This file is indexed.

/usr/lib/python3/dist-packages/matplotlib/animation.py is in python3-matplotlib 2.1.1-2ubuntu3.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   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
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
# TODO:
# * Loop Delay is broken on GTKAgg. This is because source_remove() is not
#   working as we want. PyGTK bug?
# * Documentation -- this will need a new section of the User's Guide.
#      Both for Animations and just timers.
#   - Also need to update http://www.scipy.org/Cookbook/Matplotlib/Animations
# * Blit
#   * Currently broken with Qt4 for widgets that don't start on screen
#   * Still a few edge cases that aren't working correctly
#   * Can this integrate better with existing matplotlib animation artist flag?
#     - If animated removes from default draw(), perhaps we could use this to
#       simplify initial draw.
# * Example
#   * Frameless animation - pure procedural with no loop
#   * Need example that uses something like inotify or subprocess
#   * Complex syncing examples
# * Movies
#   * Can blit be enabled for movies?
# * Need to consider event sources to allow clicking through multiple figures
from __future__ import (absolute_import, division, print_function,
                        unicode_literals)

import six
from six.moves import xrange, zip

import numpy as np
import os
import platform
import sys
import itertools
try:
    # python3
    from base64 import encodebytes
except ImportError:
    # python2
    from base64 import encodestring as encodebytes
import abc
import contextlib
import tempfile
import uuid
import warnings
from matplotlib._animation_data import (DISPLAY_TEMPLATE, INCLUDED_FRAMES,
                                        JS_INCLUDE)
from matplotlib.cbook import iterable, deprecated
from matplotlib.compat import subprocess
from matplotlib import verbose
from matplotlib import rcParams, rcParamsDefault, rc_context
if sys.version_info < (3, 0):
    from cStringIO import StringIO as InMemory
else:
    from io import BytesIO as InMemory

# Process creation flag for subprocess to prevent it raising a terminal
# window. See for example:
# https://stackoverflow.com/questions/24130623/using-python-subprocess-popen-cant-prevent-exe-stopped-working-prompt
if platform.system() == 'Windows':
    subprocess_creation_flags = CREATE_NO_WINDOW = 0x08000000
else:
    # Apparently None won't work here
    subprocess_creation_flags = 0

# Other potential writing methods:
# * http://pymedia.org/
# * libmng (produces swf) python wrappers: https://github.com/libming/libming
# * Wrap x264 API:

# (http://stackoverflow.com/questions/2940671/
# how-to-encode-series-of-images-into-h264-using-x264-api-c-c )


def adjusted_figsize(w, h, dpi, n):
    '''Compute figure size so that pixels are a multiple of n

    Parameters
    ----------
    w, h : float
        Size in inches

    dpi : float
        The dpi

    n : int
        The target multiple

    Returns
    -------
    wnew, hnew : float
        The new figure size in inches.
    '''

    # this maybe simplified if / when we adopt consistent rounding for
    # pixel size across the whole library
    def correct_roundoff(x, dpi, n):
        if int(x*dpi) % n != 0:
            if int(np.nextafter(x, np.inf)*dpi) % n == 0:
                x = np.nextafter(x, np.inf)
            elif int(np.nextafter(x, -np.inf)*dpi) % n == 0:
                x = np.nextafter(x, -np.inf)
        return x

    wnew = int(w * dpi / n) * n / dpi
    hnew = int(h * dpi / n) * n / dpi
    return (correct_roundoff(wnew, dpi, n), correct_roundoff(hnew, dpi, n))


# A registry for available MovieWriter classes
class MovieWriterRegistry(object):
    '''Registry of available writer classes by human readable name.'''
    def __init__(self):
        self.avail = dict()
        self._registered = dict()
        self._dirty = False

    def set_dirty(self):
        """Sets a flag to re-setup the writers."""
        self._dirty = True

    def register(self, name):
        """Decorator for registering a class under a name.

        Example use::

            @registry.register(name)
            class Foo:
                pass
        """
        def wrapper(writerClass):
            self._registered[name] = writerClass
            if writerClass.isAvailable():
                self.avail[name] = writerClass
            return writerClass
        return wrapper

    def ensure_not_dirty(self):
        """If dirty, reasks the writers if they are available"""
        if self._dirty:
            self.reset_available_writers()

    def reset_available_writers(self):
        """Reset the available state of all registered writers"""
        self.avail = {}
        for name, writerClass in self._registered.items():
            if writerClass.isAvailable():
                self.avail[name] = writerClass
        self._dirty = False

    def list(self):
        '''Get a list of available MovieWriters.'''
        self.ensure_not_dirty()
        return list(self.avail)

    def is_available(self, name):
        '''Check if given writer is available by name.

        Parameters
        ----------
        name : str

        Returns
        -------
        available : bool
        '''
        self.ensure_not_dirty()
        return name in self.avail

    def __getitem__(self, name):
        self.ensure_not_dirty()
        if not self.avail:
            raise RuntimeError("No MovieWriters available!")
        return self.avail[name]

writers = MovieWriterRegistry()


class AbstractMovieWriter(six.with_metaclass(abc.ABCMeta)):
    '''
    Abstract base class for writing movies. Fundamentally, what a MovieWriter
    does is provide is a way to grab frames by calling grab_frame().

    setup() is called to start the process and finish() is called afterwards.

    This class is set up to provide for writing movie frame data to a pipe.
    saving() is provided as a context manager to facilitate this process as::

        with moviewriter.saving(fig, outfile='myfile.mp4', dpi=100):
            # Iterate over frames
            moviewriter.grab_frame(**savefig_kwargs)

    The use of the context manager ensures that setup() and finish() are
    performed as necessary.

    An instance of a concrete subclass of this class can be given as the
    ``writer`` argument of `Animation.save()`.
    '''

    @abc.abstractmethod
    def setup(self, fig, outfile, dpi=None):
        '''
        Perform setup for writing the movie file.

        Parameters
        ----------
        fig: `matplotlib.figure.Figure` instance
            The figure object that contains the information for frames
        outfile: string
            The filename of the resulting movie file
        dpi: int, optional
            The DPI (or resolution) for the file.  This controls the size
            in pixels of the resulting movie file. Default is ``fig.dpi``.
        '''

    @abc.abstractmethod
    def grab_frame(self, **savefig_kwargs):
        '''
        Grab the image information from the figure and save as a movie frame.

        All keyword arguments in savefig_kwargs are passed on to the `savefig`
        command that saves the figure.
        '''

    @abc.abstractmethod
    def finish(self):
        '''Finish any processing for writing the movie.'''

    @contextlib.contextmanager
    def saving(self, fig, outfile, dpi, *args, **kwargs):
        '''
        Context manager to facilitate writing the movie file.

        ``*args, **kw`` are any parameters that should be passed to `setup`.
        '''
        # This particular sequence is what contextlib.contextmanager wants
        self.setup(fig, outfile, dpi, *args, **kwargs)
        try:
            yield self
        finally:
            self.finish()


class MovieWriter(AbstractMovieWriter):
    '''Base class for writing movies.

    This class is set up to provide for writing movie frame data to a pipe.
    See examples for how to use these classes.

    Attributes
    ----------
    frame_format : str
        The format used in writing frame data, defaults to 'rgba'
    fig : `~matplotlib.figure.Figure`
        The figure to capture data from.
        This must be provided by the sub-classes.

