summaryrefslogtreecommitdiff
path: root/Build/source/libs/gd/gd_gif_out.c
blob: 7fd7f144be522f718795945324140e1c9bcdf303 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "gd.h"
#include "gdhelpers.h"

/* Code drawn from ppmtogif.c, from the pbmplus package
**
** Based on GIFENCOD by David Rowley <mgardi@watdscu.waterloo.edu>. A
** Lempel-Zim compression based on "compress".
**
** Modified by Marcel Wijkstra <wijkstra@fwi.uva.nl>
**
** Copyright (C) 1989 by Jef Poskanzer.
**
** 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 software is provided "as is" without express or
** implied warranty.
**
** The Graphics Interchange Format(c) is the Copyright property of
** CompuServe Incorporated.  GIF(sm) is a Service Mark property of
** CompuServe Incorporated.
*/

/*
 * a code_int must be able to hold 2**GIFBITS values of type int, and also -1
 */
typedef int             code_int;

#ifdef SIGNED_COMPARE_SLOW
typedef unsigned long int count_int;
typedef unsigned short int count_short;
#else /*SIGNED_COMPARE_SLOW*/
typedef long int          count_int;
#endif /*SIGNED_COMPARE_SLOW*/

/* 2.0.28: threadsafe */

#define maxbits GIFBITS

/* should NEVER generate this code */
#define maxmaxcode ((code_int)1 << GIFBITS)

#define HSIZE  5003            /* 80% occupancy */
#define hsize HSIZE            /* Apparently invariant, left over from 
					compress */

typedef struct {
	int Width, Height;
	int curx, cury;
	long CountDown;
	int Pass;
	int Interlace;
        int n_bits;                        /* number of bits/code */
        code_int maxcode;                  /* maximum code, given n_bits */
        count_int htab [HSIZE];
        unsigned short codetab [HSIZE];
	code_int free_ent;                  /* first unused entry */
	/*
	 * block compression parameters -- after all codes are used up,
	 * and compression rate changes, start over.
	 */
	int clear_flg;
	int offset;
	long int in_count;            /* length of input */
	long int out_count;           /* # of codes output (for debugging) */

	int g_init_bits;
	gdIOCtx * g_outfile;

	int ClearCode;
	int EOFCode;
	unsigned long cur_accum;
	int cur_bits;
        /*
         * Number of characters so far in this 'packet'
         */
        int a_count;
        /*
         * Define the storage for the packet accumulator
         */
        char accum[ 256 ];
} GifCtx;

static int gifPutWord(int w, gdIOCtx *out);
static int colorstobpp(int colors);
static void BumpPixel (GifCtx *ctx);
static int GIFNextPixel (gdImagePtr im, GifCtx *ctx);
static void GIFEncode (gdIOCtxPtr fp, int GWidth, int GHeight, int GInterlace, int Background, int Transparent, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im);
static void GIFAnimEncode (gdIOCtxPtr fp, int IWidth, int IHeight, int LeftOfs, int TopOfs, int GInterlace, int Transparent, int Delay, int Disposal, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im);
static void compress (int init_bits, gdIOCtx *outfile, gdImagePtr im, GifCtx *ctx);
static void output (code_int code, GifCtx *ctx);
static void cl_block (GifCtx *ctx);
static void cl_hash (register count_int chsize, GifCtx *ctx);
static void char_init (GifCtx *ctx);
static void char_out (int c, GifCtx *ctx);
static void flush_char (GifCtx *ctx);
BGD_DECLARE(void *) gdImageGifPtr (gdImagePtr im, int *size)
{
  void *rv;
  gdIOCtx *out = gdNewDynamicCtx (2048, NULL);
  gdImageGifCtx (im, out);
  rv = gdDPExtractData (out, size);
  out->gd_free (out);
  return rv;
}

BGD_DECLARE(void) gdImageGif (gdImagePtr im, FILE * outFile)
{
  gdIOCtx *out = gdNewFileCtx (outFile);
  gdImageGifCtx (im, out);
  out->gd_free (out);
}

