summaryrefslogtreecommitdiffstats
path: root/layout/generic/WritingModes.h
blob: 4f6e9eaec1a2ca601fd4ba44db25ca0af99e28be (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
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
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
/* -*- 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/. */

#ifndef WritingModes_h_
#define WritingModes_h_

#include <ostream>

#include "mozilla/intl/BidiEmbeddingLevel.h"
#include "mozilla/ComputedStyle.h"
#include "mozilla/EnumSet.h"
#include "nsRect.h"
#include "nsStyleStruct.h"

// It is the caller's responsibility to operate on logical-coordinate objects
// with matched writing modes. Failure to do so will be a runtime bug; the
// compiler can't catch it, but in debug mode, we'll throw an assertion.
// NOTE that in non-debug builds, a writing mode mismatch error will NOT be
// detected, yet the results will be nonsense (and may lead to further layout
// failures). Therefore, it is important to test (and fuzz-test) writing-mode
// support using debug builds.

// Methods in logical-coordinate classes that take another logical-coordinate
// object as a parameter should call CHECK_WRITING_MODE on it to verify that
// the writing modes match.
// (In some cases, there are internal (private) methods that don't do this;
// such methods should only be used by other methods that have already checked
// the writing modes.)
// The check ignores the StyleWritingMode::VERTICAL_SIDEWAYS and
// StyleWritingMode::TEXT_SIDEWAYS bit of writing mode, because
// this does not affect the interpretation of logical coordinates.

#define CHECK_WRITING_MODE(param)                                           \
  NS_ASSERTION(param.IgnoreSideways() == GetWritingMode().IgnoreSideways(), \
               "writing-mode mismatch")

namespace mozilla {

namespace widget {
struct IMENotification;
}  // namespace widget

// Logical axis, edge, side and corner constants for use in various places.
enum class LogicalAxis : uint8_t {
  Block,
  Inline,
};
enum class LogicalEdge : uint8_t { Start, End };

enum class LogicalSide : uint8_t {
  BStart,
  BEnd,
  IStart,
  IEnd,
};

enum class LogicalCorner : uint8_t {
  BStartIStart,
  BStartIEnd,
  BEndIEnd,
  BEndIStart,
};

// Physical axis constants.
enum class PhysicalAxis : uint8_t { Vertical, Horizontal };

// Represents zero or more physical axes.
enum class PhysicalAxes : uint8_t {
  None = 0x0,
  Horizontal = 0x1,
  Vertical = 0x2,
  Both = Horizontal | Vertical,
};
MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(PhysicalAxes)

inline LogicalAxis GetOrthogonalAxis(LogicalAxis aAxis) {
  return aAxis == LogicalAxis::Block ? LogicalAxis::Inline : LogicalAxis::Block;
}

inline bool IsInline(LogicalSide aSide) {
  return (aSide == LogicalSide::IStart) || (aSide == LogicalSide::IEnd);
}

inline bool IsBlock(LogicalSide aSide) { return !IsInline(aSide); }

inline bool IsEnd(LogicalSide aSide) {
  return (aSide == LogicalSide::BEnd) || (aSide == LogicalSide::IEnd);
}

inline bool IsStart(LogicalSide aSide) { return !IsEnd(aSide); }

inline LogicalAxis GetAxis(LogicalSide aSide) {
  return IsInline(aSide) ? LogicalAxis::Inline : LogicalAxis::Block;
}

inline LogicalEdge GetEdge(LogicalSide aSide) {
  return IsEnd(aSide) ? LogicalEdge::End : LogicalEdge::Start;
}

inline LogicalEdge GetOppositeEdge(LogicalEdge aEdge) {
  return aEdge == LogicalEdge::Start ? LogicalEdge::End : LogicalEdge::Start;
}

inline LogicalSide MakeLogicalSide(LogicalAxis aAxis, LogicalEdge aEdge) {
  if (aAxis == LogicalAxis::Inline) {
    return aEdge == LogicalEdge::Start ? LogicalSide::IStart
                                       : LogicalSide::IEnd;
  }
  return aEdge == LogicalEdge::Start ? LogicalSide::BStart : LogicalSide::BEnd;
}

inline LogicalSide GetOppositeSide(LogicalSide aSide) {
  return MakeLogicalSide(GetAxis(aSide), GetOppositeEdge(GetEdge(aSide)));
}

enum class LineRelativeDir : uint8_t {
  Over = static_cast<uint8_t>(LogicalSide::BStart),
  Under = static_cast<uint8_t>(LogicalSide::BEnd),
  Left = static_cast<uint8_t>(LogicalSide::IStart),
  Right = static_cast<uint8_t>(LogicalSide::IEnd)
};

/**
 * mozilla::WritingMode is an immutable class representing a
 * writing mode.
 *
 * It efficiently stores the writing mode and can rapidly compute
 * interesting things about it for use in layout.
 *
 * Writing modes are computed from the CSS 'direction',
 * 'writing-mode', and 'text-orientation' properties.
 * See CSS3 Writing Modes for more information
 *   http://www.w3.org/TR/css3-writing-modes/
 */
class WritingMode {
 public:
  /**
   * Absolute inline flow direction
   */
  enum class InlineDir : uint8_t {
    LTR,  // text flows horizontally left to right
    RTL,  // text flows horizontally right to left
    TTB,  // text flows vertically top to bottom
    BTT,  // text flows vertically bottom to top
  };

  /**
   * Absolute block flow direction
   */
  enum class BlockDir : uint8_t {
    TB,  // horizontal lines stack top to bottom
    RL,  // vertical lines stack right to left
    LR,  // vertical lines stack left to right
  };

  /**
   * Return the absolute inline flow direction as an InlineDir
   */
  InlineDir GetInlineDir() const {
    if (IsVertical()) {
      return IsInlineReversed() ? InlineDir::BTT : InlineDir::TTB;
    }
    return IsInlineReversed() ? InlineDir::RTL : InlineDir::LTR;
  }

  /**
   * Return the absolute block flow direction as a BlockDir
   */
  BlockDir GetBlockDir() const {
    if (IsVertical()) {
      return mWritingMode & StyleWritingMode::VERTICAL_LR ? BlockDir::LR
                                                          : BlockDir::RL;
    }
    return BlockDir::TB;
  }

  /**
   * Return true if the inline flow direction is against physical direction
   * (i.e. right-to-left or bottom-to-top).
   * This occurs when writing-mode is sideways-lr OR direction is rtl (but not
   * if both of those are true).
   */
  bool IsInlineReversed() const {
    return !!(mWritingMode & StyleWritingMode::INLINE_REVERSED);
  }

  /**
   * Return true if bidi direction is LTR.
   */
  bool IsBidiLTR() const { return !IsBidiRTL(); }

  /**
   * Return true if bidi direction is RTL.
   */
  bool IsBidiRTL() const { return !!(mWritingMode & StyleWritingMode::RTL); }

  /**
   * True if it is vertical and vertical-lr, or is horizontal and bidi LTR.
   */
  bool IsPhysicalLTR() const {
    return IsVertical() ? IsVerticalLR() : IsBidiLTR();
  }

  /**
   * True if it is vertical and vertical-rl, or is horizontal and bidi RTL.
   */
  bool IsPhysicalRTL() const {
    return IsVertical() ? IsVerticalRL() : IsBidiRTL();
  }

  /**
   * True if vertical-mode block direction is LR (convenience method).
   */
  bool IsVerticalLR() const { return GetBlockDir() == BlockDir::LR; }

  /**
   * True if vertical-mode block direction is RL (convenience method).
   */
  bool IsVerticalRL() const { return GetBlockDir() == BlockDir::RL; }

  /**
   * True if vertical writing mode, i.e. when
   * writing-mode: vertical-lr | vertical-rl.
   */
  bool IsVertical() const {
    return !!(mWritingMode & StyleWritingMode::VERTICAL);
  }

  /**
   * True if line-over/line-under are inverted from block-start/block-end.
   * This is true only when writing-mode is vertical-lr.
   */
  bool IsLineInverted() const {
    return !!(mWritingMode & StyleWritingMode::LINE_INVERTED);
  }

  /**
   * Block-axis flow-relative to line-relative factor.
   * May be used as a multiplication factor for block-axis coordinates
   * to convert between flow- and line-relative coordinate systems (e.g.
   * positioning an over- or under-line decoration).
   */
  int FlowRelativeToLineRelativeFactor() const {
    return IsLineInverted() ? -1 : 1;
  }

  /**
   * True if vertical sideways writing mode, i.e. when
   * writing-mode: sideways-lr | sideways-rl.
   */
  bool IsVerticalSideways() const {
    return !!(mWritingMode & StyleWritingMode::VERTICAL_SIDEWAYS);
  }

  /**
   * True if this is writing-mode: sideways-rl (convenience method).
   */
  bool IsSidewaysRL() const { return IsVerticalRL() && IsVerticalSideways(); }

  /**
   * True if this is writing-mode: sideways-lr (convenience method).
   */
  bool IsSidewaysLR() const { return IsVerticalLR() && IsVerticalSideways(); }

  /**
   * True if either text-orientation or writing-mode will force all text to be
   * rendered sideways in vertical lines, in which case we should prefer an
   * alphabetic baseline; otherwise, the default is centered.
   *
   * Note that some glyph runs may be rendered sideways even if this is false,
   * due to text-orientation:mixed resolution, but in that case the dominant
   * baseline remains centered.
   */
  bool IsSideways() const {
    return !!(mWritingMode & (StyleWritingMode::VERTICAL_SIDEWAYS |
                              StyleWritingMode::TEXT_SIDEWAYS));
  }

