summaryrefslogtreecommitdiffstats
path: root/dom/base/nsImageLoadingContent.cpp
blob: b76bc533f634ca28aa370c7a9e651b57af1308fe (plain)
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
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * A base class which implements nsIImageLoadingContent and can be
 * subclassed by various content nodes that want to provide image
 * loading functionality (eg <img>, <object>, etc).
 */

#include "nsImageLoadingContent.h"
#include "nsError.h"
#include "nsIContent.h"
#include "nsIDocument.h"
#include "nsIScriptGlobalObject.h"
#include "nsIDOMWindow.h"
#include "nsServiceManagerUtils.h"
#include "nsContentPolicyUtils.h"
#include "nsIURI.h"
#include "nsILoadGroup.h"
#include "imgIContainer.h"
#include "imgLoader.h"
#include "imgRequestProxy.h"
#include "nsThreadUtils.h"
#include "nsNetUtil.h"
#include "nsImageFrame.h"

#include "nsIPresShell.h"

#include "nsIChannel.h"
#include "nsIStreamListener.h"

#include "nsIFrame.h"
#include "nsIDOMNode.h"

#include "nsContentUtils.h"
#include "nsLayoutUtils.h"
#include "nsIContentPolicy.h"
#include "nsSVGEffects.h"

#include "gfxPrefs.h"

#include "mozAutoDocUpdate.h"
#include "mozilla/AsyncEventDispatcher.h"
#include "mozilla/EventStates.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/ImageTracker.h"
#include "mozilla/dom/ScriptSettings.h"
#include "mozilla/Preferences.h"

#ifdef LoadImage
// Undefine LoadImage to prevent naming conflict with Windows.
#undef LoadImage
#endif

using namespace mozilla;
using namespace mozilla::dom;

#ifdef DEBUG_chb
static void PrintReqURL(imgIRequest* req) {
  if (!req) {
    printf("(null req)\n");
    return;
  }

  nsCOMPtr<nsIURI> uri;
  req->GetURI(getter_AddRefs(uri));
  if (!uri) {
    printf("(null uri)\n");
    return;
  }

  nsAutoCString spec;
  uri->GetSpec(spec);
  printf("spec='%s'\n", spec.get());
}
#endif /* DEBUG_chb */


nsImageLoadingContent::nsImageLoadingContent()
  : mCurrentRequestFlags(0),
    mPendingRequestFlags(0),
    mObserverList(nullptr),
    mImageBlockingStatus(nsIContentPolicy::ACCEPT),
    mLoadingEnabled(true),
    mIsImageStateForced(false),
    mLoading(false),
    // mBroken starts out true, since an image without a URI is broken....
    mBroken(true),
    mUserDisabled(false),
    mSuppressed(false),
    mNewRequestsWillNeedAnimationReset(false),
    mStateChangerDepth(0),
    mCurrentRequestRegistered(false),
    mPendingRequestRegistered(false),
    mFrameCreateCalled(false)
{
  if (!nsContentUtils::GetImgLoaderForChannel(nullptr, nullptr)) {
    mLoadingEnabled = false;
  }

  bool isInconsistent;
  mMostRecentRequestChange = TimeStamp::ProcessCreation(isInconsistent);
}

void
nsImageLoadingContent::DestroyImageLoadingContent()
{
  // Cancel our requests so they won't hold stale refs to us
  // NB: Don't ask to discard the images here.
  ClearCurrentRequest(NS_BINDING_ABORTED);
  ClearPendingRequest(NS_BINDING_ABORTED);
}

nsImageLoadingContent::~nsImageLoadingContent()
{
  NS_ASSERTION(!mCurrentRequest && !mPendingRequest,
               "DestroyImageLoadingContent not called");
  NS_ASSERTION(!mObserverList.mObserver && !mObserverList.mNext,
               "Observers still registered?");
}

/*
 * imgINotificationObserver impl
 */
NS_IMETHODIMP
nsImageLoadingContent::Notify(imgIRequest* aRequest,
                              int32_t aType,
                              const nsIntRect* aData)
{
  if (aType == imgINotificationObserver::IS_ANIMATED) {
    return OnImageIsAnimated(aRequest);
  }

  if (aType == imgINotificationObserver::UNLOCKED_DRAW) {
    OnUnlockedDraw();
    return NS_OK;
  }

  if (aType == imgINotificationObserver::LOAD_COMPLETE) {
    // We should definitely have a request here
    MOZ_ASSERT(aRequest, "no request?");

    NS_PRECONDITION(aRequest == mCurrentRequest || aRequest == mPendingRequest,
                    "Unknown request");
  }

  {
    // Calling Notify on observers can modify the list of observers so make
    // a local copy.
    AutoTArray<nsCOMPtr<imgINotificationObserver>, 2> observers;
    for (ImageObserver* observer = &mObserverList, *next; observer;
         observer = next) {
      next = observer->mNext;
      if (observer->mObserver) {
        observers.AppendElement(observer->mObserver);
      }
    }

    nsAutoScriptBlocker scriptBlocker;

    for (auto& observer : observers) {
        observer->Notify(aRequest, aType, aData);
    }
  }

  if (aType == imgINotificationObserver::SIZE_AVAILABLE) {
    // Have to check for state changes here, since we might have been in
    // the LOADING state before.
    UpdateImageState(true);
  }

  if (aType == imgINotificationObserver::LOAD_COMPLETE) {
    uint32_t reqStatus;
    aRequest->GetImageStatus(&reqStatus);
    /* triage STATUS_ERROR */
    if (reqStatus & imgIRequest::STATUS_ERROR) {
      nsresult errorCode = NS_OK;
      aRequest->GetImageErrorCode(&errorCode);

      /* Handle image not loading error because source was a tracking URL.
       * We make a note of this image node by including it in a dedicated
       * array of blocked tracking nodes under its parent document.
       */
      if (errorCode == NS_ERROR_TRACKING_URI) {
        nsCOMPtr<nsIContent> thisNode
          = do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));

        nsIDocument *doc = GetOurOwnerDoc();
        doc->AddBlockedTrackingNode(thisNode);
      }
    }
    nsresult status =
        reqStatus & imgIRequest::STATUS_ERROR ? NS_ERROR_FAILURE : NS_OK;
    return OnLoadComplete(aRequest, status);
  }

  if (aType == imgINotificationObserver::DECODE_COMPLETE) {
    nsCOMPtr<imgIContainer> container;
    aRequest->GetImage(getter_AddRefs(container));
    if (container) {
      container->PropagateUseCounters(GetOurOwnerDoc());
    }

    UpdateImageState(true);
  }

  return NS_OK;
}

nsresult
nsImageLoadingContent::OnLoadComplete(imgIRequest* aRequest, nsresult aStatus)
{
  uint32_t oldStatus;
  aRequest->GetImageStatus(&oldStatus);

