364 lines
10 KiB
C++
364 lines
10 KiB
C++
//
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// "$Id: gif.cxx,v 1.3 1999/01/07 19:17:14 mike Exp $"
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//
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// GIF support for the Fast Light Tool Kit (FLTK).
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//
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// Copyright 1998-1999 by Bill Spitzak and others.
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Library General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Library General Public License for more details.
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//
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// You should have received a copy of the GNU Library General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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// USA.
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//
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// Please report all bugs and problems to "fltk-bugs@easysw.com".
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//
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// Read a .gif file and convert it to a "xpm" format (actually my
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// modified one with compressed colormaps).
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// Extensively modified from original code for gif2ras by
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// Patrick J. Naughton of Sun Microsystems. The original
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// copyright notice follows:
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/* gif2ras.c - Converts from a Compuserve GIF (tm) image to a Sun Raster image.
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*
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* Copyright (c) 1988 by Patrick J. Naughton
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*
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* Author: Patrick J. Naughton
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* naughton@wind.sun.com
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose and without fee is hereby granted,
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* provided that the above copyright notice appear in all copies and that
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* both that copyright notice and this permission notice appear in
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* supporting documentation.
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*
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* This file is provided AS IS with no warranties of any kind. The author
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* shall have no liability with respect to the infringement of copyrights,
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* trade secrets or any patents by this file or any part thereof. In no
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* event will the author be liable for any lost revenue or profits or
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* other special, indirect and consequential damages.
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*
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* Comments and additions should be sent to the author:
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*
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* Patrick J. Naughton
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* Sun Microsystems, Inc.
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* 2550 Garcia Ave, MS 14-40
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* Mountain View, CA 94043
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* (415) 336-1080
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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typedef unsigned char uchar;
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#define NEXTBYTE getc(GifFile)
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#define GETSHORT(var) var = NEXTBYTE; var += NEXTBYTE << 8
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int gif2xpm(
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const char *infname,// filename for error messages
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FILE *GifFile, // file to read
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char*** datap, // return xpm data here
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int** lengthp, // return line lengths here
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int inumber // which image in movie (0 = first)
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) {
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{char b[6];
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if (fread(b,1,6,GifFile)<6) return 0; /* quit on eof */
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if (b[0]!='G' || b[1]!='I' || b[2] != 'F') {
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fprintf(stderr,"%s is not a GIF file.\n", infname); return 0;}
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if (b[3]!='8' || b[4]>'9' || b[5]!= 'a')
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fprintf(stderr,"%s is version %c%c%c.\n",infname,b[3],b[4],b[5]);
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}
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int Width; GETSHORT(Width);
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int Height; GETSHORT(Height);
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uchar ch = NEXTBYTE;
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char HasColormap = ((ch & 0x80) != 0);
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int BitsPerPixel = (ch & 7) + 1;
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int ColorMapSize = 1 << BitsPerPixel;
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// int OriginalResolution = ((ch>>4)&7)+1;
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// int SortedTable = (ch&8)!=0;
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NEXTBYTE; // Background Color index
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NEXTBYTE; // Aspect ratio is N/64
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// Read in global colormap:
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uchar transparent_pixel = 0;
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char has_transparent = 0;
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uchar Red[256], Green[256], Blue[256]; /* color map */
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if (HasColormap) {
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for (int i=0; i < ColorMapSize; i++) {
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Red[i] = NEXTBYTE;
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Green[i] = NEXTBYTE;
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Blue[i] = NEXTBYTE;
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}
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} else {
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fprintf(stderr,"%s does not have a colormap.\n", infname);
