2 * Gif extracting routines - derived from libungif
4 * Portions Copyright 2006 Mike McCormack
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
22 * Original copyright notice:
24 * The GIFLIB distribution is Copyright (c) 1997 Eric S. Raymond
26 * Permission is hereby granted, free of charge, to any person obtaining a copy
27 * of this software and associated documentation files (the "Software"), to deal
28 * in the Software without restriction, including without limitation the rights
29 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
30 * copies of the Software, and to permit persons to whom the Software is
31 * furnished to do so, subject to the following conditions:
33 * The above copyright notice and this permission notice shall be included in
34 * all copies or substantial portions of the Software.
38 /******************************************************************************
39 * "Gif-Lib" - Yet another gif library.
41 * Written by: Gershon Elber IBM PC Ver 1.1, Aug. 1990
42 ******************************************************************************
43 * The kernel of the GIF Decoding process can be found here.
44 ******************************************************************************
46 * 16 Jun 89 - Version 1.0 by Gershon Elber.
47 * 3 Sep 90 - Version 1.1 by Gershon Elber (Support for Gif89, Unique names).
48 *****************************************************************************/
59 static void *ungif_alloc( size_t sz
)
61 return HeapAlloc( GetProcessHeap(), 0, sz
);
64 static void *ungif_calloc( size_t num
, size_t sz
)
66 return HeapAlloc( GetProcessHeap(), HEAP_ZERO_MEMORY
, num
*sz
);
69 static void *ungif_realloc( void *ptr
, size_t sz
)
71 return HeapReAlloc( GetProcessHeap(), 0, ptr
, sz
);
74 static void ungif_free( void *ptr
)
76 HeapFree( GetProcessHeap(), 0, ptr
);
79 #define LZ_MAX_CODE 4095 /* Biggest code possible in 12 bits. */
82 #define NO_SUCH_CODE 4098 /* Impossible code, to signal empty. */
84 typedef struct GifFilePrivateType
{
85 GifWord BitsPerPixel
, /* Bits per pixel (Codes uses at least this + 1). */
86 ClearCode
, /* The CLEAR LZ code. */
87 EOFCode
, /* The EOF LZ code. */
88 RunningCode
, /* The next code algorithm can generate. */
89 RunningBits
, /* The number of bits required to represent RunningCode. */
90 MaxCode1
, /* 1 bigger than max. possible code, in RunningBits bits. */
91 LastCode
, /* The code before the current code. */
92 CrntCode
, /* Current algorithm code. */
93 StackPtr
, /* For character stack (see below). */
94 CrntShiftState
; /* Number of bits in CrntShiftDWord. */
95 unsigned long CrntShiftDWord
; /* For bytes decomposition into codes. */
96 unsigned long PixelCount
; /* Number of pixels in image. */
97 InputFunc Read
; /* function to read gif input (TVT) */
98 GifByteType Buf
[256]; /* Compressed input is buffered here. */
99 GifByteType Stack
[LZ_MAX_CODE
]; /* Decoded pixels are stacked here. */
100 GifByteType Suffix
[LZ_MAX_CODE
+ 1]; /* So we can trace the codes. */
101 GifPrefixType Prefix
[LZ_MAX_CODE
+ 1];
102 } GifFilePrivateType
;
104 /* avoid extra function call in case we use fread (TVT) */
105 #define READ(_gif,_buf,_len) \
106 ((GifFilePrivateType*)_gif->Private)->Read(_gif,_buf,_len)
108 static int DGifGetWord(GifFileType
*GifFile
, GifWord
*Word
);
109 static int DGifSetupDecompress(GifFileType
*GifFile
);
110 static int DGifDecompressLine(GifFileType
*GifFile
, GifPixelType
*Line
, int LineLen
);
111 static int DGifGetPrefixChar(const GifPrefixType
*Prefix
, int Code
, int ClearCode
);
112 static int DGifDecompressInput(GifFileType
*GifFile
, int *Code
);
113 static int DGifBufferedInput(GifFileType
*GifFile
, GifByteType
*Buf
,
114 GifByteType
*NextByte
);
116 static int DGifGetExtensionNext(GifFileType
* GifFile
, GifByteType
** GifExtension
);
117 static int DGifGetCodeNext(GifFileType
* GifFile
, GifByteType
** GifCodeBlock
);
119 /******************************************************************************
120 * Miscellaneous utility functions
121 *****************************************************************************/
123 /* return smallest bitfield size n will fit in */
129 for (i
= 1; i
<= 8; i
++)
135 /******************************************************************************
136 * Color map object functions
137 *****************************************************************************/
140 * Allocate a color map of given size; initialize with contents of
141 * ColorMap if that pointer is non-NULL.
