/*

SDL_image: An example image loading library for use with SDL

Copyright (C) 1999-2004 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

slouken@libsdl.org

*/

/* $Id$ */

/* This is a GIF image file loading framework */

#include <stdio.h>

#include <string.h>

#include "SDL_image.h"

#ifdef LOAD_GIF

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

int IMG_isGIF(SDL_RWops *src)

{

int is_GIF;

char magic[6];

is_GIF = 0;

if ( SDL_RWread(src, magic, 6, 1) ) {

if ( (strncmp(magic, "GIF", 3) == 0) &&

((memcmp(magic + 3, "87a", 3) == 0) ||

(memcmp(magic + 3, "89a", 3) == 0)) ) {

is_GIF = 1;

}

}

return(is_GIF);

}

/* Code from here to end of file has been adapted from XPaint: */

/* +-------------------------------------------------------------------+ */

/* | Copyright 1990, 1991, 1993 David Koblas. | */

/* | Copyright 1996 Torsten Martinsen. | */

/* | Permission to use, copy, modify, and distribute this software | */

/* | and its documentation for any purpose and without fee is hereby | */

/* | granted, provided that the above copyright notice appear in all | */

/* | copies and that both that copyright notice and this permission | */

/* | notice appear in supporting documentation. This software is | */

/* | provided "as is" without express or implied warranty. | */

/* +-------------------------------------------------------------------+ */

/* Adapted for use in SDL by Sam Lantinga -- 7/20/98 */

#define USED_BY_SDL

#include <stdio.h>

#include <string.h>

#ifdef USED_BY_SDL

/* Changes to work with SDL:

Include SDL header file

Use SDL_Surface rather than xpaint Image structure

Define SDL versions of RWSetMsg(), ImageNewCmap() and ImageSetCmap()

*/

#include "SDL.h"

#define Image SDL_Surface

#define RWSetMsg IMG_SetError

#define ImageNewCmap(w, h, s) SDL_AllocSurface(SDL_SWSURFACE,w,h,8,0,0,0,0)

#define ImageSetCmap(s, i, R, G, B) do { \

s->format->palette->colors[i].r = R; \

s->format->palette->colors[i].g = G; \

s->format->palette->colors[i].b = B; \

} while (0)

/* * * * * */

#else

/* Original XPaint sources */

#include "image.h"

#include "rwTable.h"

#define SDL_RWops FILE

#define SDL_RWclose fclose

#endif /* USED_BY_SDL */

#define MAXCOLORMAPSIZE 256

#define TRUE 1

#define FALSE 0

#define CM_RED 0

#define CM_GREEN 1

#define CM_BLUE 2

#define MAX_LWZ_BITS 12

#define INTERLACE 0x40

#define LOCALCOLORMAP 0x80

#define BitSet(byte, bit) (((byte) & (bit)) == (bit))

#define ReadOK(file,buffer,len) SDL_RWread(file, buffer, len, 1)

#define LM_to_uint(a,b) (((b)<<8)|(a))

static struct {

unsigned int Width;

unsigned int Height;

unsigned char ColorMap[3][MAXCOLORMAPSIZE];

unsigned int BitPixel;

unsigned int ColorResolution;

unsigned int Background;

unsigned int AspectRatio;

int GrayScale;

} GifScreen;

static struct {

int transparent;

int delayTime;

int inputFlag;

int disposal;

} Gif89;

static int ReadColorMap(SDL_RWops * src, int number,

unsigned char buffer[3][MAXCOLORMAPSIZE], int *flag);

static int DoExtension(SDL_RWops * src, int label);

static int GetDataBlock(SDL_RWops * src, unsigned char *buf);

static int GetCode(SDL_RWops * src, int code_size, int flag);

static int LWZReadByte(SDL_RWops * src, int flag, int input_code_size);

static Image *ReadImage(SDL_RWops * src, int len, int height, int,

unsigned char cmap[3][MAXCOLORMAPSIZE],

int gray, int interlace, int ignore);

