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XEphem/libip/explodegif.c

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/* explode a raw gif file already in any array of char.
* return 0 if ok, else -1.
* code from fit2gif.tar.gz, author unknown but thanks!
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#define RDSZ 4096 /* bytes per read attempt */
#define True 1
#define False 0
typedef unsigned char byte;
typedef struct { byte *pic; /* image data */
int w, h; /* size */
byte r[256],g[256],b[256]; /* colormap */
} PICINFO;
typedef int boolean;
#define EXTENSION 0x21
#define IMAGESEP 0x2c
#define TRAILER 0x3b
#define INTERLACEMASK 0x40
#define COLORMAPMASK 0x80
static int BitOffset = 0, /* Bit Offset of next code */
XC = 0, YC = 0, /* Output X and Y coords of current pixel */
Pass = 0, /* Used by output routine if interlaced pic */
OutCount = 0, /* Decompressor output 'stack count' */
RWidth, RHeight, /* screen dimensions */
Width, Height, /* image dimensions */
LeftOfs, TopOfs, /* image offset */
BitsPerPixel, /* Bits per pixel, read from GIF header */
ColorMapSize, /* number of colors */
Background, /* background color */
CodeSize, /* Code size, read from GIF header */
InitCodeSize, /* Starting code size, used during Clear */
Code, /* Value returned by ReadCode */
MaxCode, /* limiting value for current code size */
ClearCode, /* GIF clear code */
EOFCode, /* GIF end-of-information code */
CurCode, OldCode, InCode, /* Decompressor variables */
FirstFree, /* First free code, generated per GIF spec */
FreeCode, /* Decompressor,next free slot in hash table */
FinChar, /* Decompressor variable */
BitMask, /* AND mask for data size */
ReadMask, /* Code AND mask for current code size */
Misc; /* miscellaneous bits (interlace, local cmap)*/
static boolean Interlace, HasColormap;
static byte *RawGIF; /* The heap array to hold it, raw */
static byte *Raster; /* The raster data stream, unblocked */
static byte *pic8;
/* The hash table used by the decompressor */
static int Prefix[4096];
static int Suffix[4096];
/* An output array used by the decompressor */
static int OutCode[4097];
static int gif89 = 0;
static char *id87 = "GIF87a";
static char *id89 = "GIF89a";
static int EGApalette[16][3] = {
{0,0,0}, {0,0,128}, {0,128,0}, {0,128,128},
{128,0,0}, {128,0,128}, {128,128,0}, {200,200,200},
{100,100,100}, {100,100,255}, {100,255,100}, {100,255,255},
{255,100,100}, {255,100,255}, {255,255,100}, {255,255,255} };
static int readImage();
static int ReadCode();
static void DoInterlace();
static int gifError();
static int filesize;
static int numcols;
static float normaspect;
static byte dummy;
static byte *dataptr;
#define NEXTBYTE (dummy = *dataptr++)
static char *g_errmsg;
static int LoadGIF();
int
explodeGIF (raw, nraw, wp, hp, pixap, ra, ga, ba, errmsg)
unsigned char *raw; /* raw gif file */
int nraw; /* bytes ingif file */
int *wp, *hp; /* RETURN: image width/height */
unsigned char *pixap[]; /* RETURN: malloced w*h pixels, rgba indices */