143 static ColorMapObject
*
144 MakeMapObject(int ColorCount
,
145 const GifColorType
* ColorMap
) {
147 ColorMapObject
*Object
;
149 /*** FIXME: Our ColorCount has to be a power of two. Is it necessary to
150 * make the user know that or should we automatically round up instead? */
151 if (ColorCount
!= (1 << BitSize(ColorCount
))) {
155 Object
= ungif_alloc(sizeof(ColorMapObject
));
156 if (Object
== NULL
) {
160 Object
->Colors
= ungif_calloc(ColorCount
, sizeof(GifColorType
));
161 if (Object
->Colors
== NULL
) {
165 Object
->ColorCount
= ColorCount
;
166 Object
->BitsPerPixel
= BitSize(ColorCount
);
169 memcpy(Object
->Colors
, ColorMap
, ColorCount
* sizeof(GifColorType
));
176 * Free a color map object
179 FreeMapObject(ColorMapObject
* Object
) {
181 if (Object
!= NULL
) {
182 ungif_free(Object
->Colors
);
185 * When we are willing to break API we need to make this function
186 * FreeMapObject(ColorMapObject **Object)
187 * and do this assignment to NULL here:
194 AddExtensionBlock(Extensions
*New
,
196 const unsigned char ExtData
[]) {
200 if (New
->ExtensionBlocks
== NULL
)
201 New
->ExtensionBlocks
= ungif_alloc(sizeof(ExtensionBlock
));
203 New
->ExtensionBlocks
= ungif_realloc(New
->ExtensionBlocks
,
204 sizeof(ExtensionBlock
) *
205 (New
->ExtensionBlockCount
+ 1));
207 if (New
->ExtensionBlocks
== NULL
)
210 ep
= &New
->ExtensionBlocks
[New
->ExtensionBlockCount
++];
212 ep
->ByteCount
=Len
+ 3;
213 ep
->Bytes
= ungif_alloc(ep
->ByteCount
+ 3);
214 if (ep
->Bytes
== NULL
)
217 /* Extension Header */
219 ep
->Bytes
[1] = New
->Function
;
223 memcpy(ep
->Bytes
+ 3, ExtData
, Len
);
224 ep
->Function
= New
->Function
;
231 AppendExtensionBlock(Extensions
*New
,
233 const unsigned char ExtData
[])
237 if (New
->ExtensionBlocks
== NULL
)
240 ep
= &New
->ExtensionBlocks
[New
->ExtensionBlockCount
- 1];
242 ep
->Bytes
= ungif_realloc(ep
->Bytes
, ep
->ByteCount
+ Len
+ 1);
243 if (ep
->Bytes
== NULL
)
246 ep
->Bytes
[ep
->ByteCount
] = Len
;
249 memcpy(ep
->Bytes
+ ep
->ByteCount
+ 1, ExtData
, Len
);
251 ep
->ByteCount
+= Len
+ 1;
257 FreeExtension(Extensions
*Extensions
)
261 if ((Extensions
== NULL
) || (Extensions
->ExtensionBlocks
== NULL
)) {
264 for (ep
= Extensions
->ExtensionBlocks
;
265 ep
< (Extensions
->ExtensionBlocks
+ Extensions
->ExtensionBlockCount
); ep
++)
266 ungif_free(ep
->Bytes
);
267 ungif_free(Extensions
->ExtensionBlocks
);
268 Extensions
->ExtensionBlocks
= NULL
;
271 /******************************************************************************
272 * Image block allocation functions
273 ******************************************************************************/
276 FreeSavedImages(GifFileType
* GifFile
) {
280 if ((GifFile
== NULL
) || (GifFile
->SavedImages
== NULL
)) {
283 for (sp
= GifFile
->SavedImages
;
284 sp
< GifFile
->SavedImages
+ GifFile
->ImageCount
; sp
++) {
285 if (sp
->ImageDesc
.ColorMap
) {
286 FreeMapObject(sp
->ImageDesc
.ColorMap
);
287 sp
->ImageDesc
.ColorMap
= NULL
;
290 ungif_free(sp
->RasterBits
);
292 if (sp
->Extensions
.ExtensionBlocks
)
293 FreeExtension(&sp
->Extensions
);
295 ungif_free(GifFile
->SavedImages
);
296 GifFile
->SavedImages
=NULL
;
299 /******************************************************************************
300 * This routine should be called before any other DGif calls. Note that
301 * this routine is called automatically from DGif file open routines.
