-
-
Notifications
You must be signed in to change notification settings - Fork 3k
/
block.rs
3715 lines (3420 loc) · 153 KB
/
block.rs
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
/* 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 https://mozilla.org/MPL/2.0/. */
//! Layout for CSS block-level elements.
//!
//! As a terminology note, the term *absolute positioning* here refers to elements with position
//! `absolute` or `fixed`. The term *positioned element* refers to elements with position
//! `relative`, `absolute`, and `fixed`. The term *containing block* (occasionally abbreviated as
//! *CB*) is the containing block for the current flow, which differs from the static containing
//! block if the flow is absolutely-positioned.
//!
//! "CSS 2.1" or "CSS 2.2" refers to the editor's draft of the W3C "Cascading Style Sheets Level 2
//! Revision 2 (CSS 2.2) Specification" available here:
//!
//! http://dev.w3.org/csswg/css2/
//!
//! "INTRINSIC" refers to L. David Baron's "More Precise Definitions of Inline Layout and Table
//! Layout" available here:
//!
//! http://dbaron.org/css/intrinsic/
//!
//! "CSS-SIZING" refers to the W3C "CSS Intrinsic & Extrinsic Sizing Module Level 3" document
//! available here:
//!
//! http://dev.w3.org/csswg/css-sizing/
use crate::context::LayoutContext;
use crate::display_list::items::DisplayListSection;
use crate::display_list::{
BorderPaintingMode, DisplayListBuildState, StackingContextCollectionFlags,
StackingContextCollectionState,
};
use crate::floats::{ClearType, FloatKind, Floats, PlacementInfo};
use crate::flow::{
BaseFlow, EarlyAbsolutePositionInfo, Flow, FlowClass, ForceNonfloatedFlag, GetBaseFlow,
};
use crate::flow::{
FlowFlags, FragmentationContext, ImmutableFlowUtils, LateAbsolutePositionInfo, OpaqueFlow,
};
use crate::flow_list::FlowList;
use crate::fragment::{
CoordinateSystem, Fragment, FragmentBorderBoxIterator, FragmentFlags, Overflow,
};
use crate::incremental::RelayoutMode;
use crate::layout_debug;
use crate::model::{
AdjoiningMargins, CollapsibleMargins, IntrinsicISizes, MarginCollapseInfo, MaybeAuto,
};
use crate::sequential;
use crate::traversal::PreorderFlowTraversal;
use app_units::{Au, MAX_AU};
use euclid::default::{Point2D, Rect, SideOffsets2D, Size2D};
use gfx_traits::print_tree::PrintTree;
use serde::{Serialize, Serializer};
use servo_geometry::MaxRect;
use std::cmp::{max, min};
use std::fmt;
use std::sync::Arc;
use style::computed_values::box_sizing::T as BoxSizing;
use style::computed_values::display::T as Display;
use style::computed_values::float::T as Float;
use style::computed_values::overflow_x::T as StyleOverflow;
use style::computed_values::position::T as Position;
use style::computed_values::text_align::T as TextAlign;
use style::context::SharedStyleContext;
use style::logical_geometry::{LogicalMargin, LogicalPoint, LogicalRect, LogicalSize, WritingMode};
use style::properties::ComputedValues;
use style::servo::restyle_damage::ServoRestyleDamage;
use style::values::computed::{LengthPercentageOrAuto, MaxSize, Size};
/// Information specific to floated blocks.
#[derive(Clone, Serialize)]
pub struct FloatedBlockInfo {
/// The amount of inline size that is available for the float.
pub containing_inline_size: Au,
/// The float ceiling, relative to `BaseFlow::position::cur_b` (i.e. the top part of the border
/// box).
pub float_ceiling: Au,
/// Left or right?
pub float_kind: FloatKind,
}
impl FloatedBlockInfo {
pub fn new(float_kind: FloatKind) -> FloatedBlockInfo {
FloatedBlockInfo {
containing_inline_size: Au(0),
float_ceiling: Au(0),
float_kind: float_kind,
}
}
}
/// The solutions for the block-size-and-margins constraint equation.