BGD_DECLARE(void) gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
{
	gdImagePtr pim = 0, tim = im;
	int interlace, transparent, BitsPerPixel;
	interlace = im->interlace;
	transparent = im->transparent;
	if (im->trueColor) {
		/* Expensive, but the only way that produces an
			acceptable result: mix down to a palette
			based temporary image. */
		pim = gdImageCreatePaletteFromTrueColor(im, 1, 256);
		if (!pim) {
			return;
		}
		tim = pim; 
	}
	BitsPerPixel = colorstobpp(tim->colorsTotal);
	/* All set, let's do it. */
	GIFEncode(
		out, tim->sx, tim->sy, interlace, 0, transparent, BitsPerPixel,
		tim->red, tim->green, tim->blue, tim);
	if (pim) {
		/* Destroy palette based temporary image. */
		gdImageDestroy(	pim);
	}
}

BGD_DECLARE(void *) gdImageGifAnimBeginPtr (gdImagePtr im, int *size, int GlobalCM, int Loops)
{
  void *rv;
  gdIOCtx *out = gdNewDynamicCtx (2048, NULL);
  gdImageGifAnimBeginCtx(im, out, GlobalCM, Loops);
  rv = gdDPExtractData (out, size);
  out->gd_free (out);
  return rv;
}

BGD_DECLARE(void) gdImageGifAnimBegin (gdImagePtr im, FILE *outFile, int GlobalCM, int Loops)
{
  gdIOCtx *out = gdNewFileCtx (outFile);
  gdImageGifAnimBeginCtx (im, out, GlobalCM, Loops);
  out->gd_free (out);
}

BGD_DECLARE(void) gdImageGifAnimBeginCtx(gdImagePtr im, gdIOCtxPtr out, int GlobalCM, int Loops)
{
	int B;
	int RWidth, RHeight;
	int Resolution;
	int ColorMapSize;
	int BitsPerPixel;
	int Background = 0;
	int i;

	/* Default is to use global color map */
	if (GlobalCM < 0) GlobalCM = 1;

	BitsPerPixel = colorstobpp(im->colorsTotal);
        ColorMapSize = 1 << BitsPerPixel;

        RWidth = im->sx;
        RHeight = im->sy;

        Resolution = BitsPerPixel;

        /*
         * Write the Magic header
         */
        gdPutBuf("GIF89a", 6, out );

        /*
         * Write out the screen width and height
         */
        gifPutWord( RWidth, out );
        gifPutWord( RHeight, out );

        /*
         * Indicate that there is a global colour map
         */
        B = GlobalCM ? 0x80 : 0;

        /*
         * OR in the resolution
         */
        B |= (Resolution - 1) << 5;

        /*
         * OR in the Bits per Pixel
         */
        B |= (BitsPerPixel - 1);

        /*
         * Write it out
         */
        gdPutC( B, out );

        /*
         * Write out the Background colour
         */
        gdPutC( Background, out );

        /*
         * Byte of 0's (future expansion)
         */
        gdPutC( 0, out );

        /*
         * Write out the Global Colour Map
         */
	if (GlobalCM)
		for( i=0; i<ColorMapSize; ++i ) {
			gdPutC( im->red[i], out );
			gdPutC( im->green[i], out );
			gdPutC( im->blue[i], out );
		}

	if (Loops >= 0) {
		gdPutBuf( "!\377\13NETSCAPE2.0\3\1", 16, out );
		gifPutWord( Loops, out );
		gdPutC( 0, out );
	}
}

BGD_DECLARE(void *) gdImageGifAnimAddPtr (gdImagePtr im, int *size, int LocalCM, int LeftOfs, int TopOfs, int Delay, int Disposal, gdImagePtr previm)
{
  void *rv;
  gdIOCtx *out = gdNewDynamicCtx (2048, NULL);
  gdImageGifAnimAddCtx(im, out, LocalCM, LeftOfs, TopOfs, Delay, Disposal, previm);
  rv = gdDPExtractData (out, size);
  out->gd_free (out);
  return rv;
}

BGD_DECLARE(void) gdImageGifAnimAdd (gdImagePtr im, FILE * outFile, int LocalCM, int LeftOfs, int TopOfs, int Delay, int Disposal, gdImagePtr previm)
{
  gdIOCtx *out = gdNewFileCtx (outFile);
  gdImageGifAnimAddCtx (im, out, LocalCM, LeftOfs, TopOfs, Delay, Disposal, previm);
  out->gd_free (out);
}

static int
comparewithmap (gdImagePtr im1, gdImagePtr im2, int c1, int c2, int *colorMap)
{
	if (!colorMap)
		return c1 == c2;
	if (-2 != colorMap[c1])
		return colorMap[c1] == c2;
	return (colorMap[c1] = gdImageColorExactAlpha (im2, im1->red[c1], im1->green[c1], im1->blue[c1], im1->alpha[c1]))
	       == c2;
}