#ifdef DEBUG
  // Used by CHECK_WRITING_MODE to compare modes without regard for the
  // StyleWritingMode::VERTICAL_SIDEWAYS or StyleWritingMode::TEXT_SIDEWAYS
  // flags.
  WritingMode IgnoreSideways() const {
    return WritingMode(mWritingMode._0 & ~(StyleWritingMode::VERTICAL_SIDEWAYS |
                                           StyleWritingMode::TEXT_SIDEWAYS)
                                              ._0);
  }
#endif

  /**
   * Return true if boxes with this writing mode should use central baselines.
   */
  bool IsCentralBaseline() const { return IsVertical() && !IsSideways(); }

  /**
   * Return true if boxes with this writing mode should use alphabetical
   * baselines.
   */
  bool IsAlphabeticalBaseline() const { return !IsCentralBaseline(); }

  static mozilla::PhysicalAxis PhysicalAxisForLogicalAxis(
      uint8_t aWritingModeValue, LogicalAxis aAxis) {
    // This relies on bit 0 of a writing-value mode indicating vertical
    // orientation and bit 0 of a LogicalAxis value indicating the inline axis,
    // so that it can correctly form mozilla::PhysicalAxis values using bit
    // manipulation.
    static_assert(uint8_t(StyleWritingModeProperty::HorizontalTb) == 0 &&
                      uint8_t(StyleWritingModeProperty::VerticalRl) == 1 &&
                      uint8_t(StyleWritingModeProperty::VerticalLr) == 3 &&
                      uint8_t(LogicalAxis::Block) == 0 &&
                      uint8_t(LogicalAxis::Inline) == 1 &&
                      uint8_t(PhysicalAxis::Vertical) == 0 &&
                      uint8_t(PhysicalAxis::Horizontal) == 1,
                  "unexpected writing-mode, logical axis or physical axis "
                  "constant values");
    return mozilla::PhysicalAxis((aWritingModeValue ^ uint8_t(aAxis)) & 0x1);
  }

  mozilla::PhysicalAxis PhysicalAxis(LogicalAxis aAxis) const {
    // This will set wm to either StyleWritingModel::HorizontalTB or
    // StyleWritingModeProperty::VerticalRL, and not the other two (real
    // and hypothetical) values.  But this is fine; we only need to
    // distinguish between vertical and horizontal in
    // PhysicalAxisForLogicalAxis.
    const auto wm = (mWritingMode & StyleWritingMode::VERTICAL)._0;
    return PhysicalAxisForLogicalAxis(wm, aAxis);
  }

  static mozilla::Side PhysicalSideForBlockAxis(uint8_t aWritingModeValue,
                                                LogicalEdge aEdge) {
    // indexes are StyleWritingModeProperty values, which are the same as these
    // two-bit values:
    //   bit 0 = the StyleWritingMode::VERTICAL value
    //   bit 1 = the StyleWritingMode::VERTICAL_LR value
    static const mozilla::Side kLogicalBlockSides[][2] = {
        {eSideTop, eSideBottom},  // horizontal-tb
        {eSideRight, eSideLeft},  // vertical-rl
        {eSideBottom, eSideTop},  // (horizontal-bt)
        {eSideLeft, eSideRight},  // vertical-lr
    };

    // Ignore the SidewaysMask bit of the writing-mode value, as this has no
    // effect on the side mappings.
    aWritingModeValue &= ~kWritingModeSidewaysMask;

    // What's left of the writing-mode should be in the range 0-3:
    NS_ASSERTION(aWritingModeValue < 4, "invalid aWritingModeValue value");

    return kLogicalBlockSides[aWritingModeValue][static_cast<uint8_t>(aEdge)];
  }

  mozilla::Side PhysicalSideForInlineAxis(LogicalEdge aEdge) const {
    // indexes are four-bit values:
    //   bit 0 = the StyleWritingMode::VERTICAL value
    //   bit 1 = the StyleWritingMode::INLINE_REVERSED value
    //   bit 2 = the StyleWritingMode::VERTICAL_LR value
    //   bit 3 = the StyleWritingMode::LINE_INVERTED value
    // Not all of these combinations can actually be specified via CSS: there
    // is no horizontal-bt writing-mode, and no text-orientation value that
    // produces "inverted" text. (The former 'sideways-left' value, no longer
    // in the spec, would have produced this in vertical-rl mode.)
    static const mozilla::Side kLogicalInlineSides[][2] = {
        {eSideLeft, eSideRight},  // horizontal-tb               ltr
        {eSideTop, eSideBottom},  // vertical-rl                 ltr
        {eSideRight, eSideLeft},  // horizontal-tb               rtl
        {eSideBottom, eSideTop},  // vertical-rl                 rtl
        {eSideRight, eSideLeft},  // (horizontal-bt)  (inverted) ltr
        {eSideTop, eSideBottom},  // sideways-lr                 rtl
        {eSideLeft, eSideRight},  // (horizontal-bt)  (inverted) rtl
        {eSideBottom, eSideTop},  // sideways-lr                 ltr
        {eSideLeft, eSideRight},  // horizontal-tb    (inverted) rtl
        {eSideTop, eSideBottom},  // vertical-rl      (inverted) rtl
        {eSideRight, eSideLeft},  // horizontal-tb    (inverted) ltr
        {eSideBottom, eSideTop},  // vertical-rl      (inverted) ltr
        {eSideLeft, eSideRight},  // (horizontal-bt)             ltr
        {eSideTop, eSideBottom},  // vertical-lr                 ltr
        {eSideRight, eSideLeft},  // (horizontal-bt)             rtl
        {eSideBottom, eSideTop},  // vertical-lr                 rtl
    };

    // Inline axis sides depend on all three of writing-mode, text-orientation
    // and direction, which are encoded in the StyleWritingMode::VERTICAL,
    // StyleWritingMode::INLINE_REVERSED, StyleWritingMode::VERTICAL_LR and
    // StyleWritingMode::LINE_INVERTED bits.  Use these four bits to index into
    // kLogicalInlineSides.
    static_assert(StyleWritingMode::VERTICAL._0 == 0x01 &&
                      StyleWritingMode::INLINE_REVERSED._0 == 0x02 &&
                      StyleWritingMode::VERTICAL_LR._0 == 0x04 &&
                      StyleWritingMode::LINE_INVERTED._0 == 0x08,
                  "Unexpected values for StyleWritingMode constants!");
    uint8_t index = mWritingMode._0 & 0x0F;
    return kLogicalInlineSides[index][static_cast<uint8_t>(aEdge)];
  }

  /**
   * Returns the physical side corresponding to the specified logical side,
   * given the current writing mode.
   */
  mozilla::Side PhysicalSide(LogicalSide aSide) const {
    if (IsBlock(aSide)) {
      static_assert(StyleWritingMode::VERTICAL._0 == 0x01 &&
                        StyleWritingMode::VERTICAL_LR._0 == 0x04,
                    "Unexpected values for StyleWritingMode constants!");
      const uint8_t wm =
          ((mWritingMode & StyleWritingMode::VERTICAL_LR)._0 >> 1) |
          (mWritingMode & StyleWritingMode::VERTICAL)._0;
      return PhysicalSideForBlockAxis(wm, GetEdge(aSide));
    }

    return PhysicalSideForInlineAxis(GetEdge(aSide));
  }

  /**
   * Returns the logical side corresponding to the specified physical side,
   * given the current writing mode.
   * (This is the inverse of the PhysicalSide() method above.)
   */
  LogicalSide LogicalSideForPhysicalSide(mozilla::Side aSide) const {
    // clang-format off
    // indexes are four-bit values:
    //   bit 0 = the StyleWritingMode::VERTICAL value
    //   bit 1 = the StyleWritingMode::INLINE_REVERSED value
    //   bit 2 = the StyleWritingMode::VERTICAL_LR value
    //   bit 3 = the StyleWritingMode::LINE_INVERTED value
    static const LogicalSide kPhysicalToLogicalSides[][4] = {
      // top                right
      // bottom             left
      { LogicalSide::BStart, LogicalSide::IEnd,
        LogicalSide::BEnd,   LogicalSide::IStart },  // horizontal-tb         ltr
      { LogicalSide::IStart, LogicalSide::BStart,
        LogicalSide::IEnd,   LogicalSide::BEnd   },  // vertical-rl           ltr
      { LogicalSide::BStart, LogicalSide::IStart,
        LogicalSide::BEnd,   LogicalSide::IEnd   },  // horizontal-tb         rtl
      { LogicalSide::IEnd,   LogicalSide::BStart,
        LogicalSide::IStart, LogicalSide::BEnd   },  // vertical-rl           rtl
      { LogicalSide::BEnd,   LogicalSide::IStart,
        LogicalSide::BStart, LogicalSide::IEnd   },  // (horizontal-bt) (inv) ltr
      { LogicalSide::IStart, LogicalSide::BEnd,
        LogicalSide::IEnd,   LogicalSide::BStart },  // vertical-lr   sw-left rtl
      { LogicalSide::BEnd,   LogicalSide::IEnd,
        LogicalSide::BStart, LogicalSide::IStart },  // (horizontal-bt) (inv) rtl
      { LogicalSide::IEnd,   LogicalSide::BEnd,
        LogicalSide::IStart, LogicalSide::BStart },  // vertical-lr   sw-left ltr
      { LogicalSide::BStart, LogicalSide::IEnd,
        LogicalSide::BEnd,   LogicalSide::IStart },  // horizontal-tb   (inv) rtl
      { LogicalSide::IStart, LogicalSide::BStart,
        LogicalSide::IEnd,   LogicalSide::BEnd   },  // vertical-rl   sw-left rtl
      { LogicalSide::BStart, LogicalSide::IStart,
        LogicalSide::BEnd,   LogicalSide::IEnd   },  // horizontal-tb   (inv) ltr
      { LogicalSide::IEnd,   LogicalSide::BStart,
        LogicalSide::IStart, LogicalSide::BEnd   },  // vertical-rl   sw-left ltr
      { LogicalSide::BEnd,   LogicalSide::IEnd,
        LogicalSide::BStart, LogicalSide::IStart },  // (horizontal-bt)       ltr
      { LogicalSide::IStart, LogicalSide::BEnd,
        LogicalSide::IEnd,   LogicalSide::BStart },  // vertical-lr           ltr
      { LogicalSide::BEnd,   LogicalSide::IStart,
        LogicalSide::BStart, LogicalSide::IEnd   },  // (horizontal-bt)       rtl
      { LogicalSide::IEnd,   LogicalSide::BEnd,
        LogicalSide::IStart, LogicalSide::BStart },  // vertical-lr           rtl
    };
    // clang-format on

