1 #include <stdio.h>
2 #include <math.h>
3 #include <string.h>
4 #include <stdlib.h>
5 #include "gd.h"
6
7 /* Code drawn from ppmtogif.c, from the pbmplus package
8 **
9 ** Based on GIFENCOD by David Rowley <mgardi@watdscu.waterloo.edu>. A
10 ** Lempel-Zim compression based on "compress".
11 **
12 ** Modified by Marcel Wijkstra <wijkstra@fwi.uva.nl>
13 **
14 ** Copyright (C) 1989 by Jef Poskanzer.
15 **
16 ** Permission to use, copy, modify, and distribute this software and its
17 ** documentation for any purpose and without fee is hereby granted, provided
18 ** that the above copyright notice appear in all copies and that both that
19 ** copyright notice and this permission notice appear in supporting
20 ** documentation. This software is provided "as is" without express or
21 ** implied warranty.
22 **
23 ** The Graphics Interchange Format(c) is the Copyright property of
24 ** CompuServe Incorporated. GIF(sm) is a Service Mark property of
25 ** CompuServe Incorporated.
26 */
27
28 /*
29 * a code_int must be able to hold 2**GIFBITS values of type int, and also -1
30 */
31 typedef int code_int;
32
33 #ifdef SIGNED_COMPARE_SLOW
34 typedef unsigned long int count_int;
35 typedef unsigned short int count_short;
36 #else /*SIGNED_COMPARE_SLOW*/
37 typedef long int count_int;
38 #endif /*SIGNED_COMPARE_SLOW*/
39
40 /* 2.0.28: threadsafe */
41
42 #define maxbits GIFBITS
43
44 /* should NEVER generate this code */
45 #define maxmaxcode ((code_int)1 << GIFBITS)
46
47 #define HSIZE 5003 /* 80% occupancy */
48 #define hsize HSIZE /* Apparently invariant, left over from
49 compress */
50
51 typedef struct {
52 int Width, Height;
53 int curx, cury;
54 long CountDown;
55 int Pass;
56 int Interlace;
57 int n_bits; /* number of bits/code */
58 code_int maxcode; /* maximum code, given n_bits */
59 count_int htab [HSIZE];
60 unsigned short codetab [HSIZE];
61 code_int free_ent; /* first unused entry */
62 /*
63 * block compression parameters -- after all codes are used up,
64 * and compression rate changes, start over.
65 */
66 int clear_flg;
67 int offset;
68 long int in_count; /* length of input */
69 long int out_count; /* # of codes output (for debugging) */
70
71 int g_init_bits;
72 gdIOCtx * g_outfile;
73
74 int ClearCode;
75 int EOFCode;
76 unsigned long cur_accum;
77 int cur_bits;
78 /*
79 * Number of characters so far in this 'packet'
80 */
81 int a_count;
82 /*
83 * Define the storage for the packet accumulator
84 */
85 char accum[ 256 ];
86 } GifCtx;
87
88 static int gifPutWord(int w, gdIOCtx *out);
89 static int colorstobpp(int colors);
90 static void BumpPixel (GifCtx *ctx);
91 static int GIFNextPixel (gdImagePtr im, GifCtx *ctx);
92 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);
93 static void compress (int init_bits, gdIOCtx *outfile, gdImagePtr im, GifCtx *ctx);
94 static void output (code_int code, GifCtx *ctx);
95 static void cl_block (GifCtx *ctx);
96 static void cl_hash (register count_int chsize, GifCtx *ctx);
97 static void char_init (GifCtx *ctx);
98 static void char_out (int c, GifCtx *ctx);
99 static void flush_char (GifCtx *ctx);
100
101 static int _gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out);
102
gdImageGifPtr(gdImagePtr im,int * size)103 void * gdImageGifPtr (gdImagePtr im, int *size)
104 {
105 void *rv;
106 gdIOCtx *out = gdNewDynamicCtx (2048, NULL);
107 if (!_gdImageGifCtx(im, out)) {
108 rv = gdDPExtractData(out, size);
109 } else {
110 rv = NULL;
111 }
112 out->gd_free (out);
113 return rv;
114 }
115
gdImageGif(gdImagePtr im,FILE * outFile)116 void gdImageGif (gdImagePtr im, FILE * outFile)