BGD_DECLARE(void) gdImageGifAnimAddCtx(gdImagePtr im, gdIOCtxPtr out, int LocalCM, int LeftOfs, int TopOfs, int Delay, int Disposal, gdImagePtr previm)
{
	gdImagePtr pim = 0, tim = im;
	int interlace, transparent, BitsPerPixel;
	interlace = im->interlace;
	transparent = im->transparent;

	/* Default is no local color map */
	if (LocalCM < 0) LocalCM = 0;
	if (im->trueColor) {
		/* Expensive, but the only way that produces an
			acceptable result: mix down to a palette
			based temporary image. */
		pim = gdImageCreatePaletteFromTrueColor(im, 1, 256);
		if (!pim) {
			return;
		}
		tim = pim; 
	}
	if (previm) {
		/* create optimized animation.  Compare this image to
		   the previous image and crop the temporary copy of
		   current image to include only changed rectangular
		   area.  Also replace unchanged pixels inside this
		   area with transparent color.  Transparent color
		   needs to be already allocated!
		   Preconditions:
		   TopOfs, LeftOfs are assumed 0

		   Images should be of same size.  If not, a temporary
		   copy is made with the same size as previous image.
		   
		*/
		gdImagePtr prev_pim = 0, prev_tim = previm;
		int x, y;
		int min_x = 0;
		int min_y = tim->sy;
		int max_x = 0;
		int max_y = 0;
		int colorMap[256];

		if (previm->trueColor) {
			prev_pim = gdImageCreatePaletteFromTrueColor(previm, 1, 256);
			if (!prev_pim) {
				return;
			}
			prev_tim = prev_pim; 
		}
		for (x = 0; x < 256; ++x)
			colorMap[x] = -2;

		/* First find bounding box of changed areas. */
		/* first find the top changed row */
		for (y = 0; y < tim->sy; ++y)
			for (x = 0; x < tim->sx; ++x)
				if (!comparewithmap(prev_tim, tim,
						    prev_tim->pixels[y][x],
						    tim->pixels[y][x],
						    colorMap)) {
					min_y = max_y = y;
					min_x = max_x = x;
					goto break_top;
				}
	break_top:
		if (tim->sy == min_y) {
			/* No changes in this frame!! Encode empty image. */
			transparent = 0;
			min_x = min_y = 1;
			max_x = max_y = 0;
		} else {
			/* Then the bottom row */
			for (y = tim->sy - 1; y > min_y; --y)
				for (x = 0; x < tim->sx; ++x)
					if (!comparewithmap
					    (prev_tim, tim,
					     prev_tim->pixels[y][x],
					     tim->pixels[y][x],
					     colorMap)) {
						max_y = y;
						if (x < min_x) min_x = x;
						if (x > max_x) max_x = x;
						goto break_bot;
					}
		break_bot:
			/* left side */
			for (x = 0; x < min_x; ++x)
				for (y = min_y; y <= max_y; ++y)
					if (!comparewithmap
					    (prev_tim, tim,
					     prev_tim->pixels[y][x],
					     tim->pixels[y][x],
					     colorMap)) {
						min_x = x;
						goto break_left;
					}
		break_left:
			/* right side */
			for (x = tim->sx-1; x > max_x; --x)
				for (y = min_y; y <= max_y; ++y)
					if (!comparewithmap
					    (prev_tim, tim,
					     prev_tim->pixels[y][x],
					     tim->pixels[y][x],
					     colorMap)) {
						max_x = x;
						goto break_right;
					}
		break_right:
			;
		}

		LeftOfs = min_x;
		TopOfs = min_y;
		Disposal = 1;

		/* Make a copy of the image with the new offsets.
		   But only if necessary. */
		if (min_x != 0 || max_x != tim->sx-1
		    || min_y != 0 || max_y != tim->sy-1
		    || transparent >= 0) {
			gdImagePtr pim2
				= gdImageCreate(max_x-min_x+1, max_y-min_y+1);
			if (!pim2) {
				if (prev_pim)
					gdImageDestroy (prev_pim);
				goto fail_end;
			}
			gdImagePaletteCopy (pim2, LocalCM ? tim : prev_tim);
			gdImageCopy (pim2, tim, 0, 0, min_x, min_y,
				     max_x-min_x+1, max_y-min_y+1);
			if (pim)
				gdImageDestroy (pim);
			tim = pim = pim2;
		}

