/* 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/. */
//! High-level interface to CSS selector matching.
#![allow(unsafe_code)]
#![deny(missing_docs)]
use crate::computed_value_flags::ComputedValueFlags;
use crate::context::{ElementCascadeInputs, QuirksMode};
use crate::context::{SharedStyleContext, StyleContext};
use crate::data::{ElementData, ElementStyles};
use crate::dom::TElement;
#[cfg(feature = "servo")]
use crate::dom::TNode;
use crate::invalidation::element::restyle_hints::RestyleHint;
use crate::properties::longhands::display::computed_value::T as Display;
use crate::properties::ComputedValues;
use crate::properties::PropertyDeclarationBlock;
use crate::rule_tree::{CascadeLevel, StrongRuleNode};
use crate::selector_parser::{PseudoElement, RestyleDamage};
use crate::shared_lock::Locked;
use crate::style_resolver::StyleResolverForElement;
use crate::style_resolver::{PseudoElementResolution, ResolvedElementStyles};
use crate::stylesheets::layer_rule::LayerOrder;
use crate::stylist::RuleInclusion;
use crate::traversal_flags::TraversalFlags;
use servo_arc::{Arc, ArcBorrow};
/// Represents the result of comparing an element's old and new style.
#[derive(Debug)]
pub struct StyleDifference {
/// The resulting damage.
pub damage: RestyleDamage,
/// Whether any styles changed.
pub change: StyleChange,
}
/// Represents whether or not the style of an element has changed.
#[derive(Clone, Copy, Debug)]
pub enum StyleChange {
/// The style hasn't changed.
Unchanged,
/// The style has changed.
Changed {
/// Whether only reset structs changed.
reset_only: bool,
},
}
/// Whether or not newly computed values for an element need to be cascaded to
/// children (or children might need to be re-matched, e.g., for container
/// queries).
#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
pub enum ChildRestyleRequirement {
/// Old and new computed values were the same, or we otherwise know that
/// we won't bother recomputing style for children, so we can skip cascading
/// the new values into child elements.
CanSkipCascade = 0,
/// The same as `MustCascadeChildren`, but we only need to actually
/// recascade if the child inherits any explicit reset style.
MustCascadeChildrenIfInheritResetStyle = 1,
/// Old and new computed values were different, so we must cascade the
/// new values to children.
MustCascadeChildren = 2,
/// The same as `MustCascadeChildren`, but for the entire subtree. This is
/// used to handle root font-size updates needing to recascade the whole
/// document.
MustCascadeDescendants = 3,
/// We need to re-match the whole subttree. This is used to handle container
/// query relative unit changes for example. Container query size changes
/// also trigger re-match, but after layout.
MustMatchDescendants = 4,
}
/// Determines which styles are being cascaded currently.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
enum CascadeVisitedMode {
/// Cascade the regular, unvisited styles.
Unvisited,
/// Cascade the styles used when an element's relevant link is visited. A
/// "relevant link" is the element being matched if it is a link or the
/// nearest ancestor link.
Visited,
}
trait PrivateMatchMethods: TElement {
fn replace_single_rule_node(
context: &SharedStyleContext,
level: CascadeLevel,
layer_order: LayerOrder,
pdb: Option<ArcBorrow<Locked<PropertyDeclarationBlock>>>,
path: &mut StrongRuleNode,
) -> bool {
let stylist = &context.stylist;
let guards = &context.guards;
let mut important_rules_changed = false;
let new_node = stylist.rule_tree().update_rule_at_level(
level,
layer_order,
pdb,
path,
guards,
&mut important_rules_changed,
);
if let Some(n) = new_node {
*path = n;
}
important_rules_changed
}
/// Updates the rule nodes without re-running selector matching, using just
/// the rule tree, for a specific visited mode.
