-
Notifications
You must be signed in to change notification settings - Fork 61
/
tkImgGIF.c
2198 lines (1909 loc) · 56.5 KB
/
tkImgGIF.c
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
/*
* tkImgGIF.c --
*
* A photo image file handler for GIF files. Reads 87a and 89a GIF files.
* At present, there only is a file write function. GIF images may be
* read using the -data option of the photo image. The data may be given
* as a binary string in a Tcl_Obj or by representing the data as BASE64
* encoded ascii. Derived from the giftoppm code found in the pbmplus
* package and tkImgFmtPPM.c in the tk4.0b2 distribution.
*
* Copyright (c) Reed Wade (wade@cs.utk.edu), University of Tennessee
* Copyright (c) 1995-1997 Sun Microsystems, Inc.
* Copyright (c) 1997 Australian National University
* Copyright (c) 2005-2010 Donal K. Fellows
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* This file also contains code from the giftoppm program, which is
* copyrighted as follows:
*
* +--------------------------------------------------------------------+
* | Copyright 1990, David Koblas. |
* | 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. |
* +--------------------------------------------------------------------+
*/
#include "tkInt.h"
/*
* GIF's are represented as data in either binary or base64 format. base64
* strings consist of 4 6-bit characters -> 3 8 bit bytes. A-Z, a-z, 0-9, +
* and / represent the 64 values (in order). '=' is a trailing padding char
* when the un-encoded data is not a multiple of 3 bytes. We'll ignore white
* space when encountered. Any other invalid character is treated as an EOF
*/
#define GIF_SPECIAL (256)
#define GIF_PAD (GIF_SPECIAL+1)
#define GIF_SPACE (GIF_SPECIAL+2)
#define GIF_BAD (GIF_SPECIAL+3)
#define GIF_DONE (GIF_SPECIAL+4)
/*
* structure to "mimic" FILE for Mread, so we can look like fread. The decoder
* state keeps track of which byte we are about to read, or EOF.
*/
typedef struct mFile {
unsigned char *data; /* mmencoded source string */
int c; /* bits left over from previous character */
int state; /* decoder state (0-4 or GIF_DONE) */
int length; /* Total amount of bytes in data */
} MFile;
/*
* Non-ASCII encoding support:
* Most data in a GIF image is binary and is treated as such. However, a few
* key bits are stashed in ASCII. If we try to compare those pieces to the
* char they represent, it will fail on any non-ASCII (eg, EBCDIC) system. To
* accomodate these systems, we test against the numeric value of the ASCII
* characters instead of the characters themselves. This is encoding
* independant.
*/
static const char GIF87a[] = { /* ASCII GIF87a */
0x47, 0x49, 0x46, 0x38, 0x37, 0x61, 0x00
};
static const char GIF89a[] = { /* ASCII GIF89a */
0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x00
};
#define GIF_TERMINATOR 0x3b /* ASCII ; */
#define GIF_EXTENSION 0x21 /* ASCII ! */
#define GIF_START 0x2c /* ASCII , */
/*
* Flags used to notify that we've got inline data instead of a file to read
* from. Note that we need to figure out which type of inline data we've got
* before handing off to the GIF reading code; this is done in StringReadGIF.
*/
#define INLINE_DATA_BINARY ((const char *) 0x01)
#define INLINE_DATA_BASE64 ((const char *) 0x02)
/*
* HACK ALERT!! HACK ALERT!! HACK ALERT!!
* This code is hard-wired for reading from files. In order to read from a
* data stream, we'll trick fread so we can reuse the same code. 0==from file;
* 1==from base64 encoded data; 2==from binary data
*/
typedef struct {
const char *fromData;
unsigned char workingBuffer[280];
struct {
int bytes;
int done;
unsigned int window;
int bitsInWindow;
unsigned char *c;
} reader;
} GIFImageConfig;
/*
* Type of a function used to do the writing to a file or buffer when
* serializing in the GIF format.