    static_assert(StyleWritingMode::VERTICAL._0 == 0x01 &&
                      StyleWritingMode::INLINE_REVERSED._0 == 0x02 &&
                      StyleWritingMode::VERTICAL_LR._0 == 0x04 &&
                      StyleWritingMode::LINE_INVERTED._0 == 0x08,
                  "Unexpected values for StyleWritingMode constants!");
    uint8_t index = mWritingMode._0 & 0x0F;
    return kPhysicalToLogicalSides[index][aSide];
  }

  /**
   * Returns the logical side corresponding to the specified
   * line-relative direction, given the current writing mode.
   */
  LogicalSide LogicalSideForLineRelativeDir(LineRelativeDir aDir) const {
    auto side = static_cast<LogicalSide>(aDir);
    if (IsInline(side)) {
      return IsBidiLTR() ? side : GetOppositeSide(side);
    }
    return !IsLineInverted() ? side : GetOppositeSide(side);
  }

  /**
   * Default constructor gives us a horizontal, LTR writing mode.
   * XXX We will probably eliminate this and require explicit initialization
   *     in all cases once transition is complete.
   */
  WritingMode() : mWritingMode{0} {}

  /**
   * Construct writing mode based on a ComputedStyle.
   */
  explicit WritingMode(const ComputedStyle* aComputedStyle) {
    NS_ASSERTION(aComputedStyle, "we need an ComputedStyle here");
    mWritingMode = aComputedStyle->WritingMode();
  }

  /**
   * This function performs fixup for elements with 'unicode-bidi: plaintext',
   * where inline directionality is derived from the Unicode bidi categories
   * of the element's content, and not the CSS 'direction' property.
   *
   * The WritingMode constructor will have already incorporated the 'direction'
   * property into our flag bits, so such elements need to use this method
   * (after resolving the bidi level of their content) to update the direction
   * bits as needed.
   *
   * If it turns out that our bidi direction already matches what plaintext
   * resolution determined, there's nothing to do here. If it didn't (i.e. if
   * the rtl-ness doesn't match), then we correct the direction by flipping the
   * same bits that get flipped in the constructor's CSS 'direction'-based
   * chunk.
   *
   * XXX change uint8_t to UBiDiLevel after bug 924851
   */
  void SetDirectionFromBidiLevel(mozilla::intl::BidiEmbeddingLevel level) {
    if (level.IsRTL() == IsBidiLTR()) {
      mWritingMode ^= StyleWritingMode::RTL | StyleWritingMode::INLINE_REVERSED;
    }
  }

  /**
   * Compare two WritingModes for equality.
   */
  bool operator==(const WritingMode& aOther) const {
    return mWritingMode == aOther.mWritingMode;
  }

  bool operator!=(const WritingMode& aOther) const {
    return mWritingMode != aOther.mWritingMode;
  }

  /**
   * Check whether two modes are orthogonal to each other.
   */
  bool IsOrthogonalTo(const WritingMode& aOther) const {
    return IsVertical() != aOther.IsVertical();
  }

  /**
   * Returns true if this WritingMode's aLogicalAxis has the same physical
   * start side as the parallel axis of WritingMode |aOther|.
   *
   * @param aLogicalAxis The axis to compare from this WritingMode.
   * @param aOther The other WritingMode (from which we'll choose the axis
   *               that's parallel to this WritingMode's aLogicalAxis, for
   *               comparison).
   */
  bool ParallelAxisStartsOnSameSide(LogicalAxis aLogicalAxis,
                                    const WritingMode& aOther) const {
    mozilla::Side myStartSide =
        this->PhysicalSide(MakeLogicalSide(aLogicalAxis, LogicalEdge::Start));

    // Figure out which of aOther's axes is parallel to |this| WritingMode's
    // aLogicalAxis, and get its physical start side as well.
    LogicalAxis otherWMAxis = aOther.IsOrthogonalTo(*this)
                                  ? GetOrthogonalAxis(aLogicalAxis)
                                  : aLogicalAxis;
    mozilla::Side otherWMStartSide =
        aOther.PhysicalSide(MakeLogicalSide(otherWMAxis, LogicalEdge::Start));

    NS_ASSERTION(myStartSide % 2 == otherWMStartSide % 2,
                 "Should end up with sides in the same physical axis");
    return myStartSide == otherWMStartSide;
  }

  uint8_t GetBits() const { return mWritingMode._0; }

 private:
  friend class LogicalPoint;
  friend class LogicalSize;
  friend struct LogicalSides;
  friend class LogicalMargin;
  friend class LogicalRect;

  friend struct IPC::ParamTraits<WritingMode>;
  // IMENotification cannot store this class directly since this has some
  // constructors.  Therefore, it stores mWritingMode and recreate the
  // instance from it.
  friend struct widget::IMENotification;

  /**
   * Unknown writing mode (should never actually be stored or used anywhere).
   */
  static constexpr uint8_t kUnknownWritingMode = 0xff;

  /**
   * Return a WritingMode representing an unknown value.
   */
  static inline WritingMode Unknown() {
    return WritingMode(kUnknownWritingMode);
  }

  /**
   * Constructing a WritingMode with an arbitrary value is a private operation
   * currently only used by the Unknown() and IgnoreSideways() methods.
   */
  explicit WritingMode(uint8_t aValue) : mWritingMode{aValue} {}

  StyleWritingMode mWritingMode;
};

inline std::ostream& operator<<(std::ostream& aStream, const WritingMode& aWM) {
  return aStream << (aWM.IsVertical()
                         ? aWM.IsVerticalLR() ? aWM.IsBidiLTR()
                                                    ? aWM.IsSideways()
                                                          ? "sw-lr-ltr"
                                                          : "v-lr-ltr"
                                                : aWM.IsSideways() ? "sw-lr-rtl"
                                                                   : "v-lr-rtl"
                           : aWM.IsBidiLTR()
                               ? aWM.IsSideways() ? "sw-rl-ltr" : "v-rl-ltr"
                           : aWM.IsSideways() ? "sw-rl-rtl"
                                              : "v-rl-rtl"
                     : aWM.IsBidiLTR() ? "h-ltr"
                                       : "h-rtl");
}

/**
 * Logical-coordinate classes:
 *
 * There are three sets of coordinate space:
 *   - physical (top, left, bottom, right)
 *       relative to graphics coord system
 *   - flow-relative (block-start, inline-start, block-end, inline-end)
 *       relative to block/inline flow directions
 *   - line-relative (line-over, line-left, line-under, line-right)
 *       relative to glyph orientation / inline bidi directions
 * See CSS3 Writing Modes for more information
 *   http://www.w3.org/TR/css3-writing-modes/#abstract-box
 *
 * For shorthand, B represents the block-axis
 *                I represents the inline-axis
 *
 * The flow-relative geometric classes store coords in flow-relative space.
 * They use a private ns{Point,Size,Rect,Margin} member to store the actual
 * coordinate values, but reinterpret them as logical instead of physical.
 * This allows us to easily perform calculations in logical space (provided
 * writing modes of the operands match), by simply mapping to nsPoint (etc)
 * methods.
 *
 * Physical-coordinate accessors/setters are responsible to translate these
 * internal logical values as necessary.
 *
 * In DEBUG builds, the logical types store their WritingMode and check
 * that the same WritingMode is passed whenever callers ask them to do a
 * writing-mode-dependent operation. Non-DEBUG builds do NOT check this,
 * to avoid the overhead of storing WritingMode fields.
 *
 * Open question: do we need a different set optimized for line-relative
 * math, for use in nsLineLayout and the like? Or is multiplying values
 * by FlowRelativeToLineRelativeFactor() enough?
 */

/**
 * Flow-relative point
 */
class LogicalPoint {
 public:
  explicit LogicalPoint(WritingMode aWritingMode)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mPoint(0, 0) {
  }

  // Construct from a writing mode and individual coordinates (which MUST be
  // values in that writing mode, NOT physical coordinates!)
  LogicalPoint(WritingMode aWritingMode, nscoord aI, nscoord aB)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mPoint(aI, aB) {
  }