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for (int i = 0; i < ColorMapSize; i++)
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Red[i] = Green[i] = Blue[i] = (i*256+ColorMapSize-1)/ColorMapSize;
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}
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int CodeSize; /* Code size, init from GIF header, increases... */
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char Interlace;
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for (;;) {
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int i = NEXTBYTE;
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if (i<0) {fprintf(stderr,"%s: unexpected EOF\n",infname); return 0;}
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int blocklen;
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// if (i == 0x3B) return 0; eof code
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if (i == 0x21) { // a "gif extension"
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ch = NEXTBYTE;
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blocklen = NEXTBYTE;
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if (ch==0xF9 && blocklen==4) { // Netscape animation extension
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char bits;
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bits = NEXTBYTE;
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NEXTBYTE; NEXTBYTE; // GETSHORT(delay);
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transparent_pixel = NEXTBYTE;
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if (bits & 1) has_transparent = 1;
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blocklen = NEXTBYTE;
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} else if (ch == 0xFF) { // Netscape repeat count
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;
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} else if (ch == 0xFE) { //Gif Comment
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#if 0
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if(blocklen>0) {
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char *comment=new char[blocklen+1];
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int l;
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for(l=0;blocklen;l++,blocklen--)
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comment[l]=NEXTBYTE;
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comment[l]=0;
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fprintf(stderr,"%s: Gif Comment: '%s'\n", infname, comment);
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delete comment;
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NEXTBYTE; //End marker
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}
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#endif
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} else {
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fprintf(stderr,"%s: unknown gif extension 0x%02x\n", infname, ch);
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}
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} else if (i == 0x2c) { // an image
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NEXTBYTE; NEXTBYTE; // GETSHORT(x_position);
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NEXTBYTE; NEXTBYTE; // GETSHORT(y_position);
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GETSHORT(Width);
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GETSHORT(Height);
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ch = NEXTBYTE;
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Interlace = ((ch & 0x40) != 0);
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if (ch&0x80) {
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// read local color map
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int n = 1<<((ch&7)+1); // does this replace ColorMapSize ??
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for (i=0; i < n; i++) {
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Red[i] = NEXTBYTE;
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Green[i] = NEXTBYTE;
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Blue[i] = NEXTBYTE;
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}
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}
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CodeSize = NEXTBYTE+1;
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if (!inumber--) break; // okay, this is the image we want
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blocklen = NEXTBYTE;
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} else {
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fprintf(stderr,"%s: unknown gif code 0x%02x\n", infname, i);
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blocklen = 0;
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}
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// skip the data:
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while (blocklen>0) {while (blocklen--) {NEXTBYTE;} blocklen=NEXTBYTE;}
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}
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uchar *Image = new uchar[Width*Height];
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if (!Image) {
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fprintf (stderr, "Insufficient memory\n");
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exit (2);
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}
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int YC = 0, Pass = 0; /* Used to de-interlace the picture */
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uchar *p = Image;
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uchar *eol = p+Width;
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int InitCodeSize = CodeSize;
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int ClearCode = (1 << (CodeSize-1));
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int EOFCode = ClearCode + 1;
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int FirstFree = ClearCode + 2;
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int FinChar = 0;
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int ReadMask = (1<<CodeSize) - 1;
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int FreeCode = FirstFree;
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int OldCode = ClearCode;
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// tables used by LZW decompresser:
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short int Prefix[4096];
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uchar Suffix[4096];
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int blocklen = NEXTBYTE;
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uchar thisbyte = NEXTBYTE; blocklen--;
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int frombit = 0;
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for (;;) {
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/* Fetch the next code from the raster data stream. The codes can be
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* any length from 3 to 12 bits, packed into 8-bit bytes, so we have to
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* maintain our location as a pointer and a bit offset.
