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
|
/*
* Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibWeb/Dump.h>
#include <LibWeb/Layout/BlockFormattingContext.h>
#include <LibWeb/Layout/Box.h>
#include <LibWeb/Layout/FlexFormattingContext.h>
#include <LibWeb/Layout/FormattingContext.h>
#include <LibWeb/Layout/GridFormattingContext.h>
#include <LibWeb/Layout/ReplacedBox.h>
#include <LibWeb/Layout/SVGFormattingContext.h>
#include <LibWeb/Layout/SVGSVGBox.h>
#include <LibWeb/Layout/TableCellBox.h>
#include <LibWeb/Layout/TableFormattingContext.h>
#include <LibWeb/Layout/Viewport.h>
namespace Web::Layout {
FormattingContext::FormattingContext(Type type, LayoutState& state, Box const& context_box, FormattingContext* parent)
: m_type(type)
, m_parent(parent)
, m_context_box(context_box)
, m_state(state)
{
}
FormattingContext::~FormattingContext() = default;
// https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Block_formatting_context
bool FormattingContext::creates_block_formatting_context(Box const& box)
{
// NOTE: Replaced elements never create a BFC.
if (box.is_replaced_box())
return false;
// display: table
if (box.display().is_table_inside()) {
return false;
}
// display: flex
if (box.display().is_flex_inside()) {
return false;
}
// display: grid
if (box.display().is_grid_inside()) {
return false;
}
// NOTE: This function uses MDN as a reference, not because it's authoritative,
// but because they've gathered all the conditions in one convenient location.
// The root element of the document (<html>).
if (box.is_root_element())
return true;
// Floats (elements where float isn't none).
if (box.is_floating())
return true;
// Absolutely positioned elements (elements where position is absolute or fixed).
if (box.is_absolutely_positioned())
return true;
// Inline-blocks (elements with display: inline-block).
if (box.display().is_inline_block())
return true;
// Table cells (elements with display: table-cell, which is the default for HTML table cells).
if (box.display().is_table_cell())
return true;
// Table captions (elements with display: table-caption, which is the default for HTML table captions).
if (box.display().is_table_caption())
return true;
// FIXME: Anonymous table cells implicitly created by the elements with display: table, table-row, table-row-group, table-header-group, table-footer-group
// (which is the default for HTML tables, table rows, table bodies, table headers, and table footers, respectively), or inline-table.
// Block elements where overflow has a value other than visible and clip.
CSS::Overflow overflow_x = box.computed_values().overflow_x();
if ((overflow_x != CSS::Overflow::Visible) && (overflow_x != CSS::Overflow::Clip))
return true;
CSS::Overflow overflow_y = box.computed_values().overflow_y();
if ((overflow_y != CSS::Overflow::Visible) && (overflow_y != CSS::Overflow::Clip))
return true;
// display: flow-root.
if (box.display().is_flow_root_inside())
return true;
// FIXME: Elements with contain: layout, content, or paint.
if (box.parent()) {
auto parent_display = box.parent()->display();
// Flex items (direct children of the element with display: flex or inline-flex) if they are neither flex nor grid nor table containers themselves.
if (parent_display.is_flex_inside())
return true;
// Grid items (direct children of the element with display: grid or inline-grid) if they are neither flex nor grid nor table containers themselves.
if (parent_display.is_grid_inside())
return true;
}
// FIXME: Multicol containers (elements where column-count or column-width isn't auto, including elements with column-count: 1).
// FIXME: column-span: all should always create a new formatting context, even when the column-span: all element isn't contained by a multicol container (Spec change, Chrome bug).
return false;
}
Optional<FormattingContext::Type> FormattingContext::formatting_context_type_created_by_box(Box const& box)
{
if (box.is_replaced_box() && !box.can_have_children()) {
return Type::InternalReplaced;
}
if (!box.can_have_children())
return {};
if (is<SVGSVGBox>(box))
return Type::SVG;
auto display = box.display();
if (display.is_flex_inside())
return Type::Flex;
if (display.is_table_inside())
return Type::Table;
if (display.is_grid_inside())
return Type::Grid;
if (creates_block_formatting_context(box))
return Type::Block;
if (box.children_are_inline())
return {};
// The box is a block container that doesn't create its own BFC.
// It will be formatted by the containing BFC.
if (!display.is_flow_inside()) {
// HACK: Instead of crashing, create a dummy formatting context that does nothing.
// FIXME: Remove this once it's no longer needed. It currently swallows problem with standalone
// table-related boxes that don't get fixed up by CSS anonymous table box generation.
return Type::InternalDummy;
}
return {};
}
// FIXME: This is a hack. Get rid of it.
struct ReplacedFormattingContext : public FormattingContext {
ReplacedFormattingContext(LayoutState& state, Box const& box)
: FormattingContext(Type::Block, state, box)
{
}
virtual CSSPixels automatic_content_width() const override { return 0; }
virtual CSSPixels automatic_content_height() const override { return 0; }
virtual void run(Box const&, LayoutMode, AvailableSpace const&) override { }
};
// FIXME: This is a hack. Get rid of it.
struct DummyFormattingContext : public FormattingContext {
DummyFormattingContext(LayoutState& state, Box const& box)
: FormattingContext(Type::Block, state, box)
{
}
virtual CSSPixels automatic_content_width() const override { return 0; }
virtual CSSPixels automatic_content_height() const override { return 0; }
virtual void run(Box const&, LayoutMode, AvailableSpace const&) override { }
};
OwnPtr<FormattingContext> FormattingContext::create_independent_formatting_context_if_needed(LayoutState& state, Box const& child_box)
{
auto type = formatting_context_type_created_by_box(child_box);
if (!type.has_value())
return nullptr;
switch (type.value()) {
case Type::Block:
return make<BlockFormattingContext>(state, verify_cast<BlockContainer>(child_box), this);
case Type::SVG:
return make<SVGFormattingContext>(state, child_box, this);
case Type::Flex:
return make<FlexFormattingContext>(state, child_box, this);
case Type::Grid:
return make<GridFormattingContext>(state, child_box, this);
case Type::Table:
return make<TableFormattingContext>(state, child_box, this);
case Type::InternalReplaced:
return make<ReplacedFormattingContext>(state, child_box);
case Type::InternalDummy:
return make<DummyFormattingContext>(state, child_box);
case Type::Inline:
// IFC should always be created by a parent BFC directly.
VERIFY_NOT_REACHED();
break;
default:
VERIFY_NOT_REACHED();
}
}
OwnPtr<FormattingContext> FormattingContext::layout_inside(Box const& child_box, LayoutMode layout_mode, AvailableSpace const& available_space)
{
{
// OPTIMIZATION: If we're doing intrinsic sizing and `child_box` has definite size in both axes,
// we don't need to layout its insides. The size is resolvable without learning
// the metrics of whatever's inside the box.