  // Construct from a writing mode and a physical point, within a given
  // containing rectangle's size (defining the conversion between LTR
  // and RTL coordinates, and between TTB and BTT coordinates).
  LogicalPoint(WritingMode aWritingMode, const nsPoint& aPoint,
               const nsSize& aContainerSize)
#ifdef DEBUG
      : mWritingMode(aWritingMode)
#endif
  {
    if (aWritingMode.IsVertical()) {
      I() = aWritingMode.IsInlineReversed() ? aContainerSize.height - aPoint.y
                                            : aPoint.y;
      B() = aWritingMode.IsVerticalLR() ? aPoint.x
                                        : aContainerSize.width - aPoint.x;
    } else {
      I() = aWritingMode.IsInlineReversed() ? aContainerSize.width - aPoint.x
                                            : aPoint.x;
      B() = aPoint.y;
    }
  }

  /**
   * Read-only (const) access to the logical coordinates.
   */
  nscoord I(WritingMode aWritingMode) const  // inline-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mPoint.x;
  }
  nscoord B(WritingMode aWritingMode) const  // block-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mPoint.y;
  }
  nscoord Pos(LogicalAxis aAxis, WritingMode aWM) const {
    return aAxis == LogicalAxis::Inline ? I(aWM) : B(aWM);
  }
  nscoord LineRelative(WritingMode aWritingMode,
                       const nsSize& aContainerSize) const  // line-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsBidiLTR()) {
      return I();
    }
    return (aWritingMode.IsVertical() ? aContainerSize.height
                                      : aContainerSize.width) -
           I();
  }

  /**
   * These non-const accessors return a reference (lvalue) that can be
   * assigned to by callers.
   */
  nscoord& I(WritingMode aWritingMode)  // inline-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mPoint.x;
  }
  nscoord& B(WritingMode aWritingMode)  // block-axis
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mPoint.y;
  }
  nscoord& Pos(LogicalAxis aAxis, WritingMode aWM) {
    return aAxis == LogicalAxis::Inline ? I(aWM) : B(aWM);
  }

  /**
   * Return a physical point corresponding to our logical coordinates,
   * converted according to our writing mode.
   */
  nsPoint GetPhysicalPoint(WritingMode aWritingMode,
                           const nsSize& aContainerSize) const {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return nsPoint(
          aWritingMode.IsVerticalLR() ? B() : aContainerSize.width - B(),
          aWritingMode.IsInlineReversed() ? aContainerSize.height - I() : I());
    } else {
      return nsPoint(
          aWritingMode.IsInlineReversed() ? aContainerSize.width - I() : I(),
          B());
    }
  }

  /**
   * Return the equivalent point in a different writing mode.
   */
  LogicalPoint ConvertTo(WritingMode aToMode, WritingMode aFromMode,
                         const nsSize& aContainerSize) const {
    CHECK_WRITING_MODE(aFromMode);
    return aToMode == aFromMode
               ? *this
               : LogicalPoint(aToMode,
                              GetPhysicalPoint(aFromMode, aContainerSize),
                              aContainerSize);
  }

  bool operator==(const LogicalPoint& aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mPoint == aOther.mPoint;
  }

  bool operator!=(const LogicalPoint& aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mPoint != aOther.mPoint;
  }

  LogicalPoint operator+(const LogicalPoint& aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    // In non-debug builds, LogicalPoint does not store the WritingMode,
    // so the first parameter here (which will always be WritingMode::Unknown())
    // is ignored.
    return LogicalPoint(GetWritingMode(), mPoint.x + aOther.mPoint.x,
                        mPoint.y + aOther.mPoint.y);
  }

  LogicalPoint& operator+=(const LogicalPoint& aOther) {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    I() += aOther.I();
    B() += aOther.B();
    return *this;
  }

  LogicalPoint operator-(const LogicalPoint& aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    // In non-debug builds, LogicalPoint does not store the WritingMode,
    // so the first parameter here (which will always be WritingMode::Unknown())
    // is ignored.
    return LogicalPoint(GetWritingMode(), mPoint.x - aOther.mPoint.x,
                        mPoint.y - aOther.mPoint.y);
  }

  LogicalPoint& operator-=(const LogicalPoint& aOther) {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    I() -= aOther.I();
    B() -= aOther.B();
    return *this;
  }

  friend std::ostream& operator<<(std::ostream& aStream,
                                  const LogicalPoint& aPoint) {
    return aStream << aPoint.mPoint;
  }

 private:
  friend class LogicalRect;

  /**
   * NOTE that in non-DEBUG builds, GetWritingMode() always returns
   * WritingMode::Unknown(), as the current mode is not stored in the logical-
   * geometry classes. Therefore, this method is private; it is used ONLY
   * by the DEBUG-mode checking macros in this class and its friends;
   * other code is not allowed to ask a logical point for its writing mode,
   * as this info will simply not be available in non-DEBUG builds.
   *
   * Also, in non-DEBUG builds, CHECK_WRITING_MODE does nothing, and the
   * WritingMode parameter to logical methods will generally be optimized
   * away altogether.
   */
#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

  // We don't allow construction of a LogicalPoint with no writing mode.
  LogicalPoint() = delete;

  // Accessors that don't take or check a WritingMode value.
  // These are for internal use only; they are called by methods that have
  // themselves already checked the WritingMode passed by the caller.
  nscoord I() const  // inline-axis
  {
    return mPoint.x;
  }
  nscoord B() const  // block-axis
  {
    return mPoint.y;
  }

  nscoord& I()  // inline-axis
  {
    return mPoint.x;
  }
  nscoord& B()  // block-axis
  {
    return mPoint.y;
  }

#ifdef DEBUG
  WritingMode mWritingMode;
#endif

  // We use an nsPoint to hold the coordinates, but reinterpret its .x and .y
  // fields as the inline and block directions. Hence, this is not exposed
  // directly, but only through accessors that will map them according to the
  // writing mode.
  nsPoint mPoint;
};

/**
 * Flow-relative size
 */
class LogicalSize {
 public:
  explicit LogicalSize(WritingMode aWritingMode)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mSize(0, 0) {
  }

  LogicalSize(WritingMode aWritingMode, nscoord aISize, nscoord aBSize)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mSize(aISize, aBSize) {
  }

  LogicalSize(WritingMode aWritingMode, const nsSize& aPhysicalSize)
#ifdef DEBUG
      : mWritingMode(aWritingMode)
#endif
  {
    if (aWritingMode.IsVertical()) {
      ISize() = aPhysicalSize.height;
      BSize() = aPhysicalSize.width;
    } else {
      ISize() = aPhysicalSize.width;
      BSize() = aPhysicalSize.height;
    }
  }

  void SizeTo(WritingMode aWritingMode, nscoord aISize, nscoord aBSize) {
    CHECK_WRITING_MODE(aWritingMode);
    mSize.SizeTo(aISize, aBSize);
  }

  /**
   * Dimensions in logical and physical terms
   */
  nscoord ISize(WritingMode aWritingMode) const  // inline-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mSize.width;
  }
  nscoord BSize(WritingMode aWritingMode) const  // block-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mSize.height;
  }
  nscoord Size(LogicalAxis aAxis, WritingMode aWM) const {
    return aAxis == LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
  }

  nscoord Width(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? BSize() : ISize();
  }
  nscoord Height(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? ISize() : BSize();
  }

  /**
   * Writable references to the logical dimensions
   */
  nscoord& ISize(WritingMode aWritingMode)  // inline-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mSize.width;
  }
  nscoord& BSize(WritingMode aWritingMode)  // block-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mSize.height;
  }
  nscoord& Size(LogicalAxis aAxis, WritingMode aWM) {
    return aAxis == LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
  }

  /**
   * Return an nsSize containing our physical dimensions
   */
  nsSize GetPhysicalSize(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? nsSize(BSize(), ISize())
                                     : nsSize(ISize(), BSize());
  }

  /**
   * Return a LogicalSize representing this size in a different writing mode
   */
  LogicalSize ConvertTo(WritingMode aToMode, WritingMode aFromMode) const {
#ifdef DEBUG
    // In DEBUG builds make sure to return a LogicalSize with the
    // expected writing mode
    CHECK_WRITING_MODE(aFromMode);
    return aToMode == aFromMode
               ? *this
               : LogicalSize(aToMode, GetPhysicalSize(aFromMode));
#else
    // optimization for non-DEBUG builds where LogicalSize doesn't store
    // the writing mode
    return (aToMode == aFromMode || !aToMode.IsOrthogonalTo(aFromMode))
               ? *this
               : LogicalSize(aToMode, BSize(), ISize());
#endif
  }

  /**
   * Test if a size is (0, 0).
   */
  bool IsAllZero() const { return ISize() == 0 && BSize() == 0; }

  /**
   * Various binary operators on LogicalSize. These are valid ONLY for operands
   * that share the same writing mode.
   */
  bool operator==(const LogicalSize& aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mSize == aOther.mSize;
  }

  bool operator!=(const LogicalSize& aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mSize != aOther.mSize;
  }

  LogicalSize operator+(const LogicalSize& aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return LogicalSize(GetWritingMode(), ISize() + aOther.ISize(),
                       BSize() + aOther.BSize());
  }
  LogicalSize& operator+=(const LogicalSize& aOther) {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    ISize() += aOther.ISize();
    BSize() += aOther.BSize();
    return *this;
  }

