/
GifImagePlugin.py
1031 lines (852 loc) · 33.4 KB
/
GifImagePlugin.py
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
#
# The Python Imaging Library.
# $Id$
#
# GIF file handling
#
# History:
# 1995-09-01 fl Created
# 1996-12-14 fl Added interlace support
# 1996-12-30 fl Added animation support
# 1997-01-05 fl Added write support, fixed local colour map bug
# 1997-02-23 fl Make sure to load raster data in getdata()
# 1997-07-05 fl Support external decoder (0.4)
# 1998-07-09 fl Handle all modes when saving (0.5)
# 1998-07-15 fl Renamed offset attribute to avoid name clash
# 2001-04-16 fl Added rewind support (seek to frame 0) (0.6)
# 2001-04-17 fl Added palette optimization (0.7)
# 2002-06-06 fl Added transparency support for save (0.8)
# 2004-02-24 fl Disable interlacing for small images
#
# Copyright (c) 1997-2004 by Secret Labs AB
# Copyright (c) 1995-2004 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
import itertools
import math
import os
import subprocess
from enum import IntEnum
from . import Image, ImageChops, ImageFile, ImagePalette, ImageSequence
from ._binary import i16le as i16
from ._binary import o8
from ._binary import o16le as o16
class LoadingStrategy(IntEnum):
""".. versionadded:: 9.1.0"""
RGB_AFTER_FIRST = 0
RGB_AFTER_DIFFERENT_PALETTE_ONLY = 1
RGB_ALWAYS = 2
#: .. versionadded:: 9.1.0
LOADING_STRATEGY = LoadingStrategy.RGB_AFTER_FIRST
# --------------------------------------------------------------------
# Identify/read GIF files
def _accept(prefix):
return prefix[:6] in [b"GIF87a", b"GIF89a"]
##
# Image plugin for GIF images. This plugin supports both GIF87 and
# GIF89 images.
class GifImageFile(ImageFile.ImageFile):
format = "GIF"
format_description = "Compuserve GIF"
_close_exclusive_fp_after_loading = False
global_palette = None
def data(self):
s = self.fp.read(1)
if s and s[0]:
return self.fp.read(s[0])
return None
def _is_palette_needed(self, p):
for i in range(0, len(p), 3):
if not (i // 3 == p[i] == p[i + 1] == p[i + 2]):
return True
return False
def _open(self):
# Screen
s = self.fp.read(13)
if not _accept(s):
raise SyntaxError("not a GIF file")
self.info["version"] = s[:6]
self._size = i16(s, 6), i16(s, 8)
self.tile = []
flags = s[10]
bits = (flags & 7) + 1
if flags & 128:
# get global palette
self.info["background"] = s[11]
# check if palette contains colour indices
p = self.fp.read(3 << bits)
if self._is_palette_needed(p):
p = ImagePalette.raw("RGB", p)
self.global_palette = self.palette = p
self._fp = self.fp # FIXME: hack
self.__rewind = self.fp.tell()
self._n_frames = None
self._is_animated = None
self._seek(0) # get ready to read first frame
@property
def n_frames(self):
if self._n_frames is None:
current = self.tell()
try:
while True:
self._seek(self.tell() + 1, False)
except EOFError:
self._n_frames = self.tell() + 1
self.seek(current)
return self._n_frames
@property
def is_animated(self):
if self._is_animated is None:
if self._n_frames is not None:
self._is_animated = self._n_frames != 1
else:
current = self.tell()
if current:
self._is_animated = True
else:
try:
self._seek(1, False)
self._is_animated = True
except EOFError:
self._is_animated = False
self.seek(current)
return self._is_animated
def seek(self, frame):
if not self._seek_check(frame):
return
if frame < self.__frame:
self.im = None
self._seek(0)
last_frame = self.__frame
for f in range(self.__frame + 1, frame + 1):