    '''

    def __init__(self, fps=5, codec=None, bitrate=None, extra_args=None,
                 metadata=None):
        '''MovieWriter

        Parameters
        ----------
        fps: int
            Framerate for movie.
        codec: string or None, optional
            The codec to use. If ``None`` (the default) the ``animation.codec``
            rcParam is used.
        bitrate: int or None, optional
            The bitrate for the saved movie file, which is one way to control
            the output file size and quality. The default value is ``None``,
            which uses the ``animation.bitrate`` rcParam.  A value of -1
            implies that the bitrate should be determined automatically by the
            underlying utility.
        extra_args: list of strings or None, optional
            A list of extra string arguments to be passed to the underlying
            movie utility. The default is ``None``, which passes the additional
            arguments in the ``animation.extra_args`` rcParam.
        metadata: Dict[str, str] or None
            A dictionary of keys and values for metadata to include in the
            output file. Some keys that may be of use include:
            title, artist, genre, subject, copyright, srcform, comment.
        '''
        self.fps = fps
        self.frame_format = 'rgba'

        if codec is None:
            self.codec = rcParams['animation.codec']
        else:
            self.codec = codec

        if bitrate is None:
            self.bitrate = rcParams['animation.bitrate']
        else:
            self.bitrate = bitrate

        if extra_args is None:
            self.extra_args = list(rcParams[self.args_key])
        else:
            self.extra_args = extra_args

        if metadata is None:
            self.metadata = dict()
        else:
            self.metadata = metadata

    @property
    def frame_size(self):
        '''A tuple ``(width, height)`` in pixels of a movie frame.'''
        w, h = self.fig.get_size_inches()
        return int(w * self.dpi), int(h * self.dpi)

    def _adjust_frame_size(self):
        if self.codec == 'h264':
            wo, ho = self.fig.get_size_inches()
            w, h = adjusted_figsize(wo, ho, self.dpi, 2)
            if not (wo, ho) == (w, h):
                self.fig.set_size_inches(w, h, forward=True)
                verbose.report('figure size (inches) has been adjusted '
                               'from %s x %s to %s x %s' % (wo, ho, w, h),
                               level='helpful')
        else:
            w, h = self.fig.get_size_inches()
        verbose.report('frame size in pixels is %s x %s' % self.frame_size,
                       level='debug')
        return w, h

    def setup(self, fig, outfile, dpi=None):
        '''
        Perform setup for writing the movie file.

        Parameters
        ----------
        fig : matplotlib.figure.Figure
            The figure object that contains the information for frames
        outfile : string
            The filename of the resulting movie file
        dpi : int, optional
            The DPI (or resolution) for the file.  This controls the size
            in pixels of the resulting movie file. Default is fig.dpi.
        '''
        self.outfile = outfile
        self.fig = fig
        if dpi is None:
            dpi = self.fig.dpi
        self.dpi = dpi
        self._w, self._h = self._adjust_frame_size()

        # Run here so that grab_frame() can write the data to a pipe. This
        # eliminates the need for temp files.
        self._run()

    def _run(self):
        # Uses subprocess to call the program for assembling frames into a
        # movie file.  *args* returns the sequence of command line arguments
        # from a few configuration options.
        command = self._args()
        if verbose.ge('debug'):
            output = sys.stdout
        else:
            output = subprocess.PIPE
        verbose.report('MovieWriter.run: running command: %s' %
                       ' '.join(command))
        self._proc = subprocess.Popen(command, shell=False,
                                      stdout=output, stderr=output,
                                      stdin=subprocess.PIPE,
                                      creationflags=subprocess_creation_flags)

    def finish(self):
        '''Finish any processing for writing the movie.'''
        self.cleanup()

    def grab_frame(self, **savefig_kwargs):
        '''
        Grab the image information from the figure and save as a movie frame.

        All keyword arguments in savefig_kwargs are passed on to the `savefig`
        command that saves the figure.
        '''
        verbose.report('MovieWriter.grab_frame: Grabbing frame.',
                       level='debug')
        try:
            # re-adjust the figure size in case it has been changed by the
            # user.  We must ensure that every frame is the same size or
            # the movie will not save correctly.
            self.fig.set_size_inches(self._w, self._h)
            # Tell the figure to save its data to the sink, using the
            # frame format and dpi.
            self.fig.savefig(self._frame_sink(), format=self.frame_format,
                             dpi=self.dpi, **savefig_kwargs)
        except (RuntimeError, IOError) as e:
            out, err = self._proc.communicate()
            verbose.report('MovieWriter -- Error '
                           'running proc:\n%s\n%s' % (out, err),
                           level='helpful')
            raise IOError('Error saving animation to file (cause: {0}) '
                          'Stdout: {1} StdError: {2}. It may help to re-run '
                          'with --verbose-debug.'.format(e, out, err))

    def _frame_sink(self):
        '''Returns the place to which frames should be written.'''
        return self._proc.stdin

    def _args(self):
        '''Assemble list of utility-specific command-line arguments.'''
        return NotImplementedError("args needs to be implemented by subclass.")

    def cleanup(self):
        '''Clean-up and collect the process used to write the movie file.'''
        out, err = self._proc.communicate()
        self._frame_sink().close()
        verbose.report('MovieWriter -- '
                       'Command stdout:\n%s' % out, level='debug')
        verbose.report('MovieWriter -- '
                       'Command stderr:\n%s' % err, level='debug')

    @classmethod
    def bin_path(cls):
        '''
        Returns the binary path to the commandline tool used by a specific
        subclass. This is a class method so that the tool can be looked for
        before making a particular MovieWriter subclass available.
        '''
        return str(rcParams[cls.exec_key])

    @classmethod
    def isAvailable(cls):
        '''
        Check to see if a MovieWriter subclass is actually available by
        running the commandline tool.
        '''
        bin_path = cls.bin_path()
        if not bin_path:
            return False
        try:
            p = subprocess.Popen(
                bin_path,
                shell=False,
                stdout=subprocess.PIPE,
                stderr=subprocess.PIPE,
                creationflags=subprocess_creation_flags)
            return cls._handle_subprocess(p)
        except OSError:
            return False

    @classmethod
    def _handle_subprocess(cls, process):
        process.communicate()
        return True


class FileMovieWriter(MovieWriter):
    '''`MovieWriter` for writing to individual files and stitching at the end.

    This must be sub-classed to be useful.
    '''
    def __init__(self, *args, **kwargs):
        MovieWriter.__init__(self, *args, **kwargs)
        self.frame_format = rcParams['animation.frame_format']

    def setup(self, fig, outfile, dpi=None, frame_prefix='_tmp',
              clear_temp=True):
        '''Perform setup for writing the movie file.

        Parameters
        ----------
        fig : matplotlib.figure.Figure
            The figure to grab the rendered frames from.
        outfile : str
            The filename of the resulting movie file.
        dpi : number, optional
            The dpi of the output file. This, with the figure size,
            controls the size in pixels of the resulting movie file.
            Default is fig.dpi.
        frame_prefix : str, optional
            The filename prefix to use for temporary files.  Defaults to
            ``'_tmp'``.
        clear_temp : bool, optional
            If the temporary files should be deleted after stitching
            the final result.  Setting this to ``False`` can be useful for
            debugging.  Defaults to ``True``.

