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

*/

/* $Id$ */

/*

* PCX file reader:

* Supports:

* 1..4 bits/pixel in multiplanar format (1 bit/plane/pixel)

* 8 bits/pixel in single-planar format (8 bits/plane/pixel)

* 24 bits/pixel in 3-plane format (8 bits/plane/pixel)

*

* (The <8bpp formats are expanded to 8bpp surfaces)

*

* Doesn't support:

* single-planar packed-pixel formats other than 8bpp

* 4-plane 32bpp format with a fourth "intensity" plane

*/

#include "SDL_endian.h"

#include "SDL_image.h"

#ifdef LOAD_PCX

struct PCXheader {

Uint8 Manufacturer;

Uint8 Version;

Uint8 Encoding;

Uint8 BitsPerPixel;

Sint16 Xmin, Ymin, Xmax, Ymax;

Sint16 HDpi, VDpi;

Uint8 Colormap[48];

Uint8 Reserved;

Uint8 NPlanes;

Sint16 BytesPerLine;

Sint16 PaletteInfo;

Sint16 HscreenSize;

Sint16 VscreenSize;

Uint8 Filler[54];

};

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

int IMG_isPCX(SDL_RWops *src)

{

int is_PCX;

const int ZSoft_Manufacturer = 10;

const int PC_Paintbrush_Version = 5;

const int PCX_RunLength_Encoding = 1;

struct PCXheader pcxh;

is_PCX = 0;

if ( SDL_RWread(src, &pcxh, sizeof(pcxh), 1) == 1 ) {

if ( (pcxh.Manufacturer == ZSoft_Manufacturer) &&

(pcxh.Version == PC_Paintbrush_Version) &&

(pcxh.Encoding == PCX_RunLength_Encoding) ) {

is_PCX = 1;

}

}

return(is_PCX);

}

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

SDL_Surface *IMG_LoadPCX_RW(SDL_RWops *src)

{

struct PCXheader pcxh;

Uint32 Rmask;

Uint32 Gmask;

Uint32 Bmask;

Uint32 Amask;

int y, bpl;

Uint8 *row, *buf = NULL;

char *error = NULL;

int bits, src_bits;

if ( ! SDL_RWread(src, &pcxh, sizeof(pcxh), 1) ) {

goto done;

}

pcxh.Xmin = SDL_SwapLE16(pcxh.Xmin);

pcxh.Ymin = SDL_SwapLE16(pcxh.Ymin);

pcxh.Xmax = SDL_SwapLE16(pcxh.Xmax);

pcxh.Ymax = SDL_SwapLE16(pcxh.Ymax);

pcxh.BytesPerLine = SDL_SwapLE16(pcxh.BytesPerLine);

/* Create the surface of the appropriate type */

width = (pcxh.Xmax - pcxh.Xmin) + 1;

height = (pcxh.Ymax - pcxh.Ymin) + 1;

Rmask = Gmask = Bmask = Amask = 0;

src_bits = pcxh.BitsPerPixel * pcxh.NPlanes;

if((pcxh.BitsPerPixel == 1 && pcxh.NPlanes >= 1 && pcxh.NPlanes <= 4)

|| (pcxh.BitsPerPixel == 8 && pcxh.NPlanes == 1)) {

bits = 8;

} else if(pcxh.BitsPerPixel == 8 && pcxh.NPlanes == 3) {

bits = 24;

if ( SDL_BYTEORDER == SDL_LIL_ENDIAN ) {

Rmask = 0x000000FF;

Gmask = 0x0000FF00;

Bmask = 0x00FF0000;

} else {

Rmask = 0xFF0000;

Gmask = 0x00FF00;

Bmask = 0x0000FF;

} else {

error = "unsupported PCX format";

goto done;

}

surface = SDL_AllocSurface(SDL_SWSURFACE, width, height,

bits, Rmask, Gmask, Bmask, Amask);

if ( surface == NULL )

goto done;

bpl = pcxh.NPlanes * pcxh.BytesPerLine;

buf = malloc(bpl);

row = surface->pixels;

/* decode a scan line to a temporary buffer first */

int i, count = 0;

Uint8 ch;

Uint8 *dst = (src_bits == 8) ? row : buf;

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

if(!count) {

if(!SDL_RWread(src, &ch, 1, 1)) {

error = "file truncated";

goto done;

}

if( (ch & 0xc0) == 0xc0) {

count = ch & 0x3f;

if(!SDL_RWread(src, &ch, 1, 1)) {

error = "file truncated";

goto done;

}

} else

}

dst[i] = ch;

count--;

}

if(src_bits <= 4) {

/* expand planes to 1 byte/pixel */

Uint8 *src = buf;

int plane;

for(plane = 0; plane < pcxh.NPlanes; plane++) {

int i, j, x = 0;

for(i = 0; i < pcxh.BytesPerLine; i++) {

Uint8 byte = *src++;

for(j = 7; j >= 0; j--) {

unsigned bit = (byte >> j) & 1;

/* skip padding bits */

if (i * 8 + j >= width)

continue;

row[x++] |= bit << plane;

}

}

} else if(src_bits == 24) {

/* de-interlace planes */

Uint8 *src = buf;

int plane;

for(plane = 0; plane < pcxh.NPlanes; plane++) {

int x;

dst = row + plane;

for(x = 0; x < width; x++) {

*dst = *src++;

dst += pcxh.NPlanes;

}

}

}

row += surface->pitch;

}

int nc = 1 << src_bits;

int i;

surface->format->palette->ncolors = nc;

if(src_bits == 8) {

Uint8 ch;

/* look for a 256-colour palette */

do {

if ( !SDL_RWread(src, &ch, 1, 1)) {

error = "file truncated";

goto done;

}

} while ( ch != 12 );

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

SDL_RWread(src, &colors[i].r, 1, 1);

SDL_RWread(src, &colors[i].g, 1, 1);

SDL_RWread(src, &colors[i].b, 1, 1);

}

} else {

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

colors[i].r = pcxh.Colormap[i * 3];

colors[i].g = pcxh.Colormap[i * 3 + 1];

colors[i].b = pcxh.Colormap[i * 3 + 2];

}

}

}

done:

free(buf);

if ( error ) {

surface = NULL;

}

return(surface);

}

#else

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

int IMG_isPCX(SDL_RWops *src)

{

return(0);

}

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

SDL_Surface *IMG_LoadPCX_RW(SDL_RWops *src)

{

return(NULL);

}

#endif /* LOAD_PCX */