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cgal/CGALimageIO/src/CGALImageIO/gif.cpp

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// Copyright (c) 2005-2008 ASCLEPIOS Project, INRIA Sophia-Antipolis (France)
// All rights reserved.
//
// This file is part of the ImageIO Library, and as been adapted for
// CGAL (www.cgal.org).
// You can redistribute it and/or modify it under the terms of the
// GNU Lesser General Public License as published by the Free Software Foundation;
// either version 3 of the License, or (at your option) any later version.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// These files are provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
//
// Author(s) : ASCLEPIOS Project (INRIA Sophia-Antipolis), Laurent Rineau
#include <string.h>
#include "gif.h"
#ifdef WIN32
#include <io.h>
#endif
/** Magic header for GIF files */
#define GIF_MAGIC "GIF8"
typedef unsigned char byte;
#define TRUE 1
#define FALSE 0
#define NEXTBYTE (*ptr++)
#define EXTENSION 0x21
#define IMAGESEP 0x2c
#define TRAILER 0x3b
#define INTERLACEMASK 0x40
#define COLORMAPMASK 0x80
#define DEBUG 0
FILE *fp;
int gif89 = 0;
const char *id87 = "GIF87a";
const 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 ReadCode();
static void DoInterlace(byte);
static int GifError(const char *);
byte *Raster; /* The raster data stream, unblocked */
byte *RawGIF;
byte *r,*g,*b; /* The colormap */
int BitOffset = 0, /* Bit Offset of next code */
XC = 0, YC = 0, /* Output X and Y coords of current pixel */
CodeSize, /* Code size, read from GIF header */
ReadMask, /* Code AND mask for current code size */
Pass = 0, /* Used by output routine if interlaced pic */
Width, Height; /* image dimensions */
unsigned char *org, *buf;
int testGifHeader(char *magic,const char *) {
if (!strcmp(magic, GIF_MAGIC))
return 0;
else
return -1;
}
PTRIMAGE_FORMAT createGifFormat() {
PTRIMAGE_FORMAT f=(PTRIMAGE_FORMAT) ImageIO_alloc(sizeof(IMAGE_FORMAT));
f->testImageFormat=&testGifHeader;
f->readImageHeader=&readGifImage;
f->writeImage=0;
strcpy(f->fileExtension,".gif");
strcpy(f->realName,"Gif");
return f;
}
void use(int) {} // warning killer
/*****************************/
int readGifImage(const char *name,_image *im) {
register byte ch, ch1;
register byte *ptr, *ptr1;
register int i, block;
int npixels, maxpixels, aspect, filesize;
float normaspect;
int OutCount = 0, /* Decompressor output 'stack count' */
RWidth, RHeight, /* screen dimensions */
/*LeftOfs, TopOfs, image offset */
BitsPerPixel, /* Bits per pixel, read from GIF header */
ColorMapSize, /* number of colors */
Background, /* background color */
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=0, InCode, /* Decompressor variables */
FirstFree, /* First free code, generated per GIF spec */
FreeCode, /* Decompressor,next free slot in hash table */
FinChar=0, /* Decompressor variable */
BitMask, /* AND mask for data size */
Misc; /* miscellaneous bits (interlace, local cmap)*/
int Interlace, HasColormap;
/* not used
*/
/* char header[10]; */
/* The hash table used by the decompressor */
int Prefix[4096];
int Suffix[4096];
/* An output array used by the decompressor */
int OutCode[4097];
/* initialize variables */
BitOffset = XC = YC = Pass = OutCount = npixels = maxpixels = 0;
RawGIF = Raster = NULL;
gif89 = 0;
#ifdef WIN32
fp = fopen(name,"rb");
#else
fp = fopen(name,"r");
#endif
fp = fopen(name,"rb");
if (!fp) {
return(GifError("could not open a GIF file"));
}
/* find the size of the file */
fseek(fp, 0L, 2);
filesize = ftell(fp);