*/
typedef int (WriteBytesFunc) (ClientData clientData, const char *bytes,
int byteCount);
/*
* The format record for the GIF file format:
*/
static int FileMatchGIF(Tcl_Channel chan, const char *fileName,
Tcl_Obj *format, int *widthPtr, int *heightPtr,
Tcl_Interp *interp);
static int FileReadGIF(Tcl_Interp *interp, Tcl_Channel chan,
const char *fileName, Tcl_Obj *format,
Tk_PhotoHandle imageHandle, int destX, int destY,
int width, int height, int srcX, int srcY);
static int StringMatchGIF(Tcl_Obj *dataObj, Tcl_Obj *format,
int *widthPtr, int *heightPtr, Tcl_Interp *interp);
static int StringReadGIF(Tcl_Interp *interp, Tcl_Obj *dataObj,
Tcl_Obj *format, Tk_PhotoHandle imageHandle,
int destX, int destY, int width, int height,
int srcX, int srcY);
static int FileWriteGIF(Tcl_Interp *interp, const char *filename,
Tcl_Obj *format, Tk_PhotoImageBlock *blockPtr);
static int StringWriteGIF(Tcl_Interp *interp, Tcl_Obj *format,
Tk_PhotoImageBlock *blockPtr);
static int CommonWriteGIF(Tcl_Interp *interp, ClientData clientData,
WriteBytesFunc *writeProc, Tcl_Obj *format,
Tk_PhotoImageBlock *blockPtr);
Tk_PhotoImageFormat tkImgFmtGIF = {
"gif", /* name */
FileMatchGIF, /* fileMatchProc */
StringMatchGIF, /* stringMatchProc */
FileReadGIF, /* fileReadProc */
StringReadGIF, /* stringReadProc */
FileWriteGIF, /* fileWriteProc */
StringWriteGIF, /* stringWriteProc */
NULL
};
#define INTERLACE 0x40
#define LOCALCOLORMAP 0x80
#define BitSet(byte, bit) (((byte) & (bit)) == (bit))
#define MAXCOLORMAPSIZE 256
#define CM_RED 0
#define CM_GREEN 1
#define CM_BLUE 2
#define CM_ALPHA 3
#define MAX_LWZ_BITS 12
#define LM_to_uint(a,b) (((b)<<8)|(a))
/*
* Prototypes for local functions defined in this file:
*/
static int DoExtension(GIFImageConfig *gifConfPtr,
Tcl_Channel chan, int label, unsigned char *buffer,
int *transparent);
static int GetCode(Tcl_Channel chan, int code_size, int flag,
GIFImageConfig *gifConfPtr);
static int GetDataBlock(GIFImageConfig *gifConfPtr,
Tcl_Channel chan, unsigned char *buf);
static int ReadColorMap(GIFImageConfig *gifConfPtr,
Tcl_Channel chan, int number,
unsigned char buffer[MAXCOLORMAPSIZE][4]);
static int ReadGIFHeader(GIFImageConfig *gifConfPtr,
Tcl_Channel chan, int *widthPtr, int *heightPtr);
static int ReadImage(GIFImageConfig *gifConfPtr,
Tcl_Interp *interp, unsigned char *imagePtr,
Tcl_Channel chan, int len, int rows,
unsigned char cmap[MAXCOLORMAPSIZE][4], int srcX,
int srcY, int interlace, int transparent);
/*
* these are for the BASE64 image reader code only
*/
static int Fread(GIFImageConfig *gifConfPtr, unsigned char *dst,
size_t size, size_t count, Tcl_Channel chan);
static int Mread(unsigned char *dst, size_t size, size_t count,
MFile *handle);
static int Mgetc(MFile *handle);
static int char64(int c);
static void mInit(unsigned char *string, MFile *handle,
int length);
/*
* Types, defines and variables needed to write and compress a GIF.
*/
#define LSB(a) ((unsigned char) (((short)(a)) & 0x00FF))
#define MSB(a) ((unsigned char) (((short)(a)) >> 8))
#define GIFBITS 12
#define HSIZE 5003 /* 80% occupancy */
#define DEFAULT_BACKGROUND_VALUE 0xD9
typedef struct {
int ssize;
int csize;
int rsize;
unsigned char *pixelOffset;
int pixelSize;
int pixelPitch;
int greenOffset;
int blueOffset;
int alphaOffset;
int num;
unsigned char mapa[MAXCOLORMAPSIZE][3];
} GifWriterState;
typedef int (* ifunptr) (GifWriterState *statePtr);
/*
* Support for compression of GIFs.