///
/// Returns true if an !important rule was replaced.
fn replace_rules_internal(
&self,
replacements: RestyleHint,
context: &mut StyleContext<Self>,
cascade_visited: CascadeVisitedMode,
cascade_inputs: &mut ElementCascadeInputs,
) -> bool {
debug_assert!(
replacements.intersects(RestyleHint::replacements()) &&
(replacements & !RestyleHint::replacements()).is_empty()
);
let primary_rules = match cascade_visited {
CascadeVisitedMode::Unvisited => cascade_inputs.primary.rules.as_mut(),
CascadeVisitedMode::Visited => cascade_inputs.primary.visited_rules.as_mut(),
};
let primary_rules = match primary_rules {
Some(r) => r,
None => return false,
};
if !context.shared.traversal_flags.for_animation_only() {
let mut result = false;
if replacements.contains(RestyleHint::RESTYLE_STYLE_ATTRIBUTE) {
let style_attribute = self.style_attribute();
result |= Self::replace_single_rule_node(
context.shared,
CascadeLevel::same_tree_author_normal(),
LayerOrder::style_attribute(),
style_attribute,
primary_rules,
);
result |= Self::replace_single_rule_node(
context.shared,
CascadeLevel::same_tree_author_important(),
LayerOrder::style_attribute(),
style_attribute,
primary_rules,
);
// FIXME(emilio): Still a hack!
self.unset_dirty_style_attribute();
}
return result;
}
// Animation restyle hints are processed prior to other restyle
// hints in the animation-only traversal.
//
// Non-animation restyle hints will be processed in a subsequent
// normal traversal.
if replacements.intersects(RestyleHint::for_animations()) {
debug_assert!(context.shared.traversal_flags.for_animation_only());
if replacements.contains(RestyleHint::RESTYLE_SMIL) {
Self::replace_single_rule_node(
context.shared,
CascadeLevel::SMILOverride,
LayerOrder::root(),
self.smil_override(),
primary_rules,
);
}
if replacements.contains(RestyleHint::RESTYLE_CSS_TRANSITIONS) {
Self::replace_single_rule_node(
context.shared,
CascadeLevel::Transitions,
LayerOrder::root(),
self.transition_rule(&context.shared)
.as_ref()
.map(|a| a.borrow_arc()),
primary_rules,
);
}
if replacements.contains(RestyleHint::RESTYLE_CSS_ANIMATIONS) {
Self::replace_single_rule_node(
context.shared,
CascadeLevel::Animations,
LayerOrder::root(),
self.animation_rule(&context.shared)
.as_ref()
.map(|a| a.borrow_arc()),
primary_rules,
);
}
}
false
}
/// If there is no transition rule in the ComputedValues, it returns None.
fn after_change_style(
&self,
context: &mut StyleContext<Self>,
primary_style: &Arc<ComputedValues>,
) -> Option<Arc<ComputedValues>> {
// Actually `PseudoElementResolution` doesn't really matter.
StyleResolverForElement::new(
*self,
context,
RuleInclusion::All,
PseudoElementResolution::IfApplicable,
)
.after_change_style(primary_style)
}
fn needs_animations_update(
&self,
context: &mut StyleContext<Self>,
old_style: Option<&ComputedValues>,
new_style: &ComputedValues,
pseudo_element: Option<PseudoElement>,
) -> bool {
let new_ui_style = new_style.get_ui();
let new_style_specifies_animations = new_ui_style.specifies_animations();
let has_animations = self.has_css_animations(&context.shared, pseudo_element);
if !new_style_specifies_animations && !has_animations {
return false;
}
let old_style = match old_style {
Some(old) => old,
// If we have no old style but have animations, we may be a
// pseudo-element which was re-created without style changes.
//
// This can happen when we reframe the pseudo-element without
// restyling it (due to content insertion on a flex container or
// such, for example). See bug 1564366.
//
// FIXME(emilio): The really right fix for this is keeping the
// pseudo-element itself around on reframes, but that's a bit
// harder. If we do that we can probably remove quite a lot of the
// EffectSet complexity though, since right now it's stored on the
// parent element for pseudo-elements given we need to keep it
// around...
None => {
return new_style_specifies_animations || new_style.is_pseudo_style();
},
};
let old_ui_style = old_style.get_ui();
let keyframes_could_have_changed = context
.shared
.traversal_flags
.contains(TraversalFlags::ForCSSRuleChanges);
// If the traversal is triggered due to changes in CSS rules changes, we
// need to try to update all CSS animations on the element if the
// element has or will have CSS animation style regardless of whether
// the animation is running or not.
