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/* 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/. */
//! Misc information about a given computed style.
bitflags! {
/// Misc information about a given computed style.
///
/// All flags are currently inherited for text, pseudo elements, and
/// anonymous boxes, see StyleBuilder::for_inheritance and its callsites.
/// If we ever want to add some flags that shouldn't inherit for them,
/// we might want to add a function to handle this.
#[repr(C)]
pub struct ComputedValueFlags: u16 {
/// Whether the style or any of the ancestors has a text-decoration-line
/// property that should get propagated to descendants.
///
/// text-decoration-line is a reset property, but gets propagated in the
/// frame/box tree.
const HAS_TEXT_DECORATION_LINES = 1 << 0;
/// Whether line break inside should be suppressed.
///
/// If this flag is set, the line should not be broken inside,
/// which means inlines act as if nowrap is set, <br> element is
/// suppressed, and blocks are inlinized.
///
/// This bit is propagated to all children of line participants.
/// It is currently used by ruby to make its content unbreakable.
const SHOULD_SUPPRESS_LINEBREAK = 1 << 1;
/// A flag used to mark text that that has text-combine-upright.
///
/// This is used from Gecko's layout engine.
const IS_TEXT_COMBINED = 1 << 2;
/// A flag used to mark styles under a relevant link that is also
/// visited.
const IS_RELEVANT_LINK_VISITED = 1 << 3;
/// A flag used to mark styles which are a pseudo-element or under one.
const IS_IN_PSEUDO_ELEMENT_SUBTREE = 1 << 4;
/// Whether this style inherits the `display` property.
///
/// This is important because it may affect our optimizations to avoid
/// computing the style of pseudo-elements, given whether the
/// pseudo-element is generated depends on the `display` value.
const INHERITS_DISPLAY = 1 << 6;
/// Whether this style inherits the `content` property.
///
/// Important because of the same reason.
const INHERITS_CONTENT = 1 << 7;
/// Whether the child explicitly inherits any reset property.
const INHERITS_RESET_STYLE = 1 << 8;
/// Whether any value on our style is font-metric-dependent.
const DEPENDS_ON_FONT_METRICS = 1 << 9;
/// Whether the style or any of the ancestors has a multicol style.
///
/// Only used in Servo.
const CAN_BE_FRAGMENTED = 1 << 10;
/// Whether this style is the style of the document element.
const IS_ROOT_ELEMENT_STYLE = 1 << 11;
}
}
impl ComputedValueFlags {
/// Flags that are unconditionally propagated to descendants.
#[inline]
fn inherited_flags() -> Self {
ComputedValueFlags::IS_RELEVANT_LINK_VISITED |
ComputedValueFlags::CAN_BE_FRAGMENTED |
ComputedValueFlags::IS_IN_PSEUDO_ELEMENT_SUBTREE |
ComputedValueFlags::HAS_TEXT_DECORATION_LINES
}
/// Flags that may be propagated to descendants.
#[inline]
fn maybe_inherited_flags() -> Self {
Self::inherited_flags() | ComputedValueFlags::SHOULD_SUPPRESS_LINEBREAK
}
/// Returns the flags that are always propagated to descendants.
///
/// See StyleAdjuster::set_bits and StyleBuilder.
#[inline]
pub fn inherited(self) -> Self {
self & Self::inherited_flags()
}
/// Flags that are conditionally propagated to descendants, just to handle
/// properly style invalidation.
#[inline]
pub fn maybe_inherited(self) -> Self {
self & Self::maybe_inherited_flags()
}
}
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