style/properties/
computed_value_flags.rs

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
4
5//! Misc information about a given computed style.
6
7use crate::derives::MallocSizeOf;
8
9/// Misc information about a given computed style.
10///
11/// All flags are currently inherited for text, pseudo elements, and
12/// anonymous boxes, see StyleBuilder::for_inheritance and its callsites.
13/// If we ever want to add some flags that shouldn't inherit for them,
14/// we might want to add a function to handle this.
15#[repr(C)]
16#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq)]
17pub struct ComputedValueFlags(u32);
18
19bitflags! {
20    impl ComputedValueFlags: u32 {
21        /// Whether the style or any of the ancestors has a text-decoration-line
22        /// property that should get propagated to descendants.
23        ///
24        /// text-decoration-line is a reset property, but gets propagated in the
25        /// frame/box tree.
26        const HAS_TEXT_DECORATION_LINES = 1 << 0;
27
28        /// Whether line break inside should be suppressed.
29        ///
30        /// If this flag is set, the line should not be broken inside,
31        /// which means inlines act as if nowrap is set, <br> element is
32        /// suppressed, and blocks are inlinized.
33        ///
34        /// This bit is propagated to all children of line participants.
35        /// It is currently used by ruby to make its content unbreakable.
36        const SHOULD_SUPPRESS_LINEBREAK = 1 << 1;
37
38        /// A flag used to mark text that that has text-combine-upright.
39        ///
40        /// This is used from Gecko's layout engine.
41        const IS_TEXT_COMBINED = 1 << 2;
42
43        /// A flag used to mark styles under a relevant link that is also
44        /// visited.
45        const IS_RELEVANT_LINK_VISITED = 1 << 3;
46
47        /// A flag used to mark styles which are a ::first-line or under one.
48        const IS_IN_FIRST_LINE_SUBTREE = 1 << 4;
49
50        /// A flag used to mark styles which have contain:style or under one.
51        const SELF_OR_ANCESTOR_HAS_CONTAIN_STYLE = 1 << 5;
52
53        /// Whether this style's `display` or `content`property depends on our parent style.
54        ///
55        /// This is important because it may affect our optimizations to avoid
56        /// computing the style of pseudo-elements, given whether the
57        /// pseudo-element is generated depends on the `display` (or `content`) value.
58        const DISPLAY_OR_CONTENT_DEPEND_ON_INHERITED_STYLE = 1 << 6;
59
60        /// Whether the child explicitly inherits any reset property.
61        const INHERITS_RESET_STYLE = 1 << 7;
62
63        /// Whether any value on our style is font-metric-dependent on our
64        /// primary font.
65        const DEPENDS_ON_SELF_FONT_METRICS = 1 << 8;
66
67        /// Whether any value on our style is font-metric-dependent on the
68        /// primary font of our parent.
69        const DEPENDS_ON_INHERITED_FONT_METRICS = 1 << 9;
70
71        /// Whether this style is the style of the document element.
72        const IS_ROOT_ELEMENT_STYLE = 1 << 10;
73
74        /// Whether this element is inside an `opacity: 0` subtree.
75        const IS_IN_OPACITY_ZERO_SUBTREE = 1 << 11;
76
77        /// Whether there are author-specified rules for border-* properties
78        /// (except border-image-*), background-color, or background-image.
79        ///
80        /// TODO(emilio): Maybe do include border-image, see:
81        ///
82        /// https://github.com/w3c/csswg-drafts/issues/4777#issuecomment-604424845
83        const HAS_AUTHOR_SPECIFIED_BORDER_BACKGROUND = 1 << 12;
84
85        /// Whether the style depends on viewport units.
86        const USES_VIEWPORT_UNITS = 1 << 13;
87
88        /// Whether the style depends on viewport units on container queries.
89        ///
90        /// This needs to be a separate flag from `USES_VIEWPORT_UNITS` because
91        /// it causes us to re-match the style (rather than re-cascascading it,
92        /// which is enough for other uses of viewport units).
93        const USES_VIEWPORT_UNITS_ON_CONTAINER_QUERIES = 1 << 14;
94
95        /// A flag used to mark styles which have `container-type` of `size` or
96        /// `inline-size`, or under one.
97        const SELF_OR_ANCESTOR_HAS_SIZE_CONTAINER_TYPE = 1 << 15;
98
99        /// Whether the style uses container query units, in which case the style depends on the
100        /// container's size and we can't reuse it across cousins (without double-checking the
101        /// container at least).
102        const USES_CONTAINER_UNITS = 1 << 16;
103
104        /// Whether there are author-specific rules for text `color`.