//
// TODO: We should check which @keyframes were added/changed/deleted and
// update only animations corresponding to those @keyframes.
if keyframes_could_have_changed {
return true;
}
// If the animations changed, well...
if !old_ui_style.animations_equals(new_ui_style) {
return true;
}
let old_display = old_style.clone_display();
let new_display = new_style.clone_display();
// If we were display: none, we may need to trigger animations.
if old_display == Display::None && new_display != Display::None {
return new_style_specifies_animations;
}
// If we are becoming display: none, we may need to stop animations.
if old_display != Display::None && new_display == Display::None {
return has_animations;
}
// We might need to update animations if writing-mode or direction
// changed, and any of the animations contained logical properties.
//
// We may want to be more granular, but it's probably not worth it.
if new_style.writing_mode != old_style.writing_mode {
return has_animations;
}
false
}
fn might_need_transitions_update(
&self,
context: &StyleContext<Self>,
old_style: Option<&ComputedValues>,
new_style: &ComputedValues,
pseudo_element: Option<PseudoElement>,
) -> bool {
let old_style = match old_style {
Some(v) => v,
None => return false,
};
if !self.has_css_transitions(context.shared, pseudo_element) &&
!new_style.get_ui().specifies_transitions()
{
return false;
}
if old_style.clone_display().is_none() {
return false;
}
return true;
}
/// Create a SequentialTask for resolving descendants in a SMIL display
/// property animation if the display property changed from none.
#[cfg(feature = "gecko")]
fn handle_display_change_for_smil_if_needed(
&self,
context: &mut StyleContext<Self>,
old_values: Option<&ComputedValues>,
new_values: &ComputedValues,
restyle_hints: RestyleHint,
) {
use crate::context::PostAnimationTasks;
if !restyle_hints.intersects(RestyleHint::RESTYLE_SMIL) {
return;
}
if new_values.is_display_property_changed_from_none(old_values) {
// When display value is changed from none to other, we need to
// traverse descendant elements in a subsequent normal
// traversal (we can't traverse them in this animation-only restyle
// since we have no way to know whether the decendants
// need to be traversed at the beginning of the animation-only
// restyle).
let task = crate::context::SequentialTask::process_post_animation(
*self,
PostAnimationTasks::DISPLAY_CHANGED_FROM_NONE_FOR_SMIL,
);
context.thread_local.tasks.push(task);
}
}
#[cfg(feature = "gecko")]
fn maybe_resolve_starting_style(
&self,
context: &mut StyleContext<Self>,
old_values: Option<&Arc<ComputedValues>>,
new_styles: &ResolvedElementStyles,
) -> Option<Arc<ComputedValues>> {
// For both cases:
// 1. If we didn't see any starting-style rules for this given element during full matching.
// 2. If there is no transitions specified.
// We don't have to resolve starting style.
if !new_styles.may_have_starting_style() ||
!new_styles.primary_style().get_ui().specifies_transitions()
{
return None;
}
// We resolve starting style only if we don't have before-change-style, or we change from
// display:none.
if old_values.is_some() &&
!new_styles
.primary_style()
.is_display_property_changed_from_none(old_values.map(|s| &**s))
{
return None;
}
// Note: Basically, we have to remove transition rules because the starting style for an
// element is the after-change style with @starting-style rules applied in addition.
// However, we expect there is no transition rules for this element when calling this
// function because we do this only when we don't have before-change style or we change
// from display:none. In these cases, it's unlikely to have running transitions on this
// element.
let mut resolver = StyleResolverForElement::new(
*self,
context,
RuleInclusion::All,
PseudoElementResolution::IfApplicable,
);
let starting_style = resolver.resolve_starting_style().style;
if starting_style.style().clone_display().is_none() {
return None;
}
Some(starting_style.0)
}
/// Handle CSS Transitions. Returns None if we don't need to update transitions. And it returns
/// the before-change style per CSS Transitions spec.
///
/// Note: The before-change style could be the computed values of all properties on the element
/// as of the previous style change event, or the starting style if we don't have the valid
/// before-change style there.