        '''
        self.fig = fig
        self.outfile = outfile
        if dpi is None:
            dpi = self.fig.dpi
        self.dpi = dpi
        self._adjust_frame_size()

        self.clear_temp = clear_temp
        self.temp_prefix = frame_prefix
        self._frame_counter = 0  # used for generating sequential file names
        self._temp_names = list()
        self.fname_format_str = '%s%%07d.%s'

    @property
    def frame_format(self):
        '''
        Format (png, jpeg, etc.) to use for saving the frames, which can be
        decided by the individual subclasses.
        '''
        return self._frame_format

    @frame_format.setter
    def frame_format(self, frame_format):
        if frame_format in self.supported_formats:
            self._frame_format = frame_format
        else:
            self._frame_format = self.supported_formats[0]

    def _base_temp_name(self):
        # Generates a template name (without number) given the frame format
        # for extension and the prefix.
        return self.fname_format_str % (self.temp_prefix, self.frame_format)

    def _frame_sink(self):
        # Creates a filename for saving using the basename and the current
        # counter.
        fname = self._base_temp_name() % self._frame_counter

        # Save the filename so we can delete it later if necessary
        self._temp_names.append(fname)
        verbose.report(
            'FileMovieWriter.frame_sink: saving frame %d to fname=%s' %
            (self._frame_counter, fname),
            level='debug')
        self._frame_counter += 1  # Ensures each created name is 'unique'

        # This file returned here will be closed once it's used by savefig()
        # because it will no longer be referenced and will be gc-ed.
        return open(fname, 'wb')

    def grab_frame(self, **savefig_kwargs):
        '''
        Grab the image information from the figure and save as a movie frame.
        All keyword arguments in savefig_kwargs are passed on to the `savefig`
        command that saves the figure.
        '''
        # Overloaded to explicitly close temp file.
        verbose.report('MovieWriter.grab_frame: Grabbing frame.',
                       level='debug')
        try:
            # Tell the figure to save its data to the sink, using the
            # frame format and dpi.
            with self._frame_sink() as myframesink:
                self.fig.savefig(myframesink, format=self.frame_format,
                                 dpi=self.dpi, **savefig_kwargs)

        except RuntimeError:
            out, err = self._proc.communicate()
            verbose.report('MovieWriter -- Error '
                           'running proc:\n%s\n%s' % (out,
                                                      err), level='helpful')
            raise

    def finish(self):
        # Call run here now that all frame grabbing is done. All temp files
        # are available to be assembled.
        self._run()
        MovieWriter.finish(self)  # Will call clean-up

        # Check error code for creating file here, since we just run
        # the process here, rather than having an open pipe.
        if self._proc.returncode:
            try:
                stdout = [s.decode() for s in self._proc._stdout_buff]
                stderr = [s.decode() for s in self._proc._stderr_buff]
                verbose.report("MovieWriter.finish: stdout: %s" % stdout,
                               level='helpful')
                verbose.report("MovieWriter.finish: stderr: %s" % stderr,
                               level='helpful')
            except Exception as e:
                pass
            msg = ('Error creating movie, return code: ' +
                   str(self._proc.returncode) +
                   ' Try setting mpl.verbose.set_level("helpful")')
            raise RuntimeError(msg)

    def cleanup(self):
        MovieWriter.cleanup(self)

        # Delete temporary files
        if self.clear_temp:
            verbose.report(
                'MovieWriter: clearing temporary fnames=%s' %
                str(self._temp_names),
                level='debug')
            for fname in self._temp_names:
                os.remove(fname)


# Base class of ffmpeg information. Has the config keys and the common set
# of arguments that controls the *output* side of things.
class FFMpegBase(object):
    '''Mixin class for FFMpeg output.

    To be useful this must be multiply-inherited from with a
    `MovieWriterBase` sub-class.
    '''

    exec_key = 'animation.ffmpeg_path'
    args_key = 'animation.ffmpeg_args'

    @property
    def output_args(self):
        args = ['-vcodec', self.codec]
        # For h264, the default format is yuv444p, which is not compatible
        # with quicktime (and others). Specifying yuv420p fixes playback on
        # iOS,as well as HTML5 video in firefox and safari (on both Win and
        # OSX). Also fixes internet explorer. This is as of 2015/10/29.
        if self.codec == 'h264' and '-pix_fmt' not in self.extra_args:
            args.extend(['-pix_fmt', 'yuv420p'])
        # The %dk adds 'k' as a suffix so that ffmpeg treats our bitrate as in
        # kbps
        if self.bitrate > 0:
            args.extend(['-b', '%dk' % self.bitrate])
        if self.extra_args:
            args.extend(self.extra_args)
        for k, v in six.iteritems(self.metadata):
            args.extend(['-metadata', '%s=%s' % (k, v)])

        return args + ['-y', self.outfile]

    @classmethod
    def _handle_subprocess(cls, process):
        _, err = process.communicate()
        # Ubuntu 12.04 ships a broken ffmpeg binary which we shouldn't use
        # NOTE : when removed, remove the same method in AVConvBase.
        if 'Libav' in err.decode():
            return False
        return True


# Combine FFMpeg options with pipe-based writing
@writers.register('ffmpeg')
class FFMpegWriter(FFMpegBase, MovieWriter):
    '''Pipe-based ffmpeg writer.

    Frames are streamed directly to ffmpeg via a pipe and written in a single
    pass.
    '''
    def _args(self):
        # Returns the command line parameters for subprocess to use
        # ffmpeg to create a movie using a pipe.
        args = [self.bin_path(), '-f', 'rawvideo', '-vcodec', 'rawvideo',
                '-s', '%dx%d' % self.frame_size, '-pix_fmt', self.frame_format,
                '-r', str(self.fps)]
        # Logging is quieted because subprocess.PIPE has limited buffer size.
        if not verbose.ge('debug'):
            args += ['-loglevel', 'quiet']
        args += ['-i', 'pipe:'] + self.output_args
        return args


# Combine FFMpeg options with temp file-based writing
@writers.register('ffmpeg_file')
class FFMpegFileWriter(FFMpegBase, FileMovieWriter):
    '''File-based ffmpeg writer.

    Frames are written to temporary files on disk and then stitched
    together at the end.

    '''
    supported_formats = ['png', 'jpeg', 'ppm', 'tiff', 'sgi', 'bmp',
                         'pbm', 'raw', 'rgba']

    def _args(self):
        # Returns the command line parameters for subprocess to use
        # ffmpeg to create a movie using a collection of temp images
        return [self.bin_path(), '-r', str(self.fps),
                '-i', self._base_temp_name(),
                '-vframes', str(self._frame_counter)] + self.output_args


# Base class of avconv information.  AVConv has identical arguments to
# FFMpeg
class AVConvBase(FFMpegBase):
    '''Mixin class for avconv output.

    To be useful this must be multiply-inherited from with a
    `MovieWriterBase` sub-class.
    '''

    exec_key = 'animation.avconv_path'
    args_key = 'animation.avconv_args'

    # NOTE : should be removed when the same method is removed in FFMpegBase.
    @classmethod
    def _handle_subprocess(cls, process):
        return MovieWriter._handle_subprocess(process)


# Combine AVConv options with pipe-based writing
@writers.register('avconv')
class AVConvWriter(AVConvBase, FFMpegWriter):
    '''Pipe-based avconv writer.

    Frames are streamed directly to avconv via a pipe and written in a single
    pass.
    '''


# Combine AVConv options with file-based writing
@writers.register('avconv_file')
class AVConvFileWriter(AVConvBase, FFMpegFileWriter):
    '''File-based avconv writer.