Image *

IMG_LoadGIF_RW(SDL_RWops *src)

{

unsigned char buf[16];

unsigned char c;

unsigned char localColorMap[3][MAXCOLORMAPSIZE];

int grayScale;

int useGlobalColormap;

int bitPixel;

int imageCount = 0;

char version[4];

int imageNumber = 1;

Image *image = NULL;

if ( src == NULL ) {

goto done;

}

if (!ReadOK(src, buf, 6)) {

RWSetMsg("error reading magic number");

goto done;

}

if (strncmp((char *) buf, "GIF", 3) != 0) {

RWSetMsg("not a GIF file");

goto done;

}

strncpy(version, (char *) buf + 3, 3);

version[3] = '\0';

if ((strcmp(version, "87a") != 0) && (strcmp(version, "89a") != 0)) {

RWSetMsg("bad version number, not '87a' or '89a'");

goto done;

}

Gif89.transparent = -1;

Gif89.delayTime = -1;

Gif89.inputFlag = -1;

Gif89.disposal = 0;

if (!ReadOK(src, buf, 7)) {

RWSetMsg("failed to read screen descriptor");

goto done;

}

GifScreen.Width = LM_to_uint(buf[0], buf[1]);

GifScreen.Height = LM_to_uint(buf[2], buf[3]);

GifScreen.BitPixel = 2 << (buf[4] & 0x07);

GifScreen.ColorResolution = (((buf[4] & 0x70) >> 3) + 1);

GifScreen.Background = buf[5];

GifScreen.AspectRatio = buf[6];

if (BitSet(buf[4], LOCALCOLORMAP)) { /* Global Colormap */

if (ReadColorMap(src, GifScreen.BitPixel, GifScreen.ColorMap,

&GifScreen.GrayScale)) {

RWSetMsg("error reading global colormap");

goto done;

}

}

do {

if (!ReadOK(src, &c, 1)) {

RWSetMsg("EOF / read error on image data");

goto done;

}

if (c == ';') { /* GIF terminator */

if (imageCount < imageNumber) {

RWSetMsg("only %d image%s found in file",

imageCount, imageCount > 1 ? "s" : "");

goto done;

}

}

if (c == '!') { /* Extension */

if (!ReadOK(src, &c, 1)) {

RWSetMsg("EOF / read error on extention function code");

goto done;

}

DoExtension(src, c);

continue;

}

if (c != ',') { /* Not a valid start character */

continue;

}

++imageCount;

if (!ReadOK(src, buf, 9)) {

RWSetMsg("couldn't read left/top/width/height");

goto done;

}

useGlobalColormap = !BitSet(buf[8], LOCALCOLORMAP);

bitPixel = 1 << ((buf[8] & 0x07) + 1);

if (!useGlobalColormap) {

if (ReadColorMap(src, bitPixel, localColorMap, &grayScale)) {

RWSetMsg("error reading local colormap");

goto done;

}

image = ReadImage(src, LM_to_uint(buf[4], buf[5]),

LM_to_uint(buf[6], buf[7]),

bitPixel, localColorMap, grayScale,

BitSet(buf[8], INTERLACE),

imageCount != imageNumber);

} else {

image = ReadImage(src, LM_to_uint(buf[4], buf[5]),

LM_to_uint(buf[6], buf[7]),

GifScreen.BitPixel, GifScreen.ColorMap,

GifScreen.GrayScale, BitSet(buf[8], INTERLACE),

imageCount != imageNumber);

}

} while (image == NULL);

#ifdef USED_BY_SDL

if ( Gif89.transparent >= 0 ) {

SDL_SetColorKey(image, SDL_SRCCOLORKEY, Gif89.transparent);

}

#endif

done:

return image;

}

static int

ReadColorMap(SDL_RWops *src, int number,

unsigned char buffer[3][MAXCOLORMAPSIZE], int *gray)

{

int i;

unsigned char rgb[3];

int flag;

flag = TRUE;

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

if (!ReadOK(src, rgb, sizeof(rgb))) {

RWSetMsg("bad colormap");

return 1;

}

buffer[CM_RED][i] = rgb[0];

buffer[CM_GREEN][i] = rgb[1];

buffer[CM_BLUE][i] = rgb[2];

flag &= (rgb[0] == rgb[1] && rgb[1] == rgb[2]);

}

#if 0

if (flag)

*gray = (number == 2) ? PBM_TYPE : PGM_TYPE;

else

*gray = PPM_TYPE;

#else

*gray = 0;

#endif

return FALSE;

}

static int

DoExtension(SDL_RWops *src, int label)

{

static unsigned char buf[256];

char *str;

switch (label) {

case 0x01: /* Plain Text Extension */

str = "Plain Text Extension";

break;

case 0xff: /* Application Extension */

str = "Application Extension";

break;

case 0xfe: /* Comment Extension */

str = "Comment Extension";

while (GetDataBlock(src, (unsigned char *) buf) != 0);

return FALSE;

case 0xf9: /* Graphic Control Extension */

str = "Graphic Control Extension";

(void) GetDataBlock(src, (unsigned char *) buf);

Gif89.disposal = (buf[0] >> 2) & 0x7;

Gif89.inputFlag = (buf[0] >> 1) & 0x1;

Gif89.delayTime = LM_to_uint(buf[1], buf[2]);

if ((buf[0] & 0x1) != 0)

Gif89.transparent = buf[3];

while (GetDataBlock(src, (unsigned char *) buf) != 0);

return FALSE;

default:

str = (char *)buf;

sprintf(str, "UNKNOWN (0x%02x)", label);

break;

}

while (GetDataBlock(src, (unsigned char *) buf) != 0);

return FALSE;

}

static int ZeroDataBlock = FALSE;

static int

GetDataBlock(SDL_RWops *src, unsigned char *buf)

{

unsigned char count;

if (!ReadOK(src, &count, 1)) {

/* pm_message("error in getting DataBlock size" ); */

return -1;

}

ZeroDataBlock = count == 0;

if ((count != 0) && (!ReadOK(src, buf, count))) {

/* pm_message("error in reading DataBlock" ); */

return -1;

}

return count;

}

static int

GetCode(SDL_RWops *src, int code_size, int flag)

{

static unsigned char buf[280];

static int curbit, lastbit, done, last_byte;

int i, j, ret;

unsigned char count;

if (flag) {

curbit = 0;

lastbit = 0;

done = FALSE;

return 0;

}

if ((curbit + code_size) >= lastbit) {

if (done) {

if (curbit >= lastbit)

RWSetMsg("ran off the end of my bits");

return -1;

}

buf[0] = buf[last_byte - 2];

buf[1] = buf[last_byte - 1];

if ((count = GetDataBlock(src, &buf[2])) == 0)

done = TRUE;

last_byte = 2 + count;

curbit = (curbit - lastbit) + 16;

lastbit = (2 + count) * 8;

}

ret = 0;

for (i = curbit, j = 0; j < code_size; ++i, ++j)

ret |= ((buf[i / 8] & (1 << (i % 8))) != 0) << j;

curbit += code_size;

return ret;

}

static int

LWZReadByte(SDL_RWops *src, int flag, int input_code_size)

{

static int fresh = FALSE;

int code, incode;

static int code_size, set_code_size;

static int max_code, max_code_size;

static int firstcode, oldcode;

static int clear_code, end_code;

static int table[2][(1 << MAX_LWZ_BITS)];

static int stack[(1 << (MAX_LWZ_BITS)) * 2], *sp;

register int i;

if (flag) {

set_code_size = input_code_size;

code_size = set_code_size + 1;

clear_code = 1 << set_code_size;

end_code = clear_code + 1;

max_code_size = 2 * clear_code;

max_code = clear_code + 2;

GetCode(src, 0, TRUE);

fresh = TRUE;