  //XXXjdm This occurs when we have a pending request created, then another
  //       pending request replaces it before the first one is finished.
  //       This begs the question of what the correct behaviour is; we used
  //       to not have to care because we ran this code in OnStopDecode which
  //       wasn't called when the first request was cancelled. For now, I choose
  //       to punt when the given request doesn't appear to have terminated in
  //       an expected state.
  if (!(oldStatus & (imgIRequest::STATUS_ERROR | imgIRequest::STATUS_LOAD_COMPLETE)))
    return NS_OK;

  // Our state may change. Watch it.
  AutoStateChanger changer(this, true);

  // If the pending request is loaded, switch to it.
  if (aRequest == mPendingRequest) {
    MakePendingRequestCurrent();
  }
  MOZ_ASSERT(aRequest == mCurrentRequest,
             "One way or another, we should be current by now");

  // Fire the appropriate DOM event.
  if (NS_SUCCEEDED(aStatus)) {
    FireEvent(NS_LITERAL_STRING("load"));

    // Do not fire loadend event for multipart/x-mixed-replace image streams.
    bool isMultipart;
    if (NS_FAILED(aRequest->GetMultipart(&isMultipart)) || !isMultipart) {
      FireEvent(NS_LITERAL_STRING("loadend"));
    }
  } else {
    FireEvent(NS_LITERAL_STRING("error"));
    FireEvent(NS_LITERAL_STRING("loadend"));
  }

  nsCOMPtr<nsINode> thisNode = do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  nsSVGEffects::InvalidateDirectRenderingObservers(thisNode->AsElement());

  return NS_OK;
}

static bool
ImageIsAnimated(imgIRequest* aRequest)
{
  if (!aRequest) {
    return false;
  }

  nsCOMPtr<imgIContainer> image;
  if (NS_SUCCEEDED(aRequest->GetImage(getter_AddRefs(image)))) {
    bool isAnimated = false;
    nsresult rv = image->GetAnimated(&isAnimated);
    if (NS_SUCCEEDED(rv) && isAnimated) {
      return true;
    }
  }

  return false;
}

void
nsImageLoadingContent::OnUnlockedDraw()
{
  // It's OK for non-animated images to wait until the next frame visibility
  // update to become locked. (And that's preferable, since in the case of
  // scrolling it keeps memory usage minimal.) For animated images, though, we
  // want to mark them visible right away so we can call
  // IncrementAnimationConsumers() on them and they'll start animating.
  if (!ImageIsAnimated(mCurrentRequest) && !ImageIsAnimated(mPendingRequest)) {
    return;
  }

  nsIFrame* frame = GetOurPrimaryFrame();
  if (!frame) {
    return;
  }

  if (frame->GetVisibility() == Visibility::APPROXIMATELY_VISIBLE) {
    // This frame is already marked visible; there's nothing to do.
    return;
  }

  nsPresContext* presContext = frame->PresContext();
  if (!presContext) {
    return;
  }

  nsIPresShell* presShell = presContext->PresShell();
  if (!presShell) {
    return;
  }

  presShell->EnsureFrameInApproximatelyVisibleList(frame);
}

nsresult
nsImageLoadingContent::OnImageIsAnimated(imgIRequest *aRequest)
{
  bool* requestFlag = GetRegisteredFlagForRequest(aRequest);
  if (requestFlag) {
    nsLayoutUtils::RegisterImageRequest(GetFramePresContext(),
                                        aRequest, requestFlag);
  }

  return NS_OK;
}

/*
 * nsIImageLoadingContent impl
 */

NS_IMETHODIMP
nsImageLoadingContent::GetLoadingEnabled(bool *aLoadingEnabled)
{
  *aLoadingEnabled = mLoadingEnabled;
  return NS_OK;
}

NS_IMETHODIMP
nsImageLoadingContent::SetLoadingEnabled(bool aLoadingEnabled)
{
  if (nsContentUtils::GetImgLoaderForChannel(nullptr, nullptr)) {
    mLoadingEnabled = aLoadingEnabled;
  }
  return NS_OK;
}

NS_IMETHODIMP
nsImageLoadingContent::GetImageBlockingStatus(int16_t* aStatus)
{
  NS_PRECONDITION(aStatus, "Null out param");
  *aStatus = ImageBlockingStatus();
  return NS_OK;
}

static void
ReplayImageStatus(imgIRequest* aRequest, imgINotificationObserver* aObserver)
{
  if (!aRequest) {
    return;
  }

  uint32_t status = 0;
  nsresult rv = aRequest->GetImageStatus(&status);
  if (NS_FAILED(rv)) {
    return;
  }

  if (status & imgIRequest::STATUS_SIZE_AVAILABLE) {
    aObserver->Notify(aRequest, imgINotificationObserver::SIZE_AVAILABLE, nullptr);
  }
  if (status & imgIRequest::STATUS_FRAME_COMPLETE) {
    aObserver->Notify(aRequest, imgINotificationObserver::FRAME_COMPLETE, nullptr);
  }
  if (status & imgIRequest::STATUS_HAS_TRANSPARENCY) {
    aObserver->Notify(aRequest, imgINotificationObserver::HAS_TRANSPARENCY, nullptr);
  }
  if (status & imgIRequest::STATUS_IS_ANIMATED) {
    aObserver->Notify(aRequest, imgINotificationObserver::IS_ANIMATED, nullptr);
  }
  if (status & imgIRequest::STATUS_DECODE_COMPLETE) {
    aObserver->Notify(aRequest, imgINotificationObserver::DECODE_COMPLETE, nullptr);
  }
  if (status & imgIRequest::STATUS_LOAD_COMPLETE) {
    aObserver->Notify(aRequest, imgINotificationObserver::LOAD_COMPLETE, nullptr);
  }
}

NS_IMETHODIMP
nsImageLoadingContent::AddObserver(imgINotificationObserver* aObserver)
{
  NS_ENSURE_ARG_POINTER(aObserver);

  if (!mObserverList.mObserver) {
    // Don't touch the linking of the list!
    mObserverList.mObserver = aObserver;

    ReplayImageStatus(mCurrentRequest, aObserver);
    ReplayImageStatus(mPendingRequest, aObserver);

    return NS_OK;
  }

  // otherwise we have to create a new entry

  ImageObserver* observer = &mObserverList;
  while (observer->mNext) {
    observer = observer->mNext;
  }

  observer->mNext = new ImageObserver(aObserver);
  ReplayImageStatus(mCurrentRequest, aObserver);
  ReplayImageStatus(mPendingRequest, aObserver);

  return NS_OK;
}

NS_IMETHODIMP
nsImageLoadingContent::RemoveObserver(imgINotificationObserver* aObserver)
{
  NS_ENSURE_ARG_POINTER(aObserver);

  if (mObserverList.mObserver == aObserver) {
    mObserverList.mObserver = nullptr;
    // Don't touch the linking of the list!
    return NS_OK;
  }