117 {
118 gdIOCtx *out = gdNewFileCtx (outFile);
119 gdImageGifCtx (im, out);
120 out->gd_free (out);
121 }
122
gdImageGifCtx(gdImagePtr im,gdIOCtxPtr out)123 void gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
124 {
125 _gdImageGifCtx(im, out);
126 }
127
128 /* returns 0 on success, 1 on failure */
_gdImageGifCtx(gdImagePtr im,gdIOCtxPtr out)129 static int _gdImageGifCtx(gdImagePtr im, gdIOCtxPtr out)
130 {
131 gdImagePtr pim = 0, tim = im;
132 int interlace, BitsPerPixel;
133 interlace = im->interlace;
134 if (im->trueColor) {
135 /* Expensive, but the only way that produces an
136 acceptable result: mix down to a palette
137 based temporary image. */
138 pim = gdImageCreatePaletteFromTrueColor(im, 1, 256);
139 if (!pim) {
140 return 1;
141 }
142 tim = pim;
143 }
144 BitsPerPixel = colorstobpp(tim->colorsTotal);
145 /* All set, let's do it. */
146 GIFEncode(
147 out, tim->sx, tim->sy, interlace, 0, tim->transparent, BitsPerPixel,
148 tim->red, tim->green, tim->blue, tim);
149 if (pim) {
150 /* Destroy palette based temporary image. */
151 gdImageDestroy( pim);
152 }
153
154 return 0;
155 }
156
157 static int
colorstobpp(int colors)158 colorstobpp(int colors)
159 {
160 int bpp = 0;
161
162 if ( colors <= 2 )
163 bpp = 1;
164 else if ( colors <= 4 )
165 bpp = 2;
166 else if ( colors <= 8 )
167 bpp = 3;
168 else if ( colors <= 16 )
169 bpp = 4;
170 else if ( colors <= 32 )
171 bpp = 5;
172 else if ( colors <= 64 )
173 bpp = 6;
174 else if ( colors <= 128 )
175 bpp = 7;
176 else if ( colors <= 256 )
177 bpp = 8;
178 return bpp;
179 }
180
181 /*****************************************************************************
182 *
183 * GIFENCODE.C - GIF Image compression interface
184 *
185 * GIFEncode( FName, GHeight, GWidth, GInterlace, Background, Transparent,
186 * BitsPerPixel, Red, Green, Blue, gdImagePtr )
187 *
188 *****************************************************************************/
189
190 #define TRUE 1
191 #define FALSE 0
192 /*
193 * Bump the 'curx' and 'cury' to point to the next pixel
194 */
195 static void
BumpPixel(GifCtx * ctx)196 BumpPixel(GifCtx *ctx)
197 {
198 /*
199 * Bump the current X position
200 */
201 ++(ctx->curx);
202
203 /*
204 * If we are at the end of a scan line, set curx back to the beginning
205 * If we are interlaced, bump the cury to the appropriate spot,
206 * otherwise, just increment it.
207 */
208 if( ctx->curx == ctx->Width ) {
209 ctx->curx = 0;
210
211 if( !ctx->Interlace )
212 ++(ctx->cury);
213 else {
214 switch( ctx->Pass ) {
215
216 case 0:
217 ctx->cury += 8;
218 if( ctx->cury >= ctx->Height ) {
219 ++(ctx->Pass);
220 ctx->cury = 4;
221 }
222 break;
223
224 case 1:
225 ctx->cury += 8;
226 if( ctx->cury >= ctx->Height ) {
227 ++(ctx->Pass);
228 ctx->cury = 2;
229 }
230 break;
231
232 case 2:
233 ctx->cury += 4;
234 if( ctx->cury >= ctx->Height ) {
235 ++(ctx->Pass);
236 ctx->cury = 1;
237 }
238 break;
239
240 case 3:
241 ctx->cury += 2;
242 break;
243 }
244 }
245 }
246 }
247
248 /*
249 * Return the next pixel from the image
250 */
251 static int
GIFNextPixel(gdImagePtr im,GifCtx * ctx)252 GIFNextPixel(gdImagePtr im, GifCtx *ctx)
253 {
254 int r;
255
256 if( ctx->CountDown == 0 )
257 return EOF;
258
259 --(ctx->CountDown);
260
261 r = gdImageGetPixel(im, ctx->curx, ctx->cury);
262
263 BumpPixel(ctx);
264
265 return r;
266 }
267
268 /* public */
269
270 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)271 GIFEncode(gdIOCtxPtr fp, int GWidth, int GHeight, int GInterlace, int Background, int Transparent, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im)