    Frames are written to temporary files on disk and then stitched
    together at the end.

    '''


# Base class of mencoder information. Contains configuration key information
# as well as arguments for controlling *output*
class MencoderBase(object):
    exec_key = 'animation.mencoder_path'
    args_key = 'animation.mencoder_args'

    # Mencoder only allows certain keys, other ones cause the program
    # to fail.
    allowed_metadata = ['name', 'artist', 'genre', 'subject', 'copyright',
                        'srcform', 'comment']

    # Mencoder mandates using name, but 'title' works better with ffmpeg.
    # If we find it, just put it's value into name
    def _remap_metadata(self):
        if 'title' in self.metadata:
            self.metadata['name'] = self.metadata['title']

    @property
    def output_args(self):
        self._remap_metadata()
        lavcopts = {'vcodec': self.codec}
        if self.bitrate > 0:
            lavcopts.update(vbitrate=self.bitrate)
        args = ['-o', self.outfile, '-ovc', 'lavc', '-lavcopts',
                ':'.join(itertools.starmap('{0}={1}'.format,
                                           lavcopts.items()))]
        if self.extra_args:
            args.extend(self.extra_args)
        if self.metadata:
            args.extend(['-info', ':'.join('%s=%s' % (k, v)
                         for k, v in six.iteritems(self.metadata)
                         if k in self.allowed_metadata)])
        return args


# The message must be a single line; internal newlines cause sphinx failure.
mencoder_dep = ("Support for mencoder is only partially functional, "
                "and will be removed entirely in 2.2. "
                "Please use ffmpeg instead.")


@writers.register('mencoder')
class MencoderWriter(MovieWriter, MencoderBase):

    @deprecated('2.0', message=mencoder_dep)
    def __init__(self, *args, **kwargs):
        with rc_context(rc={'animation.codec': 'mpeg4'}):
            super(MencoderWriter, self).__init__(*args, **kwargs)

    def _args(self):
        # Returns the command line parameters for subprocess to use
        # mencoder to create a movie
        return [self.bin_path(), '-', '-demuxer', 'rawvideo', '-rawvideo',
                ('w=%i:h=%i:' % self.frame_size +
                'fps=%i:format=%s' % (self.fps,
                                      self.frame_format))] + self.output_args


# Combine Mencoder options with temp file-based writing
@writers.register('mencoder_file')
class MencoderFileWriter(FileMovieWriter, MencoderBase):
    supported_formats = ['png', 'jpeg', 'tga', 'sgi']

    @deprecated('2.0', message=mencoder_dep)
    def __init__(self, *args, **kwargs):
        with rc_context(rc={'animation.codec': 'mpeg4'}):
            super(MencoderFileWriter, self).__init__(*args, **kwargs)

    def _args(self):
        # Returns the command line parameters for subprocess to use
        # mencoder to create a movie
        return [self.bin_path(),
                'mf://%s*.%s' % (self.temp_prefix, self.frame_format),
                '-frames', str(self._frame_counter), '-mf',
                'type=%s:fps=%d' % (self.frame_format,
                                    self.fps)] + self.output_args


# Base class for animated GIFs with convert utility
class ImageMagickBase(object):
    '''Mixin class for ImageMagick output.

    To be useful this must be multiply-inherited from with a
    `MovieWriterBase` sub-class.
    '''

    exec_key = 'animation.convert_path'
    args_key = 'animation.convert_args'

    @property
    def delay(self):
        return 100. / self.fps

    @property
    def output_args(self):
        return [self.outfile]

    @classmethod
    def _init_from_registry(cls):
        if sys.platform != 'win32' or rcParams[cls.exec_key] != 'convert':
            return
        from six.moves import winreg
        for flag in (0, winreg.KEY_WOW64_32KEY, winreg.KEY_WOW64_64KEY):
            try:
                hkey = winreg.OpenKeyEx(winreg.HKEY_LOCAL_MACHINE,
                                        'Software\\Imagemagick\\Current',
                                        0, winreg.KEY_QUERY_VALUE | flag)
                binpath = winreg.QueryValueEx(hkey, 'BinPath')[0]
                winreg.CloseKey(hkey)
                binpath += '\\convert.exe'
                break
            except Exception:
                binpath = ''
        rcParams[cls.exec_key] = rcParamsDefault[cls.exec_key] = binpath

    @classmethod
    def isAvailable(cls):
        '''
        Check to see if a ImageMagickWriter is actually available.

        Done by first checking the windows registry (if applicable) and then
        running the commandline tool.
        '''
        bin_path = cls.bin_path()
        if bin_path == "convert":
            cls._init_from_registry()
        return super(ImageMagickBase, cls).isAvailable()

ImageMagickBase._init_from_registry()


# Note: the base classes need to be in that order to get
# isAvailable() from ImageMagickBase called and not the
# one from MovieWriter. The latter is then called by the
# former.
@writers.register('imagemagick')
class ImageMagickWriter(ImageMagickBase, MovieWriter):
    '''Pipe-based animated gif.

    Frames are streamed directly to ImageMagick via a pipe and written
    in a single pass.

    '''
    def _args(self):
        return ([self.bin_path(),
                 '-size', '%ix%i' % self.frame_size, '-depth', '8',
                 '-delay', str(self.delay), '-loop', '0',
                 '%s:-' % self.frame_format]
                + self.output_args)


# Note: the base classes need to be in that order to get
# isAvailable() from ImageMagickBase called and not the
# one from MovieWriter. The latter is then called by the
# former.
@writers.register('imagemagick_file')
class ImageMagickFileWriter(ImageMagickBase, FileMovieWriter):
    '''File-based animated gif writer.

    Frames are written to temporary files on disk and then stitched
    together at the end.

    '''

    supported_formats = ['png', 'jpeg', 'ppm', 'tiff', 'sgi', 'bmp',
                         'pbm', 'raw', 'rgba']

    def _args(self):
        return ([self.bin_path(), '-delay', str(self.delay), '-loop', '0',
                 '%s*.%s' % (self.temp_prefix, self.frame_format)]
                + self.output_args)


# Taken directly from jakevdp's JSAnimation package at
# http://github.com/jakevdp/JSAnimation
def _included_frames(frame_list, frame_format):
    """frame_list should be a list of filenames"""
    return INCLUDED_FRAMES.format(Nframes=len(frame_list),
                                  frame_dir=os.path.dirname(frame_list[0]),
                                  frame_format=frame_format)


def _embedded_frames(frame_list, frame_format):
    """frame_list should be a list of base64-encoded png files"""
    template = '  frames[{0}] = "data:image/{1};base64,{2}"\n'
    embedded = "\n"
    for i, frame_data in enumerate(frame_list):
        embedded += template.format(i, frame_format,
                                    frame_data.replace('\n', '\\\n'))
    return embedded


@writers.register('html')
class HTMLWriter(FileMovieWriter):
    supported_formats = ['png', 'jpeg', 'tiff', 'svg']
    args_key = 'animation.html_args'

    @classmethod
    def isAvailable(cls):
        return True

    def __init__(self, fps=30, codec=None, bitrate=None, extra_args=None,
                 metadata=None, embed_frames=False, default_mode='loop',
                 embed_limit=None):
        self.embed_frames = embed_frames
        self.default_mode = default_mode.lower()

        # Save embed limit, which is given in MB
        if embed_limit is None:
            self._bytes_limit = rcParams['animation.embed_limit']
        else:
            self._bytes_limit = embed_limit