302 *****************************************************************************/
304 DGifGetScreenDesc(GifFileType
* GifFile
) {
306 int i
, BitsPerPixel
, SortFlag
;
309 /* Put the screen descriptor into the file: */
310 if (DGifGetWord(GifFile
, &GifFile
->SWidth
) == GIF_ERROR
||
311 DGifGetWord(GifFile
, &GifFile
->SHeight
) == GIF_ERROR
)
314 if (READ(GifFile
, Buf
, 3) != 3) {
317 GifFile
->SColorResolution
= (((Buf
[0] & 0x70) + 1) >> 4) + 1;
318 SortFlag
= (Buf
[0] & 0x08) != 0;
319 BitsPerPixel
= (Buf
[0] & 0x07) + 1;
320 GifFile
->SBackGroundColor
= Buf
[1];
321 GifFile
->SAspectRatio
= Buf
[2];
322 if (Buf
[0] & 0x80) { /* Do we have global color map? */
324 GifFile
->SColorMap
= MakeMapObject(1 << BitsPerPixel
, NULL
);
325 if (GifFile
->SColorMap
== NULL
) {
329 /* Get the global color map: */
330 GifFile
->SColorMap
->SortFlag
= SortFlag
;
331 for (i
= 0; i
< GifFile
->SColorMap
->ColorCount
; i
++) {
332 if (READ(GifFile
, Buf
, 3) != 3) {
333 FreeMapObject(GifFile
->SColorMap
);
334 GifFile
->SColorMap
= NULL
;
337 GifFile
->SColorMap
->Colors
[i
].Red
= Buf
[0];
338 GifFile
->SColorMap
->Colors
[i
].Green
= Buf
[1];
339 GifFile
->SColorMap
->Colors
[i
].Blue
= Buf
[2];
342 GifFile
->SColorMap
= NULL
;
348 /******************************************************************************
349 * This routine should be called before any attempt to read an image.
350 *****************************************************************************/
352 DGifGetRecordType(GifFileType
* GifFile
,
353 GifRecordType
* Type
) {
357 if (READ(GifFile
, &Buf
, 1) != 1) {
358 /* Wine-specific behavior: Native accepts broken GIF files that have no
359 * terminator, so we match this by treating EOF as a terminator. */
360 *Type
= TERMINATE_RECORD_TYPE
;
366 *Type
= IMAGE_DESC_RECORD_TYPE
;
369 *Type
= EXTENSION_RECORD_TYPE
;
372 *Type
= TERMINATE_RECORD_TYPE
;
375 *Type
= UNDEFINED_RECORD_TYPE
;
382 /******************************************************************************
383 * This routine should be called before any attempt to read an image.
384 * Note it is assumed the Image desc. header (',') has been read.
385 *****************************************************************************/
387 DGifGetImageDesc(GifFileType
* GifFile
) {
389 int i
, BitsPerPixel
, SortFlag
;
391 GifFilePrivateType
*Private
= GifFile
->Private
;
394 if (DGifGetWord(GifFile
, &GifFile
->Image
.Left
) == GIF_ERROR
||
395 DGifGetWord(GifFile
, &GifFile
->Image
.Top
) == GIF_ERROR
||
396 DGifGetWord(GifFile
, &GifFile
->Image
.Width
) == GIF_ERROR
||
397 DGifGetWord(GifFile
, &GifFile
->Image
.Height
) == GIF_ERROR
)
399 if (READ(GifFile
, Buf
, 1) != 1) {
402 BitsPerPixel
= (Buf
[0] & 0x07) + 1;
403 SortFlag
= (Buf
[0] & 0x20) != 0;
404 GifFile
->Image
.Interlace
= (Buf
[0] & 0x40);
405 if (Buf
[0] & 0x80) { /* Does this image have local color map? */
407 /*** FIXME: Why do we check both of these in order to do this?