  // otherwise have to find it and splice it out
  ImageObserver* observer = &mObserverList;
  while (observer->mNext && observer->mNext->mObserver != aObserver) {
    observer = observer->mNext;
  }

  // At this point, we are pointing to the list element whose mNext is
  // the right observer (assuming of course that mNext is not null)
  if (observer->mNext) {
    // splice it out
    ImageObserver* oldObserver = observer->mNext;
    observer->mNext = oldObserver->mNext;
    oldObserver->mNext = nullptr;  // so we don't destroy them all
    delete oldObserver;
  }
#ifdef DEBUG
  else {
    NS_WARNING("Asked to remove nonexistent observer");
  }
#endif
  return NS_OK;
}

already_AddRefed<imgIRequest>
nsImageLoadingContent::GetRequest(int32_t aRequestType,
                                  ErrorResult& aError)
{
  nsCOMPtr<imgIRequest> request;
  switch(aRequestType) {
  case CURRENT_REQUEST:
    request = mCurrentRequest;
    break;
  case PENDING_REQUEST:
    request = mPendingRequest;
    break;
  default:
    NS_ERROR("Unknown request type");
    aError.Throw(NS_ERROR_UNEXPECTED);
  }

  return request.forget();
}

NS_IMETHODIMP
nsImageLoadingContent::GetRequest(int32_t aRequestType,
                                  imgIRequest** aRequest)
{
  NS_ENSURE_ARG_POINTER(aRequest);

  ErrorResult result;
  *aRequest = GetRequest(aRequestType, result).take();

  return result.StealNSResult();
}

NS_IMETHODIMP_(bool)
nsImageLoadingContent::CurrentRequestHasSize()
{
  return HaveSize(mCurrentRequest);
}

NS_IMETHODIMP_(void)
nsImageLoadingContent::FrameCreated(nsIFrame* aFrame)
{
  NS_ASSERTION(aFrame, "aFrame is null");

  mFrameCreateCalled = true;

  TrackImage(mCurrentRequest, aFrame);
  TrackImage(mPendingRequest, aFrame);

  // We need to make sure that our image request is registered, if it should
  // be registered.
  nsPresContext* presContext = aFrame->PresContext();
  if (mCurrentRequest) {
    nsLayoutUtils::RegisterImageRequestIfAnimated(presContext, mCurrentRequest,
                                                  &mCurrentRequestRegistered);
  }

  if (mPendingRequest) {
    nsLayoutUtils::RegisterImageRequestIfAnimated(presContext, mPendingRequest,
                                                  &mPendingRequestRegistered);
  }
}

NS_IMETHODIMP_(void)
nsImageLoadingContent::FrameDestroyed(nsIFrame* aFrame)
{
  NS_ASSERTION(aFrame, "aFrame is null");

  mFrameCreateCalled = false;

  // We need to make sure that our image request is deregistered.
  nsPresContext* presContext = GetFramePresContext();
  if (mCurrentRequest) {
    nsLayoutUtils::DeregisterImageRequest(presContext,
                                          mCurrentRequest,
                                          &mCurrentRequestRegistered);
  }

  if (mPendingRequest) {
    nsLayoutUtils::DeregisterImageRequest(presContext,
                                          mPendingRequest,
                                          &mPendingRequestRegistered);
  }

  UntrackImage(mCurrentRequest);
  UntrackImage(mPendingRequest);

  nsIPresShell* presShell = presContext ? presContext->GetPresShell() : nullptr;
  if (presShell) {
    presShell->RemoveFrameFromApproximatelyVisibleList(aFrame);
  }
}

/* static */
nsContentPolicyType
nsImageLoadingContent::PolicyTypeForLoad(ImageLoadType aImageLoadType)
{
  if (aImageLoadType == eImageLoadType_Imageset) {
    return nsIContentPolicy::TYPE_IMAGESET;
  }

  MOZ_ASSERT(aImageLoadType == eImageLoadType_Normal,
             "Unknown ImageLoadType type in PolicyTypeForLoad");
  return nsIContentPolicy::TYPE_INTERNAL_IMAGE;
}

int32_t
nsImageLoadingContent::GetRequestType(imgIRequest* aRequest,
                                      ErrorResult& aError)
{
  if (aRequest == mCurrentRequest) {
    return CURRENT_REQUEST;
  }

  if (aRequest == mPendingRequest) {
    return PENDING_REQUEST;
  }

  NS_ERROR("Unknown request");
  aError.Throw(NS_ERROR_UNEXPECTED);
  return UNKNOWN_REQUEST;
}

NS_IMETHODIMP
nsImageLoadingContent::GetRequestType(imgIRequest* aRequest,
                                      int32_t* aRequestType)
{
  NS_PRECONDITION(aRequestType, "Null out param");

  ErrorResult result;
  *aRequestType = GetRequestType(aRequest, result);
  return result.StealNSResult();
}

already_AddRefed<nsIURI>
nsImageLoadingContent::GetCurrentURI(ErrorResult& aError)
{
  nsCOMPtr<nsIURI> uri;
  if (mCurrentRequest) {
    mCurrentRequest->GetURI(getter_AddRefs(uri));
  } else if (mCurrentURI) {
    nsresult rv = NS_EnsureSafeToReturn(mCurrentURI, getter_AddRefs(uri));
    if (NS_FAILED(rv)) {
      aError.Throw(rv);
    }
  }

  return uri.forget();
}

NS_IMETHODIMP
nsImageLoadingContent::GetCurrentURI(nsIURI** aURI)
{
  NS_ENSURE_ARG_POINTER(aURI);

  ErrorResult result;
  *aURI = GetCurrentURI(result).take();
  return result.StealNSResult();
}

NS_IMETHODIMP
nsImageLoadingContent::LoadImageWithChannel(nsIChannel* aChannel,
                                            nsIStreamListener** aListener)
{
  imgLoader* loader =
    nsContentUtils::GetImgLoaderForChannel(aChannel, GetOurOwnerDoc());
  if (!loader) {
    return NS_ERROR_NULL_POINTER;
  }

  nsCOMPtr<nsIDocument> doc = GetOurOwnerDoc();
  if (!doc) {
    // Don't bother
    *aListener = nullptr;
    return NS_OK;
  }

  // XXX what should we do with content policies here, if anything?
  // Shouldn't that be done before the start of the load?
  // XXX what about shouldProcess?