*/
#define MAXCODE(numBits) (((long) 1 << (numBits)) - 1)
#ifdef SIGNED_COMPARE_SLOW
#define U(x) ((unsigned) (x))
#else
#define U(x) (x)
#endif
typedef struct {
int numBits; /* Number of bits/code. */
long maxCode; /* Maximum code, given numBits. */
int hashTable[HSIZE];
unsigned int codeTable[HSIZE];
long hSize; /* For dynamic table sizing. */
/*
* 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 codeTable. The tab_suffix table needs 2**GIFBITS characters. We get
* this from the beginning of hashTable. The output stack uses the rest of
* hashTable, and contains characters. There is plenty of room for any
* possible stack (stack used to be 8000 characters).
*/
int freeEntry; /* First unused entry. */
/*
* Block compression parameters. After all codes are used up, and
* compression rate changes, start over.
*/
int clearFlag;
int offset;
unsigned int inCount; /* Length of input */
unsigned int outCount; /* # of codes output (for debugging) */
/*
* 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.
*/
int initialBits;
ClientData destination;
WriteBytesFunc *writeProc;
int clearCode;
int eofCode;
unsigned long currentAccumulated;
int currentBits;
/*
* Number of characters so far in this 'packet'
*/
int accumulatedByteCount;
/*
* Define the storage for the packet accumulator
*/
unsigned char packetAccumulator[256];
} GIFState_t;
/*
* Definition of new functions to write GIFs
*/
static int ColorNumber(GifWriterState *statePtr,
int red, int green, int blue);
static void Compress(int initBits, ClientData handle,
WriteBytesFunc *writeProc, ifunptr readValue,
GifWriterState *statePtr);
static int IsNewColor(GifWriterState *statePtr,
int red, int green, int blue);
static void SaveMap(GifWriterState *statePtr,
Tk_PhotoImageBlock *blockPtr);
static int ReadValue(GifWriterState *statePtr);
static WriteBytesFunc WriteToChannel;
static WriteBytesFunc WriteToByteArray;
static void Output(GIFState_t *statePtr, long code);
static void ClearForBlock(GIFState_t *statePtr);
static void ClearHashTable(GIFState_t *statePtr, int hSize);
static void CharInit(GIFState_t *statePtr);
static void CharOut(GIFState_t *statePtr, int c);
static void FlushChar(GIFState_t *statePtr);
/*
*----------------------------------------------------------------------
*
* FileMatchGIF --
*
* This function is invoked by the photo image type to see if a file
* contains image data in GIF format.
*
* Results:
* The return value is 1 if the first characters in file f look like GIF
* data, and 0 otherwise.
*
* Side effects:
* The access position in f may change.
*
*----------------------------------------------------------------------
*/
static int
FileMatchGIF(
Tcl_Channel chan, /* The image file, open for reading. */
const char *fileName, /* The name of the image file. */
Tcl_Obj *format, /* User-specified format object, or NULL. */
int *widthPtr, int *heightPtr,
/* The dimensions of the image are returned
* here if the file is a valid raw GIF file. */
Tcl_Interp *interp) /* not used */
{
GIFImageConfig gifConf;
memset(&gifConf, 0, sizeof(GIFImageConfig));
return ReadGIFHeader(&gifConf, chan, widthPtr, heightPtr);
}
/*
*----------------------------------------------------------------------
*
* FileReadGIF --
*
* This function is called by the photo image type to read GIF format
* data from a file and write it into a given photo image.
*
* Results:
* A standard TCL completion code. If TCL_ERROR is returned then an error
* message is left in the interp's result.
*
* Side effects:
* The access position in file f is changed, and new data is added to the
* image given by imageHandle.
