2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
13 % Read/Write Compuserv Graphics Interchange Format %
20 % Copyright 1999-2017 ImageMagick Studio LLC, a non-profit organization %
21 % dedicated to making software imaging solutions freely available. %
23 % You may not use this file except in compliance with the License. You may %
24 % obtain a copy of the License at %
26 % http://www.imagemagick.org/script/license.php %
28 % Unless required by applicable law or agreed to in writing, software %
29 % distributed under the License is distributed on an "AS IS" BASIS, %
30 % WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. %
31 % See the License for the specific language governing permissions and %
32 % limitations under the License. %
34 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
42 #include "MagickCore/studio.h"
43 #include "MagickCore/attribute.h"
44 #include "MagickCore/blob.h"
45 #include "MagickCore/blob-private.h"
46 #include "MagickCore/cache.h"
47 #include "MagickCore/color.h"
48 #include "MagickCore/color-private.h"
49 #include "MagickCore/colormap.h"
50 #include "MagickCore/colormap-private.h"
51 #include "MagickCore/colorspace.h"
52 #include "MagickCore/colorspace-private.h"
53 #include "MagickCore/exception.h"
54 #include "MagickCore/exception-private.h"
55 #include "MagickCore/image.h"
56 #include "MagickCore/image-private.h"
57 #include "MagickCore/list.h"
58 #include "MagickCore/profile.h"
59 #include "MagickCore/magick.h"
60 #include "MagickCore/memory_.h"
61 #include "MagickCore/monitor.h"
62 #include "MagickCore/monitor-private.h"
63 #include "MagickCore/option.h"
64 #include "MagickCore/pixel.h"
65 #include "MagickCore/pixel-accessor.h"
66 #include "MagickCore/property.h"
67 #include "MagickCore/quantize.h"
68 #include "MagickCore/quantum-private.h"
69 #include "MagickCore/static.h"
70 #include "MagickCore/string_.h"
71 #include "MagickCore/string-private.h"
72 #include "MagickCore/module.h"
77 #define MaximumLZWBits 12
78 #define MaximumLZWCode (1UL << MaximumLZWBits)
83 typedef struct _LZWCodeInfo
96 typedef struct _LZWStack
104 typedef struct _LZWInfo
132 Forward declarations.
135 GetNextLZWCode(LZWInfo *,const size_t);
137 static MagickBooleanType
138 WriteGIFImage(const ImageInfo *,Image *,ExceptionInfo *);
141 ReadBlobBlock(Image *,unsigned char *);
144 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
148 % D e c o d e I m a g e %
152 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
154 % DecodeImage uncompresses an image via GIF-coding.
156 % The format of the DecodeImage method is:
158 % MagickBooleanType DecodeImage(Image *image,const ssize_t opacity)
160 % A description of each parameter follows:
162 % o image: the address of a structure of type Image.
164 % o opacity: The colormap index associated with the transparent color.
168 static LZWInfo *RelinquishLZWInfo(LZWInfo *lzw_info)
170 if (lzw_info->table[0] != (size_t *) NULL)
171 lzw_info->table[0]=(size_t *) RelinquishMagickMemory(
173 if (lzw_info->table[1] != (size_t *) NULL)
174 lzw_info->table[1]=(size_t *) RelinquishMagickMemory(
176 if (lzw_info->stack != (LZWStack *) NULL)
178 if (lzw_info->stack->codes != (size_t *) NULL)
179 lzw_info->stack->codes=(size_t *) RelinquishMagickMemory(
180 lzw_info->stack->codes);
181 lzw_info->stack=(LZWStack *) RelinquishMagickMemory(lzw_info->stack);
183 lzw_info=(LZWInfo *) RelinquishMagickMemory(lzw_info);
184 return((LZWInfo *) NULL);
187 static inline void ResetLZWInfo(LZWInfo *lzw_info)
192 lzw_info->bits=lzw_info->data_size+1;
194 lzw_info->maximum_code=one << lzw_info->bits;
195 lzw_info->slot=lzw_info->maximum_data_value+3;
196 lzw_info->genesis=MagickTrue;
199 static LZWInfo *AcquireLZWInfo(Image *image,const size_t data_size)
210 lzw_info=(LZWInfo *) AcquireMagickMemory(sizeof(*lzw_info));
211 if (lzw_info == (LZWInfo *) NULL)
212 return((LZWInfo *) NULL);
213 (void) ResetMagickMemory(lzw_info,0,sizeof(*lzw_info));
214 lzw_info->image=image;
215 lzw_info->data_size=data_size;
217 lzw_info->maximum_data_value=(one << data_size)-1;
218 lzw_info->clear_code=lzw_info->maximum_data_value+1;
219 lzw_info->end_code=lzw_info->maximum_data_value+2;
220 lzw_info->table[0]=(size_t *) AcquireQuantumMemory(MaximumLZWCode,
221 sizeof(**lzw_info->table));
222 lzw_info->table[1]=(size_t *) AcquireQuantumMemory(MaximumLZWCode,
223 sizeof(**lzw_info->table));
224 if ((lzw_info->table[0] == (size_t *) NULL) ||
225 (lzw_info->table[1] == (size_t *) NULL))
227 lzw_info=RelinquishLZWInfo(lzw_info);
228 return((LZWInfo *) NULL);
230 for (i=0; i <= (ssize_t) lzw_info->maximum_data_value; i++)
232 lzw_info->table[0][i]=0;
233 lzw_info->table[1][i]=(size_t) i;
235 ResetLZWInfo(lzw_info);
236 lzw_info->code_info.buffer[0]='\0';
237 lzw_info->code_info.buffer[1]='\0';
238 lzw_info->code_info.count=2;
239 lzw_info->code_info.bit=8*lzw_info->code_info.count;
240 lzw_info->code_info.eof=MagickFalse;
241 lzw_info->genesis=MagickTrue;
242 lzw_info->stack=(LZWStack *) AcquireMagickMemory(sizeof(*lzw_info->stack));
243 if (lzw_info->stack == (LZWStack *) NULL)
245 lzw_info=RelinquishLZWInfo(lzw_info);
246 return((LZWInfo *) NULL);