408 * Why do we have both Image and SavedImages? */
409 if (GifFile
->Image
.ColorMap
&& GifFile
->SavedImages
== NULL
)
410 FreeMapObject(GifFile
->Image
.ColorMap
);
412 GifFile
->Image
.ColorMap
= MakeMapObject(1 << BitsPerPixel
, NULL
);
413 if (GifFile
->Image
.ColorMap
== NULL
) {
417 /* Get the image local color map: */
418 GifFile
->Image
.ColorMap
->SortFlag
= SortFlag
;
419 for (i
= 0; i
< GifFile
->Image
.ColorMap
->ColorCount
; i
++) {
420 if (READ(GifFile
, Buf
, 3) != 3) {
421 FreeMapObject(GifFile
->Image
.ColorMap
);
422 GifFile
->Image
.ColorMap
= NULL
;
425 GifFile
->Image
.ColorMap
->Colors
[i
].Red
= Buf
[0];
426 GifFile
->Image
.ColorMap
->Colors
[i
].Green
= Buf
[1];
427 GifFile
->Image
.ColorMap
->Colors
[i
].Blue
= Buf
[2];
429 } else if (GifFile
->Image
.ColorMap
) {
430 FreeMapObject(GifFile
->Image
.ColorMap
);
431 GifFile
->Image
.ColorMap
= NULL
;
434 if (GifFile
->SavedImages
) {
435 if ((GifFile
->SavedImages
= ungif_realloc(GifFile
->SavedImages
,
437 (GifFile
->ImageCount
+ 1))) == NULL
) {
441 if ((GifFile
->SavedImages
= ungif_alloc(sizeof(SavedImage
))) == NULL
) {
446 sp
= &GifFile
->SavedImages
[GifFile
->ImageCount
];
447 sp
->ImageDesc
= GifFile
->Image
;
448 if (GifFile
->Image
.ColorMap
!= NULL
) {
449 sp
->ImageDesc
.ColorMap
= MakeMapObject(
450 GifFile
->Image
.ColorMap
->ColorCount
,
451 GifFile
->Image
.ColorMap
->Colors
);
452 if (sp
->ImageDesc
.ColorMap
== NULL
) {
455 sp
->ImageDesc
.ColorMap
->SortFlag
= GifFile
->Image
.ColorMap
->SortFlag
;
457 sp
->RasterBits
= NULL
;
458 sp
->Extensions
.ExtensionBlockCount
= 0;
459 sp
->Extensions
.ExtensionBlocks
= NULL
;
461 GifFile
->ImageCount
++;
463 Private
->PixelCount
= (long)GifFile
->Image
.Width
*
464 (long)GifFile
->Image
.Height
;
466 DGifSetupDecompress(GifFile
); /* Reset decompress algorithm parameters. */
471 /******************************************************************************
472 * Get one full scanned line (Line) of length LineLen from GIF file.
473 *****************************************************************************/
475 DGifGetLine(GifFileType
* GifFile
,
480 GifFilePrivateType
*Private
= GifFile
->Private
;
483 LineLen
= GifFile
->Image
.Width
;
485 if ((Private
->PixelCount
-= LineLen
) > 0xffff0000UL
) {
489 if (DGifDecompressLine(GifFile
, Line
, LineLen
) == GIF_OK
) {
490 if (Private
->PixelCount
== 0) {
491 /* We probably would not be called any more, so lets clean
492 * everything before we return: need to flush out all rest of
493 * image until empty block (size 0) detected. We use GetCodeNext. */
495 if (DGifGetCodeNext(GifFile
, &Dummy
) == GIF_ERROR
)
497 while (Dummy
!= NULL
) ;
504 /******************************************************************************
505 * Get an extension block (see GIF manual) from gif file. This routine only
506 * returns the first data block, and DGifGetExtensionNext should be called
507 * after this one until NULL extension is returned.
508 * The Extension should NOT be freed by the user (not dynamically allocated).
509 * Note it is assumed the Extension desc. header ('!') has been read.
510 *****************************************************************************/
512 DGifGetExtension(GifFileType
* GifFile
,
514 GifByteType
** Extension
) {
518 if (READ(GifFile
, &Buf
, 1) != 1) {
523 return DGifGetExtensionNext(GifFile
, Extension
);
526 /******************************************************************************
527 * Get a following extension block (see GIF manual) from gif file. This
528 * routine should be called until NULL Extension is returned.
529 * The Extension should NOT be freed by the user (not dynamically allocated).