auto const& used_values = m_state.get(child_box);
if (layout_mode == LayoutMode::IntrinsicSizing
&& used_values.width_constraint == SizeConstraint::None
&& used_values.height_constraint == SizeConstraint::None
&& used_values.has_definite_width()
&& used_values.has_definite_height()) {
return nullptr;
}
}
if (!child_box.can_have_children())
return {};
auto independent_formatting_context = create_independent_formatting_context_if_needed(m_state, child_box);
if (independent_formatting_context)
independent_formatting_context->run(child_box, layout_mode, available_space);
else
run(child_box, layout_mode, available_space);
return independent_formatting_context;
}
CSSPixels FormattingContext::greatest_child_width(Box const& box) const
{
CSSPixels max_width = 0;
if (box.children_are_inline()) {
for (auto& line_box : m_state.get(box).line_boxes) {
max_width = max(max_width, line_box.width());
}
} else {
box.for_each_child_of_type<Box>([&](Box const& child) {
if (!child.is_absolutely_positioned())
max_width = max(max_width, m_state.get(child).margin_box_width());
});
}
return max_width;
}
FormattingContext::ShrinkToFitResult FormattingContext::calculate_shrink_to_fit_widths(Box const& box)
{
return {
.preferred_width = calculate_max_content_width(box),
.preferred_minimum_width = calculate_min_content_width(box),
};
}
static CSSPixelSize solve_replaced_size_constraint(LayoutState const& state, CSSPixels input_width, CSSPixels input_height, ReplacedBox const& box)
{
// 10.4 Minimum and maximum widths: 'min-width' and 'max-width'
auto const& containing_block = *box.non_anyonymous_containing_block();
auto const& containing_block_state = state.get(containing_block);
auto width_of_containing_block = containing_block_state.content_width();
auto height_of_containing_block = containing_block_state.content_height();
CSSPixels specified_min_width = box.computed_values().min_width().is_auto() ? 0 : box.computed_values().min_width().to_px(box, width_of_containing_block);
CSSPixels specified_max_width = box.computed_values().max_width().is_none() ? input_width : box.computed_values().max_width().to_px(box, width_of_containing_block);
CSSPixels specified_min_height = box.computed_values().min_height().is_auto() ? 0 : box.computed_values().min_height().to_px(box, height_of_containing_block);
CSSPixels specified_max_height = box.computed_values().max_height().is_none() ? input_height : box.computed_values().max_height().to_px(box, height_of_containing_block);
auto min_width = min(specified_min_width, specified_max_width);
auto max_width = max(specified_min_width, specified_max_width);
auto min_height = min(specified_min_height, specified_max_height);
auto max_height = max(specified_min_height, specified_max_height);
struct Size {
CSSPixels width;
CSSPixels height;
} size = { input_width, input_height };
auto& w = size.width;
auto& h = size.height;
if (w > max_width)
size = { max_width, max(max_width * (h / w), min_height) };
if (w < min_width)
size = { min_width, min(min_width * (h / w), max_height) };
if (h > max_height)
size = { max(max_height * (w / h), min_width), max_height };
if (h < min_height)
size = { min(min_height * (w / h), max_width), min_height };
if ((w > max_width && h > max_height) && (max_width / w <= max_height / h))
size = { max_width, max(min_height, max_width * (h / w)) };
if ((w > max_width && h > max_height) && (max_width / w > max_height / h))
size = { max(min_width, max_height * (w / h)), max_height };
if ((w < min_width && h < min_height) && (min_width / w <= min_height / h))
size = { min(max_width, min_height * (w / h)), min_height };
if ((w < min_width && h < min_height) && (min_width / w > min_height / h))
size = { min_width, min(max_height, min_width * (h / w)) };
if (w < min_width && h > max_height)
size = { min_width, max_height };
if (w > max_width && h < min_height)
size = { max_width, min_height };
return { w, h };
}
// https://www.w3.org/TR/CSS22/visudet.html#root-height
CSSPixels FormattingContext::compute_auto_height_for_block_formatting_context_root(Box const& root) const
{
// 10.6.7 'Auto' heights for block formatting context roots
Optional<CSSPixels> top;
Optional<CSSPixels> bottom;
if (root.children_are_inline()) {
// If it only has inline-level children, the height is the distance between
// the top content edge and the bottom of the bottommost line box.
auto const& line_boxes = m_state.get(root).line_boxes;
top = 0;
if (!line_boxes.is_empty())
bottom = line_boxes.last().bottom();
} else {
// If it has block-level children, the height is the distance between
// the top margin-edge of the topmost block-level child box
// and the bottom margin-edge of the bottommost block-level child box.
root.for_each_child_of_type<Box>([&](Layout::Box& child_box) {
// Absolutely positioned children are ignored,
// and relatively positioned boxes are considered without their offset.
// Note that the child box may be an anonymous block box.
if (child_box.is_absolutely_positioned())
return IterationDecision::Continue;
// FIXME: This doesn't look right.
if ((root.computed_values().overflow_y() == CSS::Overflow::Visible) && child_box.is_floating())
return IterationDecision::Continue;
auto const& child_box_state = m_state.get(child_box);
CSSPixels child_box_top = child_box_state.offset.y() - child_box_state.margin_box_top();
CSSPixels child_box_bottom = child_box_state.offset.y() + child_box_state.content_height() + child_box_state.margin_box_bottom();
if (!top.has_value() || child_box_top < top.value())
top = child_box_top;
if (!bottom.has_value() || child_box_bottom > bottom.value())
bottom = child_box_bottom;
return IterationDecision::Continue;
});
}
// In addition, if the element has any floating descendants
// whose bottom margin edge is below the element's bottom content edge,
// then the height is increased to include those edges.
for (auto floating_box : m_state.get(root).floating_descendants()) {
// NOTE: Floating box coordinates are relative to their own containing block,
// which may or may not be the BFC root.
auto margin_box = margin_box_rect_in_ancestor_coordinate_space(*floating_box, root, m_state);
CSSPixels floating_box_bottom_margin_edge = margin_box.bottom();
if (!bottom.has_value() || floating_box_bottom_margin_edge > bottom.value())
bottom = floating_box_bottom_margin_edge;
}
return max(CSSPixels(0.0f), bottom.value_or(0) - top.value_or(0));
}
// 10.3.2 Inline, replaced elements, https://www.w3.org/TR/CSS22/visudet.html#inline-replaced-width
CSSPixels FormattingContext::tentative_width_for_replaced_element(LayoutState const& state, ReplacedBox const& box, CSS::Size const& computed_width, AvailableSpace const& available_space)
{
// Treat percentages of indefinite containing block widths as 0 (the initial width).
if (computed_width.is_percentage() && !state.get(*box.containing_block()).has_definite_width())
return 0;
auto height_of_containing_block = CSS::Length::make_px(containing_block_height_for(box, state));
auto computed_height = should_treat_height_as_auto(box, available_space) ? CSS::Size::make_auto() : box.computed_values().height();
CSSPixels used_width = computed_width.to_px(box, available_space.width.to_px());
// If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic width,
// then that intrinsic width is the used value of 'width'.
if (computed_height.is_auto() && computed_width.is_auto() && box.has_intrinsic_width())
return box.intrinsic_width().value();
// If 'height' and 'width' both have computed values of 'auto' and the element has no intrinsic width,
// but does have an intrinsic height and intrinsic ratio;
// or if 'width' has a computed value of 'auto',
// 'height' has some other computed value, and the element does have an intrinsic ratio; then the used value of 'width' is:
//
// (used height) * (intrinsic ratio)
if ((computed_height.is_auto() && computed_width.is_auto() && !box.has_intrinsic_width() && box.has_intrinsic_height() && box.has_intrinsic_aspect_ratio())
|| (computed_width.is_auto() && !computed_height.is_auto() && box.has_intrinsic_aspect_ratio())) {
return compute_height_for_replaced_element(state, box, available_space) * static_cast<double>(box.intrinsic_aspect_ratio().value());
}
// If 'height' and 'width' both have computed values of 'auto' and the element has an intrinsic ratio but no intrinsic height or width,
// then the used value of 'width' is undefined in CSS 2.2. However, it is suggested that, if the containing block's width does not itself
// depend on the replaced element's width, then the used value of 'width' is calculated from the constraint equation used for block-level,
// non-replaced elements in normal flow.
if (computed_height.is_auto() && computed_width.is_auto() && !box.has_intrinsic_width() && !box.has_intrinsic_height() && box.has_intrinsic_aspect_ratio()) {
return calculate_stretch_fit_width(box, available_space.width, state);
}
// Otherwise, if 'width' has a computed value of 'auto', and the element has an intrinsic width, then that intrinsic width is the used value of 'width'.
if (computed_width.is_auto() && box.has_intrinsic_width())
return box.intrinsic_width().value();
// Otherwise, if 'width' has a computed value of 'auto', but none of the conditions above are met, then the used value of 'width' becomes 300px.