272 {
273 int B;
274 int RWidth, RHeight;
275 int LeftOfs, TopOfs;
276 int Resolution;
277 int ColorMapSize;
278 int InitCodeSize;
279 int i;
280 GifCtx ctx;
281
282 memset(&ctx, 0, sizeof(ctx));
283 ctx.Interlace = GInterlace;
284 ctx.in_count = 1;
285
286 ColorMapSize = 1 << BitsPerPixel;
287
288 RWidth = ctx.Width = GWidth;
289 RHeight = ctx.Height = GHeight;
290 LeftOfs = TopOfs = 0;
291
292 Resolution = BitsPerPixel;
293
294 /*
295 * Calculate number of bits we are expecting
296 */
297 ctx.CountDown = (long)ctx.Width * (long)ctx.Height;
298
299 /*
300 * Indicate which pass we are on (if interlace)
301 */
302 ctx.Pass = 0;
303
304 /*
305 * The initial code size
306 */
307 if( BitsPerPixel <= 1 )
308 InitCodeSize = 2;
309 else
310 InitCodeSize = BitsPerPixel;
311
312 /*
313 * Set up the current x and y position
314 */
315 ctx.curx = ctx.cury = 0;
316
317 /*
318 * Write the Magic header
319 */
320 gdPutBuf(Transparent < 0 ? "GIF87a" : "GIF89a", 6, fp );
321
322 /*
323 * Write out the screen width and height
324 */
325 gifPutWord( RWidth, fp );
326 gifPutWord( RHeight, fp );
327
328 /*
329 * Indicate that there is a global colour map
330 */
331 B = 0x80; /* Yes, there is a color map */
332
333 /*
334 * OR in the resolution
335 */
336 B |= (Resolution - 1) << 4;
337
338 /*
339 * OR in the Bits per Pixel
340 */
341 B |= (BitsPerPixel - 1);
342
343 /*
344 * Write it out
345 */
346 gdPutC( B, fp );
347
348 /*
349 * Write out the Background colour
350 */
351 gdPutC( Background, fp );
352
353 /*
354 * Byte of 0's (future expansion)
355 */
356 gdPutC( 0, fp );
357
358 /*
359 * Write out the Global Colour Map
360 */
361 for( i=0; i<ColorMapSize; ++i ) {
362 gdPutC( Red[i], fp );
363 gdPutC( Green[i], fp );
364 gdPutC( Blue[i], fp );
365 }
366
367 /*
368 * Write out extension for transparent colour index, if necessary.
369 */
370 if ( Transparent >= 0 ) {
371 gdPutC( '!', fp );
372 gdPutC( 0xf9, fp );
373 gdPutC( 4, fp );
374 gdPutC( 1, fp );
375 gdPutC( 0, fp );
376 gdPutC( 0, fp );
377 gdPutC( (unsigned char) Transparent, fp );
378 gdPutC( 0, fp );
379 }
380
381 /*
382 * Write an Image separator
383 */
384 gdPutC( ',', fp );
385
386 /*
387 * Write the Image header
388 */
389
390 gifPutWord( LeftOfs, fp );
391 gifPutWord( TopOfs, fp );
392 gifPutWord( ctx.Width, fp );
393 gifPutWord( ctx.Height, fp );
394
395 /*
396 * Write out whether or not the image is interlaced
397 */
398 if( ctx.Interlace )
399 gdPutC( 0x40, fp );
400 else
401 gdPutC( 0x00, fp );
402
403 /*
404 * Write out the initial code size
405 */
406 gdPutC( InitCodeSize, fp );
407
408 /*
409 * Go and actually compress the data
410 */
411 compress( InitCodeSize+1, fp, im, &ctx );
412
413 /*
414 * Write out a Zero-length packet (to end the series)
415 */
416 gdPutC( 0, fp );
417
418 /*
419 * Write the GIF file terminator
420 */
421 gdPutC( ';', fp );
422 }
423
424 /***************************************************************************
425 *
426 * GIFCOMPR.C - GIF Image compression routines
427 *
428 * Lempel-Ziv compression based on 'compress'. GIF modifications by
429 * David Rowley (mgardi@watdcsu.waterloo.edu)
430 *
431 ***************************************************************************/
432
433 /*
434 * General DEFINEs
435 */
436
437 #define GIFBITS 12
438
439 #ifdef NO_UCHAR
440 typedef char char_type;
441 #else /*NO_UCHAR*/
442 typedef unsigned char char_type;
443 #endif /*NO_UCHAR*/
444
445 /*
446 *
447 * GIF Image compression - modified 'compress'
448 *
449 * Based on: compress.c - File compression ala IEEE Computer, June 1984.
