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

style/properties/
computed_value_flags.rs