// If 300px is too wide to fit the device, UAs should use the width of the largest rectangle that has a 2:1 ratio and fits the device instead.
if (computed_width.is_auto())
return 300;
return used_width;
}
void FormattingContext::compute_width_for_absolutely_positioned_element(Box const& box, AvailableSpace const& available_space)
{
if (is<ReplacedBox>(box))
compute_width_for_absolutely_positioned_replaced_element(verify_cast<ReplacedBox>(box), available_space);
else
compute_width_for_absolutely_positioned_non_replaced_element(box, available_space);
}
void FormattingContext::compute_height_for_absolutely_positioned_element(Box const& box, AvailableSpace const& available_space, BeforeOrAfterInsideLayout before_or_after_inside_layout)
{
if (is<ReplacedBox>(box))
compute_height_for_absolutely_positioned_replaced_element(static_cast<ReplacedBox const&>(box), available_space, before_or_after_inside_layout);
else
compute_height_for_absolutely_positioned_non_replaced_element(box, available_space, before_or_after_inside_layout);
}
CSSPixels FormattingContext::compute_width_for_replaced_element(LayoutState const& state, ReplacedBox const& box, AvailableSpace const& available_space)
{
// 10.3.4 Block-level, replaced elements in normal flow...
// 10.3.2 Inline, replaced elements
auto zero_value = CSS::Length::make_px(0);
auto width_of_containing_block = available_space.width.to_px();
auto width_of_containing_block_as_length = CSS::Length::make_px(width_of_containing_block);
auto computed_width = should_treat_width_as_auto(box, available_space) ? CSS::Size::make_auto() : box.computed_values().width();
auto computed_height = should_treat_height_as_auto(box, available_space) ? CSS::Size::make_auto() : box.computed_values().height();
// 1. The tentative used width is calculated (without 'min-width' and 'max-width')
auto used_width = tentative_width_for_replaced_element(state, box, computed_width, available_space);
if (computed_width.is_auto() && computed_height.is_auto() && box.has_intrinsic_aspect_ratio()) {
CSSPixels w = used_width;
CSSPixels h = tentative_height_for_replaced_element(state, box, computed_height, available_space);
used_width = solve_replaced_size_constraint(state, w, h, box).width();
return used_width;
}
// 2. The tentative used width is greater than 'max-width', the rules above are applied again,
// but this time using the computed value of 'max-width' as the computed value for 'width'.
auto computed_max_width = box.computed_values().max_width();
if (!computed_max_width.is_none()) {
if (used_width > computed_max_width.to_px(box, width_of_containing_block)) {
used_width = tentative_width_for_replaced_element(state, box, computed_max_width, available_space);
}
}
// 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
// but this time using the value of 'min-width' as the computed value for 'width'.
auto computed_min_width = box.computed_values().min_width();
if (!computed_min_width.is_auto()) {
if (used_width < computed_min_width.to_px(box, width_of_containing_block)) {
used_width = tentative_width_for_replaced_element(state, box, computed_min_width, available_space);
}
}
return used_width;
}
// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow, 'inline-block' replaced elements in normal flow and floating replaced elements
// https://www.w3.org/TR/CSS22/visudet.html#inline-replaced-height
CSSPixels FormattingContext::tentative_height_for_replaced_element(LayoutState const& state, ReplacedBox const& box, CSS::Size const& computed_height, AvailableSpace const& available_space)
{
// If 'height' and 'width' both have computed values of 'auto' and the element also has
// an intrinsic height, then that intrinsic height is the used value of 'height'.
if (should_treat_width_as_auto(box, available_space) && should_treat_height_as_auto(box, available_space) && box.has_intrinsic_height())
return box.intrinsic_height().value();
// Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic ratio then the used value of 'height' is:
//
// (used width) / (intrinsic ratio)
if (computed_height.is_auto() && box.has_intrinsic_aspect_ratio())
return state.get(box).content_width() / static_cast<double>(box.intrinsic_aspect_ratio().value());
// Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic height, then that intrinsic height is the used value of 'height'.
if (computed_height.is_auto() && box.has_intrinsic_height())
return box.intrinsic_height().value();
// Otherwise, if 'height' has a computed value of 'auto', but none of the conditions above are met,
// then the used value of 'height' must be set to the height of the largest rectangle that has a 2:1 ratio, has a height not greater than 150px,
// and has a width not greater than the device width.
if (computed_height.is_auto())
return 150;
// FIXME: Handle cases when available_space is not definite.
return computed_height.to_px(box, available_space.height.to_px_or_zero());
}
CSSPixels FormattingContext::compute_height_for_replaced_element(LayoutState const& state, ReplacedBox const& box, AvailableSpace const& available_space)
{
// 10.6.2 Inline replaced elements
// 10.6.4 Block-level replaced elements in normal flow
// 10.6.6 Floating replaced elements
// 10.6.10 'inline-block' replaced elements in normal flow
auto height_of_containing_block = state.get(*box.non_anyonymous_containing_block()).content_height();
auto computed_width = should_treat_width_as_auto(box, available_space) ? CSS::Size::make_auto() : box.computed_values().width();
auto computed_height = should_treat_height_as_auto(box, available_space) ? CSS::Size::make_auto() : box.computed_values().height();
// 1. The tentative used height is calculated (without 'min-height' and 'max-height')
CSSPixels used_height = tentative_height_for_replaced_element(state, box, computed_height, available_space);
// However, for replaced elements with both 'width' and 'height' computed as 'auto',
// use the algorithm under 'Minimum and maximum widths'
// https://www.w3.org/TR/CSS22/visudet.html#min-max-widths
// to find the used width and height.
if (computed_width.is_auto() && computed_height.is_auto() && box.has_intrinsic_aspect_ratio()) {
CSSPixels w = tentative_width_for_replaced_element(state, box, computed_width, available_space);
CSSPixels h = used_height;
used_height = solve_replaced_size_constraint(state, w, h, box).height();
return used_height;
}
// 2. If this tentative height is greater than 'max-height', the rules above are applied again,
// but this time using the value of 'max-height' as the computed value for 'height'.
auto computed_max_height = box.computed_values().max_height();
if (!computed_max_height.is_none()) {
if (used_height > computed_max_height.to_px(box, height_of_containing_block)) {
used_height = tentative_height_for_replaced_element(state, box, computed_max_height, available_space);
}
}
// 3. If the resulting height is smaller than 'min-height', the rules above are applied again,
// but this time using the value of 'min-height' as the computed value for 'height'.