unsigned char ra[], ga[], ba[]; /* RETURN: color map, 256 each */
char errmsg[]; /* excuse, if return -1 */
{
PICINFO pi;
dataptr = raw;
filesize = nraw;
g_errmsg = errmsg;
if (LoadGIF (&pi) != 1)
return (-1);
*wp = pi.w;
*hp = pi.h;
*pixap = pi.pic;
memcpy (ra, pi.r, 256);
memcpy (ga, pi.g, 256);
memcpy (ba, pi.b, 256);
return (0);
}
/*****************************/
static int LoadGIF(pinfo)
PICINFO *pinfo;
/*****************************/
{
/* returns '1' if successful */
register byte ch, *origptr;
register int i, block;
int aspect, gotimage;
/* initialize variables */
BitOffset = XC = YC = Pass = OutCount = gotimage = 0;
Raster = pic8 = NULL;
gif89 = 0;
pinfo->pic = (byte *) NULL;
RawGIF = dataptr;
/* the +256's are so we can read truncated GIF files without fear of
segmentation violation */
if (!(Raster = (byte *) calloc(filesize+256,1)))
return( gifError(pinfo, "not enough memory to read gif file") );
origptr = dataptr;
if (strncmp((char *) dataptr, id87, 6)==0) gif89 = 0;
else if (strncmp((char *) dataptr, id89, 6)==0) gif89 = 1;
else return( gifError(pinfo, "not a GIF file"));
dataptr += 6;
/* Get variables from the GIF screen descriptor */
ch = NEXTBYTE;
RWidth = ch + 0x100 * NEXTBYTE; /* screen dimensions... not used. */
ch = NEXTBYTE;
RHeight = ch + 0x100 * NEXTBYTE;
ch = NEXTBYTE;
HasColormap = ((ch & COLORMAPMASK) ? True : False);
BitsPerPixel = (ch & 7) + 1;
numcols = ColorMapSize = 1 << BitsPerPixel;
BitMask = ColorMapSize - 1;
Background = NEXTBYTE; /* background color... not used. */
aspect = NEXTBYTE;
if (aspect) {
if (!gif89) return(gifError(pinfo,"corrupt GIF file (screen descriptor)"));
else normaspect = (float)((aspect + 15) / 64.0); /* gif89 aspect ratio */
}
/* Read in global colormap. */
if (HasColormap) {
for (i=0; i<ColorMapSize; i++) {
pinfo->r[i] = NEXTBYTE;
pinfo->g[i] = NEXTBYTE;
pinfo->b[i] = NEXTBYTE;
}
/* fill out with last color to avoid garbage clobbering xephem colormap.
* from Jean-Etienne.LAMIAUD@tcc.thomson-csf.com
*/
for( ; i < 256; i++ ) {
pinfo->r[i] = pinfo->r[ColorMapSize-1];
pinfo->g[i] = pinfo->g[ColorMapSize-1];
pinfo->b[i] = pinfo->b[ColorMapSize-1];
}
} else { /* no colormap in GIF file */
/* put std EGA palette (repeated 16 times) into colormap, for lack of
anything better to do */
for (i=0; i<256; i++) {
pinfo->r[i] = EGApalette[i&15][0];
pinfo->g[i] = EGApalette[i&15][1];
pinfo->b[i] = EGApalette[i&15][2];
}
}
/* possible things at this point are:
* an application extension block
* a comment extension block
* an (optional) graphic control extension block
* followed by either an image
* or a plaintext extension
*/
while (1) {
block = NEXTBYTE;
if (block == EXTENSION) { /* parse extension blocks */
int i, fn, blocksize, aspnum, aspden;
/* read extension block */
fn = NEXTBYTE;
if (fn == 'R') { /* GIF87 aspect extension */
int sbsize;
blocksize = NEXTBYTE;
if (blocksize == 2) {
aspnum = NEXTBYTE;
aspden = NEXTBYTE;
if (aspden>0 && aspnum>0)
normaspect = (float) aspnum / (float) aspden;
else { normaspect = 1.0; aspnum = aspden = 1; }
}