*
*----------------------------------------------------------------------
*/
static int
FileReadGIF(
Tcl_Interp *interp, /* Interpreter to use for reporting errors. */
Tcl_Channel chan, /* The image file, open for reading. */
const char *fileName, /* The name of the image file. */
Tcl_Obj *format, /* User-specified format object, or NULL. */
Tk_PhotoHandle imageHandle, /* The photo image to write into. */
int destX, int destY, /* Coordinates of top-left pixel in photo
* image to be written to. */
int width, int height, /* Dimensions of block of photo image to be
* written to. */
int srcX, int srcY) /* Coordinates of top-left pixel to be used in
* image being read. */
{
int fileWidth, fileHeight, imageWidth, imageHeight;
int nBytes, index = 0, argc = 0, i, result = TCL_ERROR;
Tcl_Obj **objv;
unsigned char buf[100];
unsigned char *trashBuffer = NULL;
int bitPixel;
unsigned char colorMap[MAXCOLORMAPSIZE][4];
int transparent = -1;
static const char *const optionStrings[] = {
"-index", NULL
};
GIFImageConfig gifConf, *gifConfPtr = &gifConf;
/*
* Decode the magic used to convey when we're sourcing data from a string
* source and not a file.
*/
memset(gifConfPtr, 0, sizeof(GIFImageConfig));
if (fileName == INLINE_DATA_BINARY || fileName == INLINE_DATA_BASE64) {
gifConfPtr->fromData = fileName;
fileName = "inline data";
}
/*
* Parse the format string to get options.
*/
if (format && Tcl_ListObjGetElements(interp, format,
&argc, &objv) != TCL_OK) {
return TCL_ERROR;
}
for (i = 1; i < argc; i++) {
if (Tcl_GetIndexFromObj(interp, objv[i], optionStrings, "option name",
0, &nBytes) != TCL_OK) {
return TCL_ERROR;
}
if (i == (argc-1)) {
Tcl_AppendResult(interp, "no value given for \"",
Tcl_GetString(objv[i]), "\" option", NULL);
return TCL_ERROR;
}
if (Tcl_GetIntFromObj(interp, objv[++i], &index) != TCL_OK) {
return TCL_ERROR;
}
}
/*
* Read the GIF file header and check for some sanity.
*/
if (!ReadGIFHeader(gifConfPtr, chan, &fileWidth, &fileHeight)) {
Tcl_AppendResult(interp, "couldn't read GIF header from file \"",
fileName, "\"", NULL);
return TCL_ERROR;
}
if ((fileWidth <= 0) || (fileHeight <= 0)) {
Tcl_AppendResult(interp, "GIF image file \"", fileName,
"\" has dimension(s) <= 0", NULL);
return TCL_ERROR;
}
/*
* Get the general colormap information.
*/
if (Fread(gifConfPtr, buf, 1, 3, chan) != 3) {
return TCL_OK;
}
bitPixel = 2 << (buf[0] & 0x07);
if (BitSet(buf[0], LOCALCOLORMAP)) { /* Global Colormap */
if (!ReadColorMap(gifConfPtr, chan, bitPixel, colorMap)) {
Tcl_AppendResult(interp, "error reading color map", NULL);
return TCL_ERROR;
}
}
if ((srcX + width) > fileWidth) {
width = fileWidth - srcX;
}
if ((srcY + height) > fileHeight) {
height = fileHeight - srcY;
}
if ((width <= 0) || (height <= 0)
|| (srcX >= fileWidth) || (srcY >= fileHeight)) {
return TCL_OK;
}
/*
* Make sure we have enough space in the photo image to hold the data from
* the GIF.
*/
if (Tk_PhotoExpand(interp, imageHandle,
destX + width, destY + height) != TCL_OK) {
return TCL_ERROR;
}
/*
* Search for the frame from the GIF to display.
*/
while (1) {
if (Fread(gifConfPtr, buf, 1, 1, chan) != 1) {
/*
* Premature end of image.
*/
Tcl_AppendResult(interp,
"premature end of image data for this index", NULL);
goto error;
}
switch (buf[0]) {
case GIF_TERMINATOR:
Tcl_AppendResult(interp, "no image data for this index", NULL);
goto error;
case GIF_EXTENSION:
/*
* This is a GIF extension.