#[derive(Clone, Copy)]
struct BSizeConstraintSolution {
block_start: Au,
block_size: Au,
margin_block_start: Au,
margin_block_end: Au,
}
impl BSizeConstraintSolution {
fn new(
block_start: Au,
block_size: Au,
margin_block_start: Au,
margin_block_end: Au,
) -> BSizeConstraintSolution {
BSizeConstraintSolution {
block_start: block_start,
block_size: block_size,
margin_block_start: margin_block_start,
margin_block_end: margin_block_end,
}
}
/// Solve the vertical constraint equation for absolute non-replaced elements.
///
/// CSS Section 10.6.4
/// Constraint equation:
/// block-start + block-end + block-size + margin-block-start + margin-block-end
/// = absolute containing block block-size - (vertical padding and border)
/// [aka available_block-size]
///
/// Return the solution for the equation.
fn solve_vertical_constraints_abs_nonreplaced(
block_size: MaybeAuto,
block_start_margin: MaybeAuto,
block_end_margin: MaybeAuto,
block_start: MaybeAuto,
block_end: MaybeAuto,
content_block_size: Au,
available_block_size: Au,
) -> BSizeConstraintSolution {
let (block_start, block_size, margin_block_start, margin_block_end) =
match (block_start, block_end, block_size) {
(MaybeAuto::Auto, MaybeAuto::Auto, MaybeAuto::Auto) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
// Now it is the same situation as block-start Specified and block-end
// and block-size Auto.
let block_size = content_block_size;
// Use a dummy value for `block_start`, since it has the static position.
(Au(0), block_size, margin_block_start, margin_block_end)
},
(
MaybeAuto::Specified(block_start),
MaybeAuto::Specified(block_end),
MaybeAuto::Specified(block_size),
) => {
match (block_start_margin, block_end_margin) {
(MaybeAuto::Auto, MaybeAuto::Auto) => {
let total_margin_val =
available_block_size - block_start - block_end - block_size;
(
block_start,
block_size,
total_margin_val.scale_by(0.5),
total_margin_val.scale_by(0.5),
)
},
(MaybeAuto::Specified(margin_block_start), MaybeAuto::Auto) => {
let sum = block_start + block_end + block_size + margin_block_start;
(
block_start,
block_size,
margin_block_start,
available_block_size - sum,
)
},
(MaybeAuto::Auto, MaybeAuto::Specified(margin_block_end)) => {
let sum = block_start + block_end + block_size + margin_block_end;
(
block_start,
block_size,
available_block_size - sum,
margin_block_end,
)
},
(
MaybeAuto::Specified(margin_block_start),
MaybeAuto::Specified(margin_block_end),
) => {
// Values are over-constrained. Ignore value for 'block-end'.
(
block_start,
block_size,
margin_block_start,
margin_block_end,
)
},
}
},
// For the rest of the cases, auto values for margin are set to 0
// If only one is Auto, solve for it
(
MaybeAuto::Auto,
MaybeAuto::Specified(block_end),
MaybeAuto::Specified(block_size),
) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
let sum = block_end + block_size + margin_block_start + margin_block_end;
(
available_block_size - sum,
block_size,
margin_block_start,
margin_block_end,
)
},
(
MaybeAuto::Specified(block_start),
MaybeAuto::Auto,
MaybeAuto::Specified(block_size),
) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
(
block_start,
block_size,
margin_block_start,
margin_block_end,
)
},
(
MaybeAuto::Specified(block_start),
MaybeAuto::Specified(block_end),
MaybeAuto::Auto,
) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
let sum = block_start + block_end + margin_block_start + margin_block_end;
(
block_start,
available_block_size - sum,
margin_block_start,
margin_block_end,
)
},
// If block-size is auto, then block-size is content block-size. Solve for the
// non-auto value.
(MaybeAuto::Specified(block_start), MaybeAuto::Auto, MaybeAuto::Auto) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
let block_size = content_block_size;
(
block_start,
block_size,
margin_block_start,
margin_block_end,
)
},
(MaybeAuto::Auto, MaybeAuto::Specified(block_end), MaybeAuto::Auto) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
let block_size = content_block_size;
let sum = block_end + block_size + margin_block_start + margin_block_end;
(
available_block_size - sum,
block_size,
margin_block_start,
margin_block_end,
)
},
(MaybeAuto::Auto, MaybeAuto::Auto, MaybeAuto::Specified(block_size)) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
// Use a dummy value for `block_start`, since it has the static position.