  // Our state might change. Watch it.
  AutoStateChanger changer(this, true);

  // Do the load.
  RefPtr<imgRequestProxy>& req = PrepareNextRequest(eImageLoadType_Normal);
  nsresult rv = loader->
    LoadImageWithChannel(aChannel, this, doc, aListener, getter_AddRefs(req));
  if (NS_SUCCEEDED(rv)) {
    TrackImage(req);
    ResetAnimationIfNeeded();
    return NS_OK;
  }

  MOZ_ASSERT(!req, "Shouldn't have non-null request here");
  // If we don't have a current URI, we might as well store this URI so people
  // know what we tried (and failed) to load.
  if (!mCurrentRequest)
    aChannel->GetURI(getter_AddRefs(mCurrentURI));

  FireEvent(NS_LITERAL_STRING("error"));
  FireEvent(NS_LITERAL_STRING("loadend"));
  return rv;
}

void
nsImageLoadingContent::ForceReload(const mozilla::dom::Optional<bool>& aNotify,
                                   mozilla::ErrorResult& aError)
{
  nsCOMPtr<nsIURI> currentURI;
  GetCurrentURI(getter_AddRefs(currentURI));
  if (!currentURI) {
    aError.Throw(NS_ERROR_NOT_AVAILABLE);
    return;
  }

  // defaults to true
  bool notify = !aNotify.WasPassed() || aNotify.Value();

  // We keep this flag around along with the old URI even for failed requests
  // without a live request object
  ImageLoadType loadType = \
    (mCurrentRequestFlags & REQUEST_IS_IMAGESET) ? eImageLoadType_Imageset
                                                 : eImageLoadType_Normal;
  nsresult rv = LoadImage(currentURI, true, notify, loadType, true, nullptr,
                          nsIRequest::VALIDATE_ALWAYS);
  if (NS_FAILED(rv)) {
    aError.Throw(rv);
  }
}

NS_IMETHODIMP
nsImageLoadingContent::ForceReload(bool aNotify /* = true */,
                                   uint8_t aArgc)
{
  mozilla::dom::Optional<bool> notify;
  if (aArgc >= 1) {
    notify.Construct() = aNotify;
  }

  ErrorResult result;
  ForceReload(notify, result);
  return result.StealNSResult();
}

NS_IMETHODIMP
nsImageLoadingContent::BlockOnload(imgIRequest* aRequest)
{
  if (aRequest == mCurrentRequest) {
    NS_ASSERTION(!(mCurrentRequestFlags & REQUEST_BLOCKS_ONLOAD),
                 "Double BlockOnload!?");
    mCurrentRequestFlags |= REQUEST_BLOCKS_ONLOAD;
  } else if (aRequest == mPendingRequest) {
    NS_ASSERTION(!(mPendingRequestFlags & REQUEST_BLOCKS_ONLOAD),
                 "Double BlockOnload!?");
    mPendingRequestFlags |= REQUEST_BLOCKS_ONLOAD;
  } else {
    return NS_OK;
  }

  nsIDocument* doc = GetOurCurrentDoc();
  if (doc) {
    doc->BlockOnload();
  }

  return NS_OK;
}

NS_IMETHODIMP
nsImageLoadingContent::UnblockOnload(imgIRequest* aRequest)
{
  if (aRequest == mCurrentRequest) {
    NS_ASSERTION(mCurrentRequestFlags & REQUEST_BLOCKS_ONLOAD,
                 "Double UnblockOnload!?");
    mCurrentRequestFlags &= ~REQUEST_BLOCKS_ONLOAD;
  } else if (aRequest == mPendingRequest) {
    NS_ASSERTION(mPendingRequestFlags & REQUEST_BLOCKS_ONLOAD,
                 "Double UnblockOnload!?");
    mPendingRequestFlags &= ~REQUEST_BLOCKS_ONLOAD;
  } else {
    return NS_OK;
  }

  nsIDocument* doc = GetOurCurrentDoc();
  if (doc) {
    doc->UnblockOnload(false);
  }

  return NS_OK;
}

/*
 * Non-interface methods
 */

nsresult
nsImageLoadingContent::LoadImage(const nsAString& aNewURI,
                                 bool aForce,
                                 bool aNotify,
                                 ImageLoadType aImageLoadType)
{
  // First, get a document (needed for security checks and the like)
  nsIDocument* doc = GetOurOwnerDoc();
  if (!doc) {
    // No reason to bother, I think...
    return NS_OK;
  }

  // Pending load/error events need to be canceled in some situations. This
  // is not documented in the spec, but can cause site compat problems if not
  // done. See bug 1309461 and https://github.com/whatwg/html/issues/1872.
  CancelPendingEvent();

  if (aNewURI.IsEmpty()) {
    // Cancel image requests and then fire only error event per spec.
    CancelImageRequests(aNotify);
    // Mark error event as cancelable only for src="" case, since only this
    // error causes site compat problem (bug 1308069) for now.
    FireEvent(NS_LITERAL_STRING("error"), true);
    return NS_OK;
  }

  // Fire loadstart event
  FireEvent(NS_LITERAL_STRING("loadstart"));

  // Parse the URI string to get image URI
  nsCOMPtr<nsIURI> imageURI;
  nsresult rv = StringToURI(aNewURI, doc, getter_AddRefs(imageURI));
  NS_ENSURE_SUCCESS(rv, rv);
  // XXXbiesi fire onerror if that failed?

  NS_TryToSetImmutable(imageURI);

  return LoadImage(imageURI, aForce, aNotify, aImageLoadType, false, doc);
}

nsresult
nsImageLoadingContent::LoadImage(nsIURI* aNewURI,
                                 bool aForce,
                                 bool aNotify,
                                 ImageLoadType aImageLoadType,
                                 bool aLoadStart,
                                 nsIDocument* aDocument,
                                 nsLoadFlags aLoadFlags)
{
  // Pending load/error events need to be canceled in some situations. This
  // is not documented in the spec, but can cause site compat problems if not
  // done. See bug 1309461 and https://github.com/whatwg/html/issues/1872.
  CancelPendingEvent();

  // Fire loadstart event if required
  if (aLoadStart) {
    FireEvent(NS_LITERAL_STRING("loadstart"));
  }

  if (!mLoadingEnabled) {
    // XXX Why fire an error here? seems like the callers to SetLoadingEnabled
    // don't want/need it.
    FireEvent(NS_LITERAL_STRING("error"));
    FireEvent(NS_LITERAL_STRING("loadend"));
    return NS_OK;
  }

  NS_ASSERTION(!aDocument || aDocument == GetOurOwnerDoc(),
               "Bogus document passed in");
  // First, get a document (needed for security checks and the like)
  if (!aDocument) {
    aDocument = GetOurOwnerDoc();
    if (!aDocument) {
      // No reason to bother, I think...
      return NS_OK;
    }
  }

  // URI equality check.
  //
  // We skip the equality check if our current image was blocked, since in that
  // case we really do want to try loading again.
  if (!aForce && NS_CP_ACCEPTED(mImageBlockingStatus)) {
    nsCOMPtr<nsIURI> currentURI;
    GetCurrentURI(getter_AddRefs(currentURI));
    bool equal;
    if (currentURI &&
        NS_SUCCEEDED(currentURI->Equals(aNewURI, &equal)) &&
        equal) {
      // Nothing to do here.
      return NS_OK;
    }
  }

  // From this point on, our image state could change. Watch it.
  AutoStateChanger changer(this, aNotify);