		/* now let's compare pixels for transparent
		   optimization.  But only if transparent is set. */
		if (transparent >= 0) {
			for (y = 0; y < tim->sy; ++y)
				for (x = 0; x < tim->sx; ++x)
					if (comparewithmap
					    (prev_tim, tim,
					     prev_tim->pixels[min_y+y][min_x+x],
					     tim->pixels[y][x], 0)) {
						gdImageSetPixel (tim, x, y,
								 transparent);
						break;
					}
		}
		if (prev_pim)
			gdImageDestroy (prev_pim);
	}
	BitsPerPixel = colorstobpp(tim->colorsTotal);
	/* All set, let's do it. */
	GIFAnimEncode(
		out, tim->sx, tim->sy, LeftOfs, TopOfs, interlace, transparent,
		Delay, Disposal, BitsPerPixel,
		LocalCM ? tim->red : 0, tim->green, tim->blue, tim);
 fail_end:
	if (pim) {
		/* Destroy palette based temporary image. */
		gdImageDestroy(	pim);
	}
}

BGD_DECLARE(void) gdImageGifAnimEnd(FILE *outFile)
{
#if 1
  putc (';', outFile);
#else
  gdIOCtx *out = gdNewFileCtx (outFile);
  gdImageGifAnimEndCtx (out);
  out->gd_free (out);
#endif
}

BGD_DECLARE(void *) gdImageGifAnimEndPtr (int *size)
{
  char *rv = (char *) gdMalloc (1);
  *rv = ';';
  *size = 1;
  return (void *)rv;
}

BGD_DECLARE(void) gdImageGifAnimEndCtx(gdIOCtx *out)
{
	/*
	 * Write the GIF file terminator
	 */
	gdPutC( ';', out );
}

static int
colorstobpp(int colors)
{
    int bpp = 0;

    if ( colors <= 2 )
        bpp = 1;
    else if ( colors <= 4 )
        bpp = 2;
    else if ( colors <= 8 )
        bpp = 3;
    else if ( colors <= 16 )
        bpp = 4;
    else if ( colors <= 32 )
        bpp = 5;
    else if ( colors <= 64 )
        bpp = 6;
    else if ( colors <= 128 )
        bpp = 7;
    else if ( colors <= 256 )
        bpp = 8;
    return bpp;
    }

/*****************************************************************************
 *
 * GIFENCODE.C    - GIF Image compression interface
 *
 * GIFEncode( FName, GHeight, GWidth, GInterlace, Background, Transparent,
 *            BitsPerPixel, Red, Green, Blue, gdImagePtr )
 *
 *****************************************************************************/

#define TRUE 1
#define FALSE 0
/*
 * Bump the 'curx' and 'cury' to point to the next pixel
 */
static void
BumpPixel(GifCtx *ctx)
{
        /*
         * Bump the current X position
         */
        ++(ctx->curx);

        /*
         * If we are at the end of a scan line, set curx back to the beginning
         * If we are interlaced, bump the cury to the appropriate spot,
         * otherwise, just increment it.
         */
        if( ctx->curx == ctx->Width ) {
                ctx->curx = 0;

                if( !ctx->Interlace )
                        ++(ctx->cury);
                else {
                     switch( ctx->Pass ) {

                       case 0:
                          ctx->cury += 8;
                          if( ctx->cury >= ctx->Height ) {
                                ++(ctx->Pass);
                                ctx->cury = 4;
                          }
                          break;

                       case 1:
                          ctx->cury += 8;
                          if( ctx->cury >= ctx->Height ) {
                                ++(ctx->Pass);
                                ctx->cury = 2;
                          }
                          break;

                       case 2:
                          ctx->cury += 4;
                          if( ctx->cury >= ctx->Height ) {
                             ++(ctx->Pass);
                             ctx->cury = 1;
                          }
                          break;

                       case 3:
                          ctx->cury += 2;
                          break;
                        }
                }
        }
}

/*
 * Return the next pixel from the image
 */
static int
GIFNextPixel(gdImagePtr im, GifCtx *ctx)
{
        int r;

        if( ctx->CountDown == 0 )
                return EOF;

        --(ctx->CountDown);

        r = gdImageGetPixel(im, ctx->curx, ctx->cury);