530 *****************************************************************************/
532 DGifGetExtensionNext(GifFileType
* GifFile
,
533 GifByteType
** Extension
) {
536 GifFilePrivateType
*Private
= GifFile
->Private
;
538 if (READ(GifFile
, &Buf
, 1) != 1) {
542 *Extension
= Private
->Buf
; /* Use private unused buffer. */
543 (*Extension
)[0] = Buf
; /* Pascal strings notation (pos. 0 is len.). */
544 if (READ(GifFile
, &((*Extension
)[1]), Buf
) != Buf
) {
553 /******************************************************************************
554 * Get 2 bytes (word) from the given file:
555 *****************************************************************************/
557 DGifGetWord(GifFileType
* GifFile
,
562 if (READ(GifFile
, c
, 2) != 2) {
566 *Word
= (((unsigned int)c
[1]) << 8) + c
[0];
570 /******************************************************************************
571 * Continue to get the image code in compressed form. This routine should be
572 * called until NULL block is returned.
573 * The block should NOT be freed by the user (not dynamically allocated).
574 *****************************************************************************/
576 DGifGetCodeNext(GifFileType
* GifFile
,
577 GifByteType
** CodeBlock
) {
580 GifFilePrivateType
*Private
= GifFile
->Private
;
582 if (READ(GifFile
, &Buf
, 1) != 1) {
587 *CodeBlock
= Private
->Buf
; /* Use private unused buffer. */
588 (*CodeBlock
)[0] = Buf
; /* Pascal strings notation (pos. 0 is len.). */
589 if (READ(GifFile
, &((*CodeBlock
)[1]), Buf
) != Buf
) {
594 Private
->Buf
[0] = 0; /* Make sure the buffer is empty! */
595 Private
->PixelCount
= 0; /* And local info. indicate image read. */
601 /******************************************************************************
602 * Setup the LZ decompression for this image:
603 *****************************************************************************/
605 DGifSetupDecompress(GifFileType
* GifFile
) {
608 GifByteType CodeSize
;
609 GifPrefixType
*Prefix
;
610 GifFilePrivateType
*Private
= GifFile
->Private
;
612 READ(GifFile
, &CodeSize
, 1); /* Read Code size from file. */
613 BitsPerPixel
= CodeSize
;
615 Private
->Buf
[0] = 0; /* Input Buffer empty. */
616 Private
->BitsPerPixel
= BitsPerPixel
;
617 Private
->ClearCode
= (1 << BitsPerPixel
);
618 Private
->EOFCode
= Private
->ClearCode
+ 1;
619 Private
->RunningCode
= Private
->EOFCode
+ 1;
620 Private
->RunningBits
= BitsPerPixel
+ 1; /* Number of bits per code. */
621 Private
->MaxCode1
= 1 << Private
->RunningBits
; /* Max. code + 1. */
622 Private
->StackPtr
= 0; /* No pixels on the pixel stack. */
623 Private
->LastCode
= NO_SUCH_CODE
;
624 Private
->CrntShiftState
= 0; /* No information in CrntShiftDWord. */
625 Private
->CrntShiftDWord
= 0;
627 Prefix
= Private
->Prefix
;
628 for (i
= 0; i
<= LZ_MAX_CODE
; i
++)
629 Prefix
[i
] = NO_SUCH_CODE
;
634 /******************************************************************************
635 * The LZ decompression routine:
636 * This version decompress the given gif file into Line of length LineLen.
637 * This routine can be called few times (one per scan line, for example), in
638 * order the complete the whole image.