try:
self._seek(f)
except EOFError as e:
self.seek(last_frame)
raise EOFError("no more images in GIF file") from e
def _seek(self, frame, update_image=True):
if frame == 0:
# rewind
self.__offset = 0
self.dispose = None
self.__frame = -1
self._fp.seek(self.__rewind)
self.disposal_method = 0
else:
# ensure that the previous frame was loaded
if self.tile and update_image:
self.load()
if frame != self.__frame + 1:
raise ValueError(f"cannot seek to frame {frame}")
self.fp = self._fp
if self.__offset:
# backup to last frame
self.fp.seek(self.__offset)
while self.data():
pass
self.__offset = 0
s = self.fp.read(1)
if not s or s == b";":
raise EOFError
self.__frame = frame
self.tile = []
palette = None
info = {}
frame_transparency = None
interlace = None
frame_dispose_extent = None
while True:
if not s:
s = self.fp.read(1)
if not s or s == b";":
break
elif s == b"!":
#
# extensions
#
s = self.fp.read(1)
block = self.data()
if s[0] == 249:
#
# graphic control extension
#
flags = block[0]
if flags & 1:
frame_transparency = block[3]
info["duration"] = i16(block, 1) * 10
# disposal method - find the value of bits 4 - 6
dispose_bits = 0b00011100 & flags
dispose_bits = dispose_bits >> 2
if dispose_bits:
# only set the dispose if it is not
# unspecified. I'm not sure if this is
# correct, but it seems to prevent the last
# frame from looking odd for some animations
self.disposal_method = dispose_bits
elif s[0] == 254:
#
# comment extension
#
while block:
if "comment" in info:
info["comment"] += block
else:
info["comment"] = block
block = self.data()
s = None
continue
elif s[0] == 255:
#
# application extension
#
info["extension"] = block, self.fp.tell()
if block[:11] == b"NETSCAPE2.0":
block = self.data()
if len(block) >= 3 and block[0] == 1:
info["loop"] = i16(block, 1)
while self.data():
pass
elif s == b",":
#
# local image
#
s = self.fp.read(9)
# extent
x0, y0 = i16(s, 0), i16(s, 2)
x1, y1 = x0 + i16(s, 4), y0 + i16(s, 6)
if (x1 > self.size[0] or y1 > self.size[1]) and update_image:
self._size = max(x1, self.size[0]), max(y1, self.size[1])
frame_dispose_extent = x0, y0, x1, y1
flags = s[8]
interlace = (flags & 64) != 0
if flags & 128:
bits = (flags & 7) + 1
p = self.fp.read(3 << bits)
if self._is_palette_needed(p):
palette = ImagePalette.raw("RGB", p)
# image data
bits = self.fp.read(1)[0]
self.__offset = self.fp.tell()
break
else:
pass
# raise OSError, "illegal GIF tag `%x`" % s[0]
s = None
if interlace is None:
# self._fp = None
raise EOFError
if not update_image:
return
if self.dispose:
self.im.paste(self.dispose, self.dispose_extent)
self._frame_palette = palette or self.global_palette
if frame == 0:
if self._frame_palette:
self.mode = (
"RGB" if LOADING_STRATEGY == LoadingStrategy.RGB_ALWAYS else "P"
)
else:
self.mode = "L"
if not palette and self.global_palette:
from copy import copy
palette = copy(self.global_palette)
self.palette = palette
else:
self._frame_transparency = frame_transparency
if self.mode == "P":
if (
LOADING_STRATEGY != LoadingStrategy.RGB_AFTER_DIFFERENT_PALETTE_ONLY
or palette
):
self.pyaccess = None
if "transparency" in self.info:
self.im.putpalettealpha(self.info["transparency"], 0)
self.im = self.im.convert("RGBA", Image.Dither.FLOYDSTEINBERG)
self.mode = "RGBA"
del self.info["transparency"]
else:
self.mode = "RGB"
self.im = self.im.convert("RGB", Image.Dither.FLOYDSTEINBERG)
def _rgb(color):
if self._frame_palette:
color = tuple(self._frame_palette.palette[color * 3 : color * 3 + 3])
else:
color = (color, color, color)
return color
self.dispose_extent = frame_dispose_extent
try:
if self.disposal_method < 2:
# do not dispose or none specified
self.dispose = None
elif self.disposal_method == 2:
# replace with background colour
# only dispose the extent in this frame
x0, y0, x1, y1 = self.dispose_extent
dispose_size = (x1 - x0, y1 - y0)
Image._decompression_bomb_check(dispose_size)
# by convention, attempt to use transparency first
dispose_mode = "P"
color = self.info.get("transparency", frame_transparency)
if color is not None:
if self.mode in ("RGB", "RGBA"):
dispose_mode = "RGBA"
color = _rgb(color) + (0,)
else:
color = self.info.get("background", 0)
if self.mode in ("RGB", "RGBA"):
dispose_mode = "RGB"
color = _rgb(color)
self.dispose = Image.core.fill(dispose_mode, dispose_size, color)
else:
# replace with previous contents
if self.im is not None:
# only dispose the extent in this frame
self.dispose = self._crop(self.im, self.dispose_extent)
elif frame_transparency is not None:
x0, y0, x1, y1 = self.dispose_extent
dispose_size = (x1 - x0, y1 - y0)
Image._decompression_bomb_check(dispose_size)
dispose_mode = "P"
color = frame_transparency
if self.mode in ("RGB", "RGBA"):
dispose_mode = "RGBA"
color = _rgb(frame_transparency) + (0,)
self.dispose = Image.core.fill(dispose_mode, dispose_size, color)
except AttributeError:
pass
if interlace is not None:
transparency = -1
if frame_transparency is not None:
if frame == 0:
self.info["transparency"] = frame_transparency
elif self.mode not in ("RGB", "RGBA"):
transparency = frame_transparency
self.tile = [
(
"gif",
(x0, y0, x1, y1),
self.__offset,
(bits, interlace, transparency),
)
]
for k in ["duration", "comment", "extension", "loop"]:
if k in info:
self.info[k] = info[k]
elif k in self.info:
del self.info[k]
def load_prepare(self):
temp_mode = "P" if self._frame_palette else "L"
self._prev_im = None
if self.__frame == 0:
if "transparency" in self.info:
self.im = Image.core.fill(
temp_mode, self.size, self.info["transparency"]
)
elif self.mode in ("RGB", "RGBA"):
self._prev_im = self.im
if self._frame_palette:
self.im = Image.core.fill("P", self.size, self._frame_transparency or 0)
self.im.putpalette(*self._frame_palette.getdata())
else:
self.im = None
self.mode = temp_mode
self._frame_palette = None
super().load_prepare()
def load_end(self):
if self.__frame == 0:
if self.mode == "P" and LOADING_STRATEGY == LoadingStrategy.RGB_ALWAYS:
self.mode = "RGB"
self.im = self.im.convert("RGB", Image.Dither.FLOYDSTEINBERG)
return
if self.mode == "P" and self._prev_im:
if self._frame_transparency is not None:
self.im.putpalettealpha(self._frame_transparency, 0)
frame_im = self.im.convert("RGBA")
else:
frame_im = self.im.convert("RGB")
else:
if not self._prev_im:
return
frame_im = self.im
frame_im = self._crop(frame_im, self.dispose_extent)
self.im = self._prev_im
self.mode = self.im.mode
if frame_im.mode == "RGBA":
self.im.paste(frame_im, self.dispose_extent, frame_im)
else:
self.im.paste(frame_im, self.dispose_extent)
def tell(self):
return self.__frame
# --------------------------------------------------------------------
# Write GIF files
RAWMODE = {"1": "L", "L": "L", "P": "P"}
def _normalize_mode(im):
"""
Takes an image (or frame), returns an image in a mode that is appropriate
for saving in a Gif.
