7 ) / 8;

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

{

memset( ptr, 0, 8 );

for ( plane=0; plane < nbplanes; plane++ )

{

color = *( MiniBuf + i + ( plane * bytesperline ) );

msk = 0x80;

for ( j=0; j<8; j++ )

{

if ( ( plane + j ) <= 7 ) ptr[j] |= (Uint8)( color & msk ) >> ( 7 - plane - j );

else ptr[j] |= (Uint8)( color & msk ) << ( plane + j - 7 );

msk >>= 1;

}

}

ptr += 8;

}

}

else

{

Uint32 finalcolor = 0;

size = ( width + 7 ) / 8;

/* 24 bitplanes ILBM : R0...R7,G0...G7,B0...B7 */

/* or HAM (6 bitplanes) or HAM8 (8 bitplanes) modes */

for ( i=0; i<width; i=i+8 )

{

Uint8 maskBit = 0x80;

for ( j=0; j<8; j++ )

{

Uint32 pixelcolor = 0;

Uint32 maskColor = 1;

Uint8 dataBody;

for ( plane=0; plane < nbplanes; plane++ )

{

dataBody = MiniBuf[ plane*size+i/8 ];

if ( dataBody&maskBit )

pixelcolor = pixelcolor | maskColor;

maskColor = maskColor<<1;

}

/* HAM : 12 bits RGB image (4 bits per color component) */

/* HAM8 : 18 bits RGB image (6 bits per color component) */

if ( flagHAM )

{

switch( pixelcolor>>(nbplanes-2) )

{

case 0: /* take direct color from palette */

finalcolor = colormap[ pixelcolor*3 ] + (colormap[ pixelcolor*3+1 ]<<8) + (colormap[ pixelcolor*3+2 ]<<16);

break;

case 1: /* modify only blue component */

finalcolor = finalcolor&0x00FFFF;

finalcolor = finalcolor | (pixelcolor<<(16+(10-nbplanes)));

break;

case 2: /* modify only red component */

finalcolor = finalcolor&0xFFFF00;

finalcolor = finalcolor | pixelcolor<<(10-nbplanes);

break;

case 3: /* modify only green component */

finalcolor = finalcolor&0xFF00FF;

finalcolor = finalcolor | (pixelcolor<<(8+(10-nbplanes)));

break;

}

}

else

{

finalcolor = pixelcolor;

}

if ( SDL_BYTEORDER == SDL_LIL_ENDIAN )

{

*ptr++ = finalcolor>>16;

*ptr++ = finalcolor>>8;

*ptr++ = finalcolor;

}

else

{

*ptr++ = finalcolor;

*ptr++ = finalcolor>>8;

*ptr++ = finalcolor>>16;

}

maskBit = maskBit>>1;

}

}

}

}

}

done:

if ( MiniBuf ) free( MiniBuf );

if ( error )

{

SDL_RWseek(src, start, SEEK_SET);

if ( Image ) {

SDL_FreeSurface( Image );

Image = NULL;

}

IMG_SetError( error );

}

return( Image );

}

#else /* LOAD_LBM */

/* See if an image is contained in a data source */

int IMG_isLBM(SDL_RWops *src)

{

return(0);

}

/* Load an IFF type image from an SDL datasource */

SDL_Surface *IMG_LoadLBM_RW(SDL_RWops *src)

{

return(NULL);

}

#endif /* LOAD_LBM */