ref: 6e68d605ee9903626b64221607a4577c2c92c6bc
dir: /DoConfig/fltk/src/Fl_GIF_Image.cxx/
//
// "$Id$"
//
// Fl_GIF_Image routines.
//
// Copyright 1997-2019 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
// file is missing or damaged, see the license at:
//
// http://www.fltk.org/COPYING.php
//
// Please report all bugs and problems on the following page:
//
// http://www.fltk.org/str.php
//
// Contents:
//
//
//
// Reference: GIF89a Specification (links valid as of Jan 05, 2019):
//
// "GRAPHICS INTERCHANGE FORMAT(sm), Version 89a" (authoritative):
// https://www.w3.org/Graphics/GIF/spec-gif89a.txt
//
// HTML version (non-authoritative):
// https://web.archive.org/web/20160304075538/http://qalle.net/gif89a.php
//
//
// Include necessary header files...
//
#include <FL/Fl.H>
#include <FL/Fl_GIF_Image.H>
#include <stdio.h>
#include <stdlib.h>
#include <FL/fl_utf8.h>
#include "flstring.h"
// Read a .gif file and convert it to a "xpm" format (actually my
// modified one with compressed colormaps).
// Extensively modified from original code for gif2ras by
// Patrick J. Naughton of Sun Microsystems. The original
// copyright notice follows:
/* gif2ras.c - Converts from a Compuserve GIF (tm) image to a Sun Raster image.
*
* Copyright (c) 1988 by Patrick J. Naughton
*
* Author: Patrick J. Naughton
* naughton@wind.sun.com
*
* 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 file is provided AS IS with no warranties of any kind. The author
* shall have no liability with respect to the infringement of copyrights,
* trade secrets or any patents by this file or any part thereof. In no
* event will the author be liable for any lost revenue or profits or
* other special, indirect and consequential damages.
*
* Comments and additions should be sent to the author:
*
* Patrick J. Naughton
* Sun Microsystems, Inc.
* 2550 Garcia Ave, MS 14-40
* Mountain View, CA 94043
* (415) 336-1080
*/
typedef unsigned char uchar;
#define NEXTBYTE (uchar)getc(GifFile)
#define GETSHORT(var) var = NEXTBYTE; var += NEXTBYTE << 8
/**
The constructor loads the named GIF image.
The destructor frees all memory and server resources that are used by
the image.
Use Fl_Image::fail() to check if Fl_GIF_Image failed to load. fail() returns
ERR_FILE_ACCESS if the file could not be opened or read, ERR_FORMAT if the
GIF format could not be decoded, and ERR_NO_IMAGE if the image could not
be loaded for another reason.
*/
Fl_GIF_Image::Fl_GIF_Image(const char *infname) : Fl_Pixmap((char *const*)0) {
FILE *GifFile; // File to read
char **new_data; // Data array
if ((GifFile = fl_fopen(infname, "rb")) == NULL) {
Fl::error("Fl_GIF_Image: Unable to open %s!", infname);
ld(ERR_FILE_ACCESS);
return;
}
{char b[6];
if (fread(b,1,6,GifFile)<6) {
fclose(GifFile);
ld(ERR_FILE_ACCESS);
return; /* quit on eof */
}
if (b[0]!='G' || b[1]!='I' || b[2] != 'F') {
fclose(GifFile);
Fl::error("Fl_GIF_Image: %s is not a GIF file.\n", infname);
ld(ERR_FORMAT);
return;
}
if (b[3]!='8' || b[4]>'9' || b[5]!= 'a')
Fl::warning("%s is version %c%c%c.",infname,b[3],b[4],b[5]);
}
int Width; GETSHORT(Width);
int Height; GETSHORT(Height);
uchar ch = NEXTBYTE;
char HasColormap = ((ch & 0x80) != 0);
int BitsPerPixel = (ch & 7) + 1;
int ColorMapSize;
if (HasColormap) {
ColorMapSize = 2 << (ch & 7);
} else {
ColorMapSize = 0;
}