        # Convert from MB to bytes
        self._bytes_limit *= 1024 * 1024

        if self.default_mode not in ['loop', 'once', 'reflect']:
            self.default_mode = 'loop'
            warnings.warn("unrecognized default_mode: using 'loop'")

        self._saved_frames = []
        self._total_bytes = 0
        self._hit_limit = False
        super(HTMLWriter, self).__init__(fps, codec, bitrate,
                                         extra_args, metadata)

    def setup(self, fig, outfile, dpi, frame_dir=None):
        if os.path.splitext(outfile)[-1] not in ['.html', '.htm']:
            raise ValueError("outfile must be *.htm or *.html")

        if not self.embed_frames:
            if frame_dir is None:
                frame_dir = outfile.rstrip('.html') + '_frames'
            if not os.path.exists(frame_dir):
                os.makedirs(frame_dir)
            frame_prefix = os.path.join(frame_dir, 'frame')
        else:
            frame_prefix = None

        super(HTMLWriter, self).setup(fig, outfile, dpi,
                                      frame_prefix, clear_temp=False)

    def grab_frame(self, **savefig_kwargs):
        if self.embed_frames:
            # Just stop processing if we hit the limit
            if self._hit_limit:
                return
            suffix = '.' + self.frame_format
            f = InMemory()
            self.fig.savefig(f, format=self.frame_format,
                             dpi=self.dpi, **savefig_kwargs)
            imgdata64 = encodebytes(f.getvalue()).decode('ascii')
            self._total_bytes += len(imgdata64)
            if self._total_bytes >= self._bytes_limit:
                warnings.warn("Animation size has reached {0._total_bytes} "
                              "bytes, exceeding the limit of "
                              "{0._bytes_limit}. If you're sure you want "
                              "a larger animation embedded, set the "
                              "animation.embed_limit rc parameter to a "
                              "larger value (in MB). This and further frames"
                              " will be dropped.".format(self))
                self._hit_limit = True
            else:
                self._saved_frames.append(imgdata64)
        else:
            return super(HTMLWriter, self).grab_frame(**savefig_kwargs)

    def _run(self):
        # make a duck-typed subprocess stand in
        # this is called by the MovieWriter base class, but not used here.
        class ProcessStandin(object):
            returncode = 0

            def communicate(self):
                return '', ''

        self._proc = ProcessStandin()

        # save the frames to an html file
        if self.embed_frames:
            fill_frames = _embedded_frames(self._saved_frames,
                                           self.frame_format)
        else:
            # temp names is filled by FileMovieWriter
            fill_frames = _included_frames(self._temp_names,
                                           self.frame_format)

        mode_dict = dict(once_checked='',
                         loop_checked='',
                         reflect_checked='')
        mode_dict[self.default_mode + '_checked'] = 'checked'

        interval = 1000 // self.fps

        with open(self.outfile, 'w') as of:
            of.write(JS_INCLUDE)
            of.write(DISPLAY_TEMPLATE.format(id=uuid.uuid4().hex,
                                             Nframes=len(self._temp_names),
                                             fill_frames=fill_frames,
                                             interval=interval,
                                             **mode_dict))


class Animation(object):
    '''This class wraps the creation of an animation using matplotlib.

    It is only a base class which should be subclassed to provide
    needed behavior.

    This class is not typically used directly.

    Parameters
    ----------
    fig : matplotlib.figure.Figure
       The figure object that is used to get draw, resize, and any
       other needed events.

    event_source : object, optional
       A class that can run a callback when desired events
       are generated, as well as be stopped and started.

       Examples include timers (see :class:`TimedAnimation`) and file
       system notifications.

    blit : bool, optional
       controls whether blitting is used to optimize drawing.  Defaults
       to ``False``.

    See Also
    --------
    FuncAnimation,  ArtistAnimation

    '''
    def __init__(self, fig, event_source=None, blit=False):
        self._fig = fig
        # Disables blitting for backends that don't support it.  This
        # allows users to request it if available, but still have a
        # fallback that works if it is not.
        self._blit = blit and fig.canvas.supports_blit

        # These are the basics of the animation.  The frame sequence represents
        # information for each frame of the animation and depends on how the
        # drawing is handled by the subclasses. The event source fires events
        # that cause the frame sequence to be iterated.
        self.frame_seq = self.new_frame_seq()
        self.event_source = event_source

        # Instead of starting the event source now, we connect to the figure's
        # draw_event, so that we only start once the figure has been drawn.
        self._first_draw_id = fig.canvas.mpl_connect('draw_event', self._start)

        # Connect to the figure's close_event so that we don't continue to
        # fire events and try to draw to a deleted figure.
        self._close_id = self._fig.canvas.mpl_connect('close_event',
                                                      self._stop)
        if self._blit:
            self._setup_blit()

    def _start(self, *args):
        '''
        Starts interactive animation. Adds the draw frame command to the GUI
        handler, calls show to start the event loop.
        '''
        # First disconnect our draw event handler
        self._fig.canvas.mpl_disconnect(self._first_draw_id)
        self._first_draw_id = None  # So we can check on save

        # Now do any initial draw
        self._init_draw()

        # Add our callback for stepping the animation and
        # actually start the event_source.
        self.event_source.add_callback(self._step)
        self.event_source.start()

    def _stop(self, *args):
        # On stop we disconnect all of our events.
        if self._blit:
            self._fig.canvas.mpl_disconnect(self._resize_id)
        self._fig.canvas.mpl_disconnect(self._close_id)
        self.event_source.remove_callback(self._step)
        self.event_source = None

    def save(self, filename, writer=None, fps=None, dpi=None, codec=None,
             bitrate=None, extra_args=None, metadata=None, extra_anim=None,
             savefig_kwargs=None):
        '''Saves a movie file by drawing every frame.

        Parameters
        ----------

        filename : str
            The output filename, e.g., :file:`mymovie.mp4`.

        writer : :class:`MovieWriter` or str, optional
            A `MovieWriter` instance to use or a key that identifies a
            class to use, such as 'ffmpeg' or 'mencoder'. If ``None``,
            defaults to ``rcParams['animation.writer']``.

        fps : number, optional
           Frames per second in the movie. Defaults to ``None``, which will use
           the animation's specified interval to set the frames per second.

        dpi : number, optional
           Controls the dots per inch for the movie frames.  This
           combined with the figure's size in inches controls the size of
           the movie.  If ``None``, defaults to ``rcparam['savefig.dpi']``.

        codec : str, optional
           The video codec to be used. Not all codecs are supported by
           a given :class:`MovieWriter`. If ``None``,
           default to ``rcParams['animation.codec']``.

        bitrate : number, optional
           Specifies the number of bits used per second in the compressed
           movie, in kilobits per second. A higher number means a higher
           quality movie, but at the cost of increased file size. If ``None``,
           defaults to ``rcParam['animation.bitrate']``.

        extra_args : list, optional
           List of extra string arguments to be passed to the
           underlying movie utility. If ``None``, defaults to
           ``rcParams['animation.extra_args']``

        metadata : Dict[str, str], optional
           Dictionary of keys and values for metadata to include in
           the output file. Some keys that may be of use include:
           title, artist, genre, subject, copyright, srcform, comment.

        extra_anim : list, optional
           Additional `Animation` objects that should be included
           in the saved movie file. These need to be from the same
           `matplotlib.figure.Figure` instance. Also, animation frames will
           just be simply combined, so there should be a 1:1 correspondence
           between the frames from the different animations.

        savefig_kwargs : dict, optional
           Is a dictionary containing keyword arguments to be passed
           on to the `savefig` command which is called repeatedly to
           save the individual frames.