248 lzw_info->stack->codes=(size_t *) AcquireQuantumMemory(2UL*
249 MaximumLZWCode,sizeof(*lzw_info->stack->codes));
250 if (lzw_info->stack->codes == (size_t *) NULL)
252 lzw_info=RelinquishLZWInfo(lzw_info);
253 return((LZWInfo *) NULL);
255 lzw_info->stack->index=lzw_info->stack->codes;
256 lzw_info->stack->top=lzw_info->stack->codes+2*MaximumLZWCode;
260 static inline int GetNextLZWCode(LZWInfo *lzw_info,const size_t bits)
271 while (((lzw_info->code_info.bit+bits) > (8*lzw_info->code_info.count)) &&
272 (lzw_info->code_info.eof == MagickFalse))
277 lzw_info->code_info.buffer[0]=lzw_info->code_info.buffer[
278 lzw_info->code_info.count-2];
279 lzw_info->code_info.buffer[1]=lzw_info->code_info.buffer[
280 lzw_info->code_info.count-1];
281 lzw_info->code_info.bit-=8*(lzw_info->code_info.count-2);
282 lzw_info->code_info.count=2;
283 count=ReadBlobBlock(lzw_info->image,&lzw_info->code_info.buffer[
284 lzw_info->code_info.count]);
286 lzw_info->code_info.count+=count;
288 lzw_info->code_info.eof=MagickTrue;
290 if ((lzw_info->code_info.bit+bits) > (8*lzw_info->code_info.count))
294 for (i=0; i < (ssize_t) bits; i++)
296 code|=((lzw_info->code_info.buffer[lzw_info->code_info.bit/8] &
297 (one << (lzw_info->code_info.bit % 8))) != 0) << i;
298 lzw_info->code_info.bit++;
303 static inline int PopLZWStack(LZWStack *stack_info)
305 if (stack_info->index <= stack_info->codes)
308 return((int) *stack_info->index);
311 static inline void PushLZWStack(LZWStack *stack_info,const size_t value)
313 if (stack_info->index >= stack_info->top)
315 *stack_info->index=value;
319 static int ReadBlobLZWByte(LZWInfo *lzw_info)
331 if (lzw_info->stack->index != lzw_info->stack->codes)
332 return(PopLZWStack(lzw_info->stack));
333 if (lzw_info->genesis != MagickFalse)
335 lzw_info->genesis=MagickFalse;
338 lzw_info->first_code=(size_t) GetNextLZWCode(lzw_info,lzw_info->bits);
339 lzw_info->last_code=lzw_info->first_code;
340 } while (lzw_info->first_code == lzw_info->clear_code);
341 return((int) lzw_info->first_code);
343 code=GetNextLZWCode(lzw_info,lzw_info->bits);
346 if ((size_t) code == lzw_info->clear_code)
348 ResetLZWInfo(lzw_info);
349 return(ReadBlobLZWByte(lzw_info));
351 if ((size_t) code == lzw_info->end_code)
353 if ((size_t) code < lzw_info->slot)
357 PushLZWStack(lzw_info->stack,lzw_info->first_code);
358 value=lzw_info->last_code;
361 while (value > lzw_info->maximum_data_value)
363 if ((size_t) count > MaximumLZWCode)
366 if ((size_t) value > MaximumLZWCode)
368 PushLZWStack(lzw_info->stack,lzw_info->table[1][value]);
369 value=lzw_info->table[0][value];
371 lzw_info->first_code=lzw_info->table[1][value];
372 PushLZWStack(lzw_info->stack,lzw_info->first_code);
374 if (lzw_info->slot < MaximumLZWCode)
376 lzw_info->table[0][lzw_info->slot]=lzw_info->last_code;
377 lzw_info->table[1][lzw_info->slot]=lzw_info->first_code;
379 if ((lzw_info->slot >= lzw_info->maximum_code) &&
380 (lzw_info->bits < MaximumLZWBits))
383 lzw_info->maximum_code=one << lzw_info->bits;
386 lzw_info->last_code=(size_t) code;
387 return(PopLZWStack(lzw_info->stack));
390 static MagickBooleanType DecodeImage(Image *image,const ssize_t opacity,
391 ExceptionInfo *exception)
411 Allocate decoder tables.
413 assert(image != (Image *) NULL);
414 assert(image->signature == MagickCoreSignature);
415 if (image->debug != MagickFalse)
416 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
417 data_size=(unsigned char) ReadBlobByte(image);
418 if (data_size > MaximumLZWBits)
419 ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
420 lzw_info=AcquireLZWInfo(image,data_size);
421 if (lzw_info == (LZWInfo *) NULL)
422 ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
426 for (y=0; y < (ssize_t) image->rows; y++)
434 q=QueueAuthenticPixels(image,0,offset,image->columns,1,exception);
435 if (q == (Quantum *) NULL)
437 for (x=0; x < (ssize_t) image->columns; )
439 c=ReadBlobLZWByte(lzw_info);
442 index=ConstrainColormapIndex(image,(ssize_t) c,exception);
443 SetPixelIndex(image,(Quantum) index,q);
444 SetPixelViaPixelInfo(image,image->colormap+index,q);
445 SetPixelAlpha(image,index == opacity ? TransparentAlpha : OpaqueAlpha,q);
447 q+=GetPixelChannels(image);
449 if (SyncAuthenticPixels(image,exception) == MagickFalse)
451 if (x < (ssize_t) image->columns)
453 if (image->interlace == NoInterlace)
481 if ((pass == 0) && (offset >= (ssize_t) image->rows))
486 if ((pass == 1) && (offset >= (ssize_t) image->rows))
491 if ((pass == 2) && (offset >= (ssize_t) image->rows))
498 lzw_info=RelinquishLZWInfo(lzw_info);
499 if (y < (ssize_t) image->rows)
500 ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
505 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
509 % E n c o d e I m a g e %
513 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
515 % EncodeImage compresses an image via GIF-coding.
517 % The format of the EncodeImage method is:
519 % MagickBooleanType EncodeImage(const ImageInfo *image_info,Image *image,
520 % const size_t data_size)
522 % A description of each parameter follows:
524 % o image_info: the image info.
526 % o image: the address of a structure of type Image.
528 % o data_size: The number of bits in the compressed packet.