#[cfg(feature = "gecko")]
fn process_transitions(
&self,
context: &mut StyleContext<Self>,
old_values: Option<&Arc<ComputedValues>>,
new_styles: &mut ResolvedElementStyles,
) -> Option<Arc<ComputedValues>> {
let starting_values = self.maybe_resolve_starting_style(context, old_values, new_styl
es);
let before_change_or_starting = if starting_values.is_some() {
starting_values.as_ref()
} else {
old_values
};
let new_values = new_styles.primary_style_mut();
if !self.might_need_transitions_update(
context,
before_change_or_starting.map(|s| &**s),
new_values,
/* pseudo_element = */ None,
) {
return None;
}
let after_change_style =
if self.has_css_transitions(context.shared, /* pseudo_element = */ None) {
self.after_change_style(context, new_values)
} else {
None
};
// In order to avoid creating a SequentialTask for transitions which
// may not be updated, we check it per property to make sure Gecko
// side will really update transition.
if !self.needs_transitions_update(
before_change_or_starting.unwrap(),
after_change_style.as_ref().unwrap_or(&new_values),
) {
return None;
}
if let Some(values_without_transitions) = after_change_style {
*new_values = values_without_transitions;
}
// Move the new-created starting style, or clone the old values.
if starting_values.is_some() {
starting_values
} else {
old_values.cloned()
}
}
#[cfg(feature = "gecko")]
fn process_animations(
&self,
context: &mut StyleContext<Self>,
old_styles: &mut ElementStyles,
new_styles: &mut ResolvedElementStyles,
restyle_hint: RestyleHint,
important_rules_changed: bool,
) {
use crate::context::UpdateAnimationsTasks;
let old_values = &old_styles.primary;
if context.shared.traversal_flags.for_animation_only() {
self.handle_display_change_for_smil_if_needed(
context,
old_values.as_deref(),
new_styles.primary_style(),
restyle_hint,
);
return;
}
// Bug 868975: These steps should examine and update the visited styles
// in addition to the unvisited styles.
let mut tasks = UpdateAnimationsTasks::empty();
if old_values.as_deref().map_or_else(
|| {
new_styles
.primary_style()
.get_ui()
.specifies_scroll_timelines()
},
|old| {
!old.get_ui()
.scroll_timelines_equals(new_styles.primary_style().get_ui())
},
) {
tasks.insert(UpdateAnimationsTasks::SCROLL_TIMELINES);
}
if old_values.as_deref().map_or_else(
|| {
new_styles
.primary_style()
.get_ui()
.specifies_view_timelines()
},
|old| {
!old.get_ui()
.view_timelines_equals(new_styles.primary_style().get_ui())
},
) {
tasks.insert(UpdateAnimationsTasks::VIEW_TIMELINES);
}
if self.needs_animations_update(
context,
old_values.as_deref(),
new_styles.primary_style(),
/* pseudo_element = */ None,
) {
tasks.insert(UpdateAnimationsTasks::CSS_ANIMATIONS);
}
let before_change_style =
self.process_transitions(context, old_values.as_ref(), new_styles);
if before_change_style.is_some() {
tasks.insert(UpdateAnimationsTasks::CSS_TRANSITIONS);
}
if self.has_animations(&context.shared) {
tasks.insert(UpdateAnimationsTasks::EFFECT_PROPERTIES);
if important_rules_changed {
tasks.insert(UpdateAnimationsTasks::CASCADE_RESULTS);
}
if new_styles
.primary_style()
.is_display_property_changed_from_none(old_values.as_deref())
{
tasks.insert(UpdateAnimationsTasks::DISPLAY_CHANGED_FROM_NONE);
}
}
if !tasks.is_empty() {
let task = crate::context::SequentialTask::update_animations(
*self,
before_change_style,
tasks,
);
context.thread_local.tasks.push(task);
}
}
#[cfg(feature = "servo")]
fn process_animations(
&self,
context: &mut StyleContext<Self>,
old_styles: &mut ElementStyles,
new_resolved_styles: &mut ResolvedElementStyles,
_restyle_hint: RestyleHint,
_important_rules_changed: bool,
) {
use crate::animation::AnimationSetKey;
use crate::dom::TDocument;
let style_changed = self.process_animations_for_style(
context,
&mut old_styles.primary,
new_resolved_styles.primary_style_mut(),
/* pseudo_element = */ None,
);
// If we have modified animation or transitions, we recascade style for this node.