450 *
451 * By Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
452 * Jim McKie (decvax!mcvax!jim)
453 * Steve Davies (decvax!vax135!petsd!peora!srd)
454 * Ken Turkowski (decvax!decwrl!turtlevax!ken)
455 * James A. Woods (decvax!ihnp4!ames!jaw)
456 * Joe Orost (decvax!vax135!petsd!joe)
457 *
458 */
459 #include <ctype.h>
460
461 #define ARGVAL() (*++(*argv) || (--argc && *++argv))
462
463 #ifdef COMPATIBLE /* But wrong! */
464 # define MAXCODE(n_bits) ((code_int) 1 << (n_bits) - 1)
465 #else /*COMPATIBLE*/
466 # define MAXCODE(n_bits) (((code_int) 1 << (n_bits)) - 1)
467 #endif /*COMPATIBLE*/
468
469 #define HashTabOf(i) ctx->htab[i]
470 #define CodeTabOf(i) ctx->codetab[i]
471
472
473 /*
474 * To save much memory, we overlay the table used by compress() with those
475 * used by decompress(). The tab_prefix table is the same size and type
476 * as the codetab. The tab_suffix table needs 2**GIFBITS characters. We
477 * get this from the beginning of htab. The output stack uses the rest
478 * of htab, and contains characters. There is plenty of room for any
479 * possible stack (stack used to be 8000 characters).
480 */
481
482 #define tab_prefixof(i) CodeTabOf(i)
483 #define tab_suffixof(i) ((char_type*)(htab))[i]
484 #define de_stack ((char_type*)&tab_suffixof((code_int)1<<GIFBITS))
485
486 /*
487 * compress stdin to stdout
488 *
489 * Algorithm: use open addressing double hashing (no chaining) on the
490 * prefix code / next character combination. We do a variant of Knuth's
491 * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
492 * secondary probe. Here, the modular division first probe is gives way
493 * to a faster exclusive-or manipulation. Also do block compression with
494 * an adaptive reset, whereby the code table is cleared when the compression
495 * ratio decreases, but after the table fills. The variable-length output
496 * codes are re-sized at this point, and a special CLEAR code is generated
497 * for the decompressor. Late addition: construct the table according to
498 * file size for noticeable speed improvement on small files. Please direct
499 * questions about this implementation to ames!jaw.