It may return the original image, or it may return an image converted to
palette or 'L' mode.
:param im: Image object
:returns: Image object
"""
if im.mode in RAWMODE:
im.load()
return im
if Image.getmodebase(im.mode) == "RGB":
im = im.convert("P", palette=Image.Palette.ADAPTIVE)
if im.palette.mode == "RGBA":
for rgba in im.palette.colors.keys():
if rgba[3] == 0:
im.info["transparency"] = im.palette.colors[rgba]
break
return im
return im.convert("L")
def _normalize_palette(im, palette, info):
"""
Normalizes the palette for image.
- Sets the palette to the incoming palette, if provided.
- Ensures that there's a palette for L mode images
- Optimizes the palette if necessary/desired.
:param im: Image object
:param palette: bytes object containing the source palette, or ....
:param info: encoderinfo
:returns: Image object
"""
source_palette = None
if palette:
# a bytes palette
if isinstance(palette, (bytes, bytearray, list)):
source_palette = bytearray(palette[:768])
if isinstance(palette, ImagePalette.ImagePalette):
source_palette = bytearray(palette.palette)
if im.mode == "P":
if not source_palette:
source_palette = im.im.getpalette("RGB")[:768]
else: # L-mode
if not source_palette:
source_palette = bytearray(i // 3 for i in range(768))
im.palette = ImagePalette.ImagePalette("RGB", palette=source_palette)
if palette:
used_palette_colors = []
for i in range(0, len(source_palette), 3):
source_color = tuple(source_palette[i : i + 3])
try:
index = im.palette.colors[source_color]
except KeyError:
index = None
used_palette_colors.append(index)
for i, index in enumerate(used_palette_colors):
if index is None:
for j in range(len(used_palette_colors)):
if j not in used_palette_colors:
used_palette_colors[i] = j
break
im = im.remap_palette(used_palette_colors)
else:
used_palette_colors = _get_optimize(im, info)
if used_palette_colors is not None:
return im.remap_palette(used_palette_colors, source_palette)
im.palette.palette = source_palette
return im
def _write_single_frame(im, fp, palette):
im_out = _normalize_mode(im)
for k, v in im_out.info.items():
im.encoderinfo.setdefault(k, v)
im_out = _normalize_palette(im_out, palette, im.encoderinfo)
for s in _get_global_header(im_out, im.encoderinfo):
fp.write(s)
# local image header
flags = 0
if get_interlace(im):
flags = flags | 64
_write_local_header(fp, im, (0, 0), flags)
im_out.encoderconfig = (8, get_interlace(im))
ImageFile._save(im_out, fp, [("gif", (0, 0) + im.size, 0, RAWMODE[im_out.mode])])
fp.write(b"\0") # end of image data
def _write_multiple_frames(im, fp, palette):
duration = im.encoderinfo.get("duration")
disposal = im.encoderinfo.get("disposal", im.info.get("disposal"))
im_frames = []
frame_count = 0
background_im = None
for imSequence in itertools.chain([im], im.encoderinfo.get("append_images", [])):
for im_frame in ImageSequence.Iterator(imSequence):
# a copy is required here since seek can still mutate the image
im_frame = _normalize_mode(im_frame.copy())
if frame_count == 0:
for k, v in im_frame.info.items():
im.encoderinfo.setdefault(k, v)
im_frame = _normalize_palette(im_frame, palette, im.encoderinfo)
encoderinfo = im.encoderinfo.copy()
if isinstance(duration, (list, tuple)):
encoderinfo["duration"] = duration[frame_count]
elif duration is None and "duration" in im_frame.info:
encoderinfo["duration"] = im_frame.info["duration"]