  // Sanity check.
  //
  // We use the principal of aDocument to avoid having to QI |this| an extra
  // time. It should always be the same as the principal of this node.
#ifdef DEBUG
  nsCOMPtr<nsIContent> thisContent = do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  MOZ_ASSERT(thisContent &&
             thisContent->NodePrincipal() == aDocument->NodePrincipal(),
             "Principal mismatch?");
#endif

  // Are we blocked?
  int16_t cpDecision = nsIContentPolicy::REJECT_REQUEST;
  nsContentPolicyType policyType = PolicyTypeForLoad(aImageLoadType);

  nsContentUtils::CanLoadImage(aNewURI,
                               static_cast<nsIImageLoadingContent*>(this),
                               aDocument,
                               aDocument->NodePrincipal(),
                               &cpDecision,
                               policyType);
  if (!NS_CP_ACCEPTED(cpDecision)) {
    FireEvent(NS_LITERAL_STRING("error"));
    FireEvent(NS_LITERAL_STRING("loadend"));
    SetBlockedRequest(aNewURI, cpDecision);
    return NS_OK;
  }

  nsLoadFlags loadFlags = aLoadFlags;
  int32_t corsmode = GetCORSMode();
  if (corsmode == CORS_ANONYMOUS) {
    loadFlags |= imgILoader::LOAD_CORS_ANONYMOUS;
  } else if (corsmode == CORS_USE_CREDENTIALS) {
    loadFlags |= imgILoader::LOAD_CORS_USE_CREDENTIALS;
  }

  // get document wide referrer policy
  // if referrer attributes are enabled in preferences, load img referrer attribute
  // if the image does not provide a referrer attribute, ignore this
  net::ReferrerPolicy referrerPolicy = aDocument->GetReferrerPolicy();
  net::ReferrerPolicy imgReferrerPolicy = GetImageReferrerPolicy();
  if (imgReferrerPolicy != net::RP_Unset) {
    referrerPolicy = imgReferrerPolicy;
  }

  // Not blocked. Do the load.
  RefPtr<imgRequestProxy>& req = PrepareNextRequest(aImageLoadType);
  nsCOMPtr<nsIContent> content =
      do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  nsCOMPtr<nsINode> thisNode =
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  nsresult rv = nsContentUtils::LoadImage(aNewURI,
                                          thisNode,
                                          aDocument,
                                          aDocument->NodePrincipal(),
                                          aDocument->GetDocumentURI(),
                                          referrerPolicy,
                                          this, loadFlags,
                                          content->LocalName(),
                                          getter_AddRefs(req),
                                          policyType);

  // Tell the document to forget about the image preload, if any, for
  // this URI, now that we might have another imgRequestProxy for it.
  // That way if we get canceled later the image load won't continue.
  aDocument->ForgetImagePreload(aNewURI);

  if (NS_SUCCEEDED(rv)) {
    TrackImage(req);
    ResetAnimationIfNeeded();

    // Handle cases when we just ended up with a pending request but it's
    // already done.  In that situation we have to synchronously switch that
    // request to being the current request, because websites depend on that
    // behavior.
    if (req == mPendingRequest) {
      uint32_t pendingLoadStatus;
      rv = req->GetImageStatus(&pendingLoadStatus);
      if (NS_SUCCEEDED(rv) &&
          (pendingLoadStatus & imgIRequest::STATUS_LOAD_COMPLETE)) {
        MakePendingRequestCurrent();
        MOZ_ASSERT(mCurrentRequest,
                   "How could we not have a current request here?");

        nsImageFrame *f = do_QueryFrame(GetOurPrimaryFrame());
        if (f) {
          f->NotifyNewCurrentRequest(mCurrentRequest, NS_OK);
        }
      }
    }
  } else {
    MOZ_ASSERT(!req, "Shouldn't have non-null request here");
    // If we don't have a current URI, we might as well store this URI so people
    // know what we tried (and failed) to load.
    if (!mCurrentRequest)
      mCurrentURI = aNewURI;

    FireEvent(NS_LITERAL_STRING("error"));
    FireEvent(NS_LITERAL_STRING("loadend"));
    return NS_OK;
  }

  return NS_OK;
}

nsresult
nsImageLoadingContent::ForceImageState(bool aForce,
                                       EventStates::InternalType aState)
{
  mIsImageStateForced = aForce;
  mForcedImageState = EventStates(aState);
  return NS_OK;
}

NS_IMETHODIMP
nsImageLoadingContent::GetNaturalWidth(uint32_t* aNaturalWidth)
{
  NS_ENSURE_ARG_POINTER(aNaturalWidth);

  nsCOMPtr<imgIContainer> image;
  if (mCurrentRequest) {
    mCurrentRequest->GetImage(getter_AddRefs(image));
  }

  int32_t width;
  if (image && NS_SUCCEEDED(image->GetWidth(&width))) {
    *aNaturalWidth = width;
  } else {
    *aNaturalWidth = 0;
  }

  return NS_OK;
}

NS_IMETHODIMP
nsImageLoadingContent::GetNaturalHeight(uint32_t* aNaturalHeight)
{
  NS_ENSURE_ARG_POINTER(aNaturalHeight);

  nsCOMPtr<imgIContainer> image;
  if (mCurrentRequest) {
    mCurrentRequest->GetImage(getter_AddRefs(image));
  }

  int32_t height;
  if (image && NS_SUCCEEDED(image->GetHeight(&height))) {
    *aNaturalHeight = height;
  } else {
    *aNaturalHeight = 0;
  }

  return NS_OK;
}

EventStates
nsImageLoadingContent::ImageState() const
{
  if (mIsImageStateForced) {
    return mForcedImageState;
  }

  EventStates states;

  if (mBroken) {
    states |= NS_EVENT_STATE_BROKEN;
  }
  if (mUserDisabled) {
    states |= NS_EVENT_STATE_USERDISABLED;
  }
  if (mSuppressed) {
    states |= NS_EVENT_STATE_SUPPRESSED;
  }
  if (mLoading) {
    states |= NS_EVENT_STATE_LOADING;
  }

  return states;
}

void
nsImageLoadingContent::UpdateImageState(bool aNotify)
{
  if (mStateChangerDepth > 0) {
    // Ignore this call; we'll update our state when the outermost state changer
    // is destroyed. Need this to work around the fact that some ImageLib
    // stuff is actually sync and hence we can get OnStopDecode called while
    // we're still under LoadImage, and OnStopDecode doesn't know anything about
    // aNotify.
    // XXX - This machinery should be removed after bug 521604.
    return;
  }

  nsCOMPtr<nsIContent> thisContent = do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  if (!thisContent) {
    return;
  }

  mLoading = mBroken = mUserDisabled = mSuppressed = false;

