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349d6e7167
This is in preparation of a cascade optimization for custom properties. This fixes various fishiness around our StyleBuilder stuff. In particular, StyleBuilder::for_derived_style (renamed to for_animation) is only used to compute specified values, and thus doesn't need to know about rules, visited style, or other things like that. The flag propagation that was done in StyleAdjuster is now done in StyleBuilder, since we know beforehand which ones are always inherited, and it simplified the callers and the StyleAdjuster code. It also fixed some fishiness wrt which flags were propagated to anon boxes and text. The text-decoration-lines bit is interesting, because the way it was implemented in #17722 meant that display: contents elements did get HAS_DECORATION_LINES flags only if its parent also had it, so in practice the Contents check preserves behavior, but it's only an optimization looking at Gecko's call-sites, so we can remove it too. MozReview-Commit-ID: 6BHCyEO2U8c
105 lines
4 KiB
Rust
105 lines
4 KiB
Rust
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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//! Misc information about a given computed style.
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bitflags! {
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/// Misc information about a given computed style.
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///
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/// All flags are currently inherited for text, pseudo elements, and
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/// anonymous boxes, see StyleBuilder::for_inheritance and its callsites.
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/// If we ever want to add some flags that shouldn't inherit for them,
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/// we might want to add a function to handle this.
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pub struct ComputedValueFlags: u16 {
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/// Whether the style or any of the ancestors has a text-decoration-line
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/// property that should get propagated to descendants.
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///
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/// text-decoration-line is a reset property, but gets propagated in the
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/// frame/box tree.
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const HAS_TEXT_DECORATION_LINES = 1 << 0;
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/// Whether line break inside should be suppressed.
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///
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/// If this flag is set, the line should not be broken inside,
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/// which means inlines act as if nowrap is set, <br> element is
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/// suppressed, and blocks are inlinized.
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///
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/// This bit is propagated to all children of line participants.
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/// It is currently used by ruby to make its content unbreakable.
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const SHOULD_SUPPRESS_LINEBREAK = 1 << 1;
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/// A flag used to mark text that that has text-combine-upright.
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///
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/// This is used from Gecko's layout engine.
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const IS_TEXT_COMBINED = 1 << 2;
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/// A flag used to mark styles under a relevant link that is also
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/// visited.
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const IS_RELEVANT_LINK_VISITED = 1 << 3;
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/// A flag used to mark styles which are a pseudo-element or under one.
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const IS_IN_PSEUDO_ELEMENT_SUBTREE = 1 << 4;
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/// A flag used to mark styles which are in a display: none subtree, or
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/// under one.
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const IS_IN_DISPLAY_NONE_SUBTREE = 1 << 5;
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/// Whether this style inherits the `display` property.
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///
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/// This is important because it may affect our optimizations to avoid
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/// computing the style of pseudo-elements, given whether the
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/// pseudo-element is generated depends on the `display` value.
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const INHERITS_DISPLAY = 1 << 6;
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/// Whether this style inherits the `content` property.
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///
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/// Important because of the same reason.
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const INHERITS_CONTENT = 1 << 7;
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/// Whether the child explicitly inherits any reset property.
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const INHERITS_RESET_STYLE = 1 << 8;
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/// A flag to mark a style which is a visited style.
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const IS_STYLE_IF_VISITED = 1 << 9;
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/// Whether the style or any of the ancestors has a multicol style.
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///
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/// Only used in Servo.
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const CAN_BE_FRAGMENTED = 1 << 10;
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}
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}
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impl ComputedValueFlags {
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/// Flags that are unconditionally propagated to descendants.
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#[inline]
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fn inherited_flags() -> Self {
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ComputedValueFlags::IS_STYLE_IF_VISITED |
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ComputedValueFlags::IS_RELEVANT_LINK_VISITED |
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ComputedValueFlags::CAN_BE_FRAGMENTED |
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ComputedValueFlags::IS_IN_DISPLAY_NONE_SUBTREE |
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ComputedValueFlags::IS_IN_PSEUDO_ELEMENT_SUBTREE |
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ComputedValueFlags::HAS_TEXT_DECORATION_LINES
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}
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/// Flags that may be propagated to descendants.
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#[inline]
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fn maybe_inherited_flags() -> Self {
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Self::inherited_flags() | ComputedValueFlags::SHOULD_SUPPRESS_LINEBREAK
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}
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/// Returns the flags that are always propagated to descendants.
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///
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/// See StyleAdjuster::set_bits and StyleBuilder.
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#[inline]
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pub fn inherited(self) -> Self {
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self & Self::inherited_flags()
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}
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/// Flags that are conditionally propagated to descendants, just to handle
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/// properly style invalidation.
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#[inline]
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pub fn maybe_inherited(self) -> Self {
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self & Self::maybe_inherited_flags()
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}
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}
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