531 static MagickBooleanType EncodeImage(const ImageInfo *image_info,Image *image,
532 const size_t data_size,ExceptionInfo *exception)
534 #define MaxCode(number_bits) ((one << (number_bits))-1)
535 #define MaxHashTable 5003
536 #define MaxGIFBits 12UL
537 #define MaxGIFTable (1UL << MaxGIFBits)
538 #define GIFOutputCode(code) \
544 datum|=(code) << bits; \
551 Add a character to current packet. \
553 packet[length++]=(unsigned char) (datum & 0xff); \
556 (void) WriteBlobByte(image,(unsigned char) length); \
557 (void) WriteBlob(image,length,packet); \
563 if (free_code > max_code) \
566 if (number_bits == MaxGIFBits) \
567 max_code=MaxGIFTable; \
569 max_code=MaxCode(number_bits); \
585 end_of_information_code,
605 Allocate encoder tables.
607 assert(image != (Image *) NULL);
609 packet=(unsigned char *) AcquireQuantumMemory(256,sizeof(*packet));
610 hash_code=(short *) AcquireQuantumMemory(MaxHashTable,sizeof(*hash_code));
611 hash_prefix=(short *) AcquireQuantumMemory(MaxHashTable,sizeof(*hash_prefix));
612 hash_suffix=(unsigned char *) AcquireQuantumMemory(MaxHashTable,
613 sizeof(*hash_suffix));
614 if ((packet == (unsigned char *) NULL) || (hash_code == (short *) NULL) ||
615 (hash_prefix == (short *) NULL) ||
616 (hash_suffix == (unsigned char *) NULL))
618 if (packet != (unsigned char *) NULL)
619 packet=(unsigned char *) RelinquishMagickMemory(packet);
620 if (hash_code != (short *) NULL)
621 hash_code=(short *) RelinquishMagickMemory(hash_code);
622 if (hash_prefix != (short *) NULL)
623 hash_prefix=(short *) RelinquishMagickMemory(hash_prefix);
624 if (hash_suffix != (unsigned char *) NULL)
625 hash_suffix=(unsigned char *) RelinquishMagickMemory(hash_suffix);
629 Initialize GIF encoder.
631 (void) ResetMagickMemory(hash_code,0,MaxHashTable*sizeof(*hash_code));
632 (void) ResetMagickMemory(hash_prefix,0,MaxHashTable*sizeof(*hash_prefix));
633 (void) ResetMagickMemory(hash_suffix,0,MaxHashTable*sizeof(*hash_suffix));
634 number_bits=data_size;
635 max_code=MaxCode(number_bits);
636 clear_code=((short) one << (data_size-1));
637 end_of_information_code=clear_code+1;
638 free_code=clear_code+2;
642 GIFOutputCode(clear_code);
649 for (y=0; y < (ssize_t) image->rows; y++)
651 register const Quantum
657 p=GetVirtualPixels(image,0,offset,image->columns,1,exception);
658 if (p == (const Quantum *) NULL)
662 waiting_code=(short) GetPixelIndex(image,p);
663 p+=GetPixelChannels(image);
665 for (x=(ssize_t) (y == 0 ? 1 : 0); x < (ssize_t) image->columns; x++)
670 index=(Quantum) ((size_t) GetPixelIndex(image,p) & 0xff);
671 p+=GetPixelChannels(image);
672 k=(ssize_t) (((size_t) index << (MaxGIFBits-8))+waiting_code);
673 if (k >= MaxHashTable)
675 next_pixel=MagickFalse;
677 if (hash_code[k] > 0)
679 if ((hash_prefix[k] == waiting_code) &&
680 (hash_suffix[k] == (unsigned char) index))
682 waiting_code=hash_code[k];
686 displacement=MaxHashTable-k;
692 if (hash_code[k] == 0)
694 if ((hash_prefix[k] == waiting_code) &&
695 (hash_suffix[k] == (unsigned char) index))
697 waiting_code=hash_code[k];
698 next_pixel=MagickTrue;
702 if (next_pixel != MagickFalse)
705 GIFOutputCode((size_t) waiting_code);
706 if (free_code < MaxGIFTable)
708 hash_code[k]=(short) free_code++;
709 hash_prefix[k]=waiting_code;
710 hash_suffix[k]=(unsigned char) index;
715 Fill the hash table with empty entries.
717 for (k=0; k < MaxHashTable; k++)
720 Reset compressor and issue a clear code.
722 free_code=clear_code+2;
723 GIFOutputCode(clear_code);
724 number_bits=data_size;
725 max_code=MaxCode(number_bits);
727 waiting_code=(short) index;
729 if (image_info->interlace == NoInterlace)
738 if (offset >= (ssize_t) image->rows)
748 if (offset >= (ssize_t) image->rows)
758 if (offset >= (ssize_t) image->rows)
773 Flush out the buffered code.
775 GIFOutputCode((size_t) waiting_code);
776 GIFOutputCode(end_of_information_code);
780 Add a character to current packet.
782 packet[length++]=(unsigned char) (datum & 0xff);
785 (void) WriteBlobByte(image,(unsigned char) length);
786 (void) WriteBlob(image,length,packet);
791 Flush accumulated data.
795 (void) WriteBlobByte(image,(unsigned char) length);
796 (void) WriteBlob(image,length,packet);
801 hash_suffix=(unsigned char *) RelinquishMagickMemory(hash_suffix);
802 hash_prefix=(short *) RelinquishMagickMemory(hash_prefix);
803 hash_code=(short *) RelinquishMagickMemory(hash_code);
804 packet=(unsigned char *) RelinquishMagickMemory(packet);
809 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
817 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
819 % IsGIF() returns MagickTrue if the image format type, identified by the
820 % magick string, is GIF.
822 % The format of the IsGIF method is:
824 % MagickBooleanType IsGIF(const unsigned char *magick,const size_t length)
826 % A description of each parameter follows:
828 % o magick: compare image format pattern against these bytes.
830 % o length: Specifies the length of the magick string.
833 static MagickBooleanType IsGIF(const unsigned char *magick,const size_t length)
837 if (LocaleNCompare((char *) magick,"GIF8",4) == 0)
843 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
847 + R e a d B l o b B l o c k %
851 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
853 % ReadBlobBlock() reads data from the image file and returns it. The
854 % amount of data is determined by first reading a count byte. The number
855 % of bytes read is returned.
857 % The format of the ReadBlobBlock method is:
859 % ssize_t ReadBlobBlock(Image *image,unsigned char *data)
861 % A description of each parameter follows:
863 % o image: the image.