  // If we were blocked by server-based content policy, we claim to be
  // suppressed.  If we were blocked by type-based content policy, we claim to
  // be user-disabled.  Otherwise, claim to be broken.
  if (mImageBlockingStatus == nsIContentPolicy::REJECT_SERVER) {
    mSuppressed = true;
  } else if (mImageBlockingStatus == nsIContentPolicy::REJECT_TYPE) {
    mUserDisabled = true;
  } else if (!mCurrentRequest) {
    // No current request means error, since we weren't disabled or suppressed
    mBroken = true;
  } else {
    uint32_t currentLoadStatus;
    nsresult rv = mCurrentRequest->GetImageStatus(&currentLoadStatus);
    if (NS_FAILED(rv) || (currentLoadStatus & imgIRequest::STATUS_ERROR)) {
      mBroken = true;
    } else if (!(currentLoadStatus & imgIRequest::STATUS_SIZE_AVAILABLE)) {
      mLoading = true;
    }
  }

  NS_ASSERTION(thisContent->IsElement(), "Not an element?");
  thisContent->AsElement()->UpdateState(aNotify);
}

void
nsImageLoadingContent::CancelImageRequests(bool aNotify)
{
  AutoStateChanger changer(this, aNotify);
  ClearPendingRequest(NS_BINDING_ABORTED, Some(OnNonvisible::DISCARD_IMAGES));
  ClearCurrentRequest(NS_BINDING_ABORTED, Some(OnNonvisible::DISCARD_IMAGES));
}

nsresult
nsImageLoadingContent::UseAsPrimaryRequest(imgRequestProxy* aRequest,
                                           bool aNotify,
                                           ImageLoadType aImageLoadType)
{
  // Our state will change. Watch it.
  AutoStateChanger changer(this, aNotify);

  // Get rid if our existing images
  ClearPendingRequest(NS_BINDING_ABORTED, Some(OnNonvisible::DISCARD_IMAGES));
  ClearCurrentRequest(NS_BINDING_ABORTED, Some(OnNonvisible::DISCARD_IMAGES));

  // Clone the request we were given.
  RefPtr<imgRequestProxy>& req = PrepareNextRequest(aImageLoadType);
  nsresult rv = aRequest->Clone(this, getter_AddRefs(req));
  if (NS_SUCCEEDED(rv)) {
    TrackImage(req);
  } else {
    MOZ_ASSERT(!req, "Shouldn't have non-null request here");
    return rv;
  }

  return NS_OK;
}

nsIDocument*
nsImageLoadingContent::GetOurOwnerDoc()
{
  nsCOMPtr<nsIContent> thisContent =
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ENSURE_TRUE(thisContent, nullptr);

  return thisContent->OwnerDoc();
}

nsIDocument*
nsImageLoadingContent::GetOurCurrentDoc()
{
  nsCOMPtr<nsIContent> thisContent =
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ENSURE_TRUE(thisContent, nullptr);

  return thisContent->GetComposedDoc();
}

nsIFrame*
nsImageLoadingContent::GetOurPrimaryFrame()
{
  nsCOMPtr<nsIContent> thisContent =
    do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  return thisContent->GetPrimaryFrame();
}

nsPresContext* nsImageLoadingContent::GetFramePresContext()
{
  nsIFrame* frame = GetOurPrimaryFrame();
  if (!frame) {
    return nullptr;
  }

  return frame->PresContext();
}

nsresult
nsImageLoadingContent::StringToURI(const nsAString& aSpec,
                                   nsIDocument* aDocument,
                                   nsIURI** aURI)
{
  NS_PRECONDITION(aDocument, "Must have a document");
  NS_PRECONDITION(aURI, "Null out param");

  // (1) Get the base URI
  nsCOMPtr<nsIContent> thisContent = do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));
  NS_ASSERTION(thisContent, "An image loading content must be an nsIContent");
  nsCOMPtr<nsIURI> baseURL = thisContent->GetBaseURI();

  // (2) Get the charset
  const nsAFlatCString &charset = aDocument->GetDocumentCharacterSet();

  // (3) Construct the silly thing
  return NS_NewURI(aURI,
                   aSpec,
                   charset.IsEmpty() ? nullptr : charset.get(),
                   baseURL,
                   nsContentUtils::GetIOService());
}

nsresult
nsImageLoadingContent::FireEvent(const nsAString& aEventType, bool aIsCancelable)
{
  if (nsContentUtils::DocumentInactiveForImageLoads(GetOurOwnerDoc())) {
    // Don't bother to fire any events, especially error events.
    return NS_OK;
  }

  // We have to fire the event asynchronously so that we won't go into infinite
  // loops in cases when onLoad handlers reset the src and the new src is in
  // cache.

  nsCOMPtr<nsINode> thisNode = do_QueryInterface(static_cast<nsIImageLoadingContent*>(this));

  RefPtr<AsyncEventDispatcher> loadBlockingAsyncDispatcher =
    new LoadBlockingAsyncEventDispatcher(thisNode, aEventType, false, false);
  loadBlockingAsyncDispatcher->PostDOMEvent();

  if (aIsCancelable) {
    mPendingEvent = loadBlockingAsyncDispatcher;
  }

  return NS_OK;
}

void
nsImageLoadingContent::AsyncEventRunning(AsyncEventDispatcher* aEvent)
{
  if (mPendingEvent == aEvent) {
    mPendingEvent = nullptr;
  }
}

void
nsImageLoadingContent::CancelPendingEvent()
{
  if (mPendingEvent) {
    mPendingEvent->Cancel();
    mPendingEvent = nullptr;
  }
}

RefPtr<imgRequestProxy>&
nsImageLoadingContent::PrepareNextRequest(ImageLoadType aImageLoadType)
{
  nsImageFrame* frame = do_QueryFrame(GetOurPrimaryFrame());
  if (frame) {
    // Detect JavaScript-based animations created by changing the |src|
    // attribute on a timer.
    TimeStamp now = TimeStamp::Now();
    TimeDuration threshold =
      TimeDuration::FromMilliseconds(
        gfxPrefs::ImageInferSrcAnimationThresholdMS());

    // If the length of time between request changes is less than the threshold,
    // then force sync decoding to eliminate flicker from the animation.
    frame->SetForceSyncDecoding(now - mMostRecentRequestChange < threshold);

    mMostRecentRequestChange = now;
  }

  // If we don't have a usable current request, get rid of any half-baked
  // request that might be sitting there and make this one current.
  if (!HaveSize(mCurrentRequest))
    return PrepareCurrentRequest(aImageLoadType);

  // Otherwise, make it pending.
  return PreparePendingRequest(aImageLoadType);
}

void
nsImageLoadingContent::SetBlockedRequest(nsIURI* aURI, int16_t aContentDecision)
{
  // Sanity
  MOZ_ASSERT(!NS_CP_ACCEPTED(aContentDecision), "Blocked but not?");

  // We do some slightly illogical stuff here to maintain consistency with
  // old behavior that people probably depend on. Even in the case where the
  // new image is blocked, the old one should really be canceled with the
  // reason "image source changed". However, apparently there's some abuse
  // over in nsImageFrame where the displaying of the "broken" icon for the
  // next image depends on the cancel reason of the previous image. ugh.
  // XXX(seth): So shouldn't we fix nsImageFrame?!
  ClearPendingRequest(NS_ERROR_IMAGE_BLOCKED,
                      Some(OnNonvisible::DISCARD_IMAGES));