auto computed_min_height = box.computed_values().min_height();
if (!computed_min_height.is_auto()) {
if (used_height < computed_min_height.to_px(box, height_of_containing_block)) {
used_height = tentative_height_for_replaced_element(state, box, computed_min_height, available_space);
}
}
return used_height;
}
void FormattingContext::compute_width_for_absolutely_positioned_non_replaced_element(Box const& box, AvailableSpace const& available_space)
{
auto width_of_containing_block = available_space.width.to_px();
auto width_of_containing_block_as_length = CSS::Length::make_px(width_of_containing_block);
auto& computed_values = box.computed_values();
auto zero_value = CSS::Length::make_px(0);
auto margin_left = CSS::Length::make_auto();
auto margin_right = CSS::Length::make_auto();
auto const border_left = computed_values.border_left().width;
auto const border_right = computed_values.border_right().width;
auto const padding_left = computed_values.padding().left().to_px(box, width_of_containing_block);
auto const padding_right = computed_values.padding().right().to_px(box, width_of_containing_block);
auto computed_left = computed_values.inset().left();
auto computed_right = computed_values.inset().right();
auto try_compute_width = [&](auto const& a_width) {
margin_left = computed_values.margin().left().resolved(box, width_of_containing_block_as_length);
margin_right = computed_values.margin().right().resolved(box, width_of_containing_block_as_length);
auto left = computed_values.inset().left().to_px(box, width_of_containing_block);
auto right = computed_values.inset().right().to_px(box, width_of_containing_block);
auto width = a_width;
auto solve_for_left = [&] {
return width_of_containing_block - margin_left.to_px(box) - border_left - padding_left - width.to_px(box) - padding_right - border_right - margin_right.to_px(box) - right;
};
auto solve_for_width = [&] {
return CSS::Length::make_px(max(CSSPixels(0), width_of_containing_block - left - margin_left.to_px(box) - border_left - padding_left - padding_right - border_right - margin_right.to_px(box) - right));
};
auto solve_for_right = [&] {
return width_of_containing_block - left - margin_left.to_px(box) - border_left - padding_left - width.to_px(box) - padding_right - border_right - margin_right.to_px(box);
};
// If all three of 'left', 'width', and 'right' are 'auto':
if (computed_left.is_auto() && width.is_auto() && computed_right.is_auto()) {
// First set any 'auto' values for 'margin-left' and 'margin-right' to 0.
if (margin_left.is_auto())
margin_left = CSS::Length::make_px(0);
if (margin_right.is_auto())
margin_right = CSS::Length::make_px(0);
// Then, if the 'direction' property of the element establishing the static-position containing block
// is 'ltr' set 'left' to the static position and apply rule number three below;
// otherwise, set 'right' to the static position and apply rule number one below.
// FIXME: This is very hackish.
left = 0;
goto Rule3;
}
if (!computed_left.is_auto() && !width.is_auto() && !computed_right.is_auto()) {
// FIXME: This should be solved in a more complicated way.
return width;
}
if (margin_left.is_auto())
margin_left = CSS::Length::make_px(0);
if (margin_right.is_auto())
margin_right = CSS::Length::make_px(0);
// 1. 'left' and 'width' are 'auto' and 'right' is not 'auto',
// then the width is shrink-to-fit. Then solve for 'left'
if (computed_left.is_auto() && width.is_auto() && !computed_right.is_auto()) {
auto result = calculate_shrink_to_fit_widths(box);
auto available_width = solve_for_width();
width = CSS::Length::make_px(min(max(result.preferred_minimum_width, available_width.to_px(box)), result.preferred_width));
left = solve_for_left();
}
// 2. 'left' and 'right' are 'auto' and 'width' is not 'auto',
// then if the 'direction' property of the element establishing
// the static-position containing block is 'ltr' set 'left'
// to the static position, otherwise set 'right' to the static position.
// Then solve for 'left' (if 'direction is 'rtl') or 'right' (if 'direction' is 'ltr').
else if (computed_left.is_auto() && computed_right.is_auto() && !width.is_auto()) {
// FIXME: Check direction
// FIXME: Use the static-position containing block
left = 0;
right = solve_for_right();
}
// 3. 'width' and 'right' are 'auto' and 'left' is not 'auto',
// then the width is shrink-to-fit. Then solve for 'right'
else if (width.is_auto() && computed_right.is_auto() && !computed_left.is_auto()) {
Rule3:
auto result = calculate_shrink_to_fit_widths(box);
auto available_width = solve_for_width();
width = CSS::Length::make_px(min(max(result.preferred_minimum_width, available_width.to_px(box)), result.preferred_width));
right = solve_for_right();
}
// 4. 'left' is 'auto', 'width' and 'right' are not 'auto', then solve for 'left'
else if (computed_left.is_auto() && !width.is_auto() && !computed_right.is_auto()) {
left = solve_for_left();
}
// 5. 'width' is 'auto', 'left' and 'right' are not 'auto', then solve for 'width'
else if (width.is_auto() && !computed_left.is_auto() && !computed_right.is_auto()) {
width = solve_for_width();
}
// 6. 'right' is 'auto', 'left' and 'width' are not 'auto', then solve for 'right'
else if (computed_right.is_auto() && !computed_left.is_auto() && !width.is_auto()) {
right = solve_for_right();
}
return width;
};
// 1. The tentative used width is calculated (without 'min-width' and 'max-width')
auto used_width = try_compute_width(calculate_inner_width(box, available_space.width, computed_values.width()));
// 2. The tentative used width is greater than 'max-width', the rules above are applied again,
// but this time using the computed value of 'max-width' as the computed value for 'width'.
if (!computed_values.max_width().is_none()) {
auto max_width = calculate_inner_width(box, available_space.width, computed_values.max_width());
if (used_width.to_px(box) > max_width.to_px(box)) {
used_width = try_compute_width(max_width);
}
}
// 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
// but this time using the value of 'min-width' as the computed value for 'width'.
if (!computed_values.min_width().is_auto()) {
auto min_width = calculate_inner_width(box, available_space.width, computed_values.min_width());
if (used_width.to_px(box) < min_width.to_px(box)) {
used_width = try_compute_width(min_width);
}
}
auto& box_state = m_state.get_mutable(box);
box_state.set_content_width(used_width.to_px(box));
box_state.margin_left = margin_left.to_px(box);
box_state.margin_right = margin_right.to_px(box);
box_state.border_left = border_left;
box_state.border_right = border_right;
box_state.padding_left = padding_left;
box_state.padding_right = padding_right;
}
void FormattingContext::compute_width_for_absolutely_positioned_replaced_element(ReplacedBox const& box, AvailableSpace const& available_space)
{
// 10.3.8 Absolutely positioned, replaced elements
// The used value of 'width' is determined as for inline replaced elements.
// FIXME: This const_cast is gross.
const_cast<ReplacedBox&>(box).prepare_for_replaced_layout();
m_state.get_mutable(box).set_content_width(compute_width_for_replaced_element(m_state, box, available_space));
}
// https://drafts.csswg.org/css-position-3/#abs-non-replaced-height
void FormattingContext::compute_height_for_absolutely_positioned_non_replaced_element(Box const& box, AvailableSpace const& available_space, BeforeOrAfterInsideLayout before_or_after_inside_layout)
{
// 5.3. The Height Of Absolutely Positioned, Non-Replaced Elements
// For absolutely positioned elements, the used values of the vertical dimensions must satisfy this constraint:
// top + margin-top + border-top-width + padding-top + height + padding-bottom + border-bottom-width + margin-bottom + bottom = height of containing block
// NOTE: This function is called twice: both before and after inside layout.
// In the before pass, if it turns out we need the automatic height of the box, we abort these steps.