(Au(0), block_size, margin_block_start, margin_block_end)
},
};
BSizeConstraintSolution::new(
block_start,
block_size,
margin_block_start,
margin_block_end,
)
}
/// Solve the vertical constraint equation for absolute replaced elements.
///
/// Assumption: The used value for block-size has already been calculated.
///
/// CSS Section 10.6.5
/// Constraint equation:
/// block-start + block-end + block-size + margin-block-start + margin-block-end
/// = absolute containing block block-size - (vertical padding and border)
/// [aka available block-size]
///
/// Return the solution for the equation.
fn solve_vertical_constraints_abs_replaced(
block_size: Au,
block_start_margin: MaybeAuto,
block_end_margin: MaybeAuto,
block_start: MaybeAuto,
block_end: MaybeAuto,
_: Au,
available_block_size: Au,
) -> BSizeConstraintSolution {
let (block_start, block_size, margin_block_start, margin_block_end) =
match (block_start, block_end) {
(MaybeAuto::Auto, MaybeAuto::Auto) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
// Use a dummy value for `block_start`, since it has the static position.
(Au(0), block_size, margin_block_start, margin_block_end)
},
(MaybeAuto::Specified(block_start), MaybeAuto::Specified(block_end)) => {
match (block_start_margin, block_end_margin) {
(MaybeAuto::Auto, MaybeAuto::Auto) => {
let total_margin_val =
available_block_size - block_start - block_end - block_size;
(
block_start,
block_size,
total_margin_val.scale_by(0.5),
total_margin_val.scale_by(0.5),
)
},
(MaybeAuto::Specified(margin_block_start), MaybeAuto::Auto) => {
let sum = block_start + block_end + block_size + margin_block_start;
(
block_start,
block_size,
margin_block_start,
available_block_size - sum,
)
},
(MaybeAuto::Auto, MaybeAuto::Specified(margin_block_end)) => {
let sum = block_start + block_end + block_size + margin_block_end;
(
block_start,
block_size,
available_block_size - sum,
margin_block_end,
)
},
(
MaybeAuto::Specified(margin_block_start),
MaybeAuto::Specified(margin_block_end),
) => {
// Values are over-constrained. Ignore value for 'block-end'.
(
block_start,
block_size,
margin_block_start,
margin_block_end,
)
},
}
},
// If only one is Auto, solve for it
(MaybeAuto::Auto, MaybeAuto::Specified(block_end)) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
let sum = block_end + block_size + margin_block_start + margin_block_end;
(
available_block_size - sum,
block_size,
margin_block_start,
margin_block_end,
)
},
(MaybeAuto::Specified(block_start), MaybeAuto::Auto) => {
let margin_block_start = block_start_margin.specified_or_zero();
let margin_block_end = block_end_margin.specified_or_zero();
(
block_start,
block_size,
margin_block_start,
margin_block_end,
)
},
};
BSizeConstraintSolution::new(
block_start,
block_size,
margin_block_start,
margin_block_end,
)
}
}
/// Performs block-size calculations potentially multiple times, taking
/// (assuming an horizontal writing mode) `height`, `min-height`, and `max-height`
/// into account. After each call to `next()`, the caller must call `.try()` with the
/// current calculated value of `height`.
///
/// See CSS 2.1 § 10.7.
pub struct CandidateBSizeIterator {
block_size: MaybeAuto,
max_block_size: Option<Au>,
min_block_size: Au,
pub candidate_value: Au,
status: CandidateBSizeIteratorStatus,
}
impl CandidateBSizeIterator {
/// Creates a new candidate block-size iterator. `block_container_block-size` is `None` if the block-size
/// of the block container has not been determined yet. It will always be `Some` in the case of
/// absolutely-positioned containing blocks.
pub fn new(
fragment: &Fragment,
block_container_block_size: Option<Au>,
) -> CandidateBSizeIterator {
// Per CSS 2.1 § 10.7, (assuming an horizontal writing mode,)
// percentages in `min-height` and `max-height` refer to the height of
// the containing block.