        BumpPixel(ctx);

        return r;
}

/* public */

static void
GIFEncode(gdIOCtxPtr fp, int GWidth, int GHeight, int GInterlace, int Background, int Transparent, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im)
{
        int B;
        int RWidth, RHeight;
        int LeftOfs, TopOfs;
        int Resolution;
        int ColorMapSize;
        int InitCodeSize;
        int i;
	GifCtx ctx;
        ctx.Interlace = GInterlace;
	ctx.in_count = 1;
	memset(&ctx, 0, sizeof(ctx));
        ColorMapSize = 1 << BitsPerPixel;

        RWidth = ctx.Width = GWidth;
        RHeight = ctx.Height = GHeight;
        LeftOfs = TopOfs = 0;

        Resolution = BitsPerPixel;

        /*
         * Calculate number of bits we are expecting
         */
        ctx.CountDown = (long)ctx.Width * (long)ctx.Height;

        /*
         * Indicate which pass we are on (if interlace)
         */
        ctx.Pass = 0;

        /*
         * The initial code size
         */
        if( BitsPerPixel <= 1 )
                InitCodeSize = 2;
        else
                InitCodeSize = BitsPerPixel;

        /*
         * Set up the current x and y position
         */
        ctx.curx = ctx.cury = 0;

        /*
         * Write the Magic header
         */
        gdPutBuf(Transparent < 0 ? "GIF87a" : "GIF89a", 6, fp );

        /*
         * Write out the screen width and height
         */
        gifPutWord( RWidth, fp );
        gifPutWord( RHeight, fp );

        /*
         * Indicate that there is a global colour map
         */
        B = 0x80;       /* Yes, there is a color map */

        /*
         * OR in the resolution
         */
        B |= (Resolution - 1) << 5;

        /*
         * OR in the Bits per Pixel
         */
        B |= (BitsPerPixel - 1);

        /*
         * Write it out
         */
        gdPutC( B, fp );

        /*
         * Write out the Background colour
         */
        gdPutC( Background, fp );

        /*
         * Byte of 0's (future expansion)
         */
        gdPutC( 0, fp );

        /*
         * Write out the Global Colour Map
         */
        for( i=0; i<ColorMapSize; ++i ) {
                gdPutC( Red[i], fp );
                gdPutC( Green[i], fp );
                gdPutC( Blue[i], fp );
        }

	/*
	 * Write out extension for transparent colour index, if necessary.
	 */
	if ( Transparent >= 0 ) {
	    gdPutC( '!', fp );
	    gdPutC( 0xf9, fp );
	    gdPutC( 4, fp );
	    gdPutC( 1, fp );
	    gdPutC( 0, fp );
	    gdPutC( 0, fp );
	    gdPutC( (unsigned char) Transparent, fp );
	    gdPutC( 0, fp );
	}

        /*
         * Write an Image separator
         */
        gdPutC( ',', fp );

        /*
         * Write the Image header
         */

        gifPutWord( LeftOfs, fp );
        gifPutWord( TopOfs, fp );
        gifPutWord( ctx.Width, fp );
        gifPutWord( ctx.Height, fp );

        /*
         * Write out whether or not the image is interlaced
         */
        if( ctx.Interlace )
                gdPutC( 0x40, fp );
        else
                gdPutC( 0x00, fp );

        /*
         * Write out the initial code size
         */
        gdPutC( InitCodeSize, fp );

        /*
         * Go and actually compress the data
         */
        compress( InitCodeSize+1, fp, im, &ctx );

        /*
         * Write out a Zero-length packet (to end the series)
         */
        gdPutC( 0, fp );

        /*
         * Write the GIF file terminator
         */
        gdPutC( ';', fp );
}

static void
GIFAnimEncode(gdIOCtxPtr fp, int IWidth, int IHeight, int LeftOfs, int TopOfs, int GInterlace, int Transparent, int Delay, int Disposal, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im)
{
	int B;
        int ColorMapSize;
        int InitCodeSize;
        int i;
	GifCtx ctx;
        ctx.Interlace = GInterlace;
	ctx.in_count = 1;
	memset(&ctx, 0, sizeof(ctx));
        ColorMapSize = 1 << BitsPerPixel;

	if (LeftOfs < 0) LeftOfs = 0;
	if (TopOfs < 0) TopOfs = 0;
	if (Delay < 0) Delay = 100;
	if (Disposal < 0) Disposal = 1;

	ctx.Width = IWidth;
        ctx.Height = IHeight;

        /*
         * Calculate number of bits we are expecting
         */
        ctx.CountDown = (long)ctx.Width * (long)ctx.Height;

        /*
         * Indicate which pass we are on (if interlace)
         */
        ctx.Pass = 0;