// This allows the box to retain an indefinite height from the perspective of inside layout.
auto margin_top = box.computed_values().margin().top();
auto margin_bottom = box.computed_values().margin().bottom();
auto top = box.computed_values().inset().top();
auto bottom = box.computed_values().inset().bottom();
auto height = box.computed_values().height();
auto width_of_containing_block = containing_block_width_for(box);
auto width_of_containing_block_as_length = CSS::Length::make_px(width_of_containing_block);
auto height_of_containing_block = available_space.height.to_px();
auto height_of_containing_block_as_length = CSS::Length::make_px(height_of_containing_block);
enum class ClampToZero {
No,
Yes,
};
auto solve_for = [&](CSS::Length length, ClampToZero clamp_to_zero = ClampToZero::No) {
auto unclamped_value = height_of_containing_block
- top.to_px(box, height_of_containing_block)
- margin_top.to_px(box, width_of_containing_block)
- box.computed_values().border_top().width
- box.computed_values().padding().top().to_px(box, width_of_containing_block)
- height.to_px(box, height_of_containing_block)
- box.computed_values().padding().bottom().to_px(box, width_of_containing_block)
- box.computed_values().border_bottom().width
- margin_bottom.to_px(box, width_of_containing_block)
- bottom.to_px(box, height_of_containing_block)
+ length.to_px(box);
if (clamp_to_zero == ClampToZero::Yes)
return CSS::Length::make_px(max(CSSPixels(0), unclamped_value));
return CSS::Length::make_px(unclamped_value);
};
auto solve_for_top = [&] {
top = solve_for(top.resolved(box, height_of_containing_block_as_length));
};
auto solve_for_bottom = [&] {
bottom = solve_for(bottom.resolved(box, height_of_containing_block_as_length));
};
auto solve_for_height = [&] {
height = CSS::Size::make_length(solve_for(height.resolved(box, height_of_containing_block_as_length), ClampToZero::Yes));
};
auto solve_for_margin_top = [&] {
margin_top = solve_for(margin_top.resolved(box, width_of_containing_block_as_length));
};
auto solve_for_margin_bottom = [&] {
margin_bottom = solve_for(margin_bottom.resolved(box, width_of_containing_block_as_length));
};
auto solve_for_margin_top_and_margin_bottom = [&] {
auto remainder = solve_for(CSS::Length::make_px(margin_top.to_px(box, width_of_containing_block) + margin_bottom.to_px(box, width_of_containing_block))).to_px(box);
margin_top = CSS::Length::make_px(remainder / 2);
margin_bottom = CSS::Length::make_px(remainder / 2);
};
// If all three of top, height, and bottom are auto:
if (top.is_auto() && height.is_auto() && bottom.is_auto()) {
// (If we haven't done inside layout yet, we can't compute the auto height.)
if (before_or_after_inside_layout == BeforeOrAfterInsideLayout::Before)
return;
// First set any auto values for margin-top and margin-bottom to 0,
if (margin_top.is_auto())
margin_top = CSS::Length::make_px(0);
if (margin_bottom.is_auto())
margin_bottom = CSS::Length::make_px(0);
// then set top to the static position,
auto static_position = calculate_static_position(box);
top = CSS::Length::make_px(static_position.y());
// and finally apply rule number three below.
height = CSS::Size::make_px(compute_auto_height_for_block_formatting_context_root(box));
solve_for_bottom();
}
// If none of the three are auto:
else if (!top.is_auto() && !height.is_auto() && !bottom.is_auto()) {
// If both margin-top and margin-bottom are auto,
if (margin_top.is_auto() && margin_bottom.is_auto()) {
// solve the equation under the extra constraint that the two margins get equal values.
solve_for_margin_top_and_margin_bottom();
}
// If one of margin-top or margin-bottom is auto,
else if (margin_top.is_auto() || margin_bottom.is_auto()) {
// solve the equation for that value.
if (margin_top.is_auto())
solve_for_margin_top();
else
solve_for_margin_bottom();
}
// If the values are over-constrained,
else {
// ignore the value for bottom and solve for that value.
solve_for_bottom();
}
}
// Otherwise,
else {
// set auto values for margin-top and margin-bottom to 0,
if (margin_top.is_auto())
margin_top = CSS::Length::make_px(0);
if (margin_bottom.is_auto())
margin_bottom = CSS::Length::make_px(0);
// and pick one of the following six rules that apply.
// 1. If top and height are auto and bottom is not auto,
if (top.is_auto() && height.is_auto() && !bottom.is_auto()) {
// (If we haven't done inside layout yet, we can't compute the auto height.)
if (before_or_after_inside_layout == BeforeOrAfterInsideLayout::Before)
return;
// then the height is based on the Auto heights for block formatting context roots,
height = CSS::Size::make_px(compute_auto_height_for_block_formatting_context_root(box));
// and solve for top.
solve_for_top();
}
// 2. If top and bottom are auto and height is not auto,
else if (top.is_auto() && bottom.is_auto() && !height.is_auto()) {
// then set top to the static position,
top = CSS::Length::make_px(calculate_static_position(box).y());
// then solve for bottom.
solve_for_bottom();
}
// 3. If height and bottom are auto and top is not auto,
else if (height.is_auto() && bottom.is_auto() && !top.is_auto()) {
// (If we haven't done inside layout yet, we can't compute the auto height.)
if (before_or_after_inside_layout == BeforeOrAfterInsideLayout::Before)
return;
// then the height is based on the Auto heights for block formatting context roots,
height = CSS::Size::make_px(compute_auto_height_for_block_formatting_context_root(box));
// and solve for bottom.
solve_for_bottom();
}
// 4. If top is auto, height and bottom are not auto,
else if (top.is_auto() && !height.is_auto() && !bottom.is_auto()) {
// then solve for top.
solve_for_top();
}
// 5. If height is auto, top and bottom are not auto,
else if (height.is_auto() && !top.is_auto() && !bottom.is_auto()) {
// then solve for height.
solve_for_height();
}
// 6. If bottom is auto, top and height are not auto,
else if (bottom.is_auto() && !top.is_auto() && !height.is_auto()) {
// then solve for bottom.
solve_for_bottom();
}
}
// Compute the height based on box type and CSS properties:
// https://www.w3.org/TR/css-sizing-3/#box-sizing
CSSPixels used_height = 0;
if (should_treat_height_as_auto(box, available_space)) {
used_height = height.to_px(box, height_of_containing_block);
} else {
used_height = calculate_inner_height(box, available_space.height, height).to_px(box);
}
auto const& computed_min_height = box.computed_values().min_height();
auto const& computed_max_height = box.computed_values().max_height();
if (!computed_max_height.is_none()) {
auto inner_max_height = calculate_inner_height(box, available_space.height, computed_max_height);
used_height = min(used_height, inner_max_height.to_px(box));
}
if (!computed_min_height.is_auto()) {
auto inner_min_height = calculate_inner_height(box, available_space.height, computed_min_height);
used_height = max(used_height, inner_min_height.to_px(box));
}
// NOTE: The following is not directly part of any spec, but this is where we resolve
// the final used values for vertical margin/border/padding.
auto& box_state = m_state.get_mutable(box);
box_state.margin_top = margin_top.to_px(box, width_of_containing_block);
box_state.margin_bottom = margin_bottom.to_px(box, width_of_containing_block);
box_state.border_top = box.computed_values().border_top().width;
box_state.border_bottom = box.computed_values().border_bottom().width;
box_state.padding_top = box.computed_values().padding().top().to_px(box, width_of_containing_block);
box_state.padding_bottom = box.computed_values().padding().bottom().to_px(box, width_of_containing_block);
// And here is where we assign the box's content height.
box_state.set_content_height(used_height);
}
// NOTE: This is different from content_box_rect_in_ancestor_coordinate_space() as this does *not* follow the containing block chain up, but rather the parent() chain.
static CSSPixelRect content_box_rect_in_static_position_ancestor_coordinate_space(Box const& box, Box const& ancestor_box, LayoutState const& state)
{
auto rect = content_box_rect(box, state);
if (&box == &ancestor_box)
return rect;
for (auto const* current = box.parent(); current; current = current->parent()) {
if (current == &ancestor_box)
return rect;
auto const& current_state = state.get(static_cast<Box const&>(*current));
rect.translate_by(current_state.offset);
}
// If we get here, ancestor_box was not an ancestor of `box`!