else {
for (i=0; i<blocksize; i++) NEXTBYTE;
}
while ((sbsize=NEXTBYTE)>0) { /* eat any following data subblocks */
for (i=0; i<sbsize; i++) NEXTBYTE;
}
}
else if (fn == 0xFE) { /* Comment Extension */
int ch, j, sbsize, cmtlen;
byte *ptr1;
cmtlen = 0;
ptr1 = dataptr; /* remember start of comments */
/* figure out length of comment */
do {
sbsize = NEXTBYTE;
cmtlen += sbsize;
for (j=0; j<sbsize; j++) ch = NEXTBYTE;
} while (sbsize);
if (cmtlen>0) {
do {
sbsize = (*ptr1++);
for (j=0; j<sbsize; j++, ptr1++) continue;
} while (sbsize);
} /* if cmtlen>0 */
}
else if (fn == 0x01) { /* PlainText Extension */
int j,sbsize,ch;
int tgLeft, tgTop, tgWidth, tgHeight, cWidth, cHeight, fg, bg;
sbsize = NEXTBYTE;
tgLeft = NEXTBYTE; tgLeft += (NEXTBYTE)<<8;
tgTop = NEXTBYTE; tgTop += (NEXTBYTE)<<8;
tgWidth = NEXTBYTE; tgWidth += (NEXTBYTE)<<8;
tgHeight = NEXTBYTE; tgHeight += (NEXTBYTE)<<8;
cWidth = NEXTBYTE;
cHeight = NEXTBYTE;
fg = NEXTBYTE;
bg = NEXTBYTE;
i=12;
for ( ; i<sbsize; i++) NEXTBYTE; /* read rest of first subblock*/
/* read (and ignore) data sub-blocks */
do {
j = 0;
sbsize = NEXTBYTE;
while (j<sbsize) {
ch = NEXTBYTE; j++;
}
} while (sbsize);
}
else if (fn == 0xF9) { /* Graphic Control Extension */
int j, sbsize;
/* read (and ignore) data sub-blocks */
do {
j = 0; sbsize = NEXTBYTE;
while (j<sbsize) { NEXTBYTE; j++; }
} while (sbsize);
}
else if (fn == 0xFF) { /* Application Extension */
int j, sbsize;
/* read (and ignore) data sub-blocks */
do {
j = 0; sbsize = NEXTBYTE;
while (j<sbsize) { NEXTBYTE; j++; }
} while (sbsize);
}
else { /* unknown extension */
int j, sbsize;
/* read (and ignore) data sub-blocks */
do {
j = 0; sbsize = NEXTBYTE;
while (j<sbsize) { NEXTBYTE; j++; }
} while (sbsize);
}
}
else if (block == IMAGESEP) {
if (gotimage) { /* just skip over remaining images */
int i,misc,ch,ch1;
/* skip image header */
NEXTBYTE; NEXTBYTE; /* left position */
NEXTBYTE; NEXTBYTE; /* top position */
NEXTBYTE; NEXTBYTE; /* width */
NEXTBYTE; NEXTBYTE; /* height */
misc = NEXTBYTE; /* misc. bits */
if (misc & 0x80) { /* image has local colormap. skip it */
for (i=0; i< 1 << ((misc&7)+1); i++) {
NEXTBYTE; NEXTBYTE; NEXTBYTE;
}
}
NEXTBYTE; /* minimum code size */
/* skip image data sub-blocks */
do {
ch = ch1 = NEXTBYTE;
while (ch--) NEXTBYTE;
if ((dataptr - RawGIF) > filesize) break; /* EOF */
} while(ch1);
}
else if (readImage(pinfo)) gotimage = 1;
}
else if (block == TRAILER) { /* stop reading blocks */
break;
}
else { /* unknown block type */
char str[128];
/* don't mention bad block if file was trunc'd, as it's all bogus */
if ((dataptr - origptr) < filesize) {
sprintf(str, "Unknown block type (0x%02x) at offset 0x%x",
block, (unsigned int)(dataptr - origptr) - 1);
if (!gotimage) return gifError(pinfo, str);
else return( gifError(pinfo, str));
}
break;
}
}
free(Raster); Raster = NULL;
if (!gotimage)
return( gifError(pinfo, "no image data found in GIF file") );
return 1;
}
/********************************************/
static int readImage(pinfo)
PICINFO *pinfo;
{