865 % o data: Specifies an area to place the information requested from
869 static ssize_t ReadBlobBlock(Image *image,unsigned char *data)
877 assert(image != (Image *) NULL);
878 assert(image->signature == MagickCoreSignature);
879 assert(data != (unsigned char *) NULL);
880 count=ReadBlob(image,1,&block_count);
883 count=ReadBlob(image,(size_t) block_count,data);
884 if (count != (ssize_t) block_count)
890 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
894 % R e a d G I F I m a g e %
898 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
900 % ReadGIFImage() reads a Compuserve Graphics image file and returns it.
901 % It allocates the memory necessary for the new Image structure and returns a
902 % pointer to the new image.
904 % The format of the ReadGIFImage method is:
906 % Image *ReadGIFImage(const ImageInfo *image_info,ExceptionInfo *exception)
908 % A description of each parameter follows:
910 % o image_info: the image info.
912 % o exception: return any errors or warnings in this structure.
915 static MagickBooleanType PingGIFImage(Image *image,ExceptionInfo *exception)
922 assert(image != (Image *) NULL);
923 assert(image->signature == MagickCoreSignature);
924 if (image->debug != MagickFalse)
925 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
926 if (ReadBlob(image,1,&data_size) != 1)
927 ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
928 if (data_size > MaximumLZWBits)
929 ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
930 if (ReadBlob(image,1,&length) != 1)
931 ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
934 if (ReadBlob(image,length,buffer) != (ssize_t) length)
935 ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
936 if (ReadBlob(image,1,&length) != 1)
937 ThrowBinaryException(CorruptImageError,"CorruptImage",image->filename);
942 static Image *ReadGIFImage(const ImageInfo *image_info,ExceptionInfo *exception)
944 #define BitSet(byte,bit) (((byte) & (bit)) == (bit))
945 #define LSBFirstOrder(x,y) (((y) << 8) | (x))
952 number_extensionss=0;
963 register unsigned char
989 assert(image_info != (const ImageInfo *) NULL);
990 assert(image_info->signature == MagickCoreSignature);
991 if (image_info->debug != MagickFalse)
992 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",
993 image_info->filename);
994 assert(exception != (ExceptionInfo *) NULL);
995 assert(exception->signature == MagickCoreSignature);
996 image=AcquireImage(image_info,exception);
997 status=OpenBlob(image_info,image,ReadBinaryBlobMode,exception);
998 if (status == MagickFalse)
1000 image=DestroyImageList(image);
1001 return((Image *) NULL);
1004 Determine if this a GIF file.
1006 count=ReadBlob(image,6,buffer);
1007 if ((count != 6) || ((LocaleNCompare((char *) buffer,"GIF87",5) != 0) &&
1008 (LocaleNCompare((char *) buffer,"GIF89",5) != 0)))
1009 ThrowReaderException(CorruptImageError,"ImproperImageHeader");
1010 page.width=ReadBlobLSBShort(image);
1011 page.height=ReadBlobLSBShort(image);
1012 flag=(unsigned char) ReadBlobByte(image);
1013 background=(unsigned char) ReadBlobByte(image);
1014 c=(unsigned char) ReadBlobByte(image); /* reserved */
1016 global_colors=one << (((size_t) flag & 0x07)+1);
1017 global_colormap=(unsigned char *) AcquireQuantumMemory((size_t)
1018 MagickMax(global_colors,256),3UL*sizeof(*global_colormap));
1019 if (global_colormap == (unsigned char *) NULL)
1020 ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
1021 if (BitSet((int) flag,0x80) != 0)
1023 count=ReadBlob(image,(size_t) (3*global_colors),global_colormap);
1024 if (count != (ssize_t) (3*global_colors))
1026 global_colormap=(unsigned char *) RelinquishMagickMemory(
1028 ThrowReaderException(CorruptImageError,"InsufficientImageDataInFile");
1037 meta_image=AcquireImage(image_info,exception); /* metadata container */
1040 count=ReadBlob(image,1,&c);
1043 if (c == (unsigned char) ';')
1044 break; /* terminator */
1045 if (c == (unsigned char) '!')
1048 GIF Extension block.
1050 count=ReadBlob(image,1,&c);
1053 global_colormap=(unsigned char *) RelinquishMagickMemory(
1055 meta_image=DestroyImage(meta_image);
1056 ThrowReaderException(CorruptImageError,
1057 "UnableToReadExtensionBlock");
1064 Read graphics control extension.
1066 while (ReadBlobBlock(image,buffer) != 0) ;
1067 dispose=(size_t) (buffer[0] >> 2);
1068 delay=(size_t) ((buffer[2] << 8) | buffer[1]);
1069 if ((ssize_t) (buffer[0] & 0x01) == 0x01)
1070 opacity=(ssize_t) buffer[3];
1082 Read comment extension.
1084 comments=AcquireString((char *) NULL);
1085 for (length=0; ; length+=count)
1087 count=(ssize_t) ReadBlobBlock(image,buffer);
1091 (void) ConcatenateString(&comments,(const char *) buffer);
1093 (void) SetImageProperty(meta_image,"comment",comments,exception);
1094 comments=DestroyString(comments);
1103 Read Netscape Loop extension.
1106 if (ReadBlobBlock(image,buffer) != 0)
1107 loop=LocaleNCompare((char *) buffer,"NETSCAPE2.0",11) == 0 ?
1108 MagickTrue : MagickFalse;
1109 if (loop != MagickFalse)
1111 while (ReadBlobBlock(image,buffer) != 0)
1112 iterations=(size_t) ((buffer[2] << 8) | buffer[1]);
1118 name[MagickPathExtent];
1138 Store GIF application extension as a generic profile.
1140 icc=LocaleNCompare((char *) buffer,"ICCRGBG1012",11) == 0 ?
1141 MagickTrue : MagickFalse;
1142 magick=LocaleNCompare((char *) buffer,"ImageMagick",11) == 0 ?
1143 MagickTrue : MagickFalse;
1144 i8bim=LocaleNCompare((char *) buffer,"MGK8BIM0000",11) == 0 ?
1145 MagickTrue : MagickFalse;
1146 iptc=LocaleNCompare((char *) buffer,"MGKIPTC0000",11) == 0 ?