if style_changed {
let mut rule_node = new_resolved_styles.primary_style().rules().clone();
let declarations = context.shared.animations.get_all_declarations(
&AnimationSetKey::new_for_non_pseudo(self.as_node().opaque()),
context.shared.current_time_for_animations,
self.as_node().owner_doc().shared_lock(),
);
Self::replace_single_rule_node(
&context.shared,
CascadeLevel::Transitions,
declarations.transitions.as_ref().map(|a| a.borrow_arc()),
&mut rule_node,
);
Self::replace_single_rule_node(
&context.shared,
CascadeLevel::Animations,
declarations.animations.as_ref().map(|a| a.borrow_arc()),
&mut rule_node,
);
if rule_node != *new_resolved_styles.primary_style().rules() {
let inputs = CascadeInputs {
rules: Some(rule_node),
visited_rules: new_resolved_styles.primary_style().visited_rules().cloned(),
};
new_resolved_styles.primary.style = StyleResolverForElement::new(
*self,
context,
RuleInclusion::All,
PseudoElementResolution::IfApplicable,
)
.cascade_style_and_visited_with_default_parents(inputs);
}
}
self.process_animations_for_pseudo(
context,
old_styles,
new_resolved_styles,
PseudoElement::Before,
);
self.process_animations_for_pseudo(
context,
old_styles,
new_resolved_styles,
PseudoElement::After,
);
}
#[cfg(feature = "servo")]
fn process_animations_for_pseudo(
&self,
context: &mut StyleContext<Self>,
old_styles: &mut ElementStyles,
new_resolved_styles: &mut ResolvedElementStyles,
pseudo_element: PseudoElement,
) {
use crate::animation::AnimationSetKey;
use crate::dom::TDocument;
let key = AnimationSetKey::new_for_pseudo(self.as_node().opaque(), pseudo_element.clone());
let mut style = match new_resolved_styles.pseudos.get(&pseudo_element) {
Some(style) => Arc::clone(style),
None => {
context
.shared
.animations
.cancel_all_animations_for_key(&key);
return;
},
};
let mut old_style = old_styles.pseudos.get(&pseudo_element).cloned();
self.process_animations_for_style(
context,
&mut old_style,
&mut style,
Some(pseudo_element.clone()),
);
let declarations = context.shared.animations.get_all_declarations(
&key,
context.shared.current_time_for_animations,
self.as_node().owner_doc().shared_lock(),
);
if declarations.is_empty() {
return;
}
let mut rule_node = style.rules().clone();
Self::replace_single_rule_node(
&context.shared,
CascadeLevel::Transitions,
LayerOrder::root(),
declarations.transitions.as_ref().map(|a| a.borrow_arc()),
&mut rule_node,
);
Self::replace_single_rule_node(
&context.shared,
CascadeLevel::Animations,
LayerOrder::root(),
declarations.animations.as_ref().map(|a| a.borrow_arc()),
&mut rule_node,
);
if rule_node == *style.rules() {
return;
}
let inputs = CascadeInputs {
rules: Some(rule_node),
visited_rules: style.visited_rules().cloned(),
};
let new_style = StyleResolverForElement::new(
*self,
context,
RuleInclusion::All,
PseudoElementResolution::IfApplicable,
)
.cascade_style_and_visited_for_pseudo_with_default_parents(
inputs,
&pseudo_element,
&new_resolved_styles.primary,
);
new_resolved_styles
.pseudos
.set(&pseudo_element, new_style.0);
}
#[cfg(feature = "servo")]
fn process_animations_for_style(
&self,
context: &mut StyleContext<Self>,
old_values: &mut Option<Arc<ComputedValues>>,
new_values: &mut Arc<ComputedValues>,
pseudo_element: Option<PseudoElement>,
) -> bool {
use crate::animation::{AnimationSetKey, AnimationState};
// We need to call this before accessing the `ElementAnimationSet` from the
// map because this call will do a RwLock::read().
let needs_animations_update = self.needs_animations_update(
context,
old_values.as_deref(),
new_values,
pseudo_element,
);
let might_need_transitions_update = self.might_need_transitions_update(
context,
old_values.as_deref(),
new_values,
pseudo_element,
);
let mut after_change_style = None;
if might_need_transitions_update {
after_change_style = self.after_change_style(context, new_values);
}
let key = AnimationSetKey::new(self.as_node().opaque(), pseudo_element);
let shared_context = context.shared;
let mut animation_set = shared_context
.animations
.sets
.write()
.remove(&key)
.unwrap_or_default();
// Starting animations is expensive, because we have to recalculate the style
// for all the keyframes. We only want to do this if we think that there's a
// chance that the animations really changed.