register byte ch, ch1, *ptr1, *picptr;
int i, npixels, maxpixels;
npixels = maxpixels = 0;
/* read in values from the image descriptor */
ch = NEXTBYTE;
LeftOfs = ch + 0x100 * NEXTBYTE;
ch = NEXTBYTE;
TopOfs = ch + 0x100 * NEXTBYTE;
ch = NEXTBYTE;
Width = ch + 0x100 * NEXTBYTE;
ch = NEXTBYTE;
Height = ch + 0x100 * NEXTBYTE;
Misc = NEXTBYTE;
Interlace = ((Misc & INTERLACEMASK) ? True : False);
if (Misc & 0x80) {
for (i=0; i< 1 << ((Misc&7)+1); i++) {
pinfo->r[i] = NEXTBYTE;
pinfo->g[i] = NEXTBYTE;
pinfo->b[i] = NEXTBYTE;
}
}
if (!HasColormap && !(Misc&0x80)) {
/* no global or local colormap */
return (gifError (pinfo, "No colormap in this GIF file."));
}
/* Start reading the raster data. First we get the intial code size
* and compute decompressor constant values, based on this code size.
*/
CodeSize = NEXTBYTE;
ClearCode = (1 << CodeSize);
EOFCode = ClearCode + 1;
FreeCode = FirstFree = ClearCode + 2;
/* The GIF spec has it that the code size is the code size used to
* compute the above values is the code size given in the file, but the
* code size used in compression/decompression is the code size given in
* the file plus one. (thus the ++).
*/
CodeSize++;
InitCodeSize = CodeSize;
MaxCode = (1 << CodeSize);
ReadMask = MaxCode - 1;
/* UNBLOCK:
* Read the raster data. Here we just transpose it from the GIF array
* to the Raster array, turning it from a series of blocks into one long
* data stream, which makes life much easier for ReadCode().
*/
ptr1 = Raster;
do {
ch = ch1 = NEXTBYTE;
while (ch--) { *ptr1 = NEXTBYTE; ptr1++; }
if ((dataptr - RawGIF) > filesize) {
break;
}
} while(ch1);
/* Allocate the 'pic' */
maxpixels = Width*Height;
picptr = pic8 = (byte *) malloc(maxpixels);
if (!pic8) return( gifError(pinfo, "couldn't malloc 'pic8'") );
/* Decompress the file, continuing until you see the GIF EOF code.
* One obvious enhancement is to add checking for corrupt files here.
*/
Code = ReadCode();
while (Code != EOFCode) {
/* Clear code sets everything back to its initial value, then reads the
* immediately subsequent code as uncompressed data.
*/
if (Code == ClearCode) {
CodeSize = InitCodeSize;
MaxCode = (1 << CodeSize);
ReadMask = MaxCode - 1;
FreeCode = FirstFree;
Code = ReadCode();
CurCode = OldCode = Code;
FinChar = CurCode & BitMask;
if (!Interlace) *picptr++ = FinChar;
else DoInterlace(FinChar);
npixels++;
}
else {
/* If not a clear code, must be data: save same as CurCode and InCode */
/* if we're at maxcode and didn't get a clear, stop loading */
if (FreeCode>=4096) { /* printf("freecode blew up\n"); */
break; }
CurCode = InCode = Code;
/* If greater or equal to FreeCode, not in the hash table yet;
* repeat the last character decoded
*/
if (CurCode >= FreeCode) {
CurCode = OldCode;
if (OutCount > 4096) { /* printf("outcount1 blew up\n"); */ break; }
OutCode[OutCount++] = FinChar;
}
/* Unless this code is raw data, pursue the chain pointed to by CurCode
* through the hash table to its end; each code in the chain puts its
* associated output code on the output queue.