        /*
         * The initial code size
         */
        if( BitsPerPixel <= 1 )
                InitCodeSize = 2;
        else
                InitCodeSize = BitsPerPixel;

        /*
         * Set up the current x and y position
         */
        ctx.curx = ctx.cury = 0;

	/*
	 * Write out extension for image animation and looping
	 */
	gdPutC( '!', fp );
	gdPutC( 0xf9, fp );
	gdPutC( 4, fp );
	gdPutC( (Transparent >= 0 ? 1 : 0)
		| (Disposal << 2), fp );
	gdPutC( (unsigned char)(Delay & 255), fp );
	gdPutC( (unsigned char)((Delay >> 8) & 255), fp );
	gdPutC( (unsigned char) Transparent, fp );
	gdPutC( 0, fp );

	/*
	 * Write an Image separator
	 */
	gdPutC( ',', fp );

        /*
         * Write out the Image header
         */
        gifPutWord( LeftOfs, fp );
        gifPutWord( TopOfs, fp );
        gifPutWord( ctx.Width, fp );
        gifPutWord( ctx.Height, fp );

        /*
         * Indicate that there is a local colour map
         */
        B = (Red && Green && Blue) ? 0x80 : 0;

        /*
         * OR in the interlacing
         */
        B |= ctx.Interlace ? 0x40 : 0;

        /*
         * OR in the Bits per Pixel
         */
        B |= (Red && Green && Blue) ? (BitsPerPixel - 1) : 0;

        /*
         * Write it out
         */
        gdPutC( B, fp );

	/*
	 * Write out the Local Colour Map
	 */
	if (Red && Green && Blue)
		for( i=0; i<ColorMapSize; ++i ) {
			gdPutC( Red[i], fp );
			gdPutC( Green[i], fp );
			gdPutC( Blue[i], fp );
		}

        /*
         * Write out the initial code size
         */
        gdPutC( InitCodeSize, fp );

        /*
         * Go and actually compress the data
         */
        compress( InitCodeSize+1, fp, im, &ctx );

        /*
         * Write out a Zero-length packet (to end the series)
         */
        gdPutC( 0, fp );
}

/***************************************************************************
 *
 *  GIFCOMPR.C       - GIF Image compression routines
 *
 *  Lempel-Ziv compression based on 'compress'.  GIF modifications by
 *  David Rowley (mgardi@watdcsu.waterloo.edu)
 *
 ***************************************************************************/

/*
 * General DEFINEs
 */

#define GIFBITS    12

#ifdef NO_UCHAR
 typedef char   char_type;
#else /*NO_UCHAR*/
 typedef        unsigned char   char_type;
#endif /*NO_UCHAR*/

/*
 *
 * GIF Image compression - modified 'compress'
 *
 * Based on: compress.c - File compression ala IEEE Computer, June 1984.
 *
 * By Authors:  Spencer W. Thomas       (decvax!harpo!utah-cs!utah-gr!thomas)
 *              Jim McKie               (decvax!mcvax!jim)
 *              Steve Davies            (decvax!vax135!petsd!peora!srd)
 *              Ken Turkowski           (decvax!decwrl!turtlevax!ken)
 *              James A. Woods          (decvax!ihnp4!ames!jaw)
 *              Joe Orost               (decvax!vax135!petsd!joe)
 *
 */
#include <ctype.h>

#define ARGVAL() (*++(*argv) || (--argc && *++argv))

#ifdef COMPATIBLE               /* But wrong! */
# define MAXCODE(n_bits)        ((code_int) 1 << (n_bits) - 1)
#else /*COMPATIBLE*/
# define MAXCODE(n_bits)        (((code_int) 1 << (n_bits)) - 1)
#endif /*COMPATIBLE*/

#define HashTabOf(i)       ctx->htab[i]
#define CodeTabOf(i)    ctx->codetab[i]


/*
 * To save much memory, we overlay the table used by compress() with those
 * used by decompress().  The tab_prefix table is the same size and type
 * as the codetab.  The tab_suffix table needs 2**GIFBITS characters.  We
 * get this from the beginning of htab.  The output stack uses the rest
 * of htab, and contains characters.  There is plenty of room for any
 * possible stack (stack used to be 8000 characters).
 */

#define tab_prefixof(i) CodeTabOf(i)
#define tab_suffixof(i)        ((char_type*)(htab))[i]
#define de_stack               ((char_type*)&tab_suffixof((code_int)1<<GIFBITS))