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* In addition, gif adds totally useless and annoying block counts
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* that must be correctly skipped over. */
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int CurCode = thisbyte;
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if (frombit+CodeSize > 7) {
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if (blocklen <= 0) {
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blocklen = NEXTBYTE;
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if (blocklen <= 0) break;
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}
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thisbyte = NEXTBYTE; blocklen--;
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CurCode |= thisbyte<<8;
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}
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if (frombit+CodeSize > 15) {
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if (blocklen <= 0) {
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blocklen = NEXTBYTE;
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if (blocklen <= 0) break;
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}
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thisbyte = NEXTBYTE; blocklen--;
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CurCode |= thisbyte<<16;
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}
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CurCode = (CurCode>>frombit)&ReadMask;
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frombit = (frombit+CodeSize)%8;
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if (CurCode == ClearCode) {
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CodeSize = InitCodeSize;
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ReadMask = (1<<CodeSize) - 1;
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FreeCode = FirstFree;
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OldCode = ClearCode;
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continue;
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}
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if (CurCode == EOFCode) break;
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uchar OutCode[1025]; // temporary array for reversing codes
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uchar *tp = OutCode;
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int i;
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if (CurCode < FreeCode) i = CurCode;
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else if (CurCode == FreeCode) {*tp++ = FinChar; i = OldCode;}
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else {fprintf(stderr,"%s : LZW Barf!\n",infname); break;}
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while (i >= ColorMapSize) {*tp++ = Suffix[i]; i = Prefix[i];}
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*tp++ = FinChar = i;
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while (tp > OutCode) {
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*p++ = *--tp;
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if (p >= eol) {
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if (!Interlace) YC++;
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else switch (Pass) {
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case 0: YC += 8; if (YC >= Height) {Pass++; YC = 4;} break;
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case 1: YC += 8; if (YC >= Height) {Pass++; YC = 2;} break;
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case 2: YC += 4; if (YC >= Height) {Pass++; YC = 1;} break;
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case 3: YC += 2; break;
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}
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if (YC>=Height) YC=0; /* cheap bug fix when excess data */
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p = Image + YC*Width;
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eol = p+Width;
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}
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}
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if (OldCode != ClearCode) {
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Prefix[FreeCode] = OldCode;
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Suffix[FreeCode] = FinChar;
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FreeCode++;
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if (FreeCode > ReadMask) {
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if (CodeSize < 12) {
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CodeSize++;
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ReadMask = (1 << CodeSize) - 1;
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}
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else FreeCode--;
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}
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}
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OldCode = CurCode;
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}
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// We are done reading the file, now convert to xpm:
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// allocate line pointer arrays:
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char** data = new char*[Height+3];
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*datap = data;
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int* length = new int[Height+2];
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*lengthp = length;
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// transparent pixel must be zero, swap if it isn't:
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if (has_transparent && transparent_pixel != 0) {
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// swap transparent pixel with zero
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p = Image+Width*Height;
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while (p-- > Image) {
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if (*p==transparent_pixel) *p = 0;
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else if (!*p) *p = transparent_pixel;
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}
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uchar t;
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t = Red[0]; Red[0] = Red[transparent_pixel]; Red[transparent_pixel] = t;
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t =Green[0];Green[0]=Green[transparent_pixel];Green[transparent_pixel]=t;
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t =Blue[0];Blue[0] =Blue[transparent_pixel];Blue[transparent_pixel] = t;
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}
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// find out what colors are actually used:
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uchar used[256]; uchar remap[256];
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int i;
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for (i = 0; i < ColorMapSize; i++) used[i] = 0;
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p = Image+Width*Height;
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while (p-- > Image) used[*p] = 1;
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// remap them to start with printing characters:
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int base = has_transparent && used[0] ? ' ' : ' '+1;
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int numcolors = 0;
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for (i = 0; i < ColorMapSize; i++) if (used[i]) {
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remap[i] = base++;
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numcolors++;
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}
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// write the first line of xpm data (use suffix as temp array):
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length[0] = sprintf((char*)(Suffix),
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"%d %d %d %d",Width,Height,-numcolors,1);
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data[0] = new char[length[0]+1];
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strcpy(data[0], (char*)Suffix);
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// write the colormap
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length[1] = 4*numcolors;
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data[1] = (char*)(p = new uchar[4*numcolors]);
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for (i = 0; i < ColorMapSize; i++) if (used[i]) {
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*p++ = remap[i];
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*p++ = Red[i];
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*p++ = Green[i];
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*p++ = Blue[i];
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}
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// remap the image data:
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p = Image+Width*Height;
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while (p-- > Image) *p = remap[*p];
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// split the image data into lines:
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for (i=0; i<Height; i++) {
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data[i+2] = (char*)(Image + i*Width);
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length[i+2] = Width;
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}
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data[Height+2] = 0; // null to end string array
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return 1;
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}
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//
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// End of "$Id: gif.cxx,v 1.3 1999/01/07 19:17:14 mike Exp $".
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//
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