  LogicalSize operator-(const LogicalSize& aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return LogicalSize(GetWritingMode(), ISize() - aOther.ISize(),
                       BSize() - aOther.BSize());
  }
  LogicalSize& operator-=(const LogicalSize& aOther) {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    ISize() -= aOther.ISize();
    BSize() -= aOther.BSize();
    return *this;
  }

  friend std::ostream& operator<<(std::ostream& aStream,
                                  const LogicalSize& aSize) {
    return aStream << aSize.mSize;
  }

 private:
  friend class LogicalRect;

  LogicalSize() = delete;

#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

  nscoord ISize() const  // inline-size
  {
    return mSize.width;
  }
  nscoord BSize() const  // block-size
  {
    return mSize.height;
  }

  nscoord& ISize()  // inline-size
  {
    return mSize.width;
  }
  nscoord& BSize()  // block-size
  {
    return mSize.height;
  }

#ifdef DEBUG
  WritingMode mWritingMode;
#endif
  nsSize mSize;
};

/**
 * LogicalSides represents a set of logical sides.
 */
struct LogicalSides final {
  static constexpr EnumSet<LogicalSide> BBoth{LogicalSide::BStart,
                                              LogicalSide::BEnd};
  static constexpr EnumSet<LogicalSide> IBoth{LogicalSide::IStart,
                                              LogicalSide::IEnd};
  static constexpr EnumSet<LogicalSide> All{
      LogicalSide::BStart, LogicalSide::BEnd, LogicalSide::IStart,
      LogicalSide::IEnd};

  explicit LogicalSides(WritingMode aWritingMode)
#ifdef DEBUG
      : mWritingMode(aWritingMode)
#endif
  {
  }
  LogicalSides(WritingMode aWritingMode, LogicalSides aSides)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mSides(aSides.mSides) {
  }
  LogicalSides(WritingMode aWritingMode, EnumSet<LogicalSide> aSides)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mSides(aSides) {
  }
  bool IsEmpty() const { return mSides.isEmpty(); }
  bool BStart() const { return mSides.contains(LogicalSide::BStart); }
  bool BEnd() const { return mSides.contains(LogicalSide::BEnd); }
  bool IStart() const { return mSides.contains(LogicalSide::IStart); }
  bool IEnd() const { return mSides.contains(LogicalSide::IEnd); }
  bool Contains(LogicalSide aSide) const { return mSides.contains(aSide); }
  LogicalSides& operator+=(LogicalSides aOther) {
    mSides += aOther.mSides;
    return *this;
  }
  LogicalSides& operator+=(LogicalSide aOther) {
    mSides += aOther;
    return *this;
  }
  bool operator==(LogicalSides aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return mSides == aOther.mSides;
  }
  bool operator!=(LogicalSides aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    return !(*this == aOther);
  }

#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

 private:
#ifdef DEBUG
  WritingMode mWritingMode;
#endif
  EnumSet<LogicalSide> mSides;
};

/**
 * Flow-relative margin
 */
class LogicalMargin {
 public:
  explicit LogicalMargin(WritingMode aWritingMode)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mMargin(0, 0, 0, 0) {
  }

  LogicalMargin(WritingMode aWritingMode, nscoord aBStart, nscoord aIEnd,
                nscoord aBEnd, nscoord aIStart)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mMargin(aBStart, aIEnd, aBEnd, aIStart) {
  }

  LogicalMargin(WritingMode aWritingMode, const nsMargin& aPhysicalMargin)
#ifdef DEBUG
      : mWritingMode(aWritingMode)
#endif
  {
    if (aWritingMode.IsVertical()) {
      if (aWritingMode.IsVerticalLR()) {
        mMargin.top = aPhysicalMargin.left;
        mMargin.bottom = aPhysicalMargin.right;
      } else {
        mMargin.top = aPhysicalMargin.right;
        mMargin.bottom = aPhysicalMargin.left;
      }
      if (aWritingMode.IsInlineReversed()) {
        mMargin.left = aPhysicalMargin.bottom;
        mMargin.right = aPhysicalMargin.top;
      } else {
        mMargin.left = aPhysicalMargin.top;
        mMargin.right = aPhysicalMargin.bottom;
      }
    } else {
      mMargin.top = aPhysicalMargin.top;
      mMargin.bottom = aPhysicalMargin.bottom;
      if (aWritingMode.IsInlineReversed()) {
        mMargin.left = aPhysicalMargin.right;
        mMargin.right = aPhysicalMargin.left;
      } else {
        mMargin.left = aPhysicalMargin.left;
        mMargin.right = aPhysicalMargin.right;
      }
    }
  }

  nscoord IStart(WritingMode aWritingMode) const  // inline-start margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.left;
  }
  nscoord IEnd(WritingMode aWritingMode) const  // inline-end margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.right;
  }
  nscoord BStart(WritingMode aWritingMode) const  // block-start margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.top;
  }
  nscoord BEnd(WritingMode aWritingMode) const  // block-end margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.bottom;
  }
  nscoord Start(LogicalAxis aAxis, WritingMode aWM) const {
    return aAxis == LogicalAxis::Inline ? IStart(aWM) : BStart(aWM);
  }
  nscoord End(LogicalAxis aAxis, WritingMode aWM) const {
    return aAxis == LogicalAxis::Inline ? IEnd(aWM) : BEnd(aWM);
  }

  nscoord& IStart(WritingMode aWritingMode)  // inline-start margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.left;
  }
  nscoord& IEnd(WritingMode aWritingMode)  // inline-end margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.right;
  }
  nscoord& BStart(WritingMode aWritingMode)  // block-start margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.top;
  }
  nscoord& BEnd(WritingMode aWritingMode)  // block-end margin
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.bottom;
  }
  nscoord& Start(LogicalAxis aAxis, WritingMode aWM) {
    return aAxis == LogicalAxis::Inline ? IStart(aWM) : BStart(aWM);
  }
  nscoord& End(LogicalAxis aAxis, WritingMode aWM) {
    return aAxis == LogicalAxis::Inline ? IEnd(aWM) : BEnd(aWM);
  }

  nscoord IStartEnd(WritingMode aWritingMode) const  // inline margins
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.LeftRight();
  }
  nscoord BStartEnd(WritingMode aWritingMode) const  // block margins
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mMargin.TopBottom();
  }
  nscoord StartEnd(LogicalAxis aAxis, WritingMode aWM) const {
    return aAxis == LogicalAxis::Inline ? IStartEnd(aWM) : BStartEnd(aWM);
  }

  nscoord Side(LogicalSide aSide, WritingMode aWM) const {
    switch (aSide) {
      case LogicalSide::BStart:
        return BStart(aWM);
      case LogicalSide::BEnd:
        return BEnd(aWM);
      case LogicalSide::IStart:
        return IStart(aWM);
      case LogicalSide::IEnd:
        return IEnd(aWM);
    }

    MOZ_ASSERT_UNREACHABLE("We should handle all sides!");
    return BStart(aWM);
  }
  nscoord& Side(LogicalSide aSide, WritingMode aWM) {
    switch (aSide) {
      case LogicalSide::BStart:
        return BStart(aWM);
      case LogicalSide::BEnd:
        return BEnd(aWM);
      case LogicalSide::IStart:
        return IStart(aWM);
      case LogicalSide::IEnd:
        return IEnd(aWM);
    }

    MOZ_ASSERT_UNREACHABLE("We should handle all sides!");
    return BStart(aWM);
  }

  /*
   * Return margin values for line-relative sides, as defined in
   * http://www.w3.org/TR/css-writing-modes-3/#line-directions:
   *
   * line-left
   *     Nominally the side from which LTR text would start.
   * line-right
   *     Nominally the side from which RTL text would start. (Opposite of
   *     line-left.)
   */
  nscoord LineLeft(WritingMode aWritingMode) const {
    // We don't need to CHECK_WRITING_MODE here because the IStart or IEnd
    // accessor that we call will do it.
    return aWritingMode.IsBidiLTR() ? IStart(aWritingMode) : IEnd(aWritingMode);
  }
  nscoord LineRight(WritingMode aWritingMode) const {
    return aWritingMode.IsBidiLTR() ? IEnd(aWritingMode) : IStart(aWritingMode);
  }

  /**
   * Return a LogicalSize representing the total size of the inline-
   * and block-dimension margins.
   */
  LogicalSize Size(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return LogicalSize(aWritingMode, IStartEnd(), BStartEnd());
  }

  /**
   * Return a LogicalPoint representing an offset to the start-sides, i.e.
   * inline-start and block-start.
   */
  LogicalPoint StartOffset(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return LogicalPoint(aWritingMode, IStart(), BStart());
  }

  /**
   * Accessors for physical margins, using our writing mode to convert from
   * logical values.
   */
  nscoord Top(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical()
               ? (aWritingMode.IsInlineReversed() ? IEnd() : IStart())
               : BStart();
  }

  nscoord Bottom(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical()
               ? (aWritingMode.IsInlineReversed() ? IStart() : IEnd())
               : BEnd();
  }

  nscoord Left(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical()
               ? (aWritingMode.IsVerticalLR() ? BStart() : BEnd())
               : (aWritingMode.IsInlineReversed() ? IEnd() : IStart());
  }

  nscoord Right(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical()
               ? (aWritingMode.IsVerticalLR() ? BEnd() : BStart())
               : (aWritingMode.IsInlineReversed() ? IStart() : IEnd());
  }

  nscoord LeftRight(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? BStartEnd() : IStartEnd();
  }

  nscoord TopBottom(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? IStartEnd() : BStartEnd();
  }

  void SizeTo(WritingMode aWritingMode, nscoord aBStart, nscoord aIEnd,
              nscoord aBEnd, nscoord aIStart) {
    CHECK_WRITING_MODE(aWritingMode);
    mMargin.SizeTo(aBStart, aIEnd, aBEnd, aIStart);
  }