/*
 * compress stdin to stdout
 *
 * Algorithm:  use open addressing double hashing (no chaining) on the
 * prefix code / next character combination.  We do a variant of Knuth's
 * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
 * secondary probe.  Here, the modular division first probe is gives way
 * to a faster exclusive-or manipulation.  Also do block compression with
 * an adaptive reset, whereby the code table is cleared when the compression
 * ratio decreases, but after the table fills.  The variable-length output
 * codes are re-sized at this point, and a special CLEAR code is generated
 * for the decompressor.  Late addition:  construct the table according to
 * file size for noticeable speed improvement on small files.  Please direct
 * questions about this implementation to ames!jaw.
 */

static void
output(code_int code, GifCtx *ctx);

static void
compress(int init_bits, gdIOCtxPtr outfile, gdImagePtr im, GifCtx *ctx)
{
    register long fcode;
    register code_int i /* = 0 */;
    register int c;
    register code_int ent;
    register code_int disp;
    register code_int hsize_reg;
    register int hshift;

    /*
     * Set up the globals:  g_init_bits - initial number of bits
     *                      g_outfile   - pointer to output file
     */
    ctx->g_init_bits = init_bits;
    ctx->g_outfile = outfile;

    /*
     * Set up the necessary values
     */
    ctx->offset = 0;
    ctx->out_count = 0;
    ctx->clear_flg = 0;
    ctx->in_count = 1;
    ctx->maxcode = MAXCODE(ctx->n_bits = ctx->g_init_bits);

    ctx->ClearCode = (1 << (init_bits - 1));
    ctx->EOFCode = ctx->ClearCode + 1;
    ctx->free_ent = ctx->ClearCode + 2;

    char_init(ctx);

    ent = GIFNextPixel( im, ctx );

    hshift = 0;
    for ( fcode = (long) hsize;  fcode < 65536L; fcode *= 2L )
        ++hshift;
    hshift = 8 - hshift;                /* set hash code range bound */

    hsize_reg = hsize;
    cl_hash( (count_int) hsize_reg, ctx );            /* clear hash table */

    output( (code_int)ctx->ClearCode, ctx );

#ifdef SIGNED_COMPARE_SLOW
    while ( (c = GIFNextPixel( im )) != (unsigned) EOF ) {
#else /*SIGNED_COMPARE_SLOW*/
    while ( (c = GIFNextPixel( im, ctx )) != EOF ) {  /* } */
#endif /*SIGNED_COMPARE_SLOW*/

        ++(ctx->in_count);

        fcode = (long) (((long) c << maxbits) + ent);
        i = (((code_int)c << hshift) ^ ent);    /* xor hashing */

        if ( HashTabOf (i) == fcode ) {
            ent = CodeTabOf (i);
            continue;
        } else if ( (long)HashTabOf (i) < 0 )      /* empty slot */
            goto nomatch;
        disp = hsize_reg - i;           /* secondary hash (after G. Knott) */
        if ( i == 0 )
            disp = 1;
probe:
        if ( (i -= disp) < 0 )
            i += hsize_reg;

        if ( HashTabOf (i) == fcode ) {
            ent = CodeTabOf (i);
            continue;
        }
        if ( (long)HashTabOf (i) > 0 )
            goto probe;
nomatch:
        output ( (code_int) ent, ctx );
        ++(ctx->out_count);
        ent = c;
#ifdef SIGNED_COMPARE_SLOW
        if ( (unsigned) ctx->free_ent < (unsigned) maxmaxcode) {
#else /*SIGNED_COMPARE_SLOW*/
        if ( ctx->free_ent < maxmaxcode ) {  /* } */
#endif /*SIGNED_COMPARE_SLOW*/
            CodeTabOf (i) = ctx->free_ent++; /* code -> hashtable */
            HashTabOf (i) = fcode;
        } else
                cl_block(ctx);
    }
    /*
     * Put out the final code.
     */
    output( (code_int)ent, ctx );
    ++(ctx->out_count);
    output( (code_int) ctx->EOFCode, ctx );
}

