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Diffstat (limited to 'servo/components/style/matching.rs')
| -rw-r--r-- | servo/components/style/matching.rs | 1083 |
1 files changed, 1083 insertions, 0 deletions
diff --git a/servo/components/style/matching.rs b/servo/components/style/matching.rs new file mode 100644 index 0000000000..1f50c0d783 --- /dev/null +++ b/servo/components/style/matching.rs @@ -0,0 +1,1083 @@ +/* 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::{CascadeInputs, 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::ResolvedElementStyles; +use crate::style_resolver::{PseudoElementResolution, StyleResolverForElement}; +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, +} + +impl ChildRestyleRequirement { + /// Whether we can unconditionally skip the cascade. + pub fn can_skip_cascade(&self) -> bool { + matches!(*self, ChildRestyleRequirement::CanSkipCascade) + } +} + +/// 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::root(), + style_attribute, + primary_rules, + ); + result |= Self::replace_single_rule_node( + context.shared, + CascadeLevel::same_tree_author_important(), + LayerOrder::root(), + 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>> { + let rule_node = primary_style.rules(); + let without_transition_rules = context + .shared + .stylist + .rule_tree() + .remove_transition_rule_if_applicable(rule_node); + if without_transition_rules == *rule_node { + // We don't have transition rule in this case, so return None to let + // the caller use the original ComputedValues. + return None; + } + + // FIXME(bug 868975): We probably need to transition visited style as + // well. + let inputs = CascadeInputs { + rules: Some(without_transition_rules), + visited_rules: primary_style.visited_rules().cloned(), + flags: primary_style.flags.for_cascade_inputs(), + }; + + // Actually `PseudoElementResolution` doesn't really matter. + let style = StyleResolverForElement::new( + *self, + context, + RuleInclusion::All, + PseudoElementResolution::IfApplicable, + ) + .cascade_style_and_visited_with_default_parents(inputs); + + Some(style.0) + } + + 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 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 new_values = new_styles.primary_style_mut(); + 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_values, + 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 self.needs_animations_update( + context, + old_values.as_deref(), + new_values, + /* pseudo_element = */ None, + ) { + tasks.insert(UpdateAnimationsTasks::CSS_ANIMATIONS); + } + + let before_change_style = if self.might_need_transitions_update( + context, + old_values.as_deref(), + new_values, + /* pseudo_element = */ 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. + let needs_transitions_update = { + // We borrow new_values here, so need to add a scope to make + // sure we release it before assigning a new value to it. + let after_change_style_ref = after_change_style.as_ref().unwrap_or(&new_values); + + self.needs_transitions_update(old_values.as_ref().unwrap(), after_change_style_ref) + }; + + if needs_transitions_update { + if let Some(values_without_transitions) = after_change_style { + *new_values = values_without_transitions; + } + tasks.insert(UpdateAnimationsTasks::CSS_TRANSITIONS); + + // We need to clone old_values into SequentialTask, so we can + // use it later. + old_values.clone() + } else { + None + } + } else { + None + }; + + if self.has_animations(&context.shared) { + tasks.insert(UpdateAnimationsTasks::EFFECT_PROPERTIES); + if important_rules_changed { + tasks.insert(UpdateAnimationsTasks::CASCADE_RESULTS); + } + if new_values.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; + } + + 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 new_font_size = new_primary_style.get_font().clone_font_size(); + let old_font_size = old_styles + .primary + .as_ref() + .map(|s| s.get_font().clone_font_size()); + + if old_font_size != Some(new_font_size) { + if is_root { + let device = context.shared.stylist.device(); + debug_assert!(self.owner_doc_matches_for_testing(device)); + device.set_root_font_size(new_font_size.computed_size().into()); + 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; + } + } + } + + 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 {} |