// int OriginalResolution = ((ch>>4)&7)+1;
// int SortedTable = (ch&8)!=0;
ch = NEXTBYTE; // Background Color index
ch = NEXTBYTE; // Aspect ratio is N/64
// Read in global colormap:
uchar transparent_pixel = 0;
char has_transparent = 0;
uchar Red[256], Green[256], Blue[256]; /* color map */
if (HasColormap) {
for (int i=0; i < ColorMapSize; i++) {
Red[i] = NEXTBYTE;
Green[i] = NEXTBYTE;
Blue[i] = NEXTBYTE;
}
}
int CodeSize; /* Code size, init from GIF header, increases... */
char Interlace;
for (;;) {
int i = NEXTBYTE;
if (i<0) {
fclose(GifFile);
Fl::error("Fl_GIF_Image: %s - unexpected EOF",infname);
w(0); h(0); d(0); ld(ERR_FORMAT);
return;
}
int blocklen;
// if (i == 0x3B) return 0; eof code
if (i == 0x21) { // a "gif extension"
ch = NEXTBYTE;
blocklen = NEXTBYTE;
if (ch==0xF9 && blocklen==4) { // Netscape animation extension
char bits;
bits = NEXTBYTE;
getc(GifFile); getc(GifFile); // GETSHORT(delay);
transparent_pixel = NEXTBYTE;
if (bits & 1) has_transparent = 1;
blocklen = NEXTBYTE;
} else if (ch == 0xFF) { // Netscape repeat count
;
} else if (ch != 0xFE) { //Gif Comment
Fl::warning("%s: unknown gif extension 0x%02x.", infname, ch);
}
} else if (i == 0x2c) { // an image
ch = NEXTBYTE; ch = NEXTBYTE; // GETSHORT(x_position);
ch = NEXTBYTE; ch = NEXTBYTE; // GETSHORT(y_position);
GETSHORT(Width);
GETSHORT(Height);
ch = NEXTBYTE;
Interlace = ((ch & 0x40) != 0);
if (ch & 0x80) { // image has local color table
BitsPerPixel = (ch & 7) + 1;
ColorMapSize = 2 << (ch & 7);
for (i=0; i < ColorMapSize; i++) {
Red[i] = NEXTBYTE;
Green[i] = NEXTBYTE;
Blue[i] = NEXTBYTE;
}
}
CodeSize = NEXTBYTE+1;
break; // okay, this is the image we want
} else {
Fl::warning("%s: unknown gif code 0x%02x", infname, i);
blocklen = 0;
}
// skip the data:
while (blocklen>0) {while (blocklen--) {ch = NEXTBYTE;} blocklen=NEXTBYTE;}
}
if (BitsPerPixel >= CodeSize)
{
// Workaround for broken GIF files...
BitsPerPixel = CodeSize - 1;
ColorMapSize = 1 << BitsPerPixel;
}
// Fix images w/o color table. The standard allows this and lets the
// decoder choose a default color table. The standard recommends the
// first two color table entries should be black and white.
if (ColorMapSize == 0) { // no global and no local color table
Fl::warning("%s does not have a color table, using default.\n", infname);
BitsPerPixel = CodeSize - 1;
ColorMapSize = 1 << BitsPerPixel;
Red[0] = Green[0] = Blue[0] = 0; // black
Red[1] = Green[1] = Blue[1] = 255; // white
for (int i = 2; i < ColorMapSize; i++) {
Red[i] = Green[i] = Blue[i] = (uchar)(255 * i / (ColorMapSize - 1));
}
#if (0)
// fill color table to maximum size
for (int i = ColorMapSize; i < 256; i++) {
Red[i] = Green[i] = Blue[i] = 0; // black
}
#endif
}
uchar *Image = new uchar[Width*Height];
int YC = 0, Pass = 0; /* Used to de-interlace the picture */
uchar *p = Image;
uchar *eol = p+Width;
int InitCodeSize = CodeSize;
int ClearCode = (1 << (CodeSize-1));
int EOFCode = ClearCode + 1;
int FirstFree = ClearCode + 2;
int FinChar = 0;
int ReadMask = (1<<CodeSize) - 1;
int FreeCode = FirstFree;
int OldCode = ClearCode;
// tables used by LZW decompresser:
short int Prefix[4096];
uchar Suffix[4096];
int blocklen = NEXTBYTE;
uchar thisbyte = NEXTBYTE; blocklen--;
int frombit = 0;
for (;;) {
/* 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 as a pointer and a bit offset.