if needs_animations_update {
let mut resolver = StyleResolverForElement::new(
*self,
context,
RuleInclusion::All,
PseudoElementResolution::IfApplicable,
);
animation_set.update_animations_for_new_style::<Self>(
*self,
&shared_context,
&new_values,
&mut resolver,
);
}
animation_set.update_transitions_for_new_style(
might_need_transitions_update,
&shared_context,
old_values.as_ref(),
after_change_style.as_ref().unwrap_or(new_values),
);
// We clear away any finished transitions, but retain animations, because they
// might still be used for proper calculation of `animation-fill-mode`. This
// should change the computed values in the style, so we don't need to mark
// this set as dirty.
animation_set
.transitions
.retain(|transition| transition.state != AnimationState::Finished);
// If the ElementAnimationSet is empty, and don't store it in order to
// save memory and to avoid extra processing later.
let changed_animations = animation_set.dirty;
if !animation_set.is_empty() {
animation_set.dirty = false;
shared_context
.animations
.sets
.write()
.insert(key, animation_set);
}
changed_animations
}
/// Computes and applies non-redundant damage.
fn accumulate_damage_for(
&self,
shared_context: &SharedStyleContext,
damage: &mut RestyleDamage,
old_values: &ComputedValues,
new_values: &ComputedValues,
pseudo: Option<&PseudoElement>,
) -> ChildRestyleRequirement {
debug!("accumulate_damage_for: {:?}", self);
debug_assert!(!shared_context
.traversal_flags
.contains(TraversalFlags::FinalAnimationTraversal));
let difference = self.compute_style_difference(old_values, new_values, pseudo);
*damage |= difference.damage;
debug!(" > style difference: {:?}", difference);
// We need to cascade the children in order to ensure the correct
// propagation of inherited computed value flags.
if old_values.flags.maybe_inherited() != new_values.flags.maybe_inherited() {
debug!(
" > flags changed: {:?} != {:?}",
old_values.flags, new_values.flags
);
return ChildRestyleRequirement::MustCascadeChildren;
}
if old_values.effective_zoom != new_values.effective_zoom {
// Zoom changes need to get propagated to children.
debug!(
" > zoom changed: {:?} != {:?}",
old_values.effective_zoom, new_values.effective_zoom
);
return ChildRestyleRequirement::MustCascadeChildren;
}
match difference.change {
StyleChange::Unchanged => return ChildRestyleRequirement::CanSkipCascade,
StyleChange::Changed { reset_only } => {
// If inherited properties changed, the best we can do is
// cascade the children.
if !reset_only {
return ChildRestyleRequirement::MustCascadeChildren;
}
},
}
let old_display = old_values.clone_display();
let new_display = new_values.clone_display();
if old_display != new_display {
// If we used to be a display: none element, and no longer are, our
// children need to be restyled because they're unstyled.
if old_display == Display::None {
return ChildRestyleRequirement::MustCascadeChildren;
}
// Blockification of children may depend on our display value,
// so we need to actually do the recascade. We could potentially
// do better, but it doesn't seem worth it.
if old_display.is_item_container() != new_display.is_item_container() {
return ChildRestyleRequirement::MustCascadeChildren;
}
// We may also need to blockify and un-blockify descendants if our
// display goes from / to display: contents, since the "layout
// parent style" changes.
if old_display.is_contents() || new_display.is_contents() {
return ChildRestyleRequirement::MustCascadeChildren;
}
// Line break suppression may also be affected if the display
// type changes from ruby to non-ruby.
#[cfg(feature = "gecko")]
{
if old_display.is_ruby_type() != new_display.is_ruby_type() {
return ChildRestyleRequirement::MustCascadeChildren;
}
}
}
// Children with justify-items: auto may depend on our
// justify-items property value.
//
// Similarly, we could potentially do better, but this really
// seems not common enough to care about.
#[cfg(feature = "gecko")]
{
use crate::values::specified::align::AlignFlags;
let old_justify_items = old_values.get_position().clone_justify_items();
let new_justify_items = new_values.get_position().clone_justify_items();
let was_legacy_justify_items =
old_justify_items.computed.0.contains(AlignFlags::LEGACY);
let is_legacy_justify_items = new_justify_items.computed.0.contains(AlignFlags::LEGACY);
if is_legacy_justify_items != was_legacy_justify_items {
return ChildRestyleRequirement::MustCascadeChildren;
}
if was_legacy_justify_items && old_justify_items.computed != new_justify_items.computed
{
return ChildRestyleRequirement::MustCascadeChildren;
}
}
#[cfg(feature = "servo")]
{
// We may need to set or propagate the CAN_BE_FRAGMENTED bit
// on our children.
if old_values.is_multicol() != new_values.is_multicol() {
return ChildRestyleRequirement::MustCascadeChildren;
}
}
// We could prove that, if our children don't inherit reset
// properties, we can stop the cascade.