if isinstance(disposal, (list, tuple)):
encoderinfo["disposal"] = disposal[frame_count]
frame_count += 1
if im_frames:
# delta frame
previous = im_frames[-1]
if encoderinfo.get("disposal") == 2:
if background_im is None:
color = im.encoderinfo.get(
"transparency", im.info.get("transparency", (0, 0, 0))
)
background = _get_background(im_frame, color)
background_im = Image.new("P", im_frame.size, background)
background_im.putpalette(im_frames[0]["im"].palette)
base_im = background_im
else:
base_im = previous["im"]
if _get_palette_bytes(im_frame) == _get_palette_bytes(base_im):
delta = ImageChops.subtract_modulo(im_frame, base_im)
else:
delta = ImageChops.subtract_modulo(
im_frame.convert("RGB"), base_im.convert("RGB")
)
bbox = delta.getbbox()
if not bbox:
# This frame is identical to the previous frame
if duration:
previous["encoderinfo"]["duration"] += encoderinfo["duration"]
continue
else:
bbox = None
im_frames.append({"im": im_frame, "bbox": bbox, "encoderinfo": encoderinfo})
if len(im_frames) > 1:
for frame_data in im_frames:
im_frame = frame_data["im"]
if not frame_data["bbox"]:
# global header
for s in _get_global_header(im_frame, frame_data["encoderinfo"]):
fp.write(s)
offset = (0, 0)
else:
# compress difference
if not palette:
frame_data["encoderinfo"]["include_color_table"] = True
im_frame = im_frame.crop(frame_data["bbox"])
offset = frame_data["bbox"][:2]
_write_frame_data(fp, im_frame, offset, frame_data["encoderinfo"])
return True
elif "duration" in im.encoderinfo and isinstance(
im.encoderinfo["duration"], (list, tuple)
):
# Since multiple frames will not be written, add together the frame durations
im.encoderinfo["duration"] = sum(im.encoderinfo["duration"])
def _save_all(im, fp, filename):
_save(im, fp, filename, save_all=True)
def _save(im, fp, filename, save_all=False):
# header
if "palette" in im.encoderinfo or "palette" in im.info:
palette = im.encoderinfo.get("palette", im.info.get("palette"))
else:
palette = None
im.encoderinfo["optimize"] = im.encoderinfo.get("optimize", True)
if not save_all or not _write_multiple_frames(im, fp, palette):
_write_single_frame(im, fp, palette)
fp.write(b";") # end of file
if hasattr(fp, "flush"):
fp.flush()
def get_interlace(im):
interlace = im.encoderinfo.get("interlace", 1)
# workaround for @PIL153
if min(im.size) < 16:
interlace = 0
return interlace
def _write_local_header(fp, im, offset, flags):
transparent_color_exists = False
try:
if "transparency" in im.encoderinfo:
transparency = im.encoderinfo["transparency"]
else:
transparency = im.info["transparency"]
transparency = int(transparency)
except (KeyError, ValueError):
pass
else:
# optimize the block away if transparent color is not used
transparent_color_exists = True
used_palette_colors = _get_optimize(im, im.encoderinfo)
if used_palette_colors is not None:
# adjust the transparency index after optimize
try:
transparency = used_palette_colors.index(transparency)
except ValueError:
transparent_color_exists = False
if "duration" in im.encoderinfo:
duration = int(im.encoderinfo["duration"] / 10)
else:
duration = 0
disposal = int(im.encoderinfo.get("disposal", 0))
if transparent_color_exists or duration != 0 or disposal:
packed_flag = 1 if transparent_color_exists else 0
packed_flag |= disposal << 2
if not transparent_color_exists:
transparency = 0
fp.write(
b"!"