VERIFY_NOT_REACHED();
}
// https://www.w3.org/TR/css-position-3/#staticpos-rect
CSSPixelPoint FormattingContext::calculate_static_position(Box const& box) const
{
// NOTE: This is very ad-hoc.
// The purpose of this function is to calculate the approximate position that `box`
// would have had if it were position:static.
CSSPixels x = 0.0f;
CSSPixels y = 0.0f;
VERIFY(box.parent());
if (box.parent()->children_are_inline()) {
// We're an abspos box with inline siblings. This is gonna get messy!
if (auto* sibling = box.previous_sibling()) {
// Hard case: there's a previous sibling. This means there's already inline content
// preceding the hypothetical static position of `box` within its containing block.
// If we had been position:static, that inline content would have been wrapped in
// anonymous block box, so now we get to imagine what the world might have looked like
// in that scenario..
// Basically, we find its last associated line box fragment and place `box` under it.
// FIXME: I'm 100% sure this can be smarter, better and faster.
LineBoxFragment const* last_fragment = nullptr;
auto& cb_state = m_state.get(*sibling->containing_block());
for (auto& line_box : cb_state.line_boxes) {
for (auto& fragment : line_box.fragments()) {
if (&fragment.layout_node() == sibling)
last_fragment = &fragment;
}
}
if (last_fragment) {
y = (last_fragment->offset().y() + last_fragment->height()).value();
}
} else {
// Easy case: no previous sibling, we're at the top of the containing block.
}
} else {
x = m_state.get(box).margin_box_left();
// We're among block siblings, Y can be calculated easily.
y = m_state.get(box).margin_box_top();
}
auto offset_to_static_parent = content_box_rect_in_static_position_ancestor_coordinate_space(box, *box.containing_block(), m_state);
return offset_to_static_parent.location().translated(x, y);
}
void FormattingContext::layout_absolutely_positioned_element(Box const& box, AvailableSpace const& available_space)
{
auto& containing_block_state = m_state.get_mutable(*box.containing_block());
auto& box_state = m_state.get_mutable(box);
auto width_of_containing_block = available_space.width.to_px();
auto height_of_containing_block = available_space.height.to_px();
auto width_of_containing_block_as_length = CSS::Length::make_px(width_of_containing_block);
auto height_of_containing_block_as_length = CSS::Length::make_px(height_of_containing_block);
compute_width_for_absolutely_positioned_element(box, available_space);
// NOTE: We compute height before *and* after doing inside layout.
// This is done so that inside layout can resolve percentage heights.
// In some situations, e.g with non-auto top & bottom values, the height can be determined early.
compute_height_for_absolutely_positioned_element(box, available_space, BeforeOrAfterInsideLayout::Before);
auto independent_formatting_context = layout_inside(box, LayoutMode::Normal, box_state.available_inner_space_or_constraints_from(available_space));
compute_height_for_absolutely_positioned_element(box, available_space, BeforeOrAfterInsideLayout::After);
box_state.margin_left = box.computed_values().margin().left().to_px(box, width_of_containing_block);
box_state.margin_top = box.computed_values().margin().top().to_px(box, width_of_containing_block);
box_state.margin_right = box.computed_values().margin().right().to_px(box, width_of_containing_block);
box_state.margin_bottom = box.computed_values().margin().bottom().to_px(box, width_of_containing_block);
box_state.border_left = box.computed_values().border_left().width;
box_state.border_right = box.computed_values().border_right().width;
box_state.border_top = box.computed_values().border_top().width;
box_state.border_bottom = box.computed_values().border_bottom().width;
auto const& computed_left = box.computed_values().inset().left();
auto const& computed_right = box.computed_values().inset().right();
auto const& computed_top = box.computed_values().inset().top();
auto const& computed_bottom = box.computed_values().inset().bottom();
box_state.inset_left = computed_left.to_px(box, width_of_containing_block);
box_state.inset_top = computed_top.to_px(box, height_of_containing_block);
box_state.inset_right = computed_right.to_px(box, width_of_containing_block);
box_state.inset_bottom = computed_bottom.to_px(box, height_of_containing_block);
if (computed_left.is_auto() && box.computed_values().width().is_auto() && computed_right.is_auto()) {
if (box.computed_values().margin().left().is_auto())
box_state.margin_left = 0;
if (box.computed_values().margin().right().is_auto())
box_state.margin_right = 0;
}
auto static_position = calculate_static_position(box);
CSSPixelPoint used_offset;
if (!computed_left.is_auto()) {
CSSPixels x_offset = box_state.inset_left
+ box_state.border_box_left();
used_offset.set_x(x_offset + box_state.margin_left);
} else if (!computed_right.is_auto()) {
CSSPixels x_offset = CSSPixels(0)
- box_state.inset_right
- box_state.border_box_right();
used_offset.set_x(width_of_containing_block + x_offset - box_state.content_width() - box_state.margin_right);
} else {
// NOTE: static position is content box position so border_box and margin should not be added
used_offset.set_x(static_position.x());
}
if (!computed_top.is_auto()) {
CSSPixels y_offset = box_state.inset_top
+ box_state.border_box_top();
used_offset.set_y(y_offset + box_state.margin_top);
} else if (!computed_bottom.is_auto()) {
CSSPixels y_offset = CSSPixels(0)
- box_state.inset_bottom
- box_state.border_box_bottom();
used_offset.set_y(height_of_containing_block + y_offset - box_state.content_height() - box_state.margin_bottom);
} else {
// NOTE: static position is content box position so border_box and margin should not be added
used_offset.set_y(static_position.y());
}
// NOTE: Absolutely positioned boxes are relative to the *padding edge* of the containing block.
used_offset.translate_by(-containing_block_state.padding_left, -containing_block_state.padding_top);
box_state.set_content_offset(used_offset);
if (independent_formatting_context)
independent_formatting_context->parent_context_did_dimension_child_root_box();
}
void FormattingContext::compute_height_for_absolutely_positioned_replaced_element(ReplacedBox const& box, AvailableSpace const& available_space, BeforeOrAfterInsideLayout)
{
// 10.6.5 Absolutely positioned, replaced elements
// The used value of 'height' is determined as for inline replaced elements.
m_state.get_mutable(box).set_content_height(compute_height_for_replaced_element(m_state, box, available_space));
}
// https://www.w3.org/TR/css-position-3/#relpos-insets
void FormattingContext::compute_inset(Box const& box)
{
if (box.computed_values().position() != CSS::Position::Relative)
return;
auto resolve_two_opposing_insets = [&](CSS::LengthPercentage const& computed_first, CSS::LengthPercentage const& computed_second, CSSPixels& used_start, CSSPixels& used_end, CSSPixels reference_for_percentage) {
auto resolved_first = computed_first.to_px(box, reference_for_percentage);
auto resolved_second = computed_second.to_px(box, reference_for_percentage);
if (computed_first.is_auto() && computed_second.is_auto()) {
// If opposing inset properties in an axis both compute to auto (their initial values),
// their used values are zero (i.e., the boxes stay in their original position in that axis).
used_start = 0;
used_end = 0;
} else if (computed_first.is_auto() || computed_second.is_auto()) {
// If only one is auto, its used value becomes the negation of the other, and the box is shifted by the specified amount.
if (computed_first.is_auto()) {
used_end = resolved_second;
used_start = -used_end;
} else {
used_start = resolved_first;
used_end = -used_start;
}
} else {
// If neither is auto, the position is over-constrained; (with respect to the writing mode of its containing block)
// the computed end side value is ignored, and its used value becomes the negation of the start side.
used_start = resolved_first;
used_end = -used_start;
}
};
auto& box_state = m_state.get_mutable(box);
auto const& computed_values = box.computed_values();
// FIXME: Respect the containing block's writing-mode.