  /**
   * Return an nsMargin containing our physical coordinates
   */
  nsMargin GetPhysicalMargin(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical()
               ? (aWritingMode.IsVerticalLR()
                      ? (aWritingMode.IsInlineReversed()
                             ? nsMargin(IEnd(), BEnd(), IStart(), BStart())
                             : nsMargin(IStart(), BEnd(), IEnd(), BStart()))
                      : (aWritingMode.IsInlineReversed()
                             ? nsMargin(IEnd(), BStart(), IStart(), BEnd())
                             : nsMargin(IStart(), BStart(), IEnd(), BEnd())))
               : (aWritingMode.IsInlineReversed()
                      ? nsMargin(BStart(), IStart(), BEnd(), IEnd())
                      : nsMargin(BStart(), IEnd(), BEnd(), IStart()));
  }

  /**
   * Return a LogicalMargin representing this margin in a different
   * writing mode
   */
  LogicalMargin ConvertTo(WritingMode aToMode, WritingMode aFromMode) const {
    CHECK_WRITING_MODE(aFromMode);
    return aToMode == aFromMode
               ? *this
               : LogicalMargin(aToMode, GetPhysicalMargin(aFromMode));
  }

  LogicalMargin& ApplySkipSides(LogicalSides aSkipSides) {
    CHECK_WRITING_MODE(aSkipSides.GetWritingMode());
    if (aSkipSides.BStart()) {
      BStart() = 0;
    }
    if (aSkipSides.BEnd()) {
      BEnd() = 0;
    }
    if (aSkipSides.IStart()) {
      IStart() = 0;
    }
    if (aSkipSides.IEnd()) {
      IEnd() = 0;
    }
    return *this;
  }

  bool IsAllZero() const {
    return (mMargin.left == 0 && mMargin.top == 0 && mMargin.right == 0 &&
            mMargin.bottom == 0);
  }

  bool operator==(const LogicalMargin& aMargin) const {
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
    return mMargin == aMargin.mMargin;
  }

  bool operator!=(const LogicalMargin& aMargin) const {
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
    return mMargin != aMargin.mMargin;
  }

  LogicalMargin operator+(const LogicalMargin& aMargin) const {
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
    return LogicalMargin(GetWritingMode(), BStart() + aMargin.BStart(),
                         IEnd() + aMargin.IEnd(), BEnd() + aMargin.BEnd(),
                         IStart() + aMargin.IStart());
  }

  LogicalMargin operator+=(const LogicalMargin& aMargin) {
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
    mMargin += aMargin.mMargin;
    return *this;
  }

  LogicalMargin operator-(const LogicalMargin& aMargin) const {
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
    return LogicalMargin(GetWritingMode(), BStart() - aMargin.BStart(),
                         IEnd() - aMargin.IEnd(), BEnd() - aMargin.BEnd(),
                         IStart() - aMargin.IStart());
  }

  friend std::ostream& operator<<(std::ostream& aStream,
                                  const LogicalMargin& aMargin) {
    return aStream << aMargin.mMargin;
  }

 private:
  friend class LogicalRect;

  LogicalMargin() = delete;

#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

  nscoord IStart() const  // inline-start margin
  {
    return mMargin.left;
  }
  nscoord IEnd() const  // inline-end margin
  {
    return mMargin.right;
  }
  nscoord BStart() const  // block-start margin
  {
    return mMargin.top;
  }
  nscoord BEnd() const  // block-end margin
  {
    return mMargin.bottom;
  }

  nscoord& IStart()  // inline-start margin
  {
    return mMargin.left;
  }
  nscoord& IEnd()  // inline-end margin
  {
    return mMargin.right;
  }
  nscoord& BStart()  // block-start margin
  {
    return mMargin.top;
  }
  nscoord& BEnd()  // block-end margin
  {
    return mMargin.bottom;
  }

  nscoord IStartEnd() const  // inline margins
  {
    return mMargin.LeftRight();
  }
  nscoord BStartEnd() const  // block margins
  {
    return mMargin.TopBottom();
  }

#ifdef DEBUG
  WritingMode mWritingMode;
#endif
  nsMargin mMargin;
};

/**
 * Flow-relative rectangle
 */
class LogicalRect {
 public:
  explicit LogicalRect(WritingMode aWritingMode)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mIStart(0),
        mBStart(0),
        mISize(0),
        mBSize(0) {
  }

  LogicalRect(WritingMode aWritingMode, nscoord aIStart, nscoord aBStart,
              nscoord aISize, nscoord aBSize)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mIStart(aIStart),
        mBStart(aBStart),
        mISize(aISize),
        mBSize(aBSize) {
  }

  LogicalRect(WritingMode aWritingMode, const LogicalPoint& aOrigin,
              const LogicalSize& aSize)
      :
#ifdef DEBUG
        mWritingMode(aWritingMode),
#endif
        mIStart(aOrigin.mPoint.x),
        mBStart(aOrigin.mPoint.y),
        mISize(aSize.mSize.width),
        mBSize(aSize.mSize.height) {
    CHECK_WRITING_MODE(aOrigin.GetWritingMode());
    CHECK_WRITING_MODE(aSize.GetWritingMode());
  }

  LogicalRect(WritingMode aWritingMode, const nsRect& aRect,
              const nsSize& aContainerSize)
#ifdef DEBUG
      : mWritingMode(aWritingMode)
#endif
  {
    if (aWritingMode.IsVertical()) {
      mBStart = aWritingMode.IsVerticalLR()
                    ? aRect.X()
                    : aContainerSize.width - aRect.XMost();
      mIStart = aWritingMode.IsInlineReversed()
                    ? aContainerSize.height - aRect.YMost()
                    : aRect.Y();
      mBSize = aRect.Width();
      mISize = aRect.Height();
    } else {
      mIStart = aWritingMode.IsInlineReversed()
                    ? aContainerSize.width - aRect.XMost()
                    : aRect.X();
      mBStart = aRect.Y();
      mISize = aRect.Width();
      mBSize = aRect.Height();
    }
  }

  /**
   * Inline- and block-dimension geometry.
   */
  nscoord IStart(WritingMode aWritingMode) const  // inline-start edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mIStart;
  }
  nscoord IEnd(WritingMode aWritingMode) const  // inline-end edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mIStart + mISize;
  }
  nscoord ISize(WritingMode aWritingMode) const  // inline-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mISize;
  }

  nscoord BStart(WritingMode aWritingMode) const  // block-start edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBStart;
  }
  nscoord BEnd(WritingMode aWritingMode) const  // block-end edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBStart + mBSize;
  }
  nscoord BSize(WritingMode aWritingMode) const  // block-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBSize;
  }

  nscoord Start(LogicalAxis aAxis, WritingMode aWM) const {
    return aAxis == LogicalAxis::Inline ? IStart(aWM) : BStart(aWM);
  }
  nscoord End(LogicalAxis aAxis, WritingMode aWM) const {
    return aAxis == LogicalAxis::Inline ? IEnd(aWM) : BEnd(aWM);
  }
  nscoord Size(LogicalAxis aAxis, WritingMode aWM) const {
    return aAxis == LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
  }

  /**
   * Writable (reference) accessors are only available for the basic logical
   * fields (Start and Size), not derivatives like End.
   */
  nscoord& IStart(WritingMode aWritingMode)  // inline-start edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mIStart;
  }
  nscoord& ISize(WritingMode aWritingMode)  // inline-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mISize;
  }
  nscoord& BStart(WritingMode aWritingMode)  // block-start edge
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBStart;
  }
  nscoord& BSize(WritingMode aWritingMode)  // block-size
  {
    CHECK_WRITING_MODE(aWritingMode);
    return mBSize;
  }
  nscoord& Start(LogicalAxis aAxis, WritingMode aWM) {
    return aAxis == LogicalAxis::Inline ? IStart(aWM) : BStart(aWM);
  }
  nscoord& Size(LogicalAxis aAxis, WritingMode aWM) {
    return aAxis == LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
  }

  /**
   * Accessors for line-relative coordinates
   */
  nscoord LineLeft(WritingMode aWritingMode,
                   const nsSize& aContainerSize) const {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsBidiLTR()) {
      return IStart();
    }
    nscoord containerISize = aWritingMode.IsVertical() ? aContainerSize.height
                                                       : aContainerSize.width;
    return containerISize - IEnd();
  }
  nscoord LineRight(WritingMode aWritingMode,
                    const nsSize& aContainerSize) const {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsBidiLTR()) {
      return IEnd();
    }
    nscoord containerISize = aWritingMode.IsVertical() ? aContainerSize.height
                                                       : aContainerSize.width;
    return containerISize - IStart();
  }