1147 MagickTrue : MagickFalse;
1148 number_extensionss++;
1149 (void) LogMagickEvent(CoderEvent,GetMagickModule(),
1150 " Reading GIF application extension");
1151 info=(unsigned char *) AcquireQuantumMemory(255UL,
1153 if (info == (unsigned char *) NULL)
1155 meta_image=DestroyImage(meta_image);
1156 ThrowReaderException(ResourceLimitError,
1157 "MemoryAllocationFailed");
1159 reserved_length=255;
1160 for (info_length=0; ; )
1162 block_length=(int) ReadBlobBlock(image,&info[info_length]);
1163 if (block_length == 0)
1165 info_length+=block_length;
1166 if (info_length > (reserved_length-255))
1168 reserved_length+=4096;
1169 info=(unsigned char *) ResizeQuantumMemory(info,(size_t)
1170 reserved_length,sizeof(*info));
1171 if (info == (unsigned char *) NULL)
1173 meta_image=DestroyImage(meta_image);
1174 ThrowReaderException(ResourceLimitError,
1175 "MemoryAllocationFailed");
1179 profile=BlobToStringInfo(info,(size_t) info_length);
1180 if (profile == (StringInfo *) NULL)
1182 meta_image=DestroyImage(meta_image);
1183 ThrowReaderException(ResourceLimitError,
1184 "MemoryAllocationFailed");
1186 if (i8bim != MagickFalse)
1187 (void) CopyMagickString(name,"8bim",sizeof(name));
1188 else if (icc != MagickFalse)
1189 (void) CopyMagickString(name,"icc",sizeof(name));
1190 else if (iptc != MagickFalse)
1191 (void) CopyMagickString(name,"iptc",sizeof(name));
1192 else if (magick != MagickFalse)
1194 (void) CopyMagickString(name,"magick",sizeof(name));
1195 meta_image->gamma=StringToDouble((char *) info+6,
1199 (void) FormatLocaleString(name,sizeof(name),"gif:%.11s",
1201 info=(unsigned char *) RelinquishMagickMemory(info);
1202 if (magick == MagickFalse)
1203 (void) SetImageProfile(meta_image,name,profile,exception);
1204 profile=DestroyStringInfo(profile);
1205 (void) LogMagickEvent(CoderEvent,GetMagickModule(),
1206 " profile name=%s",name);
1212 while (ReadBlobBlock(image,buffer) != 0) ;
1217 if (c != (unsigned char) ',')
1219 if (image_count != 0)
1222 Allocate next image structure.
1224 AcquireNextImage(image_info,image,exception);
1225 if (GetNextImageInList(image) == (Image *) NULL)
1227 image=DestroyImageList(image);
1228 global_colormap=(unsigned char *) RelinquishMagickMemory(
1230 return((Image *) NULL);
1232 image=SyncNextImageInList(image);
1236 Read image attributes.
1238 meta_image->scene=image->scene;
1239 (void) CloneImageProperties(image,meta_image);
1240 DestroyImageProperties(meta_image);
1241 (void) CloneImageProfiles(image,meta_image);
1242 DestroyImageProfiles(meta_image);
1243 image->storage_class=PseudoClass;
1244 image->compression=LZWCompression;
1245 page.x=(ssize_t) ReadBlobLSBShort(image);
1246 page.y=(ssize_t) ReadBlobLSBShort(image);
1247 image->columns=ReadBlobLSBShort(image);
1248 image->rows=ReadBlobLSBShort(image);
1250 flag=(unsigned char) ReadBlobByte(image);
1251 image->interlace=BitSet((int) flag,0x40) != 0 ? GIFInterlace : NoInterlace;
1252 image->colors=BitSet((int) flag,0x80) == 0 ? global_colors : one <<
1253 ((size_t) (flag & 0x07)+1);
1254 if (opacity >= (ssize_t) image->colors)
1256 image->page.width=page.width;
1257 image->page.height=page.height;
1258 image->page.y=page.y;
1259 image->page.x=page.x;
1261 image->ticks_per_second=100;
1262 image->dispose=(DisposeType) dispose;
1263 image->iterations=iterations;
1264 image->alpha_trait=opacity >= 0 ? BlendPixelTrait : UndefinedPixelTrait;
1267 if ((image->columns == 0) || (image->rows == 0))
1269 global_colormap=(unsigned char *) RelinquishMagickMemory(
1271 meta_image=DestroyImage(meta_image);
1272 ThrowReaderException(CorruptImageError,"NegativeOrZeroImageSize");
1275 Inititialize colormap.
1277 if (AcquireImageColormap(image,image->colors,exception) == MagickFalse)
1279 global_colormap=(unsigned char *) RelinquishMagickMemory(
1281 meta_image=DestroyImage(meta_image);
1282 ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
1284 if (BitSet((int) flag,0x80) == 0)
1287 Use global colormap.
1290 for (i=0; i < (ssize_t) image->colors; i++)
1292 image->colormap[i].red=(double) ScaleCharToQuantum(*p++);
1293 image->colormap[i].green=(double) ScaleCharToQuantum(*p++);
1294 image->colormap[i].blue=(double) ScaleCharToQuantum(*p++);
1297 image->colormap[i].alpha=(double) TransparentAlpha;
1298 image->transparent_color=image->colormap[opacity];
1301 image->background_color=image->colormap[MagickMin((ssize_t) background,
1302 (ssize_t) image->colors-1)];
1310 Read local colormap.
1312 colormap=(unsigned char *) AcquireQuantumMemory(image->colors,3*
1314 if (colormap == (unsigned char *) NULL)
1316 global_colormap=(unsigned char *) RelinquishMagickMemory(
1318 meta_image=DestroyImage(meta_image);
1319 ThrowReaderException(ResourceLimitError,"MemoryAllocationFailed");
1321 count=ReadBlob(image,(3*image->colors)*sizeof(*colormap),colormap);
1322 if (count != (ssize_t) (3*image->colors))
1324 global_colormap=(unsigned char *) RelinquishMagickMemory(
1326 colormap=(unsigned char *) RelinquishMagickMemory(colormap);
1327 meta_image=DestroyImage(meta_image);
1328 ThrowReaderException(CorruptImageError,
1329 "InsufficientImageDataInFile");
1332 for (i=0; i < (ssize_t) image->colors; i++)
1334 image->colormap[i].red=(double) ScaleCharToQuantum(*p++);
1335 image->colormap[i].green=(double) ScaleCharToQuantum(*p++);
1336 image->colormap[i].blue=(double) ScaleCharToQuantum(*p++);
1338 image->colormap[i].alpha=(double) TransparentAlpha;
1340 colormap=(unsigned char *) RelinquishMagickMemory(colormap);
1342 if (image->gamma == 1.0)
1344 for (i=0; i < (ssize_t) image->colors; i++)
1345 if (IsPixelInfoGray(image->colormap+i) == MagickFalse)
1347 (void) SetImageColorspace(image,i == (ssize_t) image->colors ?