ChildRestyleRequirement::MustCascadeChildrenIfInheritResetStyle
}
}
impl<E: TElement> PrivateMatchMethods for E {}
/// The public API that elements expose for selector matching.
pub trait MatchMethods: TElement {
/// Returns the closest parent element that doesn't have a display: contents
/// style (and thus generates a box).
///
/// This is needed to correctly handle blockification of flex and grid
/// items.
///
/// Returns itself if the element has no parent. In practice this doesn't
/// happen because the root element is blockified per spec, but it could
/// happen if we decide to not blockify for roots of disconnected subtrees,
/// which is a kind of dubious behavior.
fn layout_parent(&self) -> Self {
let mut current = self.clone();
loop {
current = match current.traversal_parent() {
Some(el) => el,
None => return current,
};
let is_display_contents = current
.borrow_data()
.unwrap()
.styles
.primary()
.is_display_contents();
if !is_display_contents {
return current;
}
}
}
/// Updates the styles with the new ones, diffs them, and stores the restyle
/// damage.
fn finish_restyle(
&self,
context: &mut StyleContext<Self>,
data: &mut ElementData,
mut new_styles: ResolvedElementStyles,
important_rules_changed: bool,
) -> ChildRestyleRequirement {
use std::cmp;
self.process_animations(
context,
&mut data.styles,
&mut new_styles,
data.hint,
important_rules_changed,
);
// First of all, update the styles.
let old_styles = data.set_styles(new_styles);
let new_primary_style = data.styles.primary.as_ref().unwrap();
let mut restyle_requirement = ChildRestyleRequirement::CanSkipCascade;
let is_root = new_primary_style
.flags
.contains(ComputedValueFlags::IS_ROOT_ELEMENT_STYLE);
let is_container = !new_primary_style
.get_box()
.clone_container_type()
.is_normal();
if is_root || is_container {
let device = context.shared.stylist.device();
let old_style = old_styles.primary.as_ref();
let new_font_size = new_primary_style.get_font().clone_font_size();
let old_font_size = old_style.map(|s| s.get_font().clone_font_size());
if old_font_size != Some(new_font_size) {
if is_root {
debug_assert!(self.owner_doc_matches_for_testing(device));
let size = new_font_size.computed_size();
device.set_root_font_size(new_primary_style.effective_zoom.unzoom(size.px()));
if device.used_root_font_size() {
// If the root font-size changed since last time, and something
// in the document did use rem units, ensure we recascade the
// entire tree.
restyle_requirement = ChildRestyleRequirement::MustCascadeDescendants;
}
}
if is_container && old_font_size.is_some() {
// TODO(emilio): Maybe only do this if we were matched
// against relative font sizes?
// Also, maybe we should do this as well for font-family /
// etc changes (for ex/ch/ic units to work correctly)? We
// should probably do the optimization mentioned above if
// so.
restyle_requirement = ChildRestyleRequirement::MustMatchDescendants;
}
}
// For line-height, we want the fully resolved value, as `normal` also depends on other
// font properties.
let new_line_height = device
.calc_line_height(
&new_primary_style.get_font(),
new_primary_style.writing_mode,
None,
)
.0;
let old_line_height = old_style.map(|s| {
device
.calc_line_height(&s.get_font(), s.writing_mode, None)
.0
});
if old_line_height != Some(new_line_height) {
if is_root {
debug_assert!(self.owner_doc_matches_for_testing(device));
device.set_root_line_height(
new_primary_style
.effective_zoom
.unzoom(new_line_height.px()),
);
if device.used_root_line_height() {
restyle_requirement = std::cmp::max(
restyle_requirement,
ChildRestyleRequirement::MustCascadeDescendants,
);
}
}
if is_container && old_line_height.is_some() {
restyle_requirement = ChildRestyleRequirement::MustMatchDescendants;
}
}
}
if context.shared.stylist.quirks_mode() == QuirksMode::Quirks {
if self.is_html_document_body_element() {
// NOTE(emilio): We _could_ handle dynamic changes to it if it
// changes and before we reach our children the cascade stops,
// but we don't track right now whether we use the document body
// color, and nobody else handles that properly anyway.