  /**
   * Physical coordinates of the rect.
   */
  nscoord X(WritingMode aWritingMode, nscoord aContainerWidth) const {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return aWritingMode.IsVerticalLR() ? mBStart : aContainerWidth - BEnd();
    }
    return aWritingMode.IsInlineReversed() ? aContainerWidth - IEnd() : mIStart;
  }

  nscoord Y(WritingMode aWritingMode, nscoord aContainerHeight) const {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return aWritingMode.IsInlineReversed() ? aContainerHeight - IEnd()
                                             : mIStart;
    }
    return mBStart;
  }

  nscoord Width(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? mBSize : mISize;
  }

  nscoord Height(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return aWritingMode.IsVertical() ? mISize : mBSize;
  }

  nscoord XMost(WritingMode aWritingMode, nscoord aContainerWidth) const {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return aWritingMode.IsVerticalLR() ? BEnd() : aContainerWidth - mBStart;
    }
    return aWritingMode.IsInlineReversed() ? aContainerWidth - mIStart : IEnd();
  }

  nscoord YMost(WritingMode aWritingMode, nscoord aContainerHeight) const {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return aWritingMode.IsInlineReversed() ? aContainerHeight - mIStart
                                             : IEnd();
    }
    return BEnd();
  }

  bool IsEmpty() const { return mISize <= 0 || mBSize <= 0; }

  bool IsAllZero() const {
    return (mIStart == 0 && mBStart == 0 && mISize == 0 && mBSize == 0);
  }

  bool IsZeroSize() const { return (mISize == 0 && mBSize == 0); }

  void SetEmpty() { mISize = mBSize = 0; }

  bool IsEqualEdges(const LogicalRect aOther) const {
    CHECK_WRITING_MODE(aOther.GetWritingMode());
    bool result = mIStart == aOther.mIStart && mBStart == aOther.mBStart &&
                  mISize == aOther.mISize && mBSize == aOther.mBSize;

    // We want the same result as nsRect, so assert we get it.
    MOZ_ASSERT(result ==
               nsRect(mIStart, mBStart, mISize, mBSize)
                   .IsEqualEdges(nsRect(aOther.mIStart, aOther.mBStart,
                                        aOther.mISize, aOther.mBSize)));
    return result;
  }

  LogicalPoint Origin(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return LogicalPoint(aWritingMode, IStart(), BStart());
  }
  void SetOrigin(WritingMode aWritingMode, const LogicalPoint& aPoint) {
    IStart(aWritingMode) = aPoint.I(aWritingMode);
    BStart(aWritingMode) = aPoint.B(aWritingMode);
  }

  LogicalSize Size(WritingMode aWritingMode) const {
    CHECK_WRITING_MODE(aWritingMode);
    return LogicalSize(aWritingMode, ISize(), BSize());
  }

  LogicalRect operator+(const LogicalPoint& aPoint) const {
    CHECK_WRITING_MODE(aPoint.GetWritingMode());
    return LogicalRect(GetWritingMode(), IStart() + aPoint.I(),
                       BStart() + aPoint.B(), ISize(), BSize());
  }

  LogicalRect& operator+=(const LogicalPoint& aPoint) {
    CHECK_WRITING_MODE(aPoint.GetWritingMode());
    mIStart += aPoint.mPoint.x;
    mBStart += aPoint.mPoint.y;
    return *this;
  }

  LogicalRect operator-(const LogicalPoint& aPoint) const {
    CHECK_WRITING_MODE(aPoint.GetWritingMode());
    return LogicalRect(GetWritingMode(), IStart() - aPoint.I(),
                       BStart() - aPoint.B(), ISize(), BSize());
  }

  LogicalRect& operator-=(const LogicalPoint& aPoint) {
    CHECK_WRITING_MODE(aPoint.GetWritingMode());
    mIStart -= aPoint.mPoint.x;
    mBStart -= aPoint.mPoint.y;
    return *this;
  }

  void MoveBy(WritingMode aWritingMode, const LogicalPoint& aDelta) {
    CHECK_WRITING_MODE(aWritingMode);
    CHECK_WRITING_MODE(aDelta.GetWritingMode());
    IStart() += aDelta.I();
    BStart() += aDelta.B();
  }

  void Inflate(nscoord aD) {
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Inflate(aD);
#endif
    mIStart -= aD;
    mBStart -= aD;
    mISize += 2 * aD;
    mBSize += 2 * aD;
    MOZ_ASSERT(
        rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }
  void Inflate(nscoord aDI, nscoord aDB) {
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Inflate(aDI, aDB);
#endif
    mIStart -= aDI;
    mBStart -= aDB;
    mISize += 2 * aDI;
    mBSize += 2 * aDB;
    MOZ_ASSERT(
        rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }
  void Inflate(WritingMode aWritingMode, const LogicalMargin& aMargin) {
    CHECK_WRITING_MODE(aWritingMode);
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Inflate(aMargin.mMargin);
#endif
    mIStart -= aMargin.mMargin.left;
    mBStart -= aMargin.mMargin.top;
    mISize += aMargin.mMargin.LeftRight();
    mBSize += aMargin.mMargin.TopBottom();
    MOZ_ASSERT(
        rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }

  void Deflate(nscoord aD) {
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Deflate(aD);
#endif
    mIStart += aD;
    mBStart += aD;
    mISize = std::max(0, mISize - 2 * aD);
    mBSize = std::max(0, mBSize - 2 * aD);
    MOZ_ASSERT(
        rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }
  void Deflate(nscoord aDI, nscoord aDB) {
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Deflate(aDI, aDB);
#endif
    mIStart += aDI;
    mBStart += aDB;
    mISize = std::max(0, mISize - 2 * aDI);
    mBSize = std::max(0, mBSize - 2 * aDB);
    MOZ_ASSERT(
        rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }
  void Deflate(WritingMode aWritingMode, const LogicalMargin& aMargin) {
    CHECK_WRITING_MODE(aWritingMode);
    CHECK_WRITING_MODE(aMargin.GetWritingMode());
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug(mIStart, mBStart, mISize, mBSize);
    rectDebug.Deflate(aMargin.mMargin);
#endif
    mIStart += aMargin.mMargin.left;
    mBStart += aMargin.mMargin.top;
    mISize = std::max(0, mISize - aMargin.mMargin.LeftRight());
    mBSize = std::max(0, mBSize - aMargin.mMargin.TopBottom());
    MOZ_ASSERT(
        rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
  }

  /**
   * Return an nsRect containing our physical coordinates within the given
   * container size.
   */
  nsRect GetPhysicalRect(WritingMode aWritingMode,
                         const nsSize& aContainerSize) const {
    CHECK_WRITING_MODE(aWritingMode);
    if (aWritingMode.IsVertical()) {
      return nsRect(aWritingMode.IsVerticalLR() ? BStart()
                                                : aContainerSize.width - BEnd(),
                    aWritingMode.IsInlineReversed()
                        ? aContainerSize.height - IEnd()
                        : IStart(),
                    BSize(), ISize());
    } else {
      return nsRect(aWritingMode.IsInlineReversed()
                        ? aContainerSize.width - IEnd()
                        : IStart(),
                    BStart(), ISize(), BSize());
    }
  }

  /**
   * Return a LogicalRect representing this rect in a different writing mode
   */
  LogicalRect ConvertTo(WritingMode aToMode, WritingMode aFromMode,
                        const nsSize& aContainerSize) const {
    CHECK_WRITING_MODE(aFromMode);
    return aToMode == aFromMode
               ? *this
               : LogicalRect(aToMode,
                             GetPhysicalRect(aFromMode, aContainerSize),
                             aContainerSize);
  }

  /**
   * Set *this to be the rectangle containing the intersection of aRect1
   * and aRect2, return whether the intersection is non-empty.
   */
  bool IntersectRect(const LogicalRect& aRect1, const LogicalRect& aRect2) {
    CHECK_WRITING_MODE(aRect1.mWritingMode);
    CHECK_WRITING_MODE(aRect2.mWritingMode);
#ifdef DEBUG
    // Compute using nsRect and assert the results match
    nsRect rectDebug;
    rectDebug.IntersectRect(
        nsRect(aRect1.mIStart, aRect1.mBStart, aRect1.mISize, aRect1.mBSize),
        nsRect(aRect2.mIStart, aRect2.mBStart, aRect2.mISize, aRect2.mBSize));
#endif

    nscoord iEnd = std::min(aRect1.IEnd(), aRect2.IEnd());
    mIStart = std::max(aRect1.mIStart, aRect2.mIStart);
    mISize = iEnd - mIStart;

    nscoord bEnd = std::min(aRect1.BEnd(), aRect2.BEnd());
    mBStart = std::max(aRect1.mBStart, aRect2.mBStart);
    mBSize = bEnd - mBStart;

    if (mISize < 0 || mBSize < 0) {
      mISize = 0;
      mBSize = 0;
    }

    MOZ_ASSERT(
        (rectDebug.IsEmpty() && (mISize == 0 || mBSize == 0)) ||
        rectDebug.IsEqualEdges(nsRect(mIStart, mBStart, mISize, mBSize)));
    return mISize > 0 && mBSize > 0;
  }

  friend std::ostream& operator<<(std::ostream& aStream,
                                  const LogicalRect& aRect) {
    return aStream << '(' << aRect.IStart() << ',' << aRect.BStart() << ','
                   << aRect.ISize() << ',' << aRect.BSize() << ')';
  }

 private:
  LogicalRect() = delete;

#ifdef DEBUG
  WritingMode GetWritingMode() const { return mWritingMode; }
#else
  WritingMode GetWritingMode() const { return WritingMode::Unknown(); }
#endif

  nscoord IStart() const  // inline-start edge
  {
    return mIStart;
  }
  nscoord IEnd() const  // inline-end edge
  {
    return mIStart + mISize;
  }
  nscoord ISize() const  // inline-size
  {
    return mISize;
  }

  nscoord BStart() const  // block-start edge
  {
    return mBStart;
  }
  nscoord BEnd() const  // block-end edge
  {
    return mBStart + mBSize;
  }
  nscoord BSize() const  // block-size
  {
    return mBSize;
  }

  nscoord& IStart()  // inline-start edge
  {
    return mIStart;
  }
  nscoord& ISize()  // inline-size
  {
    return mISize;
  }
  nscoord& BStart()  // block-start edge
  {
    return mBStart;
  }
  nscoord& BSize()  // block-size
  {
    return mBSize;
  }