+ o8(249) # extension intro
+ o8(4) # length
+ o8(packed_flag) # packed fields
+ o16(duration) # duration
+ o8(transparency) # transparency index
+ o8(0)
)
if "comment" in im.encoderinfo and 1 <= len(im.encoderinfo["comment"]):
fp.write(b"!" + o8(254)) # extension intro
comment = im.encoderinfo["comment"]
if isinstance(comment, str):
comment = comment.encode()
for i in range(0, len(comment), 255):
subblock = comment[i : i + 255]
fp.write(o8(len(subblock)) + subblock)
fp.write(o8(0))
if "loop" in im.encoderinfo:
number_of_loops = im.encoderinfo["loop"]
fp.write(
b"!"
+ o8(255) # extension intro
+ o8(11)
+ b"NETSCAPE2.0"
+ o8(3)
+ o8(1)
+ o16(number_of_loops) # number of loops
+ o8(0)
)
include_color_table = im.encoderinfo.get("include_color_table")
if include_color_table:
palette_bytes = _get_palette_bytes(im)
color_table_size = _get_color_table_size(palette_bytes)
if color_table_size:
flags = flags | 128 # local color table flag
flags = flags | color_table_size
fp.write(
b","
+ o16(offset[0]) # offset
+ o16(offset[1])
+ o16(im.size[0]) # size
+ o16(im.size[1])
+ o8(flags) # flags
)
if include_color_table and color_table_size:
fp.write(_get_header_palette(palette_bytes))
fp.write(o8(8)) # bits
def _save_netpbm(im, fp, filename):
# Unused by default.
# To use, uncomment the register_save call at the end of the file.
#
# If you need real GIF compression and/or RGB quantization, you
# can use the external NETPBM/PBMPLUS utilities. See comments
# below for information on how to enable this.
tempfile = im._dump()
try:
with open(filename, "wb") as f:
if im.mode != "RGB":
subprocess.check_call(
["ppmtogif", tempfile], stdout=f, stderr=subprocess.DEVNULL
)
else:
# Pipe ppmquant output into ppmtogif
# "ppmquant 256 %s | ppmtogif > %s" % (tempfile, filename)
quant_cmd = ["ppmquant", "256", tempfile]
togif_cmd = ["ppmtogif"]
quant_proc = subprocess.Popen(
quant_cmd, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL
)
togif_proc = subprocess.Popen(
togif_cmd,
stdin=quant_proc.stdout,
stdout=f,
stderr=subprocess.DEVNULL,
)
# Allow ppmquant to receive SIGPIPE if ppmtogif exits
quant_proc.stdout.close()
retcode = quant_proc.wait()
if retcode:
raise subprocess.CalledProcessError(retcode, quant_cmd)
retcode = togif_proc.wait()
if retcode:
raise subprocess.CalledProcessError(retcode, togif_cmd)
finally:
try:
os.unlink(tempfile)
except OSError:
pass
# Force optimization so that we can test performance against
# cases where it took lots of memory and time previously.
_FORCE_OPTIMIZE = False
def _get_optimize(im, info):
"""
Palette optimization is a potentially expensive operation.
This function determines if the palette should be optimized using
some heuristics, then returns the list of palette entries in use.
:param im: Image object
:param info: encoderinfo
:returns: list of indexes of palette entries in use, or None
"""
if im.mode in ("P", "L") and info and info.get("optimize", 0):