        Notes
        -----
        fps, codec, bitrate, extra_args, metadata are used to
        construct a :class:`MovieWriter` instance and can only be
        passed if `writer` is a string.  If they are passed as
        non-`None` and ``writer`` is a :class:`MovieWriter`, a
        `RuntimeError` will be raised.

        '''
        # If the writer is None, use the rc param to find the name of the one
        # to use
        if writer is None:
            writer = rcParams['animation.writer']
        elif (not isinstance(writer, six.string_types) and
                any(arg is not None
                    for arg in (fps, codec, bitrate, extra_args, metadata))):
            raise RuntimeError('Passing in values for arguments '
                               'fps, codec, bitrate, extra_args, or metadata '
                               'is not supported when writer is an existing '
                               'MovieWriter instance. These should instead be '
                               'passed as arguments when creating the '
                               'MovieWriter instance.')

        if savefig_kwargs is None:
            savefig_kwargs = {}

        # Need to disconnect the first draw callback, since we'll be doing
        # draws. Otherwise, we'll end up starting the animation.
        if self._first_draw_id is not None:
            self._fig.canvas.mpl_disconnect(self._first_draw_id)
            reconnect_first_draw = True
        else:
            reconnect_first_draw = False

        if fps is None and hasattr(self, '_interval'):
            # Convert interval in ms to frames per second
            fps = 1000. / self._interval

        # Re-use the savefig DPI for ours if none is given
        if dpi is None:
            dpi = rcParams['savefig.dpi']
        if dpi == 'figure':
            dpi = self._fig.dpi

        if codec is None:
            codec = rcParams['animation.codec']

        if bitrate is None:
            bitrate = rcParams['animation.bitrate']

        all_anim = [self]
        if extra_anim is not None:
            all_anim.extend(anim
                            for anim
                            in extra_anim if anim._fig is self._fig)

        # If we have the name of a writer, instantiate an instance of the
        # registered class.
        if isinstance(writer, six.string_types):
            if writer in writers.avail:
                writer = writers[writer](fps, codec, bitrate,
                                         extra_args=extra_args,
                                         metadata=metadata)
            else:
                warnings.warn("MovieWriter %s unavailable" % writer)

                try:
                    writer = writers[writers.list()[0]](fps, codec, bitrate,
                                                        extra_args=extra_args,
                                                        metadata=metadata)
                except IndexError:
                    raise ValueError("Cannot save animation: no writers are "
                                     "available. Please install "
                                     "ffmpeg to save animations.")

        verbose.report('Animation.save using %s' % type(writer),
                       level='helpful')

        if 'bbox_inches' in savefig_kwargs:
            warnings.warn("Warning: discarding the 'bbox_inches' argument in "
                          "'savefig_kwargs' as it may cause frame size "
                          "to vary, which is inappropriate for animation.")
            savefig_kwargs.pop('bbox_inches')

        # Create a new sequence of frames for saved data. This is different
        # from new_frame_seq() to give the ability to save 'live' generated
        # frame information to be saved later.
        # TODO: Right now, after closing the figure, saving a movie won't work
        # since GUI widgets are gone. Either need to remove extra code to
        # allow for this non-existent use case or find a way to make it work.
        with rc_context():
            if rcParams['savefig.bbox'] == 'tight':
                verbose.report("Disabling savefig.bbox = 'tight', as it "
                               "may cause frame size to vary, which "
                               "is inappropriate for animation.",
                               level='helpful')
                rcParams['savefig.bbox'] = None
            with writer.saving(self._fig, filename, dpi):
                for anim in all_anim:
                    # Clear the initial frame
                    anim._init_draw()
                for data in zip(*[a.new_saved_frame_seq()
                                  for a in all_anim]):
                    for anim, d in zip(all_anim, data):
                        # TODO: See if turning off blit is really necessary
                        anim._draw_next_frame(d, blit=False)
                    writer.grab_frame(**savefig_kwargs)

        # Reconnect signal for first draw if necessary
        if reconnect_first_draw:
            self._first_draw_id = self._fig.canvas.mpl_connect('draw_event',
                                                               self._start)

    def _step(self, *args):
        '''
        Handler for getting events. By default, gets the next frame in the
        sequence and hands the data off to be drawn.
        '''
        # Returns True to indicate that the event source should continue to
        # call _step, until the frame sequence reaches the end of iteration,
        # at which point False will be returned.
        try:
            framedata = next(self.frame_seq)
            self._draw_next_frame(framedata, self._blit)
            return True
        except StopIteration:
            return False

    def new_frame_seq(self):
        '''Creates a new sequence of frame information.'''
        # Default implementation is just an iterator over self._framedata
        return iter(self._framedata)

    def new_saved_frame_seq(self):
        '''Creates a new sequence of saved/cached frame information.'''
        # Default is the same as the regular frame sequence
        return self.new_frame_seq()

    def _draw_next_frame(self, framedata, blit):
        # Breaks down the drawing of the next frame into steps of pre- and
        # post- draw, as well as the drawing of the frame itself.
        self._pre_draw(framedata, blit)
        self._draw_frame(framedata)
        self._post_draw(framedata, blit)

    def _init_draw(self):
        # Initial draw to clear the frame. Also used by the blitting code
        # when a clean base is required.
        pass

    def _pre_draw(self, framedata, blit):
        # Perform any cleaning or whatnot before the drawing of the frame.
        # This default implementation allows blit to clear the frame.
        if blit:
            self._blit_clear(self._drawn_artists, self._blit_cache)

    def _draw_frame(self, framedata):
        # Performs actual drawing of the frame.
        raise NotImplementedError('Needs to be implemented by subclasses to'
                                  ' actually make an animation.')

    def _post_draw(self, framedata, blit):
        # After the frame is rendered, this handles the actual flushing of
        # the draw, which can be a direct draw_idle() or make use of the
        # blitting.
        if blit and self._drawn_artists:
            self._blit_draw(self._drawn_artists, self._blit_cache)
        else:
            self._fig.canvas.draw_idle()

    # The rest of the code in this class is to facilitate easy blitting
    def _blit_draw(self, artists, bg_cache):
        # Handles blitted drawing, which renders only the artists given instead
        # of the entire figure.
        updated_ax = []
        for a in artists:
            # If we haven't cached the background for this axes object, do
            # so now. This might not always be reliable, but it's an attempt
            # to automate the process.
            if a.axes not in bg_cache:
                bg_cache[a.axes] = a.figure.canvas.copy_from_bbox(a.axes.bbox)
            a.axes.draw_artist(a)
            updated_ax.append(a.axes)