500 */
501
502 static void
503 output(code_int code, GifCtx *ctx);
504
505 static void
compress(int init_bits,gdIOCtxPtr outfile,gdImagePtr im,GifCtx * ctx)506 compress(int init_bits, gdIOCtxPtr outfile, gdImagePtr im, GifCtx *ctx)
507 {
508 register long fcode;
509 register code_int i /* = 0 */;
510 register int c;
511 register code_int ent;
512 register code_int disp;
513 register code_int hsize_reg;
514 register int hshift;
515
516 /*
517 * Set up the globals: g_init_bits - initial number of bits
518 * g_outfile - pointer to output file
519 */
520 ctx->g_init_bits = init_bits;
521 ctx->g_outfile = outfile;
522
523 /*
524 * Set up the necessary values
525 */
526 ctx->offset = 0;
527 ctx->out_count = 0;
528 ctx->clear_flg = 0;
529 ctx->in_count = 1;
530 ctx->maxcode = MAXCODE(ctx->n_bits = ctx->g_init_bits);
531
532 ctx->ClearCode = (1 << (init_bits - 1));
533 ctx->EOFCode = ctx->ClearCode + 1;
534 ctx->free_ent = ctx->ClearCode + 2;
535
536 char_init(ctx);
537
538 ent = GIFNextPixel( im, ctx );
539
540 hshift = 0;
541 for ( fcode = (long) hsize; fcode < 65536L; fcode *= 2L )
542 ++hshift;
543 hshift = 8 - hshift; /* set hash code range bound */
544
545 hsize_reg = hsize;
546 cl_hash( (count_int) hsize_reg, ctx ); /* clear hash table */
547
548 output( (code_int)ctx->ClearCode, ctx );
549
550 #ifdef SIGNED_COMPARE_SLOW
551 while ( (c = GIFNextPixel( im, ctx )) != (unsigned) EOF ) {
552 #else /*SIGNED_COMPARE_SLOW*/
553 while ( (c = GIFNextPixel( im, ctx )) != EOF ) { /* } */
554 #endif /*SIGNED_COMPARE_SLOW*/
555
556 ++(ctx->in_count);
557
558 fcode = (long) (((long) c << maxbits) + ent);
559 i = (((code_int)c << hshift) ^ ent); /* xor hashing */
560
561 if ( HashTabOf (i) == fcode ) {
562 ent = CodeTabOf (i);
563 continue;
564 } else if ( (long)HashTabOf (i) < 0 ) /* empty slot */
565 goto nomatch;
566 disp = hsize_reg - i; /* secondary hash (after G. Knott) */
567 if ( i == 0 )
568 disp = 1;
569 probe:
570 if ( (i -= disp) < 0 )
571 i += hsize_reg;
572
573 if ( HashTabOf (i) == fcode ) {
574 ent = CodeTabOf (i);
575 continue;
576 }
577 if ( (long)HashTabOf (i) > 0 )
578 goto probe;
579 nomatch:
580 output ( (code_int) ent, ctx );
581 ++(ctx->out_count);
582 ent = c;
583 #ifdef SIGNED_COMPARE_SLOW
584 if ( (unsigned) ctx->free_ent < (unsigned) maxmaxcode) {
585 #else /*SIGNED_COMPARE_SLOW*/
586 if ( ctx->free_ent < maxmaxcode ) { /* } */
587 #endif /*SIGNED_COMPARE_SLOW*/
588 CodeTabOf (i) = ctx->free_ent++; /* code -> hashtable */
589 HashTabOf (i) = fcode;
590 } else
591 cl_block(ctx);
592 }
593 /*
594 * Put out the final code.
595 */
596 output( (code_int)ent, ctx );
597 ++(ctx->out_count);
598 output( (code_int) ctx->EOFCode, ctx );
599 }
600
601 /*****************************************************************
602 * TAG( output )
603 *
604 * Output the given code.
605 * Inputs:
606 * code: A n_bits-bit integer. If == -1, then EOF. This assumes
607 * that n_bits =< (long)wordsize - 1.
608 * Outputs:
609 * Outputs code to the file.
610 * Assumptions:
611 * Chars are 8 bits long.
612 * Algorithm:
613 * Maintain a GIFBITS character long buffer (so that 8 codes will
614 * fit in it exactly). Use the VAX insv instruction to insert each
615 * code in turn. When the buffer fills up empty it and start over.
616 */
617
618 static const unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F,
619 0x001F, 0x003F, 0x007F, 0x00FF,
620 0x01FF, 0x03FF, 0x07FF, 0x0FFF,
621 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF };
622
623
624 /* Arbitrary value to mark output is done. When we see EOFCode, then we don't
625 * expect to see any more data. If we do (e.g. corrupt image inputs), cur_bits
626 * might be negative, so flag it to return early.
627 */
628 #define CUR_BITS_FINISHED -1000
629
630
631 static void
632 output(code_int code, GifCtx *ctx)
633 {
634 if (ctx->cur_bits == CUR_BITS_FINISHED) {
635 return;
636 }
637
638 ctx->cur_accum &= masks[ ctx->cur_bits ];
639
640 if( ctx->cur_bits > 0 )
641 ctx->cur_accum |= ((long)code << ctx->cur_bits);
642 else
643 ctx->cur_accum = code;
644
645 ctx->cur_bits += ctx->n_bits;
646
647 while( ctx->cur_bits >= 8 ) {
648 char_out( (unsigned int)(ctx->cur_accum & 0xff), ctx );
649 ctx->cur_accum >>= 8;
650 ctx->cur_bits -= 8;
651 }
652
653 /*
654 * If the next entry is going to be too big for the code size,
655 * then increase it, if possible.