639 *****************************************************************************/
641 DGifDecompressLine(GifFileType
* GifFile
,
646 int j
, CrntCode
, EOFCode
, ClearCode
, CrntPrefix
, LastCode
, StackPtr
;
647 GifByteType
*Stack
, *Suffix
;
648 GifPrefixType
*Prefix
;
649 GifFilePrivateType
*Private
= GifFile
->Private
;
651 StackPtr
= Private
->StackPtr
;
652 Prefix
= Private
->Prefix
;
653 Suffix
= Private
->Suffix
;
654 Stack
= Private
->Stack
;
655 EOFCode
= Private
->EOFCode
;
656 ClearCode
= Private
->ClearCode
;
657 LastCode
= Private
->LastCode
;
660 /* Let pop the stack off before continuing to read the gif file: */
661 while (StackPtr
!= 0 && i
< LineLen
)
662 Line
[i
++] = Stack
[--StackPtr
];
665 while (i
< LineLen
) { /* Decode LineLen items. */
666 if (DGifDecompressInput(GifFile
, &CrntCode
) == GIF_ERROR
)
669 if (CrntCode
== EOFCode
) {
670 /* Note, however, that usually we will not be here as we will stop
671 * decoding as soon as we got all the pixel, or EOF code will
672 * not be read at all, and DGifGetLine/Pixel clean everything. */
673 if (i
!= LineLen
- 1 || Private
->PixelCount
!= 0) {
677 } else if (CrntCode
== ClearCode
) {
678 /* We need to start over again: */
679 for (j
= 0; j
<= LZ_MAX_CODE
; j
++)
680 Prefix
[j
] = NO_SUCH_CODE
;
681 Private
->RunningCode
= Private
->EOFCode
+ 1;
682 Private
->RunningBits
= Private
->BitsPerPixel
+ 1;
683 Private
->MaxCode1
= 1 << Private
->RunningBits
;
684 LastCode
= Private
->LastCode
= NO_SUCH_CODE
;
686 /* It's a regular code - if in pixel range simply add it to output
687 * stream, otherwise trace to codes linked list until the prefix
688 * is in pixel range: */
689 if (CrntCode
< ClearCode
) {
690 /* This is simple - its pixel scalar, so add it to output: */
691 Line
[i
++] = CrntCode
;
693 /* It's a code to be traced: trace the linked list
694 * until the prefix is a pixel, while pushing the suffix
695 * pixels on our stack. If we done, pop the stack in reverse
696 * order (that's what stack is good for!) for output. */
697 if (Prefix
[CrntCode
] == NO_SUCH_CODE
) {
698 /* Only allowed if CrntCode is exactly the running code:
699 * In that case CrntCode = XXXCode, CrntCode or the
700 * prefix code is last code and the suffix char is
701 * exactly the prefix of last code! */
702 if (CrntCode
== Private
->RunningCode
- 2) {
703 CrntPrefix
= LastCode
;
704 Suffix
[Private
->RunningCode
- 2] =
705 Stack
[StackPtr
++] = DGifGetPrefixChar(Prefix
,
712 CrntPrefix
= CrntCode
;
714 /* Now (if image is O.K.) we should not get a NO_SUCH_CODE
715 * during the trace. As we might loop forever, in case of
716 * defective image, we count the number of loops we trace
717 * and stop if we got LZ_MAX_CODE. Obviously we cannot
718 * loop more than that. */
720 while (j
++ <= LZ_MAX_CODE
&&
721 CrntPrefix
> ClearCode
&& CrntPrefix
<= LZ_MAX_CODE
) {
722 Stack
[StackPtr
++] = Suffix
[CrntPrefix
];
723 CrntPrefix
= Prefix
[CrntPrefix
];
725 if (j
>= LZ_MAX_CODE
|| CrntPrefix
> LZ_MAX_CODE
) {
728 /* Push the last character on stack: */
729 Stack
[StackPtr
++] = CrntPrefix
;
731 /* Now lets pop all the stack into output: */
732 while (StackPtr
!= 0 && i
< LineLen
)
733 Line
[i
++] = Stack
[--StackPtr
];
735 if (LastCode
!= NO_SUCH_CODE
) {
736 Prefix
[Private
->RunningCode
- 2] = LastCode
;
738 if (CrntCode
== Private
->RunningCode
- 2) {
739 /* Only allowed if CrntCode is exactly the running code:
740 * In that case CrntCode = XXXCode, CrntCode or the
741 * prefix code is last code and the suffix char is
742 * exactly the prefix of last code! */
743 Suffix
[Private
->RunningCode
- 2] =
744 DGifGetPrefixChar(Prefix
, LastCode
, ClearCode
);
746 Suffix
[Private
->RunningCode
- 2] =
747 DGifGetPrefixChar(Prefix
, CrntCode
, ClearCode
);
754 Private
->LastCode
= LastCode
;
755 Private
->StackPtr
= StackPtr
;
760 /******************************************************************************
761 * Routine to trace the Prefixes linked list until we get a prefix which is
762 * not code, but a pixel value (less than ClearCode). Returns that pixel value.
763 * If image is defective, we might loop here forever, so we limit the loops to
764 * the maximum possible if image O.k. - LZ_MAX_CODE times.
765 *****************************************************************************/
767 DGifGetPrefixChar(const GifPrefixType
*Prefix
,
773 while (Code
> ClearCode
&& i
++ <= LZ_MAX_CODE
)
778 /******************************************************************************
779 * The LZ decompression input routine:
780 * This routine is responsible for the decompression of the bit stream from
781 * 8 bits (bytes) packets, into the real codes.