        # After rendering all the needed artists, blit each axes individually.
        for ax in set(updated_ax):
            ax.figure.canvas.blit(ax.bbox)

    def _blit_clear(self, artists, bg_cache):
        # Get a list of the axes that need clearing from the artists that
        # have been drawn. Grab the appropriate saved background from the
        # cache and restore.
        axes = set(a.axes for a in artists)
        for a in axes:
            if a in bg_cache:
                a.figure.canvas.restore_region(bg_cache[a])

    def _setup_blit(self):
        # Setting up the blit requires: a cache of the background for the
        # axes
        self._blit_cache = dict()
        self._drawn_artists = []
        self._resize_id = self._fig.canvas.mpl_connect('resize_event',
                                                       self._handle_resize)
        self._post_draw(None, self._blit)

    def _handle_resize(self, *args):
        # On resize, we need to disable the resize event handling so we don't
        # get too many events. Also stop the animation events, so that
        # we're paused. Reset the cache and re-init. Set up an event handler
        # to catch once the draw has actually taken place.
        self._fig.canvas.mpl_disconnect(self._resize_id)
        self.event_source.stop()
        self._blit_cache.clear()
        self._init_draw()
        self._resize_id = self._fig.canvas.mpl_connect('draw_event',
                                                       self._end_redraw)

    def _end_redraw(self, evt):
        # Now that the redraw has happened, do the post draw flushing and
        # blit handling. Then re-enable all of the original events.
        self._post_draw(None, False)
        self.event_source.start()
        self._fig.canvas.mpl_disconnect(self._resize_id)
        self._resize_id = self._fig.canvas.mpl_connect('resize_event',
                                                       self._handle_resize)

    def to_html5_video(self, embed_limit=None):
        '''Returns animation as an HTML5 video tag.

        This saves the animation as an h264 video, encoded in base64
        directly into the HTML5 video tag. This respects the rc parameters
        for the writer as well as the bitrate. This also makes use of the
        ``interval`` to control the speed, and uses the ``repeat``
        parameter to decide whether to loop.
        '''
        VIDEO_TAG = r'''<video {size} {options}>
  <source type="video/mp4" src="data:video/mp4;base64,{video}">
  Your browser does not support the video tag.
</video>'''
        # Cache the rendering of the video as HTML
        if not hasattr(self, '_base64_video'):
            # Save embed limit, which is given in MB
            if embed_limit is None:
                embed_limit = rcParams['animation.embed_limit']

            # Convert from MB to bytes
            embed_limit *= 1024 * 1024

            # First write the video to a tempfile. Set delete to False
            # so we can re-open to read binary data.
            with tempfile.NamedTemporaryFile(suffix='.m4v',
                                             delete=False) as f:
                # We create a writer manually so that we can get the
                # appropriate size for the tag
                Writer = writers[rcParams['animation.writer']]
                writer = Writer(codec='h264',
                                bitrate=rcParams['animation.bitrate'],
                                fps=1000. / self._interval)
                self.save(f.name, writer=writer)

            # Now open and base64 encode
            with open(f.name, 'rb') as video:
                vid64 = encodebytes(video.read())
                vid_len = len(vid64)
                if vid_len >= embed_limit:
                    warnings.warn("Animation movie is {} bytes, exceeding "
                                  "the limit of {}. If you're sure you want a "
                                  "large animation embedded, set the "
                                  "animation.embed_limit rc parameter to a "
                                  "larger value (in MB).".format(vid_len,
                                                                 embed_limit))
                else:
                    self._base64_video = vid64.decode('ascii')
                    self._video_size = 'width="{}" height="{}"'.format(
                            *writer.frame_size)

            # Now we can remove
            os.remove(f.name)

        # If we exceeded the size, this attribute won't exist
        if hasattr(self, '_base64_video'):
            # Default HTML5 options are to autoplay and display video controls
            options = ['controls', 'autoplay']

            # If we're set to repeat, make it loop
            if hasattr(self, 'repeat') and self.repeat:
                options.append('loop')

            return VIDEO_TAG.format(video=self._base64_video,
                                    size=self._video_size,
                                    options=' '.join(options))
        else:
            return 'Video too large to embed.'

    def to_jshtml(self, fps=None, embed_frames=True, default_mode=None):
        """Generate HTML representation of the animation"""
        if fps is None and hasattr(self, '_interval'):
            # Convert interval in ms to frames per second
            fps = 1000 / self._interval

        # If we're not given a default mode, choose one base on the value of
        # the repeat attribute
        if default_mode is None:
            default_mode = 'loop' if self.repeat else 'once'

        if hasattr(self, "_html_representation"):
            return self._html_representation
        else:
            # Can't open a second time while opened on windows. So we avoid
            # deleting when closed, and delete manually later.
            with tempfile.NamedTemporaryFile(suffix='.html',
                                             delete=False) as f:
                self.save(f.name, writer=HTMLWriter(fps=fps,
                                                    embed_frames=embed_frames,
                                                    default_mode=default_mode))
            # Re-open and get content
            with open(f.name) as fobj:
                html = fobj.read()

            # Now we can delete
            os.remove(f.name)

            self._html_representation = html
            return html

    def _repr_html_(self):
        '''IPython display hook for rendering.'''
        fmt = rcParams['animation.html']
        if fmt == 'html5':
            return self.to_html5_video()
        elif fmt == 'jshtml':
            return self.to_jshtml()


class TimedAnimation(Animation):
    ''':class:`Animation` subclass for time-based animation.

    A new frame is drawn every *interval* milliseconds.

    Parameters
    ----------
    fig : matplotlib.figure.Figure
       The figure object that is used to get draw, resize, and any
       other needed events.

    interval : number, optional
       Delay between frames in milliseconds.  Defaults to 200.

    repeat_delay : number, optional
        If the animation in repeated, adds a delay in milliseconds
        before repeating the animation.  Defaults to ``None``.

    repeat : bool, optional
        Controls whether the animation should repeat when the sequence
        of frames is completed.  Defaults to ``True``.

    blit : bool, optional
        Controls whether blitting is used to optimize drawing.  Defaults
        to ``False``.

    '''
    def __init__(self, fig, interval=200, repeat_delay=None, repeat=True,
                 event_source=None, *args, **kwargs):
        # Store the timing information
        self._interval = interval
        self._repeat_delay = repeat_delay
        self.repeat = repeat

        # If we're not given an event source, create a new timer. This permits
        # sharing timers between animation objects for syncing animations.
        if event_source is None:
            event_source = fig.canvas.new_timer()
            event_source.interval = self._interval

        Animation.__init__(self, fig, event_source=event_source,
                           *args, **kwargs)

    def _step(self, *args):
        '''
        Handler for getting events.
        '''
        # Extends the _step() method for the Animation class.  If
        # Animation._step signals that it reached the end and we want to
        # repeat, we refresh the frame sequence and return True. If
        # _repeat_delay is set, change the event_source's interval to our loop
        # delay and set the callback to one which will then set the interval
        # back.
        still_going = Animation._step(self, *args)
        if not still_going and self.repeat:
            self._init_draw()
            self.frame_seq = self.new_frame_seq()
            if self._repeat_delay:
                self.event_source.remove_callback(self._step)
                self.event_source.add_callback(self._loop_delay)
                self.event_source.interval = self._repeat_delay
                return True
            else:
                return Animation._step(self, *args)
        else:
            return still_going

    def _stop(self, *args):
        # If we stop in the middle of a loop delay (which is relatively likely
        # given the potential pause here, remove the loop_delay callback as
        # well.
        self.event_source.remove_callback(self._loop_delay)
        Animation._stop(self)

    def _loop_delay(self, *args):
        # Reset the interval and change callbacks after the delay.
        self.event_source.remove_callback(self._loop_delay)
        self.event_source.interval = self._interval
        self.event_source.add_callback(self._step)
        Animation._step(self)


class ArtistAnimation(TimedAnimation):
    '''Animation using a fixed set of `Artist` objects.

    Before creating an instance, all plotting should have taken place
    and the relevant artists saved.