/*****************************************************************
 * TAG( output )
 *
 * Output the given code.
 * Inputs:
 *      code:   A n_bits-bit integer.  If == -1, then EOF.  This assumes
 *              that n_bits =< (long)wordsize - 1.
 * Outputs:
 *      Outputs code to the file.
 * Assumptions:
 *      Chars are 8 bits long.
 * Algorithm:
 *      Maintain a GIFBITS character long buffer (so that 8 codes will
 * fit in it exactly).  Use the VAX insv instruction to insert each
 * code in turn.  When the buffer fills up empty it and start over.
 */

static unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
                                  0x001F, 0x003F, 0x007F, 0x00FF,
                                  0x01FF, 0x03FF, 0x07FF, 0x0FFF,
                                  0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };

static void
output(code_int code, GifCtx *ctx)
{
    ctx->cur_accum &= masks[ ctx->cur_bits ];

    if( ctx->cur_bits > 0 )
        ctx->cur_accum |= ((long)code << ctx->cur_bits);
    else
        ctx->cur_accum = code;

    ctx->cur_bits += ctx->n_bits;

    while( ctx->cur_bits >= 8 ) {
        char_out( (unsigned int)(ctx->cur_accum & 0xff), ctx );
        ctx->cur_accum >>= 8;
        ctx->cur_bits -= 8;
    }

    /*
     * If the next entry is going to be too big for the code size,
     * then increase it, if possible.
     */
   if ( ctx->free_ent > ctx->maxcode || ctx->clear_flg ) {

            if( ctx->clear_flg ) {

                ctx->maxcode = MAXCODE (ctx->n_bits = ctx->g_init_bits);
                ctx->clear_flg = 0;

            } else {

                ++(ctx->n_bits);
                if ( ctx->n_bits == maxbits )
                    ctx->maxcode = maxmaxcode;
                else
                    ctx->maxcode = MAXCODE(ctx->n_bits);
            }
        }

    if( code == ctx->EOFCode ) {
        /*
         * At EOF, write the rest of the buffer.
         */
        while( ctx->cur_bits > 0 ) {
                char_out( (unsigned int)(ctx->cur_accum & 0xff), ctx);
                ctx->cur_accum >>= 8;
                ctx->cur_bits -= 8;
        }

        flush_char(ctx);

    }
}

/*
 * Clear out the hash table
 */
static void
cl_block (GifCtx *ctx)             /* table clear for block compress */
{

        cl_hash ( (count_int) hsize, ctx );
        ctx->free_ent = ctx->ClearCode + 2;
        ctx->clear_flg = 1;

        output( (code_int)ctx->ClearCode, ctx);
}

static void
cl_hash(register count_int chsize, GifCtx *ctx)          /* reset code table */
                         
{

        register count_int *htab_p = ctx->htab+chsize;

        register long i;
        register long m1 = -1;

        i = chsize - 16;
        do {                            /* might use Sys V memset(3) here */
                *(htab_p-16) = m1;
                *(htab_p-15) = m1;
                *(htab_p-14) = m1;
                *(htab_p-13) = m1;
                *(htab_p-12) = m1;
                *(htab_p-11) = m1;
                *(htab_p-10) = m1;
                *(htab_p-9) = m1;
                *(htab_p-8) = m1;
                *(htab_p-7) = m1;
                *(htab_p-6) = m1;
                *(htab_p-5) = m1;
                *(htab_p-4) = m1;
                *(htab_p-3) = m1;
                *(htab_p-2) = m1;
                *(htab_p-1) = m1;
                htab_p -= 16;
        } while ((i -= 16) >= 0);

        for ( i += 16; i > 0; --i )
                *--htab_p = m1;
}

/******************************************************************************
 *
 * GIF Specific routines
 *
 ******************************************************************************/

/*
 * Set up the 'byte output' routine
 */
static void
char_init(GifCtx *ctx)
{
        ctx->a_count = 0;
}

/*
 * Add a character to the end of the current packet, and if it is 254
 * characters, flush the packet to disk.
 */
static void
char_out(int c, GifCtx *ctx)
{
        ctx->accum[ ctx->a_count++ ] = c;
        if( ctx->a_count >= 254 )
                flush_char(ctx);
}

/*
 * Flush the packet to disk, and reset the accumulator
 */
static void
flush_char(GifCtx *ctx)
{
        if( ctx->a_count > 0 ) {
                gdPutC( ctx->a_count, ctx->g_outfile );
                gdPutBuf( ctx->accum, ctx->a_count, ctx->g_outfile );
                ctx->a_count = 0;
        }
}

static int gifPutWord(int w, gdIOCtx *out)
{
	/* Byte order is little-endian */
	gdPutC(w & 0xFF, out);
	gdPutC((w >> 8) & 0xFF, out);
	return 0;
}