fseek(fp, 0L, 0);
/* the +256's are so we can read truncated GIF files without fear of
segmentation violation */
if (!(ptr = RawGIF = (byte *) ImageIO_alloc(filesize+256)))
return( GifError("not enough memory to read gif file") );
if (!(Raster = (byte *) ImageIO_alloc(filesize+256)))
return( GifError("not enough memory to read gif file") );
if (fread(ptr, filesize, 1, fp) != 1)
return( GifError("GIF data read failed") );
if (strncmp((char *) ptr, id87, 6)==0) gif89 = 0;
else if (strncmp((char *) ptr, id89, 6)==0) gif89 = 1;
else return( GifError("not a GIF file"));
ptr += 6;
/* Get variables from the GIF screen descriptor */
ch = NEXTBYTE;
RWidth = ch + 0x100 * NEXTBYTE; /* screen dimensions... not used. */
ch = NEXTBYTE;
RHeight = ch + 0x100 * NEXTBYTE;
use(RWidth);
use(RHeight);
ch = NEXTBYTE;
HasColormap = ((ch & COLORMAPMASK) ? TRUE : FALSE);
BitsPerPixel = (ch & 7) + 1;
ColorMapSize = 1 << BitsPerPixel;
BitMask = ColorMapSize - 1;
Background = NEXTBYTE; /* background color... not used. */
use(Background);
aspect = NEXTBYTE;
if (aspect) {
if (!gif89) return(GifError("corrupt GIF file (screen descriptor)"));
else normaspect = (float) (aspect + 15) / 64.0f; /* gif89 aspect ratio */
if (DEBUG) fprintf(stderr,"GIF89 aspect = %f\n", normaspect);
}
/* Read in global colormap. */
if (HasColormap)
{
r = (byte *) ImageIO_alloc(ColorMapSize * sizeof(byte));
g = (byte *) ImageIO_alloc(ColorMapSize * sizeof(byte));
b = (byte *) ImageIO_alloc(ColorMapSize * sizeof(byte));
for (i = 0; i < ColorMapSize; i++) {
r[i] = NEXTBYTE;
g[i] = NEXTBYTE;
b[i] = NEXTBYTE;
}
}
else {
/* no colormap in GIF file */
/* put std EGA palette (repeated 16 times) into colormap, for lack of
anything better to do */
ColorMapSize = 256;
r = (byte *) ImageIO_alloc(256 * sizeof(byte));
g = (byte *) ImageIO_alloc(256 * sizeof(byte));
b = (byte *) ImageIO_alloc(256 * sizeof(byte));
for (i = 0; i < 256; i++) {
r[i] = EGApalette[i&15][0];
g[i] = EGApalette[i&15][1];
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 (DEBUG) fprintf(stderr,"GIF extension type 0x%02x\n", fn);
if (fn == 'R') { /* GIF87 aspect extension */
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; }
if (DEBUG) fprintf(stderr,"GIF87 aspect extension: %d:%d = %f\n\n",
aspnum, aspden,normaspect);
}
else {
for (i=0; i<blocksize; i++) (void)NEXTBYTE;
}
}
else if (fn == 0xFE) { /* Comment Extension. just eat it */
int ch, j, sbsize;
if (DEBUG) fprintf(stderr,"Comment extension: ");
/* read (and ignore) data sub-blocks */
do {
j = 0; sbsize = NEXTBYTE;
while (j<sbsize) {
ch = NEXTBYTE; j++;
if (DEBUG) fprintf(stderr,"%c", ch);
}
} while (sbsize);
if (DEBUG) fprintf(stderr,"\n\n");
}
else if (fn == 0x01) { /* PlainText Extension */
int j,sbsize,ch;
int tgLeft, tgTop, tgWidth, tgHeight, cWidth, cHeight, fg, bg;
/* SetISTR(ISTR_WARNING,
"PlainText extension found in GIF file. Ignored.");*/
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++) (void)NEXTBYTE; /* read rest of first subblock */
if (DEBUG) fprintf(stderr,
"PlainText: tgrid=%d,%d %dx%d cell=%dx%d col=%d,%d\n",
tgLeft, tgTop, tgWidth, tgHeight, cWidth, cHeight,
fg, bg);
/* read (and ignore) data sub-blocks */
do {
j = 0;
sbsize = NEXTBYTE;
while (j<sbsize) {
ch = NEXTBYTE; j++;
if (DEBUG) fprintf(stderr,"%c", ch);
}
} while (sbsize);
if (DEBUG) fprintf(stderr,"\n\n");
}
else if (fn == 0xF9) { /* Graphic Control Extension */
int j, sbsize;
if (DEBUG) fprintf(stderr,"Graphic Control extension\n\n");
/* SetISTR(ISTR_WARNING,
"Graphic Control Extension in GIF file. Ignored.");*/