1348 GRAYColorspace : RGBColorspace,exception);
1350 if ((image_info->ping != MagickFalse) && (image_info->number_scenes != 0))
1351 if (image->scene >= (image_info->scene+image_info->number_scenes-1))
1353 status=SetImageExtent(image,image->columns,image->rows,exception);
1354 if (status == MagickFalse)
1355 return(DestroyImageList(image));
1359 if (image_info->ping != MagickFalse)
1360 status=PingGIFImage(image,exception);
1362 status=DecodeImage(image,opacity,exception);
1363 if ((image_info->ping == MagickFalse) && (status == MagickFalse))
1365 global_colormap=(unsigned char *) RelinquishMagickMemory(
1367 meta_image=DestroyImage(meta_image);
1368 ThrowReaderException(CorruptImageError,"CorruptImage");
1370 duration+=image->delay*image->iterations;
1371 if (image_info->number_scenes != 0)
1372 if (image->scene >= (image_info->scene+image_info->number_scenes-1))
1375 status=SetImageProgress(image,LoadImageTag,(MagickOffsetType) image->scene-
1377 if (status == MagickFalse)
1380 image->duration=duration;
1381 meta_image=DestroyImage(meta_image);
1382 global_colormap=(unsigned char *) RelinquishMagickMemory(global_colormap);
1383 if ((image->columns == 0) || (image->rows == 0))
1384 ThrowReaderException(CorruptImageError,"NegativeOrZeroImageSize");
1385 (void) CloseBlob(image);
1386 return(GetFirstImageInList(image));
1390 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1394 % R e g i s t e r G I F I m a g e %
1398 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1400 % RegisterGIFImage() adds properties for the GIF image format to
1401 % the list of supported formats. The properties include the image format
1402 % tag, a method to read and/or write the format, whether the format
1403 % supports the saving of more than one frame to the same file or blob,
1404 % whether the format supports native in-memory I/O, and a brief
1405 % description of the format.
1407 % The format of the RegisterGIFImage method is:
1409 % size_t RegisterGIFImage(void)
1412 ModuleExport size_t RegisterGIFImage(void)
1417 entry=AcquireMagickInfo("GIF","GIF",
1418 "CompuServe graphics interchange format");
1419 entry->decoder=(DecodeImageHandler *) ReadGIFImage;
1420 entry->encoder=(EncodeImageHandler *) WriteGIFImage;
1421 entry->magick=(IsImageFormatHandler *) IsGIF;
1422 entry->mime_type=ConstantString("image/gif");
1423 (void) RegisterMagickInfo(entry);
1424 entry=AcquireMagickInfo("GIF","GIF87",
1425 "CompuServe graphics interchange format");
1426 entry->decoder=(DecodeImageHandler *) ReadGIFImage;
1427 entry->encoder=(EncodeImageHandler *) WriteGIFImage;
1428 entry->magick=(IsImageFormatHandler *) IsGIF;
1429 entry->flags^=CoderAdjoinFlag;
1430 entry->version=ConstantString("version 87a");
1431 entry->mime_type=ConstantString("image/gif");
1432 (void) RegisterMagickInfo(entry);
1433 return(MagickImageCoderSignature);
1437 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1441 % U n r e g i s t e r G I F I m a g e %
1445 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1447 % UnregisterGIFImage() removes format registrations made by the
1448 % GIF module from the list of supported formats.
1450 % The format of the UnregisterGIFImage method is:
1452 % UnregisterGIFImage(void)
1455 ModuleExport void UnregisterGIFImage(void)
1457 (void) UnregisterMagickInfo("GIF");
1458 (void) UnregisterMagickInfo("GIF87");
1462 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1466 % W r i t e G I F I m a g e %
1470 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1472 % WriteGIFImage() writes an image to a file in the Compuserve Graphics
1475 % The format of the WriteGIFImage method is:
1477 % MagickBooleanType WriteGIFImage(const ImageInfo *image_info,
1478 % Image *image,ExceptionInfo *exception)
1480 % A description of each parameter follows.
1482 % o image_info: the image info.
1484 % o image: The image.
1486 % o exception: return any errors or warnings in this structure.
1489 static MagickBooleanType WriteGIFImage(const ImageInfo *image_info,Image *image,
1490 ExceptionInfo *exception)
1510 register unsigned char
1528 Open output image file.
1530 assert(image_info != (const ImageInfo *) NULL);
1531 assert(image_info->signature == MagickCoreSignature);
1532 assert(image != (Image *) NULL);
1533 assert(image->signature == MagickCoreSignature);
1534 if (image->debug != MagickFalse)
1535 (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
1536 assert(exception != (ExceptionInfo *) NULL);
1537 assert(exception->signature == MagickCoreSignature);
1538 status=OpenBlob(image_info,image,WriteBinaryBlobMode,exception);
1539 if (status == MagickFalse)
1544 global_colormap=(unsigned char *) AcquireQuantumMemory(768UL,
1545 sizeof(*global_colormap));
1546 colormap=(unsigned char *) AcquireQuantumMemory(768UL,sizeof(*colormap));
1547 if ((global_colormap == (unsigned char *) NULL) ||
1548 (colormap == (unsigned char *) NULL))
1549 ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
1550 for (i=0; i < 768; i++)
1551 colormap[i]=(unsigned char) 0;
1555 write_info=CloneImageInfo(image_info);
1556 if (LocaleCompare(write_info->magick,"GIF87") != 0)
1557 (void) WriteBlob(image,6,(unsigned char *) "GIF89a");
1560 (void) WriteBlob(image,6,(unsigned char *) "GIF87a");
1561 write_info->adjoin=MagickFalse;