  // For the blocked case, we only want to cancel the existing current request
  // if size is not available. bz says the web depends on this behavior.
  if (!HaveSize(mCurrentRequest)) {

    mImageBlockingStatus = aContentDecision;
    uint32_t keepFlags = mCurrentRequestFlags & REQUEST_IS_IMAGESET;
    ClearCurrentRequest(NS_ERROR_IMAGE_BLOCKED,
                        Some(OnNonvisible::DISCARD_IMAGES));

    // We still want to remember what URI we were and if it was an imageset,
    // despite not having an actual request. These are both cleared as part of
    // ClearCurrentRequest() before a new request is started.
    mCurrentURI = aURI;
    mCurrentRequestFlags = keepFlags;
  }
}

RefPtr<imgRequestProxy>&
nsImageLoadingContent::PrepareCurrentRequest(ImageLoadType aImageLoadType)
{
  // Blocked images go through SetBlockedRequest, which is a separate path. For
  // everything else, we're unblocked.
  mImageBlockingStatus = nsIContentPolicy::ACCEPT;

  // Get rid of anything that was there previously.
  ClearCurrentRequest(NS_ERROR_IMAGE_SRC_CHANGED,
                      Some(OnNonvisible::DISCARD_IMAGES));

  if (mNewRequestsWillNeedAnimationReset) {
    mCurrentRequestFlags |= REQUEST_NEEDS_ANIMATION_RESET;
  }

  if (aImageLoadType == eImageLoadType_Imageset) {
    mCurrentRequestFlags |= REQUEST_IS_IMAGESET;
  }

  // Return a reference.
  return mCurrentRequest;
}

RefPtr<imgRequestProxy>&
nsImageLoadingContent::PreparePendingRequest(ImageLoadType aImageLoadType)
{
  // Get rid of anything that was there previously.
  ClearPendingRequest(NS_ERROR_IMAGE_SRC_CHANGED,
                      Some(OnNonvisible::DISCARD_IMAGES));

  if (mNewRequestsWillNeedAnimationReset) {
    mPendingRequestFlags |= REQUEST_NEEDS_ANIMATION_RESET;
  }

  if (aImageLoadType == eImageLoadType_Imageset) {
    mPendingRequestFlags |= REQUEST_IS_IMAGESET;
  }

  // Return a reference.
  return mPendingRequest;
}

namespace {

class ImageRequestAutoLock
{
public:
  explicit ImageRequestAutoLock(imgIRequest* aRequest)
    : mRequest(aRequest)
  {
    if (mRequest) {
      mRequest->LockImage();
    }
  }

  ~ImageRequestAutoLock()
  {
    if (mRequest) {
      mRequest->UnlockImage();
    }
  }

private:
  nsCOMPtr<imgIRequest> mRequest;
};

} // namespace

void
nsImageLoadingContent::MakePendingRequestCurrent()
{
  MOZ_ASSERT(mPendingRequest);

  // Lock mCurrentRequest for the duration of this method.  We do this because
  // PrepareCurrentRequest() might unlock mCurrentRequest.  If mCurrentRequest
  // and mPendingRequest are both requests for the same image, unlocking
  // mCurrentRequest before we lock mPendingRequest can cause the lock count
  // to go to 0 and the image to be discarded!
  ImageRequestAutoLock autoLock(mCurrentRequest);

  ImageLoadType loadType = \
    (mPendingRequestFlags & REQUEST_IS_IMAGESET) ? eImageLoadType_Imageset
                                                 : eImageLoadType_Normal;

  PrepareCurrentRequest(loadType) = mPendingRequest;
  mPendingRequest = nullptr;
  mCurrentRequestFlags = mPendingRequestFlags;
  mPendingRequestFlags = 0;
  ResetAnimationIfNeeded();
}

void
nsImageLoadingContent::ClearCurrentRequest(nsresult aReason,
                                           const Maybe<OnNonvisible>& aNonvisibleAction)
{
  if (!mCurrentRequest) {
    // Even if we didn't have a current request, we might have been keeping
    // a URI and flags as a placeholder for a failed load. Clear that now.
    mCurrentURI = nullptr;
    mCurrentRequestFlags = 0;
    return;
  }
  MOZ_ASSERT(!mCurrentURI,
             "Shouldn't have both mCurrentRequest and mCurrentURI!");

  // Deregister this image from the refresh driver so it no longer receives
  // notifications.
  nsLayoutUtils::DeregisterImageRequest(GetFramePresContext(), mCurrentRequest,
                                        &mCurrentRequestRegistered);

  // Clean up the request.
  UntrackImage(mCurrentRequest, aNonvisibleAction);
  mCurrentRequest->CancelAndForgetObserver(aReason);
  mCurrentRequest = nullptr;
  mCurrentRequestFlags = 0;
}

void
nsImageLoadingContent::ClearPendingRequest(nsresult aReason,
                                           const Maybe<OnNonvisible>& aNonvisibleAction)
{
  if (!mPendingRequest)
    return;

  // Deregister this image from the refresh driver so it no longer receives
  // notifications.
  nsLayoutUtils::DeregisterImageRequest(GetFramePresContext(), mPendingRequest,
                                        &mPendingRequestRegistered);

  UntrackImage(mPendingRequest, aNonvisibleAction);
  mPendingRequest->CancelAndForgetObserver(aReason);
  mPendingRequest = nullptr;
  mPendingRequestFlags = 0;
}

bool*
nsImageLoadingContent::GetRegisteredFlagForRequest(imgIRequest* aRequest)
{
  if (aRequest == mCurrentRequest) {
    return &mCurrentRequestRegistered;
  } else if (aRequest == mPendingRequest) {
    return &mPendingRequestRegistered;
  } else {
    return nullptr;
  }
}

void
nsImageLoadingContent::ResetAnimationIfNeeded()
{
  if (mCurrentRequest &&
      (mCurrentRequestFlags & REQUEST_NEEDS_ANIMATION_RESET)) {
    nsCOMPtr<imgIContainer> container;
    mCurrentRequest->GetImage(getter_AddRefs(container));
    if (container)
      container->ResetAnimation();
    mCurrentRequestFlags &= ~REQUEST_NEEDS_ANIMATION_RESET;
  }
}

bool
nsImageLoadingContent::HaveSize(imgIRequest *aImage)
{
  // Handle the null case
  if (!aImage)
    return false;

  // Query the image
  uint32_t status;
  nsresult rv = aImage->GetImageStatus(&status);
  return (NS_SUCCEEDED(rv) && (status & imgIRequest::STATUS_SIZE_AVAILABLE));
}

void
nsImageLoadingContent::BindToTree(nsIDocument* aDocument, nsIContent* aParent,
                                  nsIContent* aBindingParent,
                                  bool aCompileEventHandlers)
{
  // We may be entering the document, so if our image should be tracked,
  // track it.
  if (!aDocument)
    return;