// If that is not determined yet by the time we need to resolve
// `min-height` and `max-height`, percentage values are ignored.
let block_size = match fragment.style.content_block_size() {
Size::Auto => MaybeAuto::Auto,
Size::LengthPercentage(ref lp) => {
MaybeAuto::from_option(lp.maybe_to_used_value(block_container_block_size))
},
};
let max_block_size = match fragment.style.max_block_size() {
MaxSize::None => None,
MaxSize::LengthPercentage(ref lp) => lp.maybe_to_used_value(block_container_block_size),
};
let min_block_size = match fragment.style.min_block_size() {
Size::Auto => MaybeAuto::Auto,
Size::LengthPercentage(ref lp) => {
MaybeAuto::from_option(lp.maybe_to_used_value(block_container_block_size))
},
}
.specified_or_zero();
// If the style includes `box-sizing: border-box`, subtract the border and padding.
let adjustment_for_box_sizing = match fragment.style.get_position().box_sizing {
BoxSizing::BorderBox => fragment.border_padding.block_start_end(),
BoxSizing::ContentBox => Au(0),
};
return CandidateBSizeIterator {
block_size: block_size.map(|size| adjust(size, adjustment_for_box_sizing)),
max_block_size: max_block_size.map(|size| adjust(size, adjustment_for_box_sizing)),
min_block_size: adjust(min_block_size, adjustment_for_box_sizing),
candidate_value: Au(0),
status: CandidateBSizeIteratorStatus::Initial,
};
fn adjust(size: Au, delta: Au) -> Au {
max(size - delta, Au(0))
}
}
}
impl Iterator for CandidateBSizeIterator {
type Item = MaybeAuto;
fn next(&mut self) -> Option<MaybeAuto> {
self.status = match self.status {
CandidateBSizeIteratorStatus::Initial => CandidateBSizeIteratorStatus::Trying,
CandidateBSizeIteratorStatus::Trying => match self.max_block_size {
Some(max_block_size) if self.candidate_value > max_block_size => {
CandidateBSizeIteratorStatus::TryingMax
},
_ if self.candidate_value < self.min_block_size => {
CandidateBSizeIteratorStatus::TryingMin
},
_ => CandidateBSizeIteratorStatus::Found,
},
CandidateBSizeIteratorStatus::TryingMax => {
if self.candidate_value < self.min_block_size {
CandidateBSizeIteratorStatus::TryingMin
} else {
CandidateBSizeIteratorStatus::Found
}
},
CandidateBSizeIteratorStatus::TryingMin | CandidateBSizeIteratorStatus::Found => {
CandidateBSizeIteratorStatus::Found
},
};
match self.status {
CandidateBSizeIteratorStatus::Trying => Some(self.block_size),
CandidateBSizeIteratorStatus::TryingMax => {
Some(MaybeAuto::Specified(self.max_block_size.unwrap()))
},
CandidateBSizeIteratorStatus::TryingMin => {
Some(MaybeAuto::Specified(self.min_block_size))
},
CandidateBSizeIteratorStatus::Found => None,
CandidateBSizeIteratorStatus::Initial => panic!(),
}
}
}
enum CandidateBSizeIteratorStatus {
Initial,
Trying,
TryingMax,
TryingMin,
Found,
}
// A helper function used in block-size calculation.
fn translate_including_floats(cur_b: &mut Au, delta: Au, floats: &mut Floats) {
*cur_b = *cur_b + delta;
let writing_mode = floats.writing_mode;
floats.translate(LogicalSize::new(writing_mode, Au(0), -delta));
}
/// The real assign-block-sizes traversal for flows with position 'absolute'.
///
/// This is a traversal of an Absolute Flow tree.
/// - Relatively positioned flows and the Root flow start new Absolute flow trees.
/// - The kids of a flow in this tree will be the flows for which it is the
/// absolute Containing Block.
/// - Thus, leaf nodes and inner non-root nodes are all Absolute Flows.
///
/// A Flow tree can have several Absolute Flow trees (depending on the number
/// of relatively positioned flows it has).
