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
|
// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/core/layout/ng/ng_fragmentation_utils.h"
#include "third_party/blink/renderer/core/layout/ng/ng_block_break_token.h"
#include "third_party/blink/renderer/core/layout/ng/ng_box_fragment.h"
#include "third_party/blink/renderer/core/layout/ng/ng_constraint_space.h"
#include "third_party/blink/renderer/core/layout/ng/ng_physical_box_fragment.h"
namespace blink {
// Return the total amount of block space spent on a node by fragments
// preceding this one (but not including this one).
LayoutUnit PreviouslyUsedBlockSpace(const NGConstraintSpace& constraint_space,
const NGPhysicalFragment& fragment) {
if (!fragment.IsBox())
return LayoutUnit();
const NGPhysicalBoxFragment& box_fragment =
To<NGPhysicalBoxFragment>(fragment);
const auto* break_token = To<NGBlockBreakToken>(box_fragment.BreakToken());
if (!break_token)
return LayoutUnit();
NGBoxFragment logical_fragment(constraint_space.GetWritingMode(),
constraint_space.Direction(), box_fragment);
return break_token->UsedBlockSize() - logical_fragment.BlockSize();
}
// At a class A break point [1], the break value with the highest precedence
// wins. If the two values have the same precedence (e.g. "left" and "right"),
// the value specified on a latter object wins.
//
// [1] https://drafts.csswg.org/css-break/#possible-breaks
inline int FragmentainerBreakPrecedence(EBreakBetween break_value) {
// "auto" has the lowest priority.
// "avoid*" values win over "auto".
// "avoid-page" wins over "avoid-column".
// "avoid" wins over "avoid-page".
// Forced break values win over "avoid".
// Any forced page break value wins over "column" forced break.
// More specific break values (left, right, recto, verso) wins over generic
// "page" values.
switch (break_value) {
default:
NOTREACHED();
FALLTHROUGH;
case EBreakBetween::kAuto:
return 0;
case EBreakBetween::kAvoidColumn:
return 1;
case EBreakBetween::kAvoidPage:
return 2;
case EBreakBetween::kAvoid:
return 3;
case EBreakBetween::kColumn:
return 4;
case EBreakBetween::kPage:
return 5;
case EBreakBetween::kLeft:
case EBreakBetween::kRight:
case EBreakBetween::kRecto:
case EBreakBetween::kVerso:
return 6;
}
}
EBreakBetween JoinFragmentainerBreakValues(EBreakBetween first_value,
EBreakBetween second_value) {
if (FragmentainerBreakPrecedence(second_value) >=
FragmentainerBreakPrecedence(first_value))
return second_value;
return first_value;
}
bool IsForcedBreakValue(const NGConstraintSpace& constraint_space,
EBreakBetween break_value) {
if (break_value == EBreakBetween::kColumn)
return constraint_space.BlockFragmentationType() == kFragmentColumn;
if (break_value == EBreakBetween::kLeft ||
break_value == EBreakBetween::kPage ||
break_value == EBreakBetween::kRecto ||
break_value == EBreakBetween::kRight ||
break_value == EBreakBetween::kVerso)
return constraint_space.BlockFragmentationType() == kFragmentPage;
return false;
}
bool ShouldIgnoreBlockStartMargin(const NGConstraintSpace& constraint_space,
NGLayoutInputNode child,
const NGBreakToken* child_break_token) {
// Always ignore margins if we're not at the start of the child.
auto* child_block_break_token =
DynamicTo<NGBlockBreakToken>(child_break_token);
if (child_block_break_token && !child_block_break_token->IsBreakBefore())
return true;
// If we're not fragmented or have been explicitly instructed to honor
// margins, don't ignore them.
if (!constraint_space.HasBlockFragmentation() ||
constraint_space.HasSeparateLeadingFragmentainerMargins())
return false;
// Only ignore margins if we're at the start of the fragmentainer.
if (constraint_space.FragmentainerBlockSize() !=
constraint_space.FragmentainerSpaceAtBfcStart())
return false;
// Otherwise, only ignore in-flow margins.
return !child.IsFloating() && !child.IsOutOfFlowPositioned();
}
} // namespace blink
|
