IMG_pcx.c
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SDL_image: An example image loading library for use with SDL
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Copyright (C) 1997-2009 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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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
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Lesser General Public License for more details.
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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
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Sam Lantinga
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slouken@libsdl.org
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*/
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/*
* 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)
*
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* (The <8bpp formats are expanded to 8bpp surfaces)
*
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* Doesn't support:
* single-planar packed-pixel formats other than 8bpp
* 4-plane 32bpp format with a fourth "intensity" plane
*/
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#include <stdio.h>
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#include <stdlib.h>
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#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)
{
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int is_PCX;
const int ZSoft_Manufacturer = 10;
const int PC_Paintbrush_Version = 5;
const int PCX_RunLength_Encoding = 1;
struct PCXheader pcxh;
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if ( !src )
return 0;
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start = SDL_RWtell(src);
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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;
}
}
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SDL_RWseek(src, start, SEEK_SET);
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return(is_PCX);
}
/* Load a PCX type image from an SDL datasource */
SDL_Surface *IMG_LoadPCX_RW(SDL_RWops *src)
{
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struct PCXheader pcxh;
Uint32 Rmask;
Uint32 Gmask;
Uint32 Bmask;
Uint32 Amask;
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SDL_Surface *surface = NULL;
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int width, height;
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int y, bpl;
Uint8 *row, *buf = NULL;
char *error = NULL;
int bits, src_bits;
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if ( !src ) {
/* The error message has been set in SDL_RWFromFile */
return NULL;
}
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start = SDL_RWtell(src);
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if ( ! SDL_RWread(src, &pcxh, sizeof(pcxh), 1) ) {
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error = "file truncated";
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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;
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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;
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if ( SDL_BYTEORDER == SDL_LIL_ENDIAN ) {
Rmask = 0x000000FF;
Gmask = 0x0000FF00;
Bmask = 0x00FF0000;
} else {
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Rmask = 0xFF0000;
Gmask = 0x00FF00;
Bmask = 0x0000FF;
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}
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} else {
error = "unsupported PCX format";
goto done;
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}
surface = SDL_AllocSurface(SDL_SWSURFACE, width, height,
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bits, Rmask, Gmask, Bmask, Amask);
if ( surface == NULL )
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goto done;
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bpl = pcxh.NPlanes * pcxh.BytesPerLine;
buf = malloc(bpl);
row = surface->pixels;
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for ( y=0; y<surface->h; ++y ) {
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/* 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";
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goto done;
}
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if( (ch & 0xc0) == 0xc0) {
count = ch & 0x3f;
if(!SDL_RWread(src, &ch, 1, 1)) {
error = "file truncated";
goto done;
}
} else
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count = 1;
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}
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;
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/* skip padding bits */
if (i * 8 + j >= width)
continue;
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row[x++] |= bit << plane;
}
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}
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}
} 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;
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}
}
}
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row += surface->pitch;
}
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if(bits == 8) {
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SDL_Color *colors = surface->format->palette->colors;
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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 );
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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];
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}
}
}
done:
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free(buf);
if ( error ) {
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SDL_RWseek(src, start, SEEK_SET);
if ( surface ) {
SDL_FreeSurface(surface);
surface = NULL;
}
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IMG_SetError(error);
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}
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 */