///
/// Note that flows with position 'fixed' just form a flat list as they all
/// have the Root flow as their CB.
pub struct AbsoluteAssignBSizesTraversal<'a>(pub &'a SharedStyleContext<'a>);
impl<'a> PreorderFlowTraversal for AbsoluteAssignBSizesTraversal<'a> {
#[inline]
fn process(&self, flow: &mut dyn Flow) {
if !flow.is_block_like() {
return;
}
// This flow might not be an absolutely positioned flow if it is the root of the tree.
let block = flow.as_mut_block();
if !block
.base
.flags
.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED)
{
return;
}
if !block
.base
.restyle_damage
.intersects(ServoRestyleDamage::REFLOW_OUT_OF_FLOW | ServoRestyleDamage::REFLOW)
{
return;
}
block.calculate_absolute_block_size_and_margins(self.0);
}
}
pub enum BlockType {
Replaced,
NonReplaced,
AbsoluteReplaced,
AbsoluteNonReplaced,
FloatReplaced,
FloatNonReplaced,
InlineBlockReplaced,
InlineBlockNonReplaced,
InlineFlexItem,
}
#[derive(Clone, PartialEq)]
pub enum MarginsMayCollapseFlag {
MarginsMayCollapse,
MarginsMayNotCollapse,
}
#[derive(Debug, PartialEq)]
pub enum FormattingContextType {
None,
Block,
Other,
}
#[allow(unsafe_code)]
unsafe impl crate::flow::HasBaseFlow for BlockFlow {}
// A block formatting context.
#[derive(Serialize)]
#[repr(C)]
pub struct BlockFlow {
/// Data common to all flows.
pub base: BaseFlow,
/// The associated fragment.
pub fragment: Fragment,
/// Additional floating flow members.
pub float: Option<Box<FloatedBlockInfo>>,
/// Various flags.
flags: BlockFlowFlags,
}
bitflags! {
struct BlockFlowFlags: u8 {
#[doc = "If this is set, then this block flow is the root flow."]
const IS_ROOT = 0b0000_0001;
#[doc = "If this is set, then this block flow has overflow and it will scroll."]
const HAS_SCROLLING_OVERFLOW = 0b0000_0010;
}
}
impl Serialize for BlockFlowFlags {
fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
self.bits().serialize(serializer)
}
}
impl BlockFlow {
pub fn from_fragment(fragment: Fragment) -> BlockFlow {
BlockFlow::from_fragment_and_float_kind(fragment, None)
}
pub fn from_fragment_and_float_kind(
fragment: Fragment,
float_kind: Option<FloatKind>,
) -> BlockFlow {
let writing_mode = fragment.style().writing_mode;
BlockFlow {
base: BaseFlow::new(
Some(fragment.style()),
writing_mode,
match float_kind {
Some(_) => ForceNonfloatedFlag::FloatIfNecessary,
None => ForceNonfloatedFlag::ForceNonfloated,
},
),
fragment: fragment,
float: float_kind.map(|kind| Box::new(FloatedBlockInfo::new(kind))),
flags: BlockFlowFlags::empty(),
}
}
/// Return the type of this block.
///
/// This determines the algorithm used to calculate inline-size, block-size, and the
/// relevant margins for this Block.
pub fn block_type(&self) -> BlockType {
if self
.base
.flags
.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED)
{
if self.fragment.is_replaced() {
BlockType::AbsoluteReplaced
} else {
BlockType::AbsoluteNonReplaced
}
} else if self.is_inline_flex_item() {
BlockType::InlineFlexItem
} else if self.base.flags.is_float() {
if self.fragment.is_replaced() {
BlockType::FloatReplaced
} else {
BlockType::FloatNonReplaced
}
} else if self.is_inline_block_or_inline_flex() {
if self.fragment.is_replaced() {
BlockType::InlineBlockReplaced
} else {
BlockType::InlineBlockNonReplaced
}
} else {
if self.fragment.is_replaced() {
BlockType::Replaced
} else {
BlockType::NonReplaced
}
}
}
/// Compute the actual inline size and position for this block.
pub fn compute_used_inline_size(
&mut self,
shared_context: &SharedStyleContext,
containing_block_inline_size: Au,
) {
let block_type = self.block_type();
match block_type {
BlockType::AbsoluteReplaced => {
let inline_size_computer = AbsoluteReplaced;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
BlockType::AbsoluteNonReplaced => {
let inline_size_computer = AbsoluteNonReplaced;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
BlockType::FloatReplaced => {
let inline_size_computer = FloatReplaced;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
BlockType::FloatNonReplaced => {
let inline_size_computer = FloatNonReplaced;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
BlockType::InlineBlockReplaced => {
let inline_size_computer = InlineBlockReplaced;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
BlockType::InlineBlockNonReplaced => {
let inline_size_computer = InlineBlockNonReplaced;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
BlockType::Replaced => {
let inline_size_computer = BlockReplaced;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
BlockType::NonReplaced => {
let inline_size_computer = BlockNonReplaced;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
BlockType::InlineFlexItem => {
let inline_size_computer = InlineFlexItem;
inline_size_computer.compute_used_inline_size(
self,
shared_context,
containing_block_inline_size,
);
},
}
}
/// Return this flow's fragment.