*/
if (Fread(gifConfPtr, buf, 1, 1, chan) != 1) {
Tcl_SetResult(interp,
"error reading extension function code in GIF image",
TCL_STATIC);
goto error;
}
if (DoExtension(gifConfPtr, chan, buf[0],
gifConfPtr->workingBuffer, &transparent) < 0) {
Tcl_SetResult(interp, "error reading extension in GIF image",
TCL_STATIC);
goto error;
}
continue;
case GIF_START:
if (Fread(gifConfPtr, buf, 1, 9, chan) != 9) {
Tcl_SetResult(interp,
"couldn't read left/top/width/height in GIF image",
TCL_STATIC);
goto error;
}
break;
default:
/*
* Not a valid start character; ignore it.
*/
continue;
}
/*
* We've read the header for a GIF frame. Work out what we are going
* to do about it.
*/
imageWidth = LM_to_uint(buf[4], buf[5]);
imageHeight = LM_to_uint(buf[6], buf[7]);
bitPixel = 1 << ((buf[8] & 0x07) + 1);
if (index--) {
/*
* This is not the GIF frame we want to read: skip it.
*/
if (BitSet(buf[8], LOCALCOLORMAP)) {
if (!ReadColorMap(gifConfPtr, chan, bitPixel, colorMap)) {
Tcl_AppendResult(interp, "error reading color map", NULL);
goto error;
}
}
/*
* If we've not yet allocated a trash buffer, do so now.
*/
if (trashBuffer == NULL) {
nBytes = fileWidth * fileHeight * 3;
trashBuffer = ckalloc(nBytes);
}
/*
* Slurp! Process the data for this image and stuff it in a trash
* buffer.
*
* Yes, it might be more efficient here to *not* store the data
* (we're just going to throw it away later). However, I elected
* to implement it this way for good reasons. First, I wanted to
* avoid duplicating the (fairly complex) LWZ decoder in
* ReadImage. Fine, you say, why didn't you just modify it to
* allow the use of a NULL specifier for the output buffer? I
* tried that, but it negatively impacted the performance of what
* I think will be the common case: reading the first image in the
* file. Rather than marginally improve the speed of the less
* frequent case, I chose to maintain high performance for the
* common case.
*/
if (ReadImage(gifConfPtr, interp, trashBuffer, chan, imageWidth,
imageHeight, colorMap, 0, 0, 0, -1) != TCL_OK) {
goto error;
}
continue;
}
break;
}
/*
* Found the frame we want to read. Next, check for a local color map for
* this frame.
*/
if (BitSet(buf[8], LOCALCOLORMAP)) {
if (!ReadColorMap(gifConfPtr, chan, bitPixel, colorMap)) {
Tcl_AppendResult(interp, "error reading color map", NULL);
goto error;
}
}
/*
* Extract the location within the overall visible image to put the data
* in this frame, together with the size of this frame.
*/
index = LM_to_uint(buf[0], buf[1]);
srcX -= index;
if (srcX<0) {
destX -= srcX; width += srcX;
srcX = 0;
}
if (width > imageWidth) {
width = imageWidth;
}
index = LM_to_uint(buf[2], buf[3]);
srcY -= index;
if (index > srcY) {
destY -= srcY; height += srcY;
srcY = 0;
}
if (height > imageHeight) {
height = imageHeight;
}
if ((width > 0) && (height > 0)) {
Tk_PhotoImageBlock block;
/*
* Read the data and put it into the photo buffer for display by the
* general image machinery.
*/
block.width = width;
block.height = height;
block.pixelSize = (transparent>=0) ? 4 : 3;
block.offset[0] = 0;
block.offset[1] = 1;
block.offset[2] = 2;
block.offset[3] = (transparent>=0) ? 3 : 0;
block.pitch = block.pixelSize * imageWidth;
nBytes = block.pitch * imageHeight;
block.pixelPtr = ckalloc(nBytes);
if (ReadImage(gifConfPtr, interp, block.pixelPtr, chan, imageWidth,
imageHeight, colorMap, srcX, srcY, BitSet(buf[8],INTERLACE),
transparent) != TCL_OK) {
ckfree(block.pixelPtr);
goto error;
}
if (Tk_PhotoPutBlock(interp, imageHandle, &block, destX, destY,
width, height, TK_PHOTO_COMPOSITE_SET) != TCL_OK) {
ckfree(block.pixelPtr);
goto error;
}
ckfree(block.pixelPtr);
}
/*
* We've successfully read the GIF frame (or there was nothing to read,
* which suits as well). We're done.