let device = context.shared.stylist.device();
// Needed for the "inherit from body" quirk.
let text_color = new_primary_style.get_inherited_text().clone_color();
device.set_body_text_color(text_color);
}
}
// Don't accumulate damage if we're in the final animation traversal.
if context
.shared
.traversal_flags
.contains(TraversalFlags::FinalAnimationTraversal)
{
return ChildRestyleRequirement::MustCascadeChildren;
}
// Also, don't do anything if there was no style.
let old_primary_style = match old_styles.primary {
Some(s) => s,
None => return ChildRestyleRequirement::MustCascadeChildren,
};
let old_container_type = old_primary_style.clone_container_type();
let new_container_type = new_primary_style.clone_container_type();
if old_container_type != new_container_type && !new_container_type.is_size_container_type()
{
// Stopped being a size container. Re-evaluate container queries and units on all our descendants.
// Changes into and between different size containment is handled in `UpdateContainerQueryStyles`.
restyle_requirement = ChildRestyleRequirement::MustMatchDescendants;
} else if old_container_type.is_size_container_type() &&
!old_primary_style.is_display_contents() &&
new_primary_style.is_display_contents()
{
// Also re-evaluate when a container gets 'display: contents', since size queries will now evaluate to unknown.
// Other displays like 'inline' will keep generating a box, so they are handled in `UpdateContainerQueryStyles`.
restyle_requirement = ChildRestyleRequirement::MustMatchDescendants;
}
restyle_requirement = cmp::max(
restyle_requirement,
self.accumulate_damage_for(
context.shared,
&mut data.damage,
&old_primary_style,
new_primary_style,
None,
),
);
if data.styles.pseudos.is_empty() && old_styles.pseudos.is_empty() {
// This is the common case; no need to examine pseudos here.
return restyle_requirement;
}
let pseudo_styles = old_styles
.pseudos
.as_array()
.iter()
.zip(data.styles.pseudos.as_array().iter());
for (i, (old, new)) in pseudo_styles.enumerate() {
match (old, new) {
(&Some(ref old), &Some(ref new)) => {
self.accumulate_damage_for(
context.shared,
&mut data.damage,
old,
new,
Some(&PseudoElement::from_eager_index(i)),
);
},
(&None, &None) => {},
_ => {
// It's possible that we're switching from not having
// ::before/::after at all to having styles for them but not
// actually having a useful pseudo-element. Check for that
// case.
let pseudo = PseudoElement::from_eager_index(i);
let new_pseudo_should_exist =
new.as_ref().map_or(false, |s| pseudo.should_exist(s));
let old_pseudo_should_exist =
old.as_ref().map_or(false, |s| pseudo.should_exist(s));
if new_pseudo_should_exist != old_pseudo_should_exist {
data.damage |= RestyleDamage::reconstruct();
return restyle_requirement;
}
},
}
}
restyle_requirement
}
/// Updates the rule nodes without re-running selector matching, using just
/// the rule tree.
///
/// Returns true if an !important rule was replaced.
fn replace_rules(
&self,
replacements: RestyleHint,
context: &mut StyleContext<Self>,
cascade_inputs: &mut ElementCascadeInputs,
) -> bool {
let mut result = false;
result |= self.replace_rules_internal(
replacements,
context,
CascadeVisitedMode::Unvisited,
cascade_inputs,
);
result |= self.replace_rules_internal(
replacements,
context,
CascadeVisitedMode::Visited,
cascade_inputs,
);
result
}
/// Given the old and new style of this element, and whether it's a
/// pseudo-element, compute the restyle damage used to determine which
/// kind of layout or painting operations we'll need.
fn compute_style_difference(
&self,
old_values: &ComputedValues,
new_values: &ComputedValues,
pseudo: Option<&PseudoElement>,
) -> StyleDifference {
debug_assert!(pseudo.map_or(true, |p| p.is_eager()));
RestyleDamage::compute_style_difference(old_values, new_values)
}
}
impl<E: TElement> MatchMethods for E {}