1564 Determine image bounding box.
1566 page.width=image->columns;
1567 if (image->page.width > page.width)
1568 page.width=image->page.width;
1569 page.height=image->rows;
1570 if (image->page.height > page.height)
1571 page.height=image->page.height;
1572 page.x=image->page.x;
1573 page.y=image->page.y;
1574 (void) WriteBlobLSBShort(image,(unsigned short) page.width);
1575 (void) WriteBlobLSBShort(image,(unsigned short) page.height);
1577 Write images to file.
1579 if ((write_info->adjoin != MagickFalse) &&
1580 (GetNextImageInList(image) != (Image *) NULL))
1581 write_info->interlace=NoInterlace;
1586 (void) TransformImageColorspace(image,sRGBColorspace,exception);
1588 if (IsImageOpaque(image,exception) != MagickFalse)
1590 if ((image->storage_class == DirectClass) || (image->colors > 256))
1591 (void) SetImageType(image,PaletteType,exception);
1600 Identify transparent colormap index.
1602 if ((image->storage_class == DirectClass) || (image->colors > 256))
1603 (void) SetImageType(image,PaletteBilevelAlphaType,exception);
1604 for (i=0; i < (ssize_t) image->colors; i++)
1605 if (image->colormap[i].alpha != OpaqueAlpha)
1612 alpha=fabs(image->colormap[i].alpha-TransparentAlpha);
1613 beta=fabs(image->colormap[opacity].alpha-TransparentAlpha);
1619 (void) SetImageType(image,PaletteBilevelAlphaType,exception);
1620 for (i=0; i < (ssize_t) image->colors; i++)
1621 if (image->colormap[i].alpha != OpaqueAlpha)
1628 alpha=fabs(image->colormap[i].alpha-TransparentAlpha);
1629 beta=fabs(image->colormap[opacity].alpha-TransparentAlpha);
1636 image->colormap[opacity].red=image->transparent_color.red;
1637 image->colormap[opacity].green=image->transparent_color.green;
1638 image->colormap[opacity].blue=image->transparent_color.blue;
1641 if ((image->storage_class == DirectClass) || (image->colors > 256))
1642 ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
1643 for (bits_per_pixel=1; bits_per_pixel < 8; bits_per_pixel++)
1644 if ((one << bits_per_pixel) >= image->colors)
1647 for (i=0; i < (ssize_t) image->colors; i++)
1649 *q++=ScaleQuantumToChar(ClampToQuantum(image->colormap[i].red));
1650 *q++=ScaleQuantumToChar(ClampToQuantum(image->colormap[i].green));
1651 *q++=ScaleQuantumToChar(ClampToQuantum(image->colormap[i].blue));
1653 for ( ; i < (ssize_t) (one << bits_per_pixel); i++)
1655 *q++=(unsigned char) 0x0;
1656 *q++=(unsigned char) 0x0;
1657 *q++=(unsigned char) 0x0;
1659 if ((GetPreviousImageInList(image) == (Image *) NULL) ||
1660 (write_info->adjoin == MagickFalse))
1663 Write global colormap.
1666 c|=(8-1) << 4; /* color resolution */
1667 c|=(bits_per_pixel-1); /* size of global colormap */
1668 (void) WriteBlobByte(image,(unsigned char) c);
1669 for (j=0; j < (ssize_t) image->colors; j++)
1670 if (IsPixelInfoEquivalent(&image->background_color,image->colormap+j))
1672 (void) WriteBlobByte(image,(unsigned char)
1673 (j == (ssize_t) image->colors ? 0 : j)); /* background color */
1674 (void) WriteBlobByte(image,(unsigned char) 0x00); /* reserved */
1675 length=(size_t) (3*(one << bits_per_pixel));
1676 (void) WriteBlob(image,length,colormap);
1677 for (j=0; j < 768; j++)
1678 global_colormap[j]=colormap[j];
1680 if (LocaleCompare(write_info->magick,"GIF87") != 0)
1686 Write graphics control extension.
1688 (void) WriteBlobByte(image,(unsigned char) 0x21);
1689 (void) WriteBlobByte(image,(unsigned char) 0xf9);
1690 (void) WriteBlobByte(image,(unsigned char) 0x04);
1691 c=image->dispose << 2;
1694 (void) WriteBlobByte(image,(unsigned char) c);
1695 delay=(size_t) (100*image->delay/MagickMax((size_t)
1696 image->ticks_per_second,1));
1697 (void) WriteBlobLSBShort(image,(unsigned short) delay);
1698 (void) WriteBlobByte(image,(unsigned char) (opacity >= 0 ? opacity :
1700 (void) WriteBlobByte(image,(unsigned char) 0x00);
1701 value=GetImageProperty(image,"comment",exception);
1702 if ((LocaleCompare(write_info->magick,"GIF87") != 0) &&
1703 (value != (const char *) NULL))
1712 Write comment extension.
1714 (void) WriteBlobByte(image,(unsigned char) 0x21);
1715 (void) WriteBlobByte(image,(unsigned char) 0xfe);
1716 for (p=value; *p != '\0'; )
1718 count=MagickMin(strlen(p),255);
1719 (void) WriteBlobByte(image,(unsigned char) count);
1720 for (i=0; i < (ssize_t) count; i++)
1721 (void) WriteBlobByte(image,(unsigned char) *p++);
1723 (void) WriteBlobByte(image,(unsigned char) 0x00);
1725 if ((GetPreviousImageInList(image) == (Image *) NULL) &&
1726 (GetNextImageInList(image) != (Image *) NULL) &&
1727 (image->iterations != 1))
1730 Write Netscape Loop extension.
1732 (void) LogMagickEvent(CoderEvent,GetMagickModule(),
1733 " Writing GIF Extension %s","NETSCAPE2.0");
1734 (void) WriteBlobByte(image,(unsigned char) 0x21);
1735 (void) WriteBlobByte(image,(unsigned char) 0xff);
1736 (void) WriteBlobByte(image,(unsigned char) 0x0b);
1737 (void) WriteBlob(image,11,(unsigned char *) "NETSCAPE2.0");
1738 (void) WriteBlobByte(image,(unsigned char) 0x03);
1739 (void) WriteBlobByte(image,(unsigned char) 0x01);
1740 (void) WriteBlobLSBShort(image,(unsigned short) image->iterations);
1741 (void) WriteBlobByte(image,(unsigned char) 0x00);
1743 if ((image->gamma != 1.0f/2.2f))
1746 attributes[MagickPathExtent];