* In addition, gif adds totally useless and annoying block counts
* that must be correctly skipped over. */
int CurCode = thisbyte;
if (frombit+CodeSize > 7) {
if (blocklen <= 0) {
blocklen = NEXTBYTE;
if (blocklen <= 0) break;
}
thisbyte = NEXTBYTE; blocklen--;
CurCode |= thisbyte<<8;
}
if (frombit+CodeSize > 15) {
if (blocklen <= 0) {
blocklen = NEXTBYTE;
if (blocklen <= 0) break;
}
thisbyte = NEXTBYTE; blocklen--;
CurCode |= thisbyte<<16;
}
CurCode = (CurCode>>frombit)&ReadMask;
frombit = (frombit+CodeSize)%8;
if (CurCode == ClearCode) {
CodeSize = InitCodeSize;
ReadMask = (1<<CodeSize) - 1;
FreeCode = FirstFree;
OldCode = ClearCode;
continue;
}
if (CurCode == EOFCode) break;
uchar OutCode[1025]; // temporary array for reversing codes
uchar *tp = OutCode;
int i;
if (CurCode < FreeCode) i = CurCode;
else if (CurCode == FreeCode) {*tp++ = (uchar)FinChar; i = OldCode;}
else {Fl::error("Fl_GIF_Image: %s - LZW Barf!", infname); break;}
while (i >= ColorMapSize) {*tp++ = Suffix[i]; i = Prefix[i];}
*tp++ = FinChar = i;
do {
*p++ = *--tp;
if (p >= eol) {
if (!Interlace) YC++;
else 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;
}
if (YC>=Height) YC=0; /* cheap bug fix when excess data */
p = Image + YC*Width;
eol = p+Width;
}
} while (tp > OutCode);
if (OldCode != ClearCode) {
Prefix[FreeCode] = (short)OldCode;
Suffix[FreeCode] = FinChar;
FreeCode++;
if (FreeCode > ReadMask) {
if (CodeSize < 12) {
CodeSize++;
ReadMask = (1 << CodeSize) - 1;
}
else FreeCode--;
}
}
OldCode = CurCode;
}
// We are done reading the file, now convert to xpm:
// allocate line pointer arrays:
w(Width);
h(Height);
d(1);
new_data = new char*[Height+2];
// transparent pixel must be zero, swap if it isn't:
if (has_transparent && transparent_pixel != 0) {
// swap transparent pixel with zero
p = Image+Width*Height;
while (p-- > Image) {
if (*p==transparent_pixel) *p = 0;
else if (!*p) *p = transparent_pixel;
}
uchar t;
t = Red[0];
Red[0] = Red[transparent_pixel];
Red[transparent_pixel] = t;
t = Green[0];
Green[0] = Green[transparent_pixel];
Green[transparent_pixel] = t;
t = Blue[0];
Blue[0] = Blue[transparent_pixel];
Blue[transparent_pixel] = t;
}
// find out what colors are actually used:
uchar used[256]; uchar remap[256];
int i;
for (i = 0; i < ColorMapSize; i++) used[i] = 0;
p = Image+Width*Height;
while (p-- > Image) used[*p] = 1;
// remap them to start with printing characters:
int base = has_transparent && used[0] ? ' ' : ' '+1;
int numcolors = 0;
for (i = 0; i < ColorMapSize; i++) if (used[i]) {
remap[i] = (uchar)(base++);
numcolors++;
}
// write the first line of xpm data (use suffix as temp array):
int length = sprintf((char*)(Suffix),
"%d %d %d %d",Width,Height,-numcolors,1);
new_data[0] = new char[length+1];
strcpy(new_data[0], (char*)Suffix);
// write the colormap
new_data[1] = (char*)(p = new uchar[4*numcolors]);
for (i = 0; i < ColorMapSize; i++) if (used[i]) {
*p++ = remap[i];
*p++ = Red[i];
*p++ = Green[i];
*p++ = Blue[i];
}
// remap the image data:
p = Image+Width*Height;
while (p-- > Image) *p = remap[*p];
// split the image data into lines:
for (i=0; i<Height; i++) {
new_data[i+2] = new char[Width+1];
memcpy(new_data[i + 2], (char*)(Image + i*Width), Width);
new_data[i + 2][Width] = 0;
}
data((const char **)new_data, Height + 2);
alloc_data = 1;
delete[] Image;
fclose(GifFile);
}
//
// End of "$Id$".
//