*/
Tcl_AppendResult(interp, tkImgFmtGIF.name, NULL);
result = TCL_OK;
error:
/*
* If a trash buffer has been allocated, free it now.
*/
if (trashBuffer != NULL) {
ckfree(trashBuffer);
}
return result;
}
/*
*----------------------------------------------------------------------
*
* StringMatchGIF --
*
* This function is invoked by the photo image type to see if an object
* contains image data in GIF format.
*
* Results:
* The return value is 1 if the first characters in the data are like GIF
* data, and 0 otherwise.
*
* Side effects:
* The size of the image is placed in widthPtr and heightPtr.
*
*----------------------------------------------------------------------
*/
static int
StringMatchGIF(
Tcl_Obj *dataObj, /* the object containing the image data */
Tcl_Obj *format, /* the image format object, or NULL */
int *widthPtr, /* where to put the string width */
int *heightPtr, /* where to put the string height */
Tcl_Interp *interp) /* not used */
{
unsigned char *data, header[10];
int got, length;
MFile handle;
data = Tcl_GetByteArrayFromObj(dataObj, &length);
/*
* Header is a minimum of 10 bytes.
*/
if (length < 10) {
return 0;
}
/*
* Check whether the data is Base64 encoded.
*/
if ((strncmp(GIF87a, (char *) data, 6) != 0) &&
(strncmp(GIF89a, (char *) data, 6) != 0)) {
/*
* Try interpreting the data as Base64 encoded
*/
mInit((unsigned char *) data, &handle, length);
got = Mread(header, 10, 1, &handle);
if (got != 10 ||
((strncmp(GIF87a, (char *) header, 6) != 0)
&& (strncmp(GIF89a, (char *) header, 6) != 0))) {
return 0;
}
} else {
memcpy(header, data, 10);
}
*widthPtr = LM_to_uint(header[6], header[7]);
*heightPtr = LM_to_uint(header[8], header[9]);
return 1;
}
/*
*----------------------------------------------------------------------
*
* StringReadGIF --
*
* This function is called by the photo image type to read GIF format
* data from an object, optionally base64 encoded, and give it to the
* photo image.
*
* Results:
* A standard TCL completion code. If TCL_ERROR is returned then an error
* message is left in the interp's result.
*
* Side effects:
* New data is added to the image given by imageHandle. This function
* calls FileReadGIF by redefining the operation of fprintf temporarily.
*
*----------------------------------------------------------------------
*/
static int
StringReadGIF(
Tcl_Interp *interp, /* interpreter for reporting errors in */
Tcl_Obj *dataObj, /* object containing the image */
Tcl_Obj *format, /* format object, or NULL */
Tk_PhotoHandle imageHandle, /* the image to write this data into */
int destX, int destY, /* The rectangular region of the */
int width, int height, /* image to copy */
int srcX, int srcY)
{
MFile handle, *hdlPtr = &handle;
int length;
const char *xferFormat;
unsigned char *data = Tcl_GetByteArrayFromObj(dataObj, &length);
mInit(data, hdlPtr, length);
/*
* Check whether the data is Base64 encoded by doing a character-by-
* charcter comparison with the binary-format headers; BASE64-encoded
* never matches (matching the other way is harder because of potential
* padding of the BASE64 data).
*/
if (strncmp(GIF87a, (char *) data, 6)
&& strncmp(GIF89a, (char *) data, 6)) {
xferFormat = INLINE_DATA_BASE64;
} else {
xferFormat = INLINE_DATA_BINARY;
}
/*
* Fall through to the file reader now that we have a correctly-configured
* pseudo-channel to pull the data from.
*/
return FileReadGIF(interp, (Tcl_Channel) hdlPtr, xferFormat, format,
imageHandle, destX, destY, width, height, srcX, srcY);
}
/*
*----------------------------------------------------------------------
*
* ReadGIFHeader --
*
* This function reads the GIF header from the beginning of a GIF file
* and returns the dimensions of the image.
*
* Results:
* The return value is 1 if file "f" appears to start with a valid GIF
* header, 0 otherwise. If the header is valid, then *widthPtr and
* *heightPtr are modified to hold the dimensions of the image.