pub fn fragment(&mut self) -> &mut Fragment {
&mut self.fragment
}
pub fn stacking_relative_border_box(&self, coor: CoordinateSystem) -> Rect<Au> {
return self.fragment.stacking_relative_border_box(
&self.base.stacking_relative_position,
&self
.base
.early_absolute_position_info
.relative_containing_block_size,
self.base
.early_absolute_position_info
.relative_containing_block_mode,
coor,
);
}
/// Return the size of the containing block for the given immediate absolute descendant of this
/// flow.
///
/// Right now, this only gets the containing block size for absolutely positioned elements.
/// Note: We assume this is called in a top-down traversal, so it is ok to reference the CB.
#[inline]
pub fn containing_block_size(
&self,
viewport_size: &Size2D<Au>,
descendant: OpaqueFlow,
) -> LogicalSize<Au> {
debug_assert!(self
.base
.flags
.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED));
if self.is_fixed() || self.is_root() {
// Initial containing block is the CB for the root
LogicalSize::from_physical(self.base.writing_mode, *viewport_size)
} else {
self.base
.absolute_cb
.generated_containing_block_size(descendant)
}
}
/// Return shrink-to-fit inline-size.
///
/// This is where we use the preferred inline-sizes and minimum inline-sizes
/// calculated in the bubble-inline-sizes traversal.
pub fn get_shrink_to_fit_inline_size(&self, available_inline_size: Au) -> Au {
let content_intrinsic_inline_sizes = self.content_intrinsic_inline_sizes();
min(
content_intrinsic_inline_sizes.preferred_inline_size,
max(
content_intrinsic_inline_sizes.minimum_inline_size,
available_inline_size,
),
)
}
/// If this is the root flow, shifts all kids down and adjusts our size to account for
/// root flow margins, which should never be collapsed according to CSS § 8.3.1.
///
/// TODO(#2017, pcwalton): This is somewhat inefficient (traverses kids twice); can we do
/// better?
fn adjust_fragments_for_collapsed_margins_if_root(
&mut self,
shared_context: &SharedStyleContext,
) {
if !self.is_root() {
return;
}
let (block_start_margin_value, block_end_margin_value) = match self.base.collapsible_margins
{
CollapsibleMargins::CollapseThrough(_) => {
panic!("Margins unexpectedly collapsed through root flow.")
},
CollapsibleMargins::Collapse(block_start_margin, block_end_margin) => {
(block_start_margin.collapse(), block_end_margin.collapse())
},
CollapsibleMargins::None(block_start, block_end) => (block_start, block_end),
};
// Shift all kids down (or up, if margins are negative) if necessary.
if block_start_margin_value != Au(0) {
for kid in self.base.child_iter_mut() {
let kid_base = kid.mut_base();
kid_base.position.start.b = kid_base.position.start.b + block_start_margin_value
}
}
// FIXME(#2003, pcwalton): The max is taken here so that you can scroll the page, but this
// is not correct behavior according to CSS 2.1 § 10.5. Instead I think we should treat the
// root element as having `overflow: scroll` and use the layers-based scrolling
// infrastructure to make it scrollable.
let viewport_size = LogicalSize::from_physical(
self.fragment.style.writing_mode,
shared_context.viewport_size(),
);
let block_size = max(
viewport_size.block,
self.fragment.border_box.size.block + block_start_margin_value + block_end_margin_value,
);
self.base.position.size.block = block_size;
self.fragment.border_box.size.block = block_size;
}
// FIXME: Record enough info to deal with fragmented decorations.