1752 Write ImageMagick extension.
1754 (void) LogMagickEvent(CoderEvent,GetMagickModule(),
1755 " Writing GIF Extension %s","ImageMagick");
1756 (void) WriteBlobByte(image,(unsigned char) 0x21);
1757 (void) WriteBlobByte(image,(unsigned char) 0xff);
1758 (void) WriteBlobByte(image,(unsigned char) 0x0b);
1759 (void) WriteBlob(image,11,(unsigned char *) "ImageMagick");
1760 count=FormatLocaleString(attributes,MagickPathExtent,"gamma=%g",
1762 (void) WriteBlobByte(image,(unsigned char) count);
1763 (void) WriteBlob(image,(size_t) count,(unsigned char *) attributes);
1764 (void) WriteBlobByte(image,(unsigned char) 0x00);
1766 ResetImageProfileIterator(image);
1775 name=GetNextImageProfile(image);
1776 if (name == (const char *) NULL)
1778 profile=GetImageProfile(image,name);
1779 if (profile != (StringInfo *) NULL)
1781 if ((LocaleCompare(name,"ICC") == 0) ||
1782 (LocaleCompare(name,"ICM") == 0) ||
1783 (LocaleCompare(name,"IPTC") == 0) ||
1784 (LocaleCompare(name,"8BIM") == 0) ||
1785 (LocaleNCompare(name,"gif:",4) == 0))
1793 datum=GetStringInfoDatum(profile);
1794 length=GetStringInfoLength(profile);
1795 (void) WriteBlobByte(image,(unsigned char) 0x21);
1796 (void) WriteBlobByte(image,(unsigned char) 0xff);
1797 (void) WriteBlobByte(image,(unsigned char) 0x0b);
1798 if ((LocaleCompare(name,"ICC") == 0) ||
1799 (LocaleCompare(name,"ICM") == 0))
1802 Write ICC extension.
1804 (void) WriteBlob(image,11,(unsigned char *) "ICCRGBG1012");
1805 (void) LogMagickEvent(CoderEvent,GetMagickModule(),
1806 " Writing GIF Extension %s","ICCRGBG1012");
1809 if ((LocaleCompare(name,"IPTC") == 0))
1812 Write IPTC extension.
1814 (void) WriteBlob(image,11,(unsigned char *) "MGKIPTC0000");
1815 (void) LogMagickEvent(CoderEvent,GetMagickModule(),
1816 " Writing GIF Extension %s","MGKIPTC0000");
1819 if ((LocaleCompare(name,"8BIM") == 0))
1822 Write 8BIM extension.
1824 (void) WriteBlob(image,11,(unsigned char *)
1826 (void) LogMagickEvent(CoderEvent,GetMagickModule(),
1827 " Writing GIF Extension %s","MGK8BIM0000");
1832 extension[MagickPathExtent];
1835 Write generic extension.
1837 (void) CopyMagickString(extension,name+4,
1839 (void) WriteBlob(image,11,(unsigned char *) extension);
1840 (void) LogMagickEvent(CoderEvent,GetMagickModule(),
1841 " Writing GIF Extension %s",name);
1844 while ((ssize_t) length > offset)
1849 if ((length-offset) < 255)
1850 block_length=length-offset;
1853 (void) WriteBlobByte(image,(unsigned char) block_length);
1854 (void) WriteBlob(image,(size_t) block_length,datum+offset);
1855 offset+=(ssize_t) block_length;
1857 (void) WriteBlobByte(image,(unsigned char) 0x00);
1862 (void) WriteBlobByte(image,','); /* image separator */
1864 Write the image header.
1866 page.x=image->page.x;
1867 page.y=image->page.y;
1868 if ((image->page.width != 0) && (image->page.height != 0))
1870 (void) WriteBlobLSBShort(image,(unsigned short) (page.x < 0 ? 0 : page.x));
1871 (void) WriteBlobLSBShort(image,(unsigned short) (page.y < 0 ? 0 : page.y));
1872 (void) WriteBlobLSBShort(image,(unsigned short) image->columns);
1873 (void) WriteBlobLSBShort(image,(unsigned short) image->rows);
1875 if (write_info->interlace != NoInterlace)
1876 c|=0x40; /* pixel data is interlaced */
1877 for (j=0; j < (ssize_t) (3*image->colors); j++)
1878 if (colormap[j] != global_colormap[j])
1880 if (j == (ssize_t) (3*image->colors))
1881 (void) WriteBlobByte(image,(unsigned char) c);
1885 c|=(bits_per_pixel-1); /* size of local colormap */
1886 (void) WriteBlobByte(image,(unsigned char) c);
1887 length=(size_t) (3*(one << bits_per_pixel));
1888 (void) WriteBlob(image,length,colormap);
1891 Write the image data.
1893 c=(int) MagickMax(bits_per_pixel,2);
1894 (void) WriteBlobByte(image,(unsigned char) c);
1895 status=EncodeImage(write_info,image,(size_t) MagickMax(bits_per_pixel,2)+1,
1897 if (status == MagickFalse)
1899 global_colormap=(unsigned char *) RelinquishMagickMemory(
1901 colormap=(unsigned char *) RelinquishMagickMemory(colormap);
1902 write_info=DestroyImageInfo(write_info);
1903 ThrowWriterException(ResourceLimitError,"MemoryAllocationFailed");
1905 (void) WriteBlobByte(image,(unsigned char) 0x00);
1906 if (GetNextImageInList(image) == (Image *) NULL)
1908 image=SyncNextImageInList(image);
1910 status=SetImageProgress(image,SaveImagesTag,scene,
1911 GetImageListLength(image));
1912 if (status == MagickFalse)
1914 } while (write_info->adjoin != MagickFalse);
1915 (void) WriteBlobByte(image,';'); /* terminator */
1916 global_colormap=(unsigned char *) RelinquishMagickMemory(global_colormap);
1917 colormap=(unsigned char *) RelinquishMagickMemory(colormap);
1918 write_info=DestroyImageInfo(write_info);
1919 (void) CloseBlob(image);