/* read (and ignore) data sub-blocks */
do {
j = 0; sbsize = NEXTBYTE;
while (j<sbsize) { (void)NEXTBYTE; j++; }
} while (sbsize);
}
else { /* unknown extension */
int j, sbsize;
if (DEBUG) fprintf(stderr,"unknown GIF extension 0x%02x\n\n", fn);
/* SetISTR(ISTR_WARNING,
"Unknown extension 0x%02x in GIF file. Ignored.",fn);*/
/* read (and ignore) data sub-blocks */
do {
j = 0; sbsize = NEXTBYTE;
while (j<sbsize) { (void)NEXTBYTE; j++; }
} while (sbsize);
}
}
else if (block == IMAGESEP) break; /* read an image */
else if (block == TRAILER) {
return( GifError("no image data found in GIF file") );
}
else return (GifError("Unknown block type found in file."));
}
/* read in values from the image descriptor */
ch = NEXTBYTE;
/* LeftOfs = ch + 0x100 * NEXTBYTE;*/
ch = NEXTBYTE;
/* TopOfs = ch + 0x100 * NEXTBYTE; */
ch = NEXTBYTE;
ch = 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++) {
r[i] = NEXTBYTE;
g[i] = NEXTBYTE;
b[i] = NEXTBYTE;
}
}
if (!HasColormap && !(Misc&0x80)) {
/* no global or local colormap */
/* SetISTR(ISTR_WARNING,
"No colormap in this GIF file. Assuming EGA colors.");*/
}
/* Start reading the raster data. First we get the intial code size
* and compute decompressor constant values, based on this code size.
*/
/* SetISTR(ISTR_FORMAT, "GIF%s, %d bits per pixel, %sinterlaced. (%d bytes)",
(gif89) ? "89" : "87", BitsPerPixel,
Interlace ? "" : "non-", filesize);*/
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 ((ptr - RawGIF) > filesize) {
/* SetISTR(ISTR_WARNING,
"This GIF file seems to be truncated. Winging it.");*/
break;
}
} while(ch1);
ImageIO_free(RawGIF); RawGIF = NULL;
if (DEBUG) {
fprintf(stderr,"xv: LoadGIF() - picture is %dx%d, %d bits, %sinterlaced\n",
Width, Height, BitsPerPixel, Interlace ? "" : "non-");
}
/* Allocate the 'pic' */
maxpixels = Width*Height;
im->xdim = Width;
im->ydim = Height;
im->zdim = 1;
im->vdim = 3;
im->wdim = 1;
im->wordKind = WK_FIXED;
im->sign = SGN_UNSIGNED;
im->data = ImageIO_alloc(Width * Height * 3);
org = buf = (unsigned char *) im->data;
if (!org)
return( GifError("not enough memory for image buffer") );
/* 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) {
*buf++ = r[FinChar];
*buf++ = g[FinChar];
*buf++ = b[FinChar];
}
else DoInterlace((byte)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) {
fprintf(stderr,"outcount2 blew up\n"); 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 'pic' */
if (npixels + OutCount > maxpixels) OutCount = maxpixels-npixels;
npixels += OutCount;
if (!Interlace) for (i=OutCount-1; i>=0; i--) {
*buf++ = r[OutCode[i]];
*buf++ = g[OutCode[i]];
*buf++ = b[OutCode[i]];
}
else for (i=OutCount-1; i>=0; i--) DoInterlace((byte)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;
}
ImageIO_free(Raster); Raster = NULL;
if (npixels != maxpixels) {
/* SetISTR(ISTR_WARNING,"This GIF file seems to be truncated. Winging it.");*/
if (!Interlace)
memset(buf, 0, 3*(maxpixels-npixels)); /* clear to EOBuffer */
}
/* SetDirRButt(F_FORMAT, F_GIF);
SetDirRButt(F_COLORS, F_FULLCOLOR);*/
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(byte Index) {
static byte *ptr = NULL;
static int oldYC = -1;
if (oldYC != YC) {
ptr = org + 3 * YC * Width;
oldYC = YC;
}
if (YC < Height) {
*ptr++ = r[Index];
*ptr++ = g[Index];
*ptr++ = b[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(const char *st) {
fprintf(stderr,"readGifImage: error: %s\n",st);
if (RawGIF != NULL) ImageIO_free(RawGIF);
if (Raster != NULL) ImageIO_free(Raster);
return -1;
}
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