656 */
657 if ( ctx->free_ent > ctx->maxcode || ctx->clear_flg ) {
658
659 if( ctx->clear_flg ) {
660
661 ctx->maxcode = MAXCODE (ctx->n_bits = ctx->g_init_bits);
662 ctx->clear_flg = 0;
663
664 } else {
665
666 ++(ctx->n_bits);
667 if ( ctx->n_bits == maxbits )
668 ctx->maxcode = maxmaxcode;
669 else
670 ctx->maxcode = MAXCODE(ctx->n_bits);
671 }
672 }
673
674 if( code == ctx->EOFCode ) {
675 /*
676 * At EOF, write the rest of the buffer.
677 */
678 while( ctx->cur_bits > 0 ) {
679 char_out( (unsigned int)(ctx->cur_accum & 0xff), ctx);
680 ctx->cur_accum >>= 8;
681 ctx->cur_bits -= 8;
682 }
683
684 /* Flag that it's done to prevent re-entry. */
685 ctx->cur_bits = CUR_BITS_FINISHED;
686
687 flush_char(ctx);
688 }
689 }
690
691 /*
692 * Clear out the hash table
693 */
694 static void
695 cl_block (GifCtx *ctx) /* table clear for block compress */
696 {
697
698 cl_hash ( (count_int) hsize, ctx );
699 ctx->free_ent = ctx->ClearCode + 2;
700 ctx->clear_flg = 1;
701
702 output( (code_int)ctx->ClearCode, ctx);
703 }
704
705 static void
706 cl_hash(register count_int chsize, GifCtx *ctx) /* reset code table */
707
708 {
709
710 register count_int *htab_p = ctx->htab+chsize;
711
712 register long i;
713 register long m1 = -1;
714
715 i = chsize - 16;
716 do { /* might use Sys V memset(3) here */
717 *(htab_p-16) = m1;
718 *(htab_p-15) = m1;
719 *(htab_p-14) = m1;
720 *(htab_p-13) = m1;
721 *(htab_p-12) = m1;
722 *(htab_p-11) = m1;
723 *(htab_p-10) = m1;
724 *(htab_p-9) = m1;
725 *(htab_p-8) = m1;
726 *(htab_p-7) = m1;
727 *(htab_p-6) = m1;
728 *(htab_p-5) = m1;
729 *(htab_p-4) = m1;
730 *(htab_p-3) = m1;
731 *(htab_p-2) = m1;
732 *(htab_p-1) = m1;
733 htab_p -= 16;
734 } while ((i -= 16) >= 0);
735
736 for ( i += 16; i > 0; --i )
737 *--htab_p = m1;
738 }
739
740 /******************************************************************************
741 *
742 * GIF Specific routines
743 *
744 ******************************************************************************/
745
746 /*
747 * Set up the 'byte output' routine
748 */
749 static void
750 char_init(GifCtx *ctx)
751 {
752 ctx->a_count = 0;
753 }
754
755 /*
756 * Add a character to the end of the current packet, and if it is 254
757 * characters, flush the packet to disk.
758 */
759 static void
760 char_out(int c, GifCtx *ctx)
761 {
762 ctx->accum[ ctx->a_count++ ] = c;
763 if( ctx->a_count >= 254 )
764 flush_char(ctx);
765 }
766
767 /*
768 * Flush the packet to disk, and reset the accumulator
769 */
770 static void
771 flush_char(GifCtx *ctx)
772 {
773 if( ctx->a_count > 0 ) {
774 gdPutC( ctx->a_count, ctx->g_outfile );
775 gdPutBuf( ctx->accum, ctx->a_count, ctx->g_outfile );
776 ctx->a_count = 0;
777 }
778 }
779
780 static int gifPutWord(int w, gdIOCtx *out)
781 {
782 /* Byte order is little-endian */
783 gdPutC(w & 0xFF, out);
784 gdPutC((w >> 8) & 0xFF, out);
785 return 0;
786 }
787
788
789