782 * Returns GIF_OK if read successfully.
783 *****************************************************************************/
785 DGifDecompressInput(GifFileType
* GifFile
,
788 GifFilePrivateType
*Private
= GifFile
->Private
;
790 GifByteType NextByte
;
791 static const unsigned short CodeMasks
[] = {
792 0x0000, 0x0001, 0x0003, 0x0007,
793 0x000f, 0x001f, 0x003f, 0x007f,
794 0x00ff, 0x01ff, 0x03ff, 0x07ff,
797 /* The image can't contain more than LZ_BITS per code. */
798 if (Private
->RunningBits
> LZ_BITS
) {
802 while (Private
->CrntShiftState
< Private
->RunningBits
) {
803 /* Needs to get more bytes from input stream for next code: */
804 if (DGifBufferedInput(GifFile
, Private
->Buf
, &NextByte
) == GIF_ERROR
) {
807 Private
->CrntShiftDWord
|=
808 ((unsigned long)NextByte
) << Private
->CrntShiftState
;
809 Private
->CrntShiftState
+= 8;
811 *Code
= Private
->CrntShiftDWord
& CodeMasks
[Private
->RunningBits
];
813 Private
->CrntShiftDWord
>>= Private
->RunningBits
;
814 Private
->CrntShiftState
-= Private
->RunningBits
;
816 /* If code cannot fit into RunningBits bits, must raise its size. Note
817 * however that codes above 4095 are used for special signaling.
818 * If we're using LZ_BITS bits already and we're at the max code, just
819 * keep using the table as it is, don't increment Private->RunningCode.
821 if (Private
->RunningCode
< LZ_MAX_CODE
+ 2 &&
822 ++Private
->RunningCode
> Private
->MaxCode1
&&
823 Private
->RunningBits
< LZ_BITS
) {
824 Private
->MaxCode1
<<= 1;
825 Private
->RunningBits
++;
830 /******************************************************************************
831 * This routines read one gif data block at a time and buffers it internally
832 * so that the decompression routine could access it.
833 * The routine returns the next byte from its internal buffer (or read next
834 * block in if buffer empty) and returns GIF_OK if successful.
835 *****************************************************************************/
837 DGifBufferedInput(GifFileType
* GifFile
,
839 GifByteType
* NextByte
) {
842 /* Needs to read the next buffer - this one is empty: */
843 if (READ(GifFile
, Buf
, 1) != 1) {
846 /* There shouldn't be any empty data blocks here as the LZW spec
847 * says the LZW termination code should come first. Therefore we
848 * shouldn't be inside this routine at that point.
853 if (READ(GifFile
, &Buf
[1], Buf
[0]) != Buf
[0]) {
857 Buf
[1] = 2; /* We use now the second place as last char read! */
860 *NextByte
= Buf
[Buf
[1]++];
867 /******************************************************************************
868 * This routine reads an entire GIF into core, hanging all its state info off
869 * the GifFileType pointer. Call DGifOpenFileName() or DGifOpenFileHandle()
870 * first to initialize I/O. Its inverse is EGifSpew().