resolve_two_opposing_insets(computed_values.inset().left(), computed_values.inset().right(), box_state.inset_left, box_state.inset_right, containing_block_width_for(box));
resolve_two_opposing_insets(computed_values.inset().top(), computed_values.inset().bottom(), box_state.inset_top, box_state.inset_bottom, containing_block_height_for(box));
}
// https://drafts.csswg.org/css-sizing-3/#fit-content-size
CSSPixels FormattingContext::calculate_fit_content_width(Layout::Box const& box, AvailableSpace const& available_space) const
{
// If the available space in a given axis is definite,
// equal to clamp(min-content size, stretch-fit size, max-content size)
// (i.e. max(min-content size, min(max-content size, stretch-fit size))).
if (available_space.width.is_definite()) {
return max(calculate_min_content_width(box),
min(calculate_stretch_fit_width(box, available_space.width),
calculate_max_content_width(box)));
}
// When sizing under a min-content constraint, equal to the min-content size.
if (available_space.width.is_min_content())
return calculate_min_content_width(box);
// Otherwise, equal to the max-content size in that axis.
return calculate_max_content_width(box);
}
// https://drafts.csswg.org/css-sizing-3/#fit-content-size
CSSPixels FormattingContext::calculate_fit_content_height(Layout::Box const& box, AvailableSpace const& available_space) const
{
// If the available space in a given axis is definite,
// equal to clamp(min-content size, stretch-fit size, max-content size)
// (i.e. max(min-content size, min(max-content size, stretch-fit size))).
if (available_space.height.is_definite()) {
return max(calculate_min_content_height(box, available_space.width),
min(calculate_stretch_fit_height(box, available_space.height),
calculate_max_content_height(box, available_space.width)));
}
// When sizing under a min-content constraint, equal to the min-content size.
if (available_space.height.is_min_content())
return calculate_min_content_height(box, available_space.width);
// Otherwise, equal to the max-content size in that axis.
return calculate_max_content_height(box, available_space.width);
}
CSSPixels FormattingContext::calculate_min_content_width(Layout::Box const& box) const
{
if (box.has_intrinsic_width())
return *box.intrinsic_width();
auto& root_state = m_state.m_root;
auto& cache = *root_state.intrinsic_sizes.ensure(&box, [] { return adopt_own(*new LayoutState::IntrinsicSizes); });
if (cache.min_content_width.has_value())
return *cache.min_content_width;
LayoutState throwaway_state(&m_state);
auto& box_state = throwaway_state.get_mutable(box);
box_state.width_constraint = SizeConstraint::MinContent;
box_state.set_indefinite_content_width();
box_state.set_indefinite_content_height();
auto context = const_cast<FormattingContext*>(this)->create_independent_formatting_context_if_needed(throwaway_state, box);
if (!context) {
context = make<BlockFormattingContext>(throwaway_state, verify_cast<BlockContainer>(box), nullptr);
}
auto available_width = AvailableSize::make_min_content();
auto available_height = AvailableSize::make_indefinite();
context->run(box, LayoutMode::IntrinsicSizing, AvailableSpace(available_width, available_height));
cache.min_content_width = context->automatic_content_width();
if (!isfinite(cache.min_content_width->value())) {
// HACK: If layout calculates a non-finite result, something went wrong. Force it to zero and log a little whine.
dbgln("FIXME: Calculated non-finite min-content width for {}", box.debug_description());
cache.min_content_width = 0;
}
return *cache.min_content_width;
}
CSSPixels FormattingContext::calculate_max_content_width(Layout::Box const& box) const
{
if (box.has_intrinsic_width())
return *box.intrinsic_width();
auto& root_state = m_state.m_root;
auto& cache = *root_state.intrinsic_sizes.ensure(&box, [] { return adopt_own(*new LayoutState::IntrinsicSizes); });
if (cache.max_content_width.has_value())
return *cache.max_content_width;
LayoutState throwaway_state(&m_state);
auto& box_state = throwaway_state.get_mutable(box);
box_state.width_constraint = SizeConstraint::MaxContent;
box_state.set_indefinite_content_width();
box_state.set_indefinite_content_height();
auto context = const_cast<FormattingContext*>(this)->create_independent_formatting_context_if_needed(throwaway_state, box);
if (!context) {
context = make<BlockFormattingContext>(throwaway_state, verify_cast<BlockContainer>(box), nullptr);
}
auto available_width = AvailableSize::make_max_content();
auto available_height = AvailableSize::make_indefinite();
context->run(box, LayoutMode::IntrinsicSizing, AvailableSpace(available_width, available_height));
cache.max_content_width = context->automatic_content_width();
if (!isfinite(cache.max_content_width->value())) {
// HACK: If layout calculates a non-finite result, something went wrong. Force it to zero and log a little whine.
dbgln("FIXME: Calculated non-finite max-content width for {}", box.debug_description());
cache.max_content_width = 0;
}
return *cache.max_content_width;
}
// https://www.w3.org/TR/css-sizing-3/#min-content-block-size
CSSPixels FormattingContext::calculate_min_content_height(Layout::Box const& box, AvailableSize const& available_width) const
{
// For block containers, tables, and inline boxes, this is equivalent to the max-content block size.
if (box.is_block_container() || box.display().is_table_inside())
return calculate_max_content_height(box, available_width);
if (box.has_intrinsic_height())
return *box.intrinsic_height();
bool is_cacheable = available_width.is_definite() || available_width.is_intrinsic_sizing_constraint();
auto get_cache_slot = [&]() -> Optional<CSSPixels>* {
if (!is_cacheable)
return {};
auto& root_state = m_state.m_root;
auto& cache = *root_state.intrinsic_sizes.ensure(&box, [] { return adopt_own(*new LayoutState::IntrinsicSizes); });
if (available_width.is_definite())
return &cache.min_content_height_with_definite_available_width.ensure(available_width.to_px());
if (available_width.is_min_content())
return &cache.min_content_height_with_min_content_available_width;
if (available_width.is_max_content())
return &cache.min_content_height_with_max_content_available_width;
return {};
};
if (auto* cache_slot = get_cache_slot(); cache_slot && cache_slot->has_value())
return cache_slot->value();
LayoutState throwaway_state(&m_state);
auto& box_state = throwaway_state.get_mutable(box);
box_state.height_constraint = SizeConstraint::MinContent;
box_state.set_indefinite_content_height();
if (available_width.is_definite())
box_state.set_content_width(available_width.to_px());
auto context = const_cast<FormattingContext*>(this)->create_independent_formatting_context_if_needed(throwaway_state, box);
if (!context) {
context = make<BlockFormattingContext>(throwaway_state, verify_cast<BlockContainer>(box), nullptr);
}
context->run(box, LayoutMode::IntrinsicSizing, AvailableSpace(available_width, AvailableSize::make_min_content()));
auto min_content_height = context->automatic_content_height();
if (!isfinite(min_content_height.value())) {
// HACK: If layout calculates a non-finite result, something went wrong. Force it to zero and log a little whine.