#ifdef DEBUG
  WritingMode mWritingMode;
#endif
  // Inline- and block-geometry dimension
  nscoord mIStart;  // inline-start edge
  nscoord mBStart;  // block-start edge
  nscoord mISize;   // inline-size
  nscoord mBSize;   // block-size
};

template <typename T>
const T& StyleRect<T>::Get(WritingMode aWM, LogicalSide aSide) const {
  return Get(aWM.PhysicalSide(aSide));
}

template <typename T>
const T& StyleRect<T>::GetIStart(WritingMode aWM) const {
  return Get(aWM, LogicalSide::IStart);
}

template <typename T>
const T& StyleRect<T>::GetBStart(WritingMode aWM) const {
  return Get(aWM, LogicalSide::BStart);
}

template <typename T>
const T& StyleRect<T>::GetIEnd(WritingMode aWM) const {
  return Get(aWM, LogicalSide::IEnd);
}

template <typename T>
const T& StyleRect<T>::GetBEnd(WritingMode aWM) const {
  return Get(aWM, LogicalSide::BEnd);
}

template <typename T>
T& StyleRect<T>::Get(WritingMode aWM, LogicalSide aSide) {
  return Get(aWM.PhysicalSide(aSide));
}

template <typename T>
T& StyleRect<T>::GetIStart(WritingMode aWM) {
  return Get(aWM, LogicalSide::IStart);
}

template <typename T>
T& StyleRect<T>::GetBStart(WritingMode aWM) {
  return Get(aWM, LogicalSide::BStart);
}

template <typename T>
T& StyleRect<T>::GetIEnd(WritingMode aWM) {
  return Get(aWM, LogicalSide::IEnd);
}

template <typename T>
T& StyleRect<T>::GetBEnd(WritingMode aWM) {
  return Get(aWM, LogicalSide::BEnd);
}

template <typename T>
const T& StyleRect<T>::Start(mozilla::LogicalAxis aAxis,
                             mozilla::WritingMode aWM) const {
  return Get(aWM, aAxis == mozilla::LogicalAxis::Inline
                      ? mozilla::LogicalSide::IStart
                      : mozilla::LogicalSide::BStart);
}

template <typename T>
const T& StyleRect<T>::End(mozilla::LogicalAxis aAxis,
                           mozilla::WritingMode aWM) const {
  return Get(aWM, aAxis == mozilla::LogicalAxis::Inline
                      ? mozilla::LogicalSide::IEnd
                      : mozilla::LogicalSide::BEnd);
}

inline AspectRatio AspectRatio::ConvertToWritingMode(
    const WritingMode& aWM) const {
  return aWM.IsVertical() ? Inverted() : *this;
}

}  // namespace mozilla

// Definitions of inline methods for nsStylePosition, declared in
// nsStyleStruct.h but not defined there because they need WritingMode.
inline const mozilla::StyleSize& nsStylePosition::ISize(WritingMode aWM) const {
  return aWM.IsVertical() ? mHeight : mWidth;
}
inline const mozilla::StyleSize& nsStylePosition::MinISize(
    WritingMode aWM) const {
  return aWM.IsVertical() ? mMinHeight : mMinWidth;
}
inline const mozilla::StyleMaxSize& nsStylePosition::MaxISize(
    WritingMode aWM) const {
  return aWM.IsVertical() ? mMaxHeight : mMaxWidth;
}
inline const mozilla::StyleSize& nsStylePosition::BSize(WritingMode aWM) const {
  return aWM.IsVertical() ? mWidth : mHeight;
}
inline const mozilla::StyleSize& nsStylePosition::MinBSize(
    WritingMode aWM) const {
  return aWM.IsVertical() ? mMinWidth : mMinHeight;
}
inline const mozilla::StyleMaxSize& nsStylePosition::MaxBSize(
    WritingMode aWM) const {
  return aWM.IsVertical() ? mMaxWidth : mMaxHeight;
}
inline const mozilla::StyleSize& nsStylePosition::Size(
    mozilla::LogicalAxis aAxis, WritingMode aWM) const {
  return aAxis == mozilla::LogicalAxis::Inline ? ISize(aWM) : BSize(aWM);
}
inline const mozilla::StyleSize& nsStylePosition::MinSize(
    mozilla::LogicalAxis aAxis, WritingMode aWM) const {
  return aAxis == mozilla::LogicalAxis::Inline ? MinISize(aWM) : MinBSize(aWM);
}
inline const mozilla::StyleMaxSize& nsStylePosition::MaxSize(
    mozilla::LogicalAxis aAxis, WritingMode aWM) const {
  return aAxis == mozilla::LogicalAxis::Inline ? MaxISize(aWM) : MaxBSize(aWM);
}

inline bool nsStylePosition::ISizeDependsOnContainer(WritingMode aWM) const {
  const auto& iSize = ISize(aWM);
  return iSize.IsAuto() || ISizeCoordDependsOnContainer(iSize);
}
inline bool nsStylePosition::MinISizeDependsOnContainer(WritingMode aWM) const {
  // NOTE: For a flex item, "min-inline-size:auto" is supposed to behave like
  // "min-content", which does depend on the container, so you might think we'd
  // need a special case for "flex item && min-inline-size:auto" here. However,
  // we don't actually need that special-case code, because flex items are
  // explicitly supposed to *ignore* their min-inline-size (i.e. behave like
  // it's 0) until the flex container explicitly considers it. So -- since the
  // flex container doesn't rely on this method, we don't need to worry about
  // special behavior for flex items' "min-inline-size:auto" values here.
  return ISizeCoordDependsOnContainer(MinISize(aWM));
}
inline bool nsStylePosition::MaxISizeDependsOnContainer(WritingMode aWM) const {
  // NOTE: The comment above MinISizeDependsOnContainer about flex items
  // applies here, too.
  return ISizeCoordDependsOnContainer(MaxISize(aWM));
}
// Note that these functions count `auto` as depending on the container
// since that's the case for absolutely positioned elements.
// However, some callers do not care about this case and should check
// for it, since it is the most common case.
// FIXME: We should probably change the assumption to be the other way
// around.
inline bool nsStylePosition::BSizeDependsOnContainer(WritingMode aWM) const {
  const auto& bSize = BSize(aWM);
  return bSize.BehavesLikeInitialValueOnBlockAxis() ||
         BSizeCoordDependsOnContainer(bSize);
}
inline bool nsStylePosition::MinBSizeDependsOnContainer(WritingMode aWM) const {
  return BSizeCoordDependsOnContainer(MinBSize(aWM));
}
inline bool nsStylePosition::MaxBSizeDependsOnContainer(WritingMode aWM) const {
  return BSizeCoordDependsOnContainer(MaxBSize(aWM));
}

inline bool nsStyleMargin::HasBlockAxisAuto(mozilla::WritingMode aWM) const {
  return mMargin.GetBStart(aWM).IsAuto() || mMargin.GetBEnd(aWM).IsAuto();
}

inline bool nsStyleMargin::HasInlineAxisAuto(mozilla::WritingMode aWM) const {
  return mMargin.GetIStart(aWM).IsAuto() || mMargin.GetIEnd(aWM).IsAuto();
}
inline bool nsStyleMargin::HasAuto(mozilla::LogicalAxis aAxis,
                                   mozilla::WritingMode aWM) const {
  return aAxis == mozilla::LogicalAxis::Inline ? HasInlineAxisAuto(aWM)
                                               : HasBlockAxisAuto(aWM);
}

inline mozilla::StyleAlignFlags nsStylePosition::UsedSelfAlignment(
    mozilla::LogicalAxis aAxis, const mozilla::ComputedStyle* aParent) const {
  return aAxis == mozilla::LogicalAxis::Block ? UsedAlignSelf(aParent)._0
                                              : UsedJustifySelf(aParent)._0;
}

inline mozilla::StyleContentDistribution nsStylePosition::UsedContentAlignment(
    mozilla::LogicalAxis aAxis) const {
  return aAxis == mozilla::LogicalAxis::Block ? mAlignContent : mJustifyContent;
}

inline mozilla::StyleContentDistribution nsStylePosition::UsedTracksAlignment(
    mozilla::LogicalAxis aAxis, uint32_t aIndex) const {
  using T = mozilla::StyleAlignFlags;
  const auto& tracksAlignment =
      aAxis == mozilla::LogicalAxis::Block ? mAlignTracks : mJustifyTracks;
  if (MOZ_LIKELY(tracksAlignment.IsEmpty())) {
    // An empty array encodes the initial value, 'normal', which behaves as
    // 'start' for Grid containers.
    return mozilla::StyleContentDistribution{T::START};
  }

  // If there are fewer values than tracks, then the last value is used for all
  // the remaining tracks.
  const auto& ta = tracksAlignment.AsSpan();
  auto align = ta[std::min<size_t>(aIndex, ta.Length() - 1)];
  if (align.primary == T::NORMAL) {
    align = mozilla::StyleContentDistribution{T::START};
  }
  return align;
}

#endif  // WritingModes_h_