    Parameters
    ----------
    fig : matplotlib.figure.Figure
       The figure object that is used to get draw, resize, and any
       other needed events.

    artists : list
        Each list entry a collection of artists that represent what
        needs to be enabled on each frame. These will be disabled for
        other frames.

    interval : number, optional
       Delay between frames in milliseconds.  Defaults to 200.

    repeat_delay : number, optional
        If the animation in repeated, adds a delay in milliseconds
        before repeating the animation.  Defaults to ``None``.

    repeat : bool, optional
        Controls whether the animation should repeat when the sequence
        of frames is completed. Defaults to ``True``.

    blit : bool, optional
        Controls whether blitting is used to optimize drawing.  Defaults
        to ``False``.

    '''
    def __init__(self, fig, artists, *args, **kwargs):
        # Internal list of artists drawn in the most recent frame.
        self._drawn_artists = []

        # Use the list of artists as the framedata, which will be iterated
        # over by the machinery.
        self._framedata = artists
        TimedAnimation.__init__(self, fig, *args, **kwargs)

    def _init_draw(self):
        # Make all the artists involved in *any* frame invisible
        figs = set()
        for f in self.new_frame_seq():
            for artist in f:
                artist.set_visible(False)
                artist.set_animated(self._blit)
                # Assemble a list of unique figures that need flushing
                if artist.get_figure() not in figs:
                    figs.add(artist.get_figure())

        # Flush the needed figures
        for fig in figs:
            fig.canvas.draw_idle()

    def _pre_draw(self, framedata, blit):
        '''
        Clears artists from the last frame.
        '''
        if blit:
            # Let blit handle clearing
            self._blit_clear(self._drawn_artists, self._blit_cache)
        else:
            # Otherwise, make all the artists from the previous frame invisible
            for artist in self._drawn_artists:
                artist.set_visible(False)

    def _draw_frame(self, artists):
        # Save the artists that were passed in as framedata for the other
        # steps (esp. blitting) to use.
        self._drawn_artists = artists

        # Make all the artists from the current frame visible
        for artist in artists:
            artist.set_visible(True)


class FuncAnimation(TimedAnimation):
    '''
    Makes an animation by repeatedly calling a function ``func``.

    Parameters
    ----------
    fig : matplotlib.figure.Figure
       The figure object that is used to get draw, resize, and any
       other needed events.

    func : callable
       The function to call at each frame.  The first argument will
       be the next value in ``frames``.   Any additional positional
       arguments can be supplied via the ``fargs`` parameter.

       The required signature is::

          def func(frame, *fargs) -> iterable_of_artists:

    frames : iterable, int, generator function, or None, optional
        Source of data to pass ``func`` and each frame of the animation

        If an iterable, then simply use the values provided.  If the
        iterable has a length, it will override the ``save_count`` kwarg.

        If an integer, then equivalent to passing ``range(frames)``

        If a generator function, then must have the signature::

           def gen_function() -> obj:

        If ``None``, then equivalent to passing ``itertools.count``.

        In all of these cases, the values in *frames* is simply passed through
        to the user-supplied *func* and thus can be of any type.

    init_func : callable, optional
       A function used to draw a clear frame. If not given, the
       results of drawing from the first item in the frames sequence
       will be used. This function will be called once before the
       first frame.

       If ``blit == True``, ``init_func`` must return an iterable of artists
       to be re-drawn.

       The required signature is::

          def init_func() -> iterable_of_artists:

    fargs : tuple or None, optional
       Additional arguments to pass to each call to *func*.

    save_count : int, optional
       The number of values from *frames* to cache.

    interval : number, optional
       Delay between frames in milliseconds.  Defaults to 200.

    repeat_delay : number, optional
       If the animation in repeated, adds a delay in milliseconds
       before repeating the animation.  Defaults to ``None``.

    repeat : bool, optional
       Controls whether the animation should repeat when the sequence
       of frames is completed.  Defaults to ``True``.

    blit : bool, optional
       Controls whether blitting is used to optimize drawing.  Defaults
       to ``False``.

    '''
    def __init__(self, fig, func, frames=None, init_func=None, fargs=None,
                 save_count=None, **kwargs):
        if fargs:
            self._args = fargs
        else:
            self._args = ()
        self._func = func

        # Amount of framedata to keep around for saving movies. This is only
        # used if we don't know how many frames there will be: in the case
        # of no generator or in the case of a callable.
        self.save_count = save_count
        # Set up a function that creates a new iterable when needed. If nothing
        # is passed in for frames, just use itertools.count, which will just
        # keep counting from 0. A callable passed in for frames is assumed to
        # be a generator. An iterable will be used as is, and anything else
        # will be treated as a number of frames.
        if frames is None:
            self._iter_gen = itertools.count
        elif callable(frames):
            self._iter_gen = frames
        elif iterable(frames):
            self._iter_gen = lambda: iter(frames)
            if hasattr(frames, '__len__'):
                self.save_count = len(frames)
        else:
            self._iter_gen = lambda: iter(xrange(frames))
            self.save_count = frames

        if self.save_count is None:
            # If we're passed in and using the default, set save_count to 100.
            self.save_count = 100
        else:
            # itertools.islice returns an error when passed a numpy int instead
            # of a native python int (http://bugs.python.org/issue30537).
            # As a workaround, convert save_count to a native python int.
            self.save_count = int(self.save_count)

        self._init_func = init_func

        # Needs to be initialized so the draw functions work without checking
        self._save_seq = []

        TimedAnimation.__init__(self, fig, **kwargs)

        # Need to reset the saved seq, since right now it will contain data
        # for a single frame from init, which is not what we want.
        self._save_seq = []

    def new_frame_seq(self):
        # Use the generating function to generate a new frame sequence
        return self._iter_gen()

    def new_saved_frame_seq(self):
        # Generate an iterator for the sequence of saved data. If there are
        # no saved frames, generate a new frame sequence and take the first
        # save_count entries in it.
        if self._save_seq:
            # While iterating we are going to update _save_seq
            # so make a copy to safely iterate over
            self._old_saved_seq = list(self._save_seq)
            return iter(self._old_saved_seq)
        else:
            return itertools.islice(self.new_frame_seq(), self.save_count)

    def _init_draw(self):
        # Initialize the drawing either using the given init_func or by
        # calling the draw function with the first item of the frame sequence.
        # For blitting, the init_func should return a sequence of modified
        # artists.
        if self._init_func is None:
            self._draw_frame(next(self.new_frame_seq()))

        else:
            self._drawn_artists = self._init_func()
            if self._blit:
                if self._drawn_artists is None:
                    raise RuntimeError('The init_func must return a '
                                       'sequence of Artist objects.')
                for a in self._drawn_artists:
                    a.set_animated(self._blit)
        self._save_seq = []

    def _draw_frame(self, framedata):
        # Save the data for potential saving of movies.
        self._save_seq.append(framedata)

        # Make sure to respect save_count (keep only the last save_count
        # around)
        self._save_seq = self._save_seq[-self.save_count:]

        # Call the func with framedata and args. If blitting is desired,
        # func needs to return a sequence of any artists that were modified.
        self._drawn_artists = self._func(framedata, *self._args)
        if self._blit:
            if self._drawn_artists is None:
                    raise RuntimeError('The animation function must return a '
                                       'sequence of Artist objects.')
            for a in self._drawn_artists:
                a.set_animated(self._blit)