// See https://drafts.csswg.org/css-break/#break-decoration
// For borders, this might be `enum FragmentPosition { First, Middle, Last }`
fn clone_with_children(&self, new_children: FlowList) -> BlockFlow {
BlockFlow {
base: self.base.clone_with_children(new_children),
fragment: self.fragment.clone(),
float: self.float.clone(),
..*self
}
}
/// Writes in the size of the relative containing block for children. (This information
/// is also needed to handle RTL.)
fn propagate_early_absolute_position_info_to_children(&mut self) {
for kid in self.base.child_iter_mut() {
kid.mut_base().early_absolute_position_info = EarlyAbsolutePositionInfo {
relative_containing_block_size: self.fragment.content_box().size,
relative_containing_block_mode: self.fragment.style().writing_mode,
}
}
}
/// Assign block-size for current flow.
///
/// * Collapse margins for flow's children and set in-flow child flows' block offsets now that
/// we know their block-sizes.
/// * Calculate and set the block-size of the current flow.
/// * Calculate block-size, vertical margins, and block offset for the flow's box using CSS §
/// 10.6.7.
///
/// For absolute flows, we store the calculated content block-size for the flow. We defer the
/// calculation of the other values until a later traversal.
///
/// When `fragmentation_context` is given (not `None`), this should fit as much of the content
/// as possible within the available block size.
/// If there is more content (that doesn’t fit), this flow is *fragmented*
/// with the extra content moved to another fragment (a flow like this one) which is returned.
/// See `Flow::fragment`.
///
/// The return value is always `None` when `fragmentation_context` is `None`.
///
/// `inline(always)` because this is only ever called by in-order or non-in-order top-level
/// methods.
#[inline(always)]
pub fn assign_block_size_block_base(
&mut self,
layout_context: &LayoutContext,
mut fragmentation_context: Option<FragmentationContext>,
margins_may_collapse: MarginsMayCollapseFlag,
) -> Option<Arc<dyn Flow>> {
let _scope = layout_debug_scope!("assign_block_size_block_base {:x}", self.base.debug_id());
let mut break_at = None;
let content_box = self.fragment.content_box();
if self
.base
.restyle_damage
.contains(ServoRestyleDamage::REFLOW)
{
// Our current border-box position.
let mut cur_b = Au(0);
// Absolute positioning establishes a block formatting context. Don't propagate floats
// in or out. (But do propagate them between kids.)
if self
.base
.flags
.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED) ||
margins_may_collapse != MarginsMayCollapseFlag::MarginsMayCollapse
{
self.base.floats = Floats::new(self.fragment.style.writing_mode);
}
let writing_mode = self.base.floats.writing_mode;
self.base.floats.translate(LogicalSize::new(
writing_mode,
-self.fragment.inline_start_offset(),
Au(0),
));
// The sum of our block-start border and block-start padding.
let block_start_offset = self.fragment.border_padding.block_start;
translate_including_floats(&mut cur_b, block_start_offset, &mut self.base.floats);
let can_collapse_block_start_margin_with_kids = margins_may_collapse ==
MarginsMayCollapseFlag::MarginsMayCollapse &&
!self
.base
.flags
.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED) &&
self.fragment.border_padding.block_start == Au(0);
let mut margin_collapse_info = MarginCollapseInfo::initialize_block_start_margin(
&self.fragment,
can_collapse_block_start_margin_with_kids,
);
// At this point, `cur_b` is at the content edge of our box. Now iterate over children.
let mut floats = self.base.floats.clone();
let thread_id = self.base.thread_id;
let (mut had_floated_children, mut had_children_with_clearance) = (false, false);
for (child_index, kid) in self.base.child_iter_mut().enumerate() {
if kid
.base()
.flags
.contains(FlowFlags::IS_ABSOLUTELY_POSITIONED)
{
// Assume that the *hypothetical box* for an absolute flow starts immediately
// after the margin-end border edge of the previous flow.
if kid
.base()
.flags
.contains(FlowFlags::BLOCK_POSITION_IS_STATIC)
{
let previous_bottom_margin = margin_collapse_info.current_float_ceiling();
kid.mut_base().position.start.b = cur_b +
kid.base()
.collapsible_margins
.block_start_margin_for_noncollapsible_context() +
previous_bottom_margin
}
kid.place_float_if_applicable();
if !kid.base().flags.is_float() {
kid.assign_block_size_for_inorder_child_if_necessary(
layout_context,
thread_id,