/
stylesheets.rs
296 lines (261 loc) · 9.25 KB
/
stylesheets.rs
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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 http://mozilla.org/MPL/2.0/. */
//! A collection of invalidations due to changes in which stylesheets affect a
//! document.
#![deny(unsafe_code)]
use Atom;
use data::StoredRestyleHint;
use dom::{TElement, TNode};
use fnv::FnvHashSet;
use selector_parser::SelectorImpl;
use selectors::parser::{Component, Selector};
use shared_lock::SharedRwLockReadGuard;
use stylesheets::{CssRule, Stylesheet};
use stylist::Stylist;
/// An invalidation scope represents a kind of subtree that may need to be
/// restyled.
#[derive(Debug, Hash, Eq, PartialEq)]
enum InvalidationScope {
/// All the descendants of an element with a given id.
ID(Atom),
/// All the descendants of an element with a given class name.
Class(Atom),
}
impl InvalidationScope {
fn is_id(&self) -> bool {
matches!(*self, InvalidationScope::ID(..))
}
fn matches<E>(&self, element: E) -> bool
where E: TElement,
{
match *self {
InvalidationScope::Class(ref class) => {
element.has_class(class)
}
InvalidationScope::ID(ref id) => {
match element.get_id() {
Some(element_id) => element_id == *id,
None => false,
}
}
}
}
}
/// A set of invalidations due to stylesheet additions.
///
/// TODO(emilio): We might be able to do the same analysis for removals and
/// media query changes too?
pub struct StylesheetInvalidationSet {
/// The style scopes we know we have to restyle so far.
invalid_scopes: FnvHashSet<InvalidationScope>,
/// Whether the whole document should be invalid.
fully_invalid: bool,
}
impl StylesheetInvalidationSet {
/// Create an empty `StylesheetInvalidationSet`.
pub fn new() -> Self {
Self {
invalid_scopes: FnvHashSet::default(),
fully_invalid: false,
}
}
/// Mark the DOM tree styles' as fully invalid.
pub fn invalidate_fully(&mut self) {
debug!("StylesheetInvalidationSet::invalidate_fully");
self.invalid_scopes.clear();
self.fully_invalid = true;
}
/// Analyze the given stylesheet, and collect invalidations from their
/// rules, in order to avoid doing a full restyle when we style the document
/// next time.
pub fn collect_invalidations_for(
&mut self,
stