/**
* File: GIF Input
*
* Read GIF images.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "gd.h"
/* Used only when debugging GIF compression code */
/* #define DEBUGGING_ENVARS */
#ifdef DEBUGGING_ENVARS
static int verbose_set = 0;
static int verbose;
#define VERBOSE (verbose_set ? verbose : set_verbose())
static int set_verbose(void)
{
verbose = !!getenv("GIF_VERBOSE");
verbose_set = 1;
return(verbose);
}
#else
#define VERBOSE 0
#endif
#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) (gdGetBuf(buffer, len, file) > 0)
#define LM_to_uint(a, b) (((b)<<8)|(a))
/* We may eventually want to use this information, but def it out for now */
#if 0
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;
} GifScreen;
#endif
#if 0
static struct {
int transparent;
int delayTime;
int inputFlag;
int disposal;
} Gif89 = { -1, -1, -1, 0 };
#endif
#define STACK_SIZE ((1<<(MAX_LWZ_BITS))*2)
#define CSD_BUF_SIZE 280
typedef struct {
unsigned char buf[CSD_BUF_SIZE];
int curbit;
int lastbit;
int done;
int last_byte;
} CODE_STATIC_DATA;
typedef struct {
int fresh;
int code_size, set_code_size;
int max_code, max_code_size;
int firstcode, oldcode;
int clear_code, end_code;
int table[2][(1<< MAX_LWZ_BITS)];
int stack[STACK_SIZE], *sp;
CODE_STATIC_DATA scd;
} LZW_STATIC_DATA;
static int ReadColorMap (gdIOCtx *fd, int number, unsigned char (*buffer)[256]);
static int DoExtension (gdIOCtx *fd, int label, int *Transparent, int *ZeroDataBlockP);
static int GetDataBlock (gdIOCtx *fd, unsigned char *buf, int *ZeroDataBlockP);
static int GetCode (gdIOCtx *fd, CODE_STATIC_DATA *scd, int code_size, int flag, int *ZeroDataBlockP);
static int LWZReadByte (gdIOCtx *fd, LZW_STATIC_DATA *sd, char flag, int input_code_size, int *ZeroDataBlockP);
static void ReadImage (gdImagePtr im, gdIOCtx *fd, int len, int height, unsigned char (*cmap)[256], int interlace, int *ZeroDataBlockP); /*1.4//, int ignore); */
/*
Function: gdImageCreateFromGif
<gdImageCreateFromGif> is called to load images from GIF format
files. Invoke <gdImageCreateFromGif> with an already opened
pointer to a file containing the desired
image.
<gdImageCreateFromGif> returns a <gdImagePtr> to the new image, or
NULL if unable to load the image (most often because the file is
corrupt or does not contain a GIF image). <gdImageCreateFromGif>
does not close the file. You can inspect the sx and sy members of
the image to determine its size. The image must eventually be
destroyed using <gdImageDestroy>.
Variants:
<gdImageCreateFromGifPtr> creates an image from GIF data (i.e. the
contents of a GIF file) already in memory.
<gdImageCreateFromGifCtx> reads in an image using the functions in
a <gdIOCtx> struct.
Parameters:
infile - The input FILE pointer
Returns:
A pointer to the new image or NULL if an error occurred.
Example:
> gdImagePtr im;
> ... inside a function ...
> FILE *in;
> in = fopen("mygif.gif", "rb");
> im = gdImageCreateFromGif(in);
> fclose(in);
> // ... Use the image ...
> gdImageDestroy(im);
*/
BGD_DECLARE(gdImagePtr) gdImageCreateFromGif(FILE *fdFile)
{
gdIOCtx *fd = gdNewFileCtx(fdFile);
gdImagePtr im;
if (fd == NULL) return NULL;
im = gdImageCreateFromGifCtx(fd);
fd->gd_free(fd);
return im;
}
/*
Function: gdImageCreateFromGifPtr
Parameters:
size - size of GIF data in bytes.
data - GIF data (i.e. contents of a GIF file).
See <gdImageCreateFromGif>.
*/
BGD_DECLARE(gdImagePtr) gdImageCreateFromGifPtr (int size, void *data)
{
gdImagePtr im;
gdIOCtx *in = gdNewDynamicCtxEx(size, data, 0);
if(!in) {
return 0;
}
im = gdImageCreateFromGifCtx(in);
in->gd_free(in);
return im;
}
/*
Function: gdImageCreateFromGifCtx
See <gdImageCreateFromGif>.
*/
BGD_DECLARE(gdImagePtr) gdImageCreateFromGifCtx(gdIOCtxPtr fd)
{
int BitPixel;
#if 0
int ColorResolution;
int Background;
int AspectRatio;
#endif
int Transparent = (-1);
unsigned char buf[16];
unsigned char c;
unsigned char ColorMap[3][MAXCOLORMAPSIZE];
unsigned char localColorMap[3][MAXCOLORMAPSIZE];
int imw, imh, screen_width, screen_height;
int useGlobalColormap;
int bitPixel, i;
/*1.4//int imageCount = 0; */
/* 2.0.28: threadsafe storage */
int ZeroDataBlock = FALSE;
int haveGlobalColormap;
gdImagePtr im = 0;
memset(ColorMap, 0, 3 * MAXCOLORMAPSIZE);
memset(localColorMap, 0, 3 * MAXCOLORMAPSIZE);
if(!ReadOK(fd, buf, 6)) {
return 0;
}
if(strncmp((char *)buf, "GIF", 3) != 0) {
return 0;
}
if(memcmp((char *)buf + 3, "87a", 3) == 0) {
/* GIF87a */
} else if(memcmp((char *)buf + 3, "89a", 3) == 0) {
/* GIF89a */
} else {
return 0;
}
if(!ReadOK(fd, buf, 7)) {
return 0;
}
BitPixel = 2 << (buf[4] & 0x07);
#if 0
ColorResolution = (int) (((buf[4]&0x70)>>3)+1);
Background = buf[5];
AspectRatio = buf[6];
#endif
screen_width = imw = LM_to_uint(buf[0], buf[1]);
screen_height = imh = LM_to_uint(buf[2], buf[3]);
haveGlobalColormap = BitSet(buf[4], LOCALCOLORMAP); /* Global Colormap */
if(haveGlobalColormap) {
if(ReadColorMap(fd, BitPixel, ColorMap)) {
return 0;
}
}
for (;;) {
int top, left;
int width, height;
if(!ReadOK(fd, &c, 1)) {
return 0;
}
if (c == ';') { /* GIF terminator */
goto terminated;
}
if(c == '!') { /* Extension */
if(!ReadOK(fd, &c, 1)) {
return 0;
}
DoExtension(fd, c, &Transparent, &ZeroDataBlock);
continue;
}
if(c != ',') { /* Not a valid start character */
continue;
}
/*1.4//++imageCount; */
if(!ReadOK(fd, buf, 9)) {
return 0;
}
useGlobalColormap = !BitSet(buf[8], LOCALCOLORMAP);
bitPixel = 1 << ((buf[8] & 0x07) + 1);
left = LM_to_uint(buf[0], buf[1]);
top = LM_to_uint(buf[2], buf[3]);
width = LM_to_uint(buf[4], buf[5]);
height = LM_to_uint(buf[6], buf[7]);
if(((left + width) > screen_width) || ((top + height) > screen_height)) {
if(VERBOSE) {
printf("Frame is not confined to screen dimension.\n");
}
return 0;
}
if(!(im = gdImageCreate(width, height))) {
return 0;
}
im->interlace = BitSet(buf[8], INTERLACE);
if(!useGlobalColormap) {
if(ReadColorMap(fd, bitPixel, localColorMap)) {
gdImageDestroy(im);
return 0;
}
ReadImage(im, fd, width, height, localColorMap, BitSet(buf[8], INTERLACE), &ZeroDataBlock);
} else {
if(!haveGlobalColormap) {
gdImageDestroy(im);
return 0;
}
ReadImage(im, fd, width, height, ColorMap, BitSet(buf[8], INTERLACE), &ZeroDataBlock);
}
if(Transparent != (-1)) {
gdImageColorTransparent(im, Transparent);
}
goto terminated;
}
terminated:
/* Terminator before any image was declared! */
if(!im) {
return 0;
}
/* Check for open colors at the end, so
* we can reduce colorsTotal and ultimately
* BitsPerPixel */
for(i = im->colorsTotal - 1; i >= 0; i--) {
if(im->open[i]) {
im->colorsTotal--;
} else {
break;
}
}
if(!im->colorsTotal) {
gdImageDestroy(im);
return 0;
}
return im;
}
static int
ReadColorMap(gdIOCtx *fd, int number, unsigned char (*buffer)[256])
{
int i;
unsigned char rgb[3];
for(i = 0; i < number; ++i) {
if(!ReadOK(fd, rgb, sizeof(rgb))) {
return TRUE;
}
buffer[CM_RED][i] = rgb[0];
buffer[CM_GREEN][i] = rgb[1];
buffer[CM_BLUE][i] = rgb[2];
}
return FALSE;
}
static int
DoExtension(gdIOCtx *fd, int label, int *Transparent, int *ZeroDataBlockP)
{
unsigned char buf[256];
switch(label) {
case 0xf9: /* Graphic Control Extension */
memset(buf, 0, 4); /* initialize a few bytes in the case the next function fails */
(void) GetDataBlock(fd, (unsigned char*) buf, ZeroDataBlockP);
#if 0
Gif89.disposal = (buf[0] >> 2) & 0x7;
Gif89.inputFlag = (buf[0] >> 1) & 0x1;
Gif89.delayTime = LM_to_uint(buf[1], buf[2]);
#endif
if((buf[0] & 0x1) != 0) {
*Transparent = buf[3];
}
while(GetDataBlock(fd, (unsigned char*) buf, ZeroDataBlockP) > 0);
return FALSE;
default:
break;
}
while(GetDataBlock(fd, (unsigned char*) buf, ZeroDataBlockP) > 0);
return FALSE;
}
static int
GetDataBlock_(gdIOCtx *fd, unsigned char *buf, int *ZeroDataBlockP)
{
unsigned char count;
if(!ReadOK(fd, &count, 1)) {
return -1;
}
*ZeroDataBlockP = count == 0;
if((count != 0) && (!ReadOK(fd, buf, count))) {
return -1;
}
return count;
}
static int
GetDataBlock(gdIOCtx *fd, unsigned char *buf, int *ZeroDataBlockP)
{
int rv, i;
rv = GetDataBlock_(fd,buf, ZeroDataBlockP);
if(VERBOSE) {
printf("[GetDataBlock returning %d",rv);
if(rv > 0) {
printf(":");
for(i = 0; i < rv; i++) {
printf(" %02x",buf[i]);
}
}
printf("]\n");
}
return rv;
}
static int
GetCode_(gdIOCtx *fd, CODE_STATIC_DATA *scd, int code_size, int flag, int *ZeroDataBlockP)
{
int i, j, ret;
int count;
if(flag) {
scd->curbit = 0;
scd->lastbit = 0;
scd->last_byte = 2;
scd->done = FALSE;
return 0;
}
if((scd->curbit + code_size) >= scd->lastbit) {
if(scd->done) {
if(scd->curbit >= scd->lastbit) {
/* Oh well */
}
return -1;
}
scd->buf[0] = scd->buf[scd->last_byte - 2];
scd->buf[1] = scd->buf[scd->last_byte - 1];
if((count = GetDataBlock(fd, &scd->buf[2], ZeroDataBlockP)) <= 0) {
scd->done = TRUE;
}
scd->last_byte = 2 + count;
scd->curbit = (scd->curbit - scd->lastbit) + 16;
scd->lastbit = (2 + count) * 8;
}
if ((scd->curbit + code_size - 1) >= (CSD_BUF_SIZE * 8)) {
ret = -1;
} else {
ret = 0;
for (i = scd->curbit, j = 0; j < code_size; ++i, ++j) {
ret |= ((scd->buf[i / 8] & (1 << (i % 8))) != 0) << j;
}
}
scd->curbit += code_size;
return ret;
}
static int
GetCode(gdIOCtx *fd, CODE_STATIC_DATA *scd, int code_size, int flag, int *ZeroDataBlockP)
{
int rv;
rv = GetCode_(fd, scd, code_size,flag, ZeroDataBlockP);
if(VERBOSE) {
printf("[GetCode(,%d,%d) returning %d]\n",code_size,flag,rv);
}
return rv;
}
static int
LWZReadByte_(gdIOCtx *fd, LZW_STATIC_DATA *sd, char flag, int input_code_size, int *ZeroDataBlockP)
{
int code, incode, i;
if(flag) {
sd->set_code_size = input_code_size;
sd->code_size = sd->set_code_size + 1;
sd->clear_code = 1 << sd->set_code_size;
sd->end_code = sd->clear_code + 1;
sd->max_code_size = 2 * sd->clear_code;
sd->max_code = sd->clear_code + 2;
GetCode(fd, &sd->scd, 0, TRUE, ZeroDataBlockP);
sd->fresh = TRUE;
for(i = 0; i < sd->clear_code; ++i) {
sd->table[0][i] = 0;
sd->table[1][i] = i;
}
for(; i < (1 << MAX_LWZ_BITS); ++i) {
sd->table[0][i] = sd->table[1][0] = 0;
}
sd->sp = sd->stack;
return 0;
} else if(sd->fresh) {
sd->fresh = FALSE;
do {
sd->firstcode = sd->oldcode =
GetCode(fd, &sd->scd, sd->code_size, FALSE, ZeroDataBlockP);
} while(sd->firstcode == sd->clear_code);
return sd->firstcode;
}
if(sd->sp > sd->stack) {
return *--sd->sp;
}
while((code = GetCode(fd, &sd->scd, sd->code_size, FALSE, ZeroDataBlockP)) >= 0) {
if(code == sd->clear_code) {
for(i = 0; i < sd->clear_code; ++i) {
sd->table[0][i] = 0;
sd->table[1][i] = i;
}
for (; i < (1 << MAX_LWZ_BITS); ++i) {
sd->table[0][i] = sd->table[1][i] = 0;
}
sd->code_size = sd->set_code_size + 1;
sd->max_code_size = 2 * sd->clear_code;
sd->max_code = sd->clear_code + 2;
sd->sp = sd->stack;
sd->firstcode = sd->oldcode =
GetCode(fd, &sd->scd, sd->code_size, FALSE, ZeroDataBlockP);
return sd->firstcode;
} else if(code == sd->end_code) {
int count;
unsigned char buf[260];
if(*ZeroDataBlockP) {
return -2;
}
while((count = GetDataBlock(fd, buf, ZeroDataBlockP)) > 0);
if(count != 0) {
return -2;
}
}
incode = code;
if(sd->sp == (sd->stack + STACK_SIZE)) {
/* Bad compressed data stream */
return -1;
}
if(code >= sd->max_code) {
*sd->sp++ = sd->firstcode;
code = sd->oldcode;
}
while(code >= sd->clear_code) {
if(sd->sp == (sd->stack + STACK_SIZE)) {
/* Bad compressed data stream */
return -1;
}
*sd->sp++ = sd->table[1][code];
if(code == sd->table[0][code]) {
/* Oh well */
}
code = sd->table[0][code];
}
*sd->sp++ = sd->firstcode = sd->table[1][code];
if((code = sd->max_code) < (1 << MAX_LWZ_BITS)) {
sd->table[0][code] = sd->oldcode;
sd->table[1][code] = sd->firstcode;
++sd->max_code;
if((sd->max_code >= sd->max_code_size) && (sd->max_code_size < (1<<MAX_LWZ_BITS))) {
sd->max_code_size *= 2;
++sd->code_size;
}
}
sd->oldcode = incode;
if(sd->sp > sd->stack) {
return *--sd->sp;
}
}
return code;
}
static int
LWZReadByte(gdIOCtx *fd, LZW_STATIC_DATA *sd, char flag, int input_code_size, int *ZeroDataBlockP)
{
int rv;
rv = LWZReadByte_(fd, sd, flag, input_code_size, ZeroDataBlockP);
if(VERBOSE) {
printf("[LWZReadByte(,%d,%d) returning %d]\n",flag,input_code_size,rv);
}
return rv;
}
static void
ReadImage(gdImagePtr im, gdIOCtx *fd, int len, int height, unsigned char (*cmap)[256], int interlace, int *ZeroDataBlockP) /*1.4//, int ignore) */
{
unsigned char c;
int xpos = 0, ypos = 0, pass = 0;
int v, i;
LZW_STATIC_DATA sd;
/* Initialize the Compression routines */
if(!ReadOK(fd, &c, 1)) {
return;
}
if(c > MAX_LWZ_BITS) {
return;
}
/* Stash the color map into the image */
for(i=0; (i < gdMaxColors); i++) {
im->red[i] = cmap[CM_RED][i];
im->green[i] = cmap[CM_GREEN][i];
im->blue[i] = cmap[CM_BLUE][i];
im->open[i] = 1;
}
/* Many (perhaps most) of these colors will remain marked open. */
im->colorsTotal = gdMaxColors;
if(LWZReadByte(fd, &sd, TRUE, c, ZeroDataBlockP) < 0) {
return;
}
/*
** If this is an "uninteresting picture" ignore it.
** REMOVED For 1.4
*/
/*if (ignore) { */
/* while (LWZReadByte(fd, &sd, FALSE, c) >= 0) */
/* ; */
/* return; */
/*} */
while((v = LWZReadByte(fd, &sd, FALSE, c, ZeroDataBlockP)) >= 0 ) {
if(v >= gdMaxColors) {
v = 0;
}
/* This how we recognize which colors are actually used. */
if(im->open[v]) {
im->open[v] = 0;
}
gdImageSetPixel(im, xpos, ypos, v);
++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:
if(LWZReadByte(fd, &sd, FALSE, c, ZeroDataBlockP) >=0) {
/* Ignore extra */
}
}