  TrackImage(mCurrentRequest);
  TrackImage(mPendingRequest);

  if (mCurrentRequestFlags & REQUEST_BLOCKS_ONLOAD)
    aDocument->BlockOnload();
}

void
nsImageLoadingContent::UnbindFromTree(bool aDeep, bool aNullParent)
{
  // We may be leaving the document, so if our image is tracked, untrack it.
  nsCOMPtr<nsIDocument> doc = GetOurCurrentDoc();
  if (!doc)
    return;

  UntrackImage(mCurrentRequest);
  UntrackImage(mPendingRequest);

  if (mCurrentRequestFlags & REQUEST_BLOCKS_ONLOAD)
    doc->UnblockOnload(false);
}

void
nsImageLoadingContent::OnVisibilityChange(Visibility aNewVisibility,
                                          const Maybe<OnNonvisible>& aNonvisibleAction)
{
  switch (aNewVisibility) {
    case Visibility::APPROXIMATELY_VISIBLE:
      TrackImage(mCurrentRequest);
      TrackImage(mPendingRequest);
      break;

    case Visibility::APPROXIMATELY_NONVISIBLE:
      UntrackImage(mCurrentRequest, aNonvisibleAction);
      UntrackImage(mPendingRequest, aNonvisibleAction);
      break;

    case Visibility::UNTRACKED:
      MOZ_ASSERT_UNREACHABLE("Shouldn't notify for untracked visibility");
      break;
  }
}

void
nsImageLoadingContent::TrackImage(imgIRequest* aImage,
                                  nsIFrame* aFrame /*= nullptr */)
{
  if (!aImage)
    return;

  MOZ_ASSERT(aImage == mCurrentRequest || aImage == mPendingRequest,
             "Why haven't we heard of this request?");

  nsIDocument* doc = GetOurCurrentDoc();
  if (!doc) {
    return;
  }

  if (!aFrame) {
    aFrame = GetOurPrimaryFrame();
  }

  /* This line is deceptively simple. It hides a lot of subtlety. Before we
   * create an nsImageFrame we call nsImageFrame::ShouldCreateImageFrameFor
   * to determine if we should create an nsImageFrame or create a frame based
   * on the display of the element (ie inline, block, etc). Inline, block, etc
   * frames don't register for visibility tracking so they will return UNTRACKED
   * from GetVisibility(). So this line is choosing to mark such images as
   * visible. Once the image loads we will get an nsImageFrame and the proper
   * visibility. This is a pitfall of tracking the visibility on the frames
   * instead of the content node.
   */
  if (!aFrame || aFrame->GetVisibility() == Visibility::APPROXIMATELY_NONVISIBLE) {
    return;
  }

  if (aImage == mCurrentRequest && !(mCurrentRequestFlags & REQUEST_IS_TRACKED)) {
    mCurrentRequestFlags |= REQUEST_IS_TRACKED;
    doc->ImageTracker()->Add(mCurrentRequest);
  }
  if (aImage == mPendingRequest && !(mPendingRequestFlags & REQUEST_IS_TRACKED)) {
    mPendingRequestFlags |= REQUEST_IS_TRACKED;
    doc->ImageTracker()->Add(mPendingRequest);
  }
}

void
nsImageLoadingContent::UntrackImage(imgIRequest* aImage,
                                    const Maybe<OnNonvisible>& aNonvisibleAction
                                      /* = Nothing() */)
{
  if (!aImage)
    return;

  MOZ_ASSERT(aImage == mCurrentRequest || aImage == mPendingRequest,
             "Why haven't we heard of this request?");

  // We may not be in the document.  If we outlived our document that's fine,
  // because the document empties out the tracker and unlocks all locked images
  // on destruction.  But if we were never in the document we may need to force
  // discarding the image here, since this is the only chance we have.
  nsIDocument* doc = GetOurCurrentDoc();
  if (aImage == mCurrentRequest) {
    if (doc && (mCurrentRequestFlags & REQUEST_IS_TRACKED)) {
      mCurrentRequestFlags &= ~REQUEST_IS_TRACKED;
      doc->ImageTracker()->Remove(
        mCurrentRequest,
        aNonvisibleAction == Some(OnNonvisible::DISCARD_IMAGES)
          ? ImageTracker::REQUEST_DISCARD
          : 0);
    } else if (aNonvisibleAction == Some(OnNonvisible::DISCARD_IMAGES)) {
      // If we're not in the document we may still need to be discarded.
      aImage->RequestDiscard();
    }
  }
  if (aImage == mPendingRequest) {
    if (doc && (mPendingRequestFlags & REQUEST_IS_TRACKED)) {
      mPendingRequestFlags &= ~REQUEST_IS_TRACKED;
      doc->ImageTracker()->Remove(
        mPendingRequest,
        aNonvisibleAction == Some(OnNonvisible::DISCARD_IMAGES)
          ? ImageTracker::REQUEST_DISCARD
          : 0);
    } else if (aNonvisibleAction == Some(OnNonvisible::DISCARD_IMAGES)) {
      // If we're not in the document we may still need to be discarded.
      aImage->RequestDiscard();
    }
  }
}


void
nsImageLoadingContent::CreateStaticImageClone(nsImageLoadingContent* aDest) const
{
  aDest->mCurrentRequest = nsContentUtils::GetStaticRequest(mCurrentRequest);
  aDest->TrackImage(aDest->mCurrentRequest);
  aDest->mForcedImageState = mForcedImageState;
  aDest->mImageBlockingStatus = mImageBlockingStatus;
  aDest->mLoadingEnabled = mLoadingEnabled;
  aDest->mStateChangerDepth = mStateChangerDepth;
  aDest->mIsImageStateForced = mIsImageStateForced;
  aDest->mLoading = mLoading;
  aDest->mBroken = mBroken;
  aDest->mUserDisabled = mUserDisabled;
  aDest->mSuppressed = mSuppressed;
}

CORSMode
nsImageLoadingContent::GetCORSMode()
{
  return CORS_NONE;
}

nsImageLoadingContent::ImageObserver::ImageObserver(imgINotificationObserver* aObserver)
  : mObserver(aObserver)
  , mNext(nullptr)
{
  MOZ_COUNT_CTOR(ImageObserver);
}

nsImageLoadingContent::ImageObserver::~ImageObserver()
{
  MOZ_COUNT_DTOR(ImageObserver);
  NS_CONTENT_DELETE_LIST_MEMBER(ImageObserver, this, mNext);
}

// Only HTMLInputElement.h overrides this for <img> tags
// all other subclasses use this one, i.e. ignore referrer attributes
mozilla::net::ReferrerPolicy
nsImageLoadingContent::GetImageReferrerPolicy()
{
  return mozilla::net::RP_Unset;
};