# Potentially expensive operation.
# The palette saves 3 bytes per color not used, but palette
# lengths are restricted to 3*(2**N) bytes. Max saving would
# be 768 -> 6 bytes if we went all the way down to 2 colors.
# * If we're over 128 colors, we can't save any space.
# * If there aren't any holes, it's not worth collapsing.
# * If we have a 'large' image, the palette is in the noise.
# create the new palette if not every color is used
optimise = _FORCE_OPTIMIZE or im.mode == "L"
if optimise or im.width * im.height < 512 * 512:
# check which colors are used
used_palette_colors = []
for i, count in enumerate(im.histogram()):
if count:
used_palette_colors.append(i)
if optimise or (
len(used_palette_colors) <= 128
and max(used_palette_colors) > len(used_palette_colors)
):
return used_palette_colors
def _get_color_table_size(palette_bytes):
# calculate the palette size for the header
if not palette_bytes:
return 0
elif len(palette_bytes) < 9:
return 1
else:
return math.ceil(math.log(len(palette_bytes) // 3, 2)) - 1
def _get_header_palette(palette_bytes):
"""
Returns the palette, null padded to the next power of 2 (*3) bytes
suitable for direct inclusion in the GIF header
:param palette_bytes: Unpadded palette bytes, in RGBRGB form
:returns: Null padded palette
"""
color_table_size = _get_color_table_size(palette_bytes)
# add the missing amount of bytes
# the palette has to be 2<<n in size
actual_target_size_diff = (2 << color_table_size) - len(palette_bytes) // 3
if actual_target_size_diff > 0:
palette_bytes += o8(0) * 3 * actual_target_size_diff
return palette_bytes
def _get_palette_bytes(im):
"""
Gets the palette for inclusion in the gif header
:param im: Image object
:returns: Bytes, len<=768 suitable for inclusion in gif header
"""
return im.palette.palette
def _get_background(im, info_background):
background = 0
if info_background:
background = info_background
if isinstance(background, tuple):
# WebPImagePlugin stores an RGBA value in info["background"]
# So it must be converted to the same format as GifImagePlugin's
# info["background"] - a global color table index
try:
background = im.palette.getcolor(background, im)
except ValueError as e:
if str(e) == "cannot allocate more than 256 colors":
# If all 256 colors are in use,
# then there is no need for the background color
return 0
else:
raise
return background
def _get_global_header(im, info):
"""Return a list of strings representing a GIF header"""
# Header Block
# https://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
version = b"87a"
if im.info.get("version") == b"89a" or (
info
and (
"transparency" in info
or "loop" in info
or info.get("duration")
or info.get("comment")
)
):
version = b"89a"
background = _get_background(im, info.get("background"))
palette_bytes = _get_palette_bytes(im)
color_table_size = _get_color_table_size(palette_bytes)
return [
b"GIF" # signature
+ version # version
+ o16(im.size[0]) # canvas width
+ o16(im.size[1]), # canvas height
# Logical Screen Descriptor
# size of global color table + global color table flag
o8(color_table_size + 128), # packed fields
# background + reserved/aspect
o8(background) + o8(0),
# Global Color Table
_get_header_palette(palette_bytes),
]
def _write_frame_data(fp, im_frame, offset, params):
try:
im_frame.encoderinfo = params
# local image header
_write_local_header(fp, im_frame, offset, 0)
ImageFile._save(
im_frame, fp, [("gif", (0, 0) + im_frame.size, 0, RAWMODE[im_frame.mode])]
)
fp.write(b"\0") # end of image data
finally:
del im_frame.encoderinfo
# --------------------------------------------------------------------
# Legacy GIF utilities
def getheader(im, palette=None, info=None):
"""
Legacy Method to get Gif data from image.
Warning:: May modify image data.
:param im: Image object
:param palette: bytes object containing the source palette, or ....
:param info: encoderinfo
:returns: tuple of(list of header items, optimized palette)
"""
used_palette_colors = _get_optimize(im, info)
if info is None:
info = {}
if "background" not in info and "background" in im.info:
info["background"] = im.info["background"]
im_mod = _normalize_palette(im, palette, info)
im.palette = im_mod.palette
im.im = im_mod.im
header = _get_global_header(im, info)
return header, used_palette_colors
def getdata(im, offset=(0, 0), **params):
"""
Legacy Method
Return a list of strings representing this image.
The first string is a local image header, the rest contains
encoded image data.
To specify duration, add the time in milliseconds,
e.g. ``getdata(im_frame, duration=1000)``
:param im: Image object
:param offset: Tuple of (x, y) pixels. Defaults to (0, 0)
:param \\**params: e.g. duration or other encoder info parameters
:returns: List of bytes containing GIF encoded frame data