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

table[0][i] = 0;

table[1][i] = i;

}

for (; i < (1 << MAX_LWZ_BITS); ++i)

table[0][i] = table[1][0] = 0;

sp = stack;

return 0;

} else if (fresh) {

fresh = FALSE;

do {

firstcode = oldcode = GetCode(src, code_size, FALSE);

} while (firstcode == clear_code);

return firstcode;

}

if (sp > stack)

return *--sp;

while ((code = GetCode(src, code_size, FALSE)) >= 0) {

if (code == clear_code) {

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

table[0][i] = 0;

table[1][i] = i;

}

for (; i < (1 << MAX_LWZ_BITS); ++i)

table[0][i] = table[1][i] = 0;

code_size = set_code_size + 1;

max_code_size = 2 * clear_code;

max_code = clear_code + 2;

sp = stack;

firstcode = oldcode = GetCode(src, code_size, FALSE);

return firstcode;

} else if (code == end_code) {

int count;

unsigned char buf[260];

if (ZeroDataBlock)

return -2;

while ((count = GetDataBlock(src, buf)) > 0);

if (count != 0) {

/*

* pm_message("missing EOD in data stream (common occurence)");

*/

}

return -2;

}

incode = code;

if (code >= max_code) {

*sp++ = firstcode;

code = oldcode;

}

while (code >= clear_code) {

*sp++ = table[1][code];

if (code == table[0][code])

RWSetMsg("circular table entry BIG ERROR");

code = table[0][code];

}

*sp++ = firstcode = table[1][code];

if ((code = max_code) < (1 << MAX_LWZ_BITS)) {

table[0][code] = oldcode;

table[1][code] = firstcode;

++max_code;

if ((max_code >= max_code_size) &&

(max_code_size < (1 << MAX_LWZ_BITS))) {

max_code_size *= 2;

++code_size;

}

}

oldcode = incode;

if (sp > stack)

return *--sp;

}

return code;

}

static Image *

ReadImage(SDL_RWops * src, int len, int height, int cmapSize,

unsigned char cmap[3][MAXCOLORMAPSIZE],

int gray, int interlace, int ignore)

{

Image *image;

unsigned char c;

int i, v;

int xpos = 0, ypos = 0, pass = 0;

/*

** Initialize the compression routines

*/

if (!ReadOK(src, &c, 1)) {

RWSetMsg("EOF / read error on image data");

return NULL;

}

if (LWZReadByte(src, TRUE, c) < 0) {

RWSetMsg("error reading image");

return NULL;

}

/*

** If this is an "uninteresting picture" ignore it.

*/

if (ignore) {

while (LWZReadByte(src, FALSE, c) >= 0);

return NULL;

}

image = ImageNewCmap(len, height, cmapSize);

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

ImageSetCmap(image, i, cmap[CM_RED][i],

cmap[CM_GREEN][i], cmap[CM_BLUE][i]);

while ((v = LWZReadByte(src, FALSE, c)) >= 0) {

#ifdef USED_BY_SDL

((Uint8 *)image->pixels)[xpos + ypos * image->pitch] = v;

#else

image->data[xpos + ypos * len] = v;

#endif

++xpos;

if (xpos == len) {

xpos = 0;

if (interlace) {

switch (pass) {

case 0:

case 1:

ypos += 8;

break;

case 2:

ypos += 4;

break;

case 3:

ypos += 2;

break;

}

if (ypos >= height) {

++pass;

switch (pass) {

case 1:

ypos = 4;

break;

case 2:

ypos = 2;

break;

case 3:

ypos = 1;

break;

default:

goto fini;

}

}

} else {

++ypos;

}

}

if (ypos >= height)

break;

}

fini:

return image;

}

#else

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

int IMG_isGIF(SDL_RWops *src)

{

return(0);

}

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

SDL_Surface *IMG_LoadGIF_RW(SDL_RWops *src)

{

return(NULL);

}

#endif /* LOAD_GIF */