*/
while (CurCode > BitMask) {
if (OutCount > 4096) break; /* corrupt file */
OutCode[OutCount++] = Suffix[CurCode];
CurCode = Prefix[CurCode];
}
if (OutCount > 4096) { /* printf("outcount blew up\n"); */ break; }
/* The last code in the chain is treated as raw data. */
FinChar = CurCode & BitMask;
OutCode[OutCount++] = FinChar;
/* Now we put the data out to the Output routine.
* It's been stacked LIFO, so deal with it that way...
*/
/* safety thing: prevent exceeding range of 'pic8' */
if (npixels + OutCount > maxpixels) OutCount = maxpixels-npixels;
npixels += OutCount;
if (!Interlace) for (i=OutCount-1; i>=0; i--) *picptr++ = OutCode[i];
else for (i=OutCount-1; i>=0; i--) DoInterlace(OutCode[i]);
OutCount = 0;
/* Build the hash table on-the-fly. No table is stored in the file. */
Prefix[FreeCode] = OldCode;
Suffix[FreeCode] = FinChar;
OldCode = InCode;
/* Point to the next slot in the table. If we exceed the current
* MaxCode value, increment the code size unless it's already 12. If it
* is, do nothing: the next code decompressed better be CLEAR
*/
FreeCode++;
if (FreeCode >= MaxCode) {
if (CodeSize < 12) {
CodeSize++;
MaxCode *= 2;
ReadMask = (1 << CodeSize) - 1;
}
}
}
Code = ReadCode();
if (npixels >= maxpixels) break;
}
if (npixels != maxpixels) {
if (!Interlace)
memset(pic8+npixels, 0, maxpixels-npixels); /* clear to EOBuffer */
}
/* fill in the PICINFO structure */
pinfo->pic = pic8;
pinfo->w = Width;
pinfo->h = Height;
return 1;
}
/* Fetch the next code from the raster data stream. The codes can be
* any length from 3 to 12 bits, packed into 8-bit bytes, so we have to
* maintain our location in the Raster array as a BIT Offset. We compute
* the byte Offset into the raster array by dividing this by 8, pick up
* three bytes, compute the bit Offset into our 24-bit chunk, shift to
* bring the desired code to the bottom, then mask it off and return it.
*/
static int ReadCode()
{
int RawCode, ByteOffset;
ByteOffset = BitOffset / 8;
RawCode = Raster[ByteOffset] + (Raster[ByteOffset + 1] << 8);
if (CodeSize >= 8)
RawCode += ( ((int) Raster[ByteOffset + 2]) << 16);
RawCode >>= (BitOffset % 8);
BitOffset += CodeSize;
return(RawCode & ReadMask);
}
/***************************/
static void DoInterlace(Index)
byte Index;
{
static byte *ptr = NULL;
static int oldYC = -1;
if (oldYC != YC) { ptr = pic8 + YC * Width; oldYC = YC; }
if (YC<Height)
*ptr++ = Index;
/* Update the X-coordinate, and if it overflows, update the Y-coordinate */
if (++XC == Width) {
/* deal with the interlace as described in the GIF
* spec. Put the decoded scan line out to the screen if we haven't gone
* past the bottom of it
*/
XC = 0;
switch (Pass) {
case 0:
YC += 8;
if (YC >= Height) { Pass++; YC = 4; }
break;
case 1:
YC += 8;
if (YC >= Height) { Pass++; YC = 2; }
break;
case 2:
YC += 4;
if (YC >= Height) { Pass++; YC = 1; }
break;
case 3:
YC += 2; break;
default:
break;
}
}
}
/*****************************/
static int gifError(pinfo, st)
PICINFO *pinfo;
char *st;
{
strcpy (g_errmsg, st);
if (Raster != NULL) free(Raster);
if (pinfo->pic) free(pinfo->pic);
if (pic8 && pic8 != pinfo->pic) free(pic8);
pinfo->pic = (byte *) NULL;
return 0;
}
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