dbgln("FIXME: Calculated non-finite min-content height for {}", box.debug_description());
min_content_height = 0;
}
if (auto* cache_slot = get_cache_slot()) {
*cache_slot = min_content_height;
}
return min_content_height;
}
CSSPixels FormattingContext::calculate_max_content_height(Layout::Box const& box, AvailableSize const& available_width) const
{
if (box.has_intrinsic_aspect_ratio() && available_width.is_definite())
return available_width.to_px() / static_cast<double>(*box.intrinsic_aspect_ratio());
if (box.has_intrinsic_height())
return *box.intrinsic_height();
bool is_cacheable = available_width.is_definite() || available_width.is_intrinsic_sizing_constraint();
auto get_cache_slot = [&]() -> Optional<CSSPixels>* {
if (!is_cacheable)
return {};
auto& root_state = m_state.m_root;
auto& cache = *root_state.intrinsic_sizes.ensure(&box, [] { return adopt_own(*new LayoutState::IntrinsicSizes); });
if (available_width.is_definite())
return &cache.max_content_height_with_definite_available_width.ensure(available_width.to_px());
if (available_width.is_min_content())
return &cache.max_content_height_with_min_content_available_width;
if (available_width.is_max_content())
return &cache.max_content_height_with_max_content_available_width;
return {};
};
if (auto* cache_slot = get_cache_slot(); cache_slot && cache_slot->has_value())
return cache_slot->value();
LayoutState throwaway_state(&m_state);
auto& box_state = throwaway_state.get_mutable(box);
box_state.height_constraint = SizeConstraint::MaxContent;
box_state.set_indefinite_content_height();
if (available_width.is_definite())
box_state.set_content_width(available_width.to_px());
auto context = const_cast<FormattingContext*>(this)->create_independent_formatting_context_if_needed(throwaway_state, box);
if (!context) {
context = make<BlockFormattingContext>(throwaway_state, verify_cast<BlockContainer>(box), nullptr);
}
context->run(box, LayoutMode::IntrinsicSizing, AvailableSpace(available_width, AvailableSize::make_max_content()));
auto max_content_height = context->automatic_content_height();
if (!isfinite(max_content_height.value())) {
// HACK: If layout calculates a non-finite result, something went wrong. Force it to zero and log a little whine.
dbgln("FIXME: Calculated non-finite max-content height for {}", box.debug_description());
max_content_height = 0;
}
if (auto* cache_slot = get_cache_slot()) {
*cache_slot = max_content_height;
}
return max_content_height;
}
CSS::Length FormattingContext::calculate_inner_width(Layout::Box const& box, AvailableSize const& available_width, CSS::Size const& width) const
{
auto width_of_containing_block = available_width.to_px();
auto width_of_containing_block_as_length_for_resolve = CSS::Length::make_px(width_of_containing_block);
if (width.is_auto()) {
return width.resolved(box, width_of_containing_block_as_length_for_resolve);
}
if (width.is_fit_content()) {
return CSS::Length::make_px(calculate_fit_content_width(box, AvailableSpace { available_width, AvailableSize::make_indefinite() }));
}
auto& computed_values = box.computed_values();
if (computed_values.box_sizing() == CSS::BoxSizing::BorderBox) {
auto const padding_left = computed_values.padding().left().resolved(box, width_of_containing_block_as_length_for_resolve);
auto const padding_right = computed_values.padding().right().resolved(box, width_of_containing_block_as_length_for_resolve);
auto inner_width = width.to_px(box, width_of_containing_block)
- computed_values.border_left().width
- padding_left.to_px(box)
- computed_values.border_right().width
- padding_right.to_px(box);
return CSS::Length::make_px(max(inner_width, 0));
}
return width.resolved(box, width_of_containing_block_as_length_for_resolve);
}
CSS::Length FormattingContext::calculate_inner_height(Layout::Box const& box, AvailableSize const&, CSS::Size const& height) const
{
auto height_of_containing_block = m_state.get(*box.non_anyonymous_containing_block()).content_height();
auto height_of_containing_block_as_length_for_resolve = CSS::Length::make_px(height_of_containing_block);
if (height.is_auto()) {
return height.resolved(box, height_of_containing_block_as_length_for_resolve);
}
auto& computed_values = box.computed_values();
if (computed_values.box_sizing() == CSS::BoxSizing::BorderBox) {
auto width_of_containing_block = CSS::Length::make_px(containing_block_width_for(box));
auto const padding_top = computed_values.padding().top().resolved(box, width_of_containing_block);
auto const padding_bottom = computed_values.padding().bottom().resolved(box, width_of_containing_block);
auto inner_height = height.to_px(box, height_of_containing_block)
- computed_values.border_top().width
- padding_top.to_px(box)
- computed_values.border_bottom().width
- padding_bottom.to_px(box);
return CSS::Length::make_px(max(inner_height, 0));
}
return height.resolved(box, height_of_containing_block_as_length_for_resolve);
}
CSSPixels FormattingContext::containing_block_width_for(Box const& box, LayoutState const& state)
{
auto& containing_block_state = state.get(*box.containing_block());
auto& box_state = state.get(box);
switch (box_state.width_constraint) {
case SizeConstraint::MinContent:
return 0;
case SizeConstraint::MaxContent:
return INFINITY;
case SizeConstraint::None:
return containing_block_state.content_width();
}
VERIFY_NOT_REACHED();
}
CSSPixels FormattingContext::containing_block_height_for(Box const& box, LayoutState const& state)
{
auto& containing_block_state = state.get(*box.containing_block());
auto& box_state = state.get(box);
switch (box_state.height_constraint) {
case SizeConstraint::MinContent:
return 0;
case SizeConstraint::MaxContent:
return INFINITY;
case SizeConstraint::None:
return containing_block_state.content_height();
}
VERIFY_NOT_REACHED();
}
// https://drafts.csswg.org/css-sizing-3/#stretch-fit-size
CSSPixels FormattingContext::calculate_stretch_fit_width(Box const& box, AvailableSize const& available_width, LayoutState const& state)
{
// The size a box would take if its outer size filled the available space in the given axis;
// in other words, the stretch fit into the available space, if that is definite.
// Undefined if the available space is indefinite.
auto const& box_state = state.get(box);
return available_width.to_px()
- box_state.margin_left
- box_state.margin_right
- box_state.padding_left
- box_state.padding_right
- box_state.border_left
- box_state.border_right;
}
CSSPixels FormattingContext::calculate_stretch_fit_width(Box const& box, AvailableSize const& available_width) const
{
return calculate_stretch_fit_width(box, available_width, m_state);
}
// https://drafts.csswg.org/css-sizing-3/#stretch-fit-size
CSSPixels FormattingContext::calculate_stretch_fit_height(Box const& box, AvailableSize const& available_height, LayoutState const& state)
{
// The size a box would take if its outer size filled the available space in the given axis;
// in other words, the stretch fit into the available space, if that is definite.
// Undefined if the available space is indefinite.
auto const& box_state = state.get(box);
return available_height.to_px()
- box_state.margin_top
- box_state.margin_bottom
- box_state.padding_top
- box_state.padding_bottom
- box_state.border_top
- box_state.border_bottom;
}
CSSPixels FormattingContext::calculate_stretch_fit_height(Box const& box, AvailableSize const& available_height) const
{
return calculate_stretch_fit_height(box, available_height, m_state);
}
bool FormattingContext::should_treat_width_as_auto(Box const& box, AvailableSpace const& available_space)
{
return box.computed_values().width().is_auto()
|| (box.computed_values().width().contains_percentage() && !available_space.width.is_definite());
}
bool FormattingContext::should_treat_height_as_auto(Box const& box, AvailableSpace const& available_space)
{
return box.computed_values().height().is_auto()
|| (box.computed_values().height().contains_percentage() && !available_space.height.is_definite());
}
bool FormattingContext::can_skip_is_anonymous_text_run(Box& box)
{
if (box.is_anonymous() && !box.is_generated() && !box.first_child_of_type<BlockContainer>()) {
bool contains_only_white_space = true;
box.for_each_in_subtree([&](auto const& node) {
if (!is<TextNode>(node) || !static_cast<TextNode const&>(node).dom_node().data().is_whitespace()) {
contains_only_white_space = false;
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
if (contains_only_white_space)
return true;
}
return false;
}
}
|