*
* Side effects:
* The access position in f advances.
*
*----------------------------------------------------------------------
*/
static int
ReadGIFHeader(
GIFImageConfig *gifConfPtr,
Tcl_Channel chan, /* Image file to read the header from */
int *widthPtr, int *heightPtr)
/* The dimensions of the image are returned
* here. */
{
unsigned char buf[7];
if ((Fread(gifConfPtr, buf, 1, 6, chan) != 6)
|| ((strncmp(GIF87a, (char *) buf, 6) != 0)
&& (strncmp(GIF89a, (char *) buf, 6) != 0))) {
return 0;
}
if (Fread(gifConfPtr, buf, 1, 4, chan) != 4) {
return 0;
}
*widthPtr = LM_to_uint(buf[0], buf[1]);
*heightPtr = LM_to_uint(buf[2], buf[3]);
return 1;
}
/*
*-----------------------------------------------------------------
* The code below is copied from the giftoppm program and modified just
* slightly.
*-----------------------------------------------------------------
*/
static int
ReadColorMap(
GIFImageConfig *gifConfPtr,
Tcl_Channel chan,
int number,
unsigned char buffer[MAXCOLORMAPSIZE][4])
{
int i;
unsigned char rgb[3];
for (i = 0; i < number; ++i) {
if (Fread(gifConfPtr, rgb, sizeof(rgb), 1, chan) <= 0) {
return 0;
}
if (buffer) {
buffer[i][CM_RED] = rgb[0];
buffer[i][CM_GREEN] = rgb[1];
buffer[i][CM_BLUE] = rgb[2];
buffer[i][CM_ALPHA] = 255;
}
}
return 1;
}
static int
DoExtension(
GIFImageConfig *gifConfPtr,
Tcl_Channel chan,
int label,
unsigned char *buf,
int *transparent)
{
int count;
switch (label) {
case 0x01: /* Plain Text Extension */
break;
case 0xff: /* Application Extension */
break;
case 0xfe: /* Comment Extension */
do {
count = GetDataBlock(gifConfPtr, chan, buf);
} while (count > 0);
return count;
case 0xf9: /* Graphic Control Extension */
count = GetDataBlock(gifConfPtr, chan, buf);
if (count < 0) {
return 1;
}
if ((buf[0] & 0x1) != 0) {
*transparent = buf[3];
}
do {
count = GetDataBlock(gifConfPtr, chan, buf);
} while (count > 0);
return count;
}
do {
count = GetDataBlock(gifConfPtr, chan, buf);
} while (count > 0);
return count;
}
static int
GetDataBlock(
GIFImageConfig *gifConfPtr,
Tcl_Channel chan,
unsigned char *buf)
{
unsigned char count;
if (Fread(gifConfPtr, &count, 1, 1, chan) <= 0) {
return -1;
}
if ((count != 0) && (Fread(gifConfPtr, buf, count, 1, chan) <= 0)) {
return -1;
}
return count;
}
/*
*----------------------------------------------------------------------
*
* ReadImage --
*
* Process a GIF image from a given source, with a given height, width,
* transparency, etc.
*
* This code is based on the code found in the ImageMagick GIF decoder,
* which is (c) 2000 ImageMagick Studio.
*
* Some thoughts on our implementation:
* It sure would be nice if ReadImage didn't take 11 parameters! I think
* that if we were smarter, we could avoid doing that.
*
* Possible further optimizations: we could pull the GetCode function
* directly into ReadImage, which would improve our speed.
*
* Results:
* Processes a GIF image and loads the pixel data into a memory array.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
static int
ReadImage(
GIFImageConfig *gifConfPtr,
Tcl_Interp *interp,
unsigned char *imagePtr,
Tcl_Channel chan,
int len, int rows,
unsigned char cmap[MAXCOLORMAPSIZE][4],
int srcX, int srcY,
int interlace,
int transparent)
{
unsigned char initialCodeSize;
int xpos = 0, ypos = 0, pass = 0, i;
register unsigned char *pixelPtr;
static const int interlaceStep[] = { 8, 8, 4, 2 };