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
|
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "AnchorPositioningUtils.h"
#include "mozilla/dom/Document.h"
#include "mozilla/dom/Element.h"
#include "mozilla/Maybe.h"
#include "mozilla/PresShell.h"
#include "nsIContent.h"
#include "nsIFrame.h"
#include "nsINode.h"
#include "nsTArray.h"
namespace mozilla {
namespace {
bool IsAnchorInScopeForPositionedElement(
const nsIFrame* /* aPossibleAnchorFrame */,
const nsIFrame* /* aPositionedFrame */) {
return true; // TODO: Implement this check. For now, always in scope.
};
bool IsFullyStyleableTreeAbidingOrNotPseudoElement(const nsIFrame* aFrame) {
if (!aFrame->Style()->IsPseudoElement()) {
return true;
}
const PseudoStyleType pseudoElementType = aFrame->Style()->GetPseudoType();
// See https://www.w3.org/TR/css-pseudo-4/#treelike
return pseudoElementType == PseudoStyleType::before ||
pseudoElementType == PseudoStyleType::after ||
pseudoElementType == PseudoStyleType::marker;
}
[[maybe_unused]] size_t GetTopLayerIndex(const nsIFrame* aFrame) {
MOZ_ASSERT(aFrame);
const nsIContent* frameContent = aFrame->GetContent();
if (!frameContent) {
return 0;
}
// Within the array returned by Document::GetTopLayer,
// a higher index means the layer sits higher in the stack,
// matching Document::GetTopLayerTop()’s top-to-bottom logic.
// See https://drafts.csswg.org/css-position-4/#in-a-higher-top-layer
const nsTArray<dom::Element*>& topLayers =
frameContent->OwnerDoc()->GetTopLayer();
for (size_t index = 0; index < topLayers.Length(); ++index) {
const auto& topLayer = topLayers.ElementAt(index);
if (nsContentUtils::ContentIsFlattenedTreeDescendantOfForStyle(
/* aPossibleDescendant */ frameContent,
/* aPossibleAncestor */ topLayer)) {
return 1 + index;
}
}
return 0;
}
bool IsAnchorLaidOutStrictlyBeforeElement(
const nsIFrame* /* aPossibleAnchorFrame */,
const nsIFrame* /* aPositionedFrame */) {
return true; // TODO: Implement this check. For now, always true.
}
bool IsPositionedElementAlsoSkippedWhenAnchorIsSkipped(
const nsIFrame* /* aPossibleAnchorFrame */,
const nsIFrame* /* aPositionedFrame */) {
return true; // TODO: Implement this check. For now, always true.
}
bool IsAcceptableAnchorElement(const nsIFrame* aPossibleAnchorFrame,
const nsIFrame* aPositionedFrame) {
MOZ_ASSERT(aPossibleAnchorFrame);
MOZ_ASSERT(aPositionedFrame);
// An element possible anchor is an acceptable anchor element for an
// absolutely positioned element positioned el if all of the following are
// true:
// - possible anchor is either an element or a fully styleable
// tree-abiding pseudo-element.
// - possible anchor is in scope for positioned el, per the effects of
// anchor-scope on positioned el or its ancestors.
// - possible anchor is laid out strictly before positioned el
//
// Note: Frames having an anchor name contain elements.
// The phrase "element or a fully styleable tree-abiding pseudo-element"
// used by the spec is taken to mean
// "either not a pseudo-element or a pseudo-element of a specific kind".
return (IsFullyStyleableTreeAbidingOrNotPseudoElement(aPossibleAnchorFrame) &&
IsAnchorInScopeForPositionedElement(aPossibleAnchorFrame,
aPositionedFrame) &&
IsAnchorLaidOutStrictlyBeforeElement(aPossibleAnchorFrame,
aPositionedFrame) &&
IsPositionedElementAlsoSkippedWhenAnchorIsSkipped(
aPossibleAnchorFrame, aPositionedFrame));
}
} // namespace
nsIFrame* AnchorPositioningUtils::FindFirstAcceptableAnchor(
const nsIFrame* aPositionedFrame,
const nsTArray<nsIFrame*>& aPossibleAnchorFrames) {
for (auto it = aPossibleAnchorFrames.rbegin();
it != aPossibleAnchorFrames.rend(); ++it) {
// Check if the possible anchor is an acceptable anchor element.
if (IsAcceptableAnchorElement(*it, aPositionedFrame)) {
return *it;
}
}
// If we reach here, we didn't find any acceptable anchor.
return nullptr;
}
} // namespace mozilla
|