105        const HAS_AUTHOR_SPECIFIED_TEXT_COLOR = 1 << 17;
106
107        /// Whether this style considered a scope style rule.
108        const CONSIDERED_NONTRIVIAL_SCOPED_STYLE = 1 << 18;
109
110        /// Whether this style is that of a `display: contents` element that is either a direct
111        /// child of an item container or another `display: contents` element, the style of which
112        /// has this flag set, marked in order to cascade beyond them to the descendants of the
113        /// the item container that do generate a box.
114        const DISPLAY_CONTENTS_IN_ITEM_CONTAINER = 1 << 19;
115
116        /// Whether there are author-specific rules for `text-shadow`.
117        const HAS_AUTHOR_SPECIFIED_TEXT_SHADOW = 1 << 20;
118
119        /// Whether this style depends on container style query.
120        const DEPENDS_ON_CONTAINER_STYLE_QUERY = 1 << 21;
121
122        /// Whether this style is in an appearance: base subtree
123        const IS_IN_APPEARANCE_BASE_SUBTREE = 1 << 22;
124
125        /// Whether grid-auto-flow is author-specified.
126        const HAS_AUTHOR_SPECIFIED_GRID_AUTO_FLOW = 1 << 23;
127
128        /// Whether this style has used font relative units. Note that this is different than the
129        /// FONT_METRICS bits, which don't include rem / em etc.
130        const USES_FONT_RELATIVE_UNITS = 1 << 24;
131
132        /// Whether this style depends on font relative units in container queries.
133        const USES_FONT_RELATIVE_UNITS_ON_CONTAINER_QUERIES = 1 << 25;
134
135        /// Whether this style uses `sibling-count()`.
136        const USES_SIBLING_COUNT = 1 << 26;
137
138        /// Whether this style uses `sibling-index()`.
139        const USES_SIBLING_INDEX = 1 << 27;
140    }
141}
142
143impl Default for ComputedValueFlags {
144    #[inline]
145    fn default() -> Self {
146        Self::empty()
147    }
148}
149
150impl ComputedValueFlags {
151    /// Flags that are unconditionally propagated to descendants.
152    #[inline]
153    fn inherited_flags() -> Self {
154        Self::IS_RELEVANT_LINK_VISITED
155            | Self::IS_IN_FIRST_LINE_SUBTREE
156            | Self::HAS_TEXT_DECORATION_LINES
157            | Self::IS_IN_OPACITY_ZERO_SUBTREE
158            | Self::SELF_OR_ANCESTOR_HAS_CONTAIN_STYLE
159            | Self::SELF_OR_ANCESTOR_HAS_SIZE_CONTAINER_TYPE
160            | Self::IS_IN_APPEARANCE_BASE_SUBTREE
161    }
162
163    /// Flags that may be propagated to descendants.
164    #[inline]
165    fn maybe_inherited_flags() -> Self {
166        Self::inherited_flags()
167            | Self::SHOULD_SUPPRESS_LINEBREAK
168            | Self::DISPLAY_CONTENTS_IN_ITEM_CONTAINER
169    }
170
171    /// Flags that are an input to the cascade.
172    #[inline]
173    fn cascade_input_flags() -> Self {
174        Self::USES_VIEWPORT_UNITS_ON_CONTAINER_QUERIES
175            | Self::CONSIDERED_NONTRIVIAL_SCOPED_STYLE
176            | Self::DEPENDS_ON_CONTAINER_STYLE_QUERY
177            | Self::USES_FONT_RELATIVE_UNITS_ON_CONTAINER_QUERIES
178    }
179
180    /// Flags corresponding to usage of tree-counting functions.
181    #[inline]
182    pub fn tree_counting_function_flags() -> Self {
183        Self::USES_SIBLING_COUNT | Self::USES_SIBLING_INDEX
184    }
185
186    /// Returns the flags that are always propagated to descendants.
187    ///
188    /// See StyleAdjuster::set_bits and StyleBuilder.
189    #[inline]
190    pub fn inherited(self) -> Self {
191        self & Self::inherited_flags()
192    }
193
194    /// Flags that are conditionally propagated to descendants, just to handle
195    /// properly style invalidation.
196    #[inline]
197    pub fn maybe_inherited(self) -> Self {
198        self & Self::maybe_inherited_flags()
199    }
200
201    /// Flags that are an input to the cascade.
202    #[inline]
203    pub fn for_cascade_inputs(self) -> Self {
204        self & Self::cascade_input_flags()
205    }
206}
style/properties/computed_value_flags.rs

style/properties/
computed_value_flags.rs