871 ******************************************************************************/
873 DGifSlurp(GifFileType
* GifFile
) {
876 GifRecordType RecordType
;
878 GifByteType
*ExtData
;
879 Extensions temp_save
;
881 temp_save
.ExtensionBlocks
= NULL
;
882 temp_save
.ExtensionBlockCount
= 0;
885 if (DGifGetRecordType(GifFile
, &RecordType
) == GIF_ERROR
)
888 switch (RecordType
) {
889 case IMAGE_DESC_RECORD_TYPE
:
890 if (DGifGetImageDesc(GifFile
) == GIF_ERROR
)
893 sp
= &GifFile
->SavedImages
[GifFile
->ImageCount
- 1];
894 ImageSize
= sp
->ImageDesc
.Width
* sp
->ImageDesc
.Height
;
896 sp
->RasterBits
= ungif_alloc(ImageSize
* sizeof(GifPixelType
));
897 if (sp
->RasterBits
== NULL
) {
900 if (DGifGetLine(GifFile
, sp
->RasterBits
, ImageSize
) ==
903 if (temp_save
.ExtensionBlocks
) {
904 sp
->Extensions
.ExtensionBlocks
= temp_save
.ExtensionBlocks
;
905 sp
->Extensions
.ExtensionBlockCount
= temp_save
.ExtensionBlockCount
;
907 temp_save
.ExtensionBlocks
= NULL
;
908 temp_save
.ExtensionBlockCount
= 0;
910 /* FIXME: The following is wrong. It is left in only for
911 * backwards compatibility. Someday it should go away. Use
912 * the sp->ExtensionBlocks->Function variable instead. */
913 sp
->Extensions
.Function
= sp
->Extensions
.ExtensionBlocks
[0].Function
;
917 case EXTENSION_RECORD_TYPE
:
920 Extensions
*Extensions
;
922 if (DGifGetExtension(GifFile
, &Function
, &ExtData
) == GIF_ERROR
)
925 if (GifFile
->ImageCount
|| Function
== GRAPHICS_EXT_FUNC_CODE
)
926 Extensions
= &temp_save
;
928 Extensions
= &GifFile
->Extensions
;
930 Extensions
->Function
= Function
;
932 /* Create an extension block with our data */
933 if (AddExtensionBlock(Extensions
, ExtData
[0], &ExtData
[1]) == GIF_ERROR
)
936 while (ExtData
!= NULL
) {
940 if (DGifGetExtensionNext(GifFile
, &ExtData
) == GIF_ERROR
)
954 if (AppendExtensionBlock(Extensions
, Len
, Data
) == GIF_ERROR
)
960 case TERMINATE_RECORD_TYPE
:
963 default: /* Should be trapped by DGifGetRecordType */
966 } while (RecordType
!= TERMINATE_RECORD_TYPE
);
968 /* Just in case the Gif has an extension block without an associated
969 * image... (Should we save this into a savefile structure with no image
970 * instead? Have to check if the present writing code can handle that as
972 if (temp_save
.ExtensionBlocks
)
973 FreeExtension(&temp_save
);
978 /******************************************************************************
979 * GifFileType constructor with user supplied input function (TVT)
980 *****************************************************************************/
982 DGifOpen(void *userData
,
983 InputFunc readFunc
) {
985 unsigned char Buf
[GIF_STAMP_LEN
+ 1];
986 GifFileType
*GifFile
;
987 GifFilePrivateType
*Private
;
989 GifFile
= ungif_alloc(sizeof(GifFileType
));
990 if (GifFile
== NULL
) {
994 memset(GifFile
, '\0', sizeof(GifFileType
));
996 Private
= ungif_alloc(sizeof(GifFilePrivateType
));
1002 GifFile
->Private
= (void*)Private
;
1004 Private
->Read
= readFunc
; /* TVT */
1005 GifFile
->UserData
= userData
; /* TVT */
1007 /* Lets see if this is a GIF file: */
1008 if (READ(GifFile
, Buf
, GIF_STAMP_LEN
) != GIF_STAMP_LEN
) {
1009 ungif_free(Private
);
1010 ungif_free(GifFile
);
1014 /* The GIF Version number is ignored at this time. Maybe we should do
1015 * something more useful with it. */
1016 Buf
[GIF_STAMP_LEN
] = 0;
1017 if (memcmp(GIF_STAMP
, Buf
, GIF_VERSION_POS
) != 0) {
1018 ungif_free(Private
);
1019 ungif_free(GifFile
);
1023 if (DGifGetScreenDesc(GifFile
) == GIF_ERROR
) {
1024 ungif_free(Private
);
1025 ungif_free(GifFile
);
1032 /******************************************************************************
1033 * This routine should be called last, to close the GIF file.
1034 *****************************************************************************/
1036 DGifCloseFile(GifFileType
* GifFile
) {
1038 GifFilePrivateType
*Private
;
1040 if (GifFile
== NULL
)
1043 Private
= GifFile
->Private
;
1045 if (GifFile
->Image
.ColorMap
) {
1046 FreeMapObject(GifFile
->Image
.ColorMap
);
1047 GifFile
->Image
.ColorMap
= NULL
;
1050 if (GifFile
->SColorMap
) {
1051 FreeMapObject(GifFile
->SColorMap
);
1052 GifFile
->SColorMap
= NULL
;
1055 ungif_free(Private
);
1058 if (GifFile
->SavedImages
) {
1059 FreeSavedImages(GifFile
);
1060 GifFile
->SavedImages
= NULL
;
1063 FreeExtension(&GifFile
->Extensions
);
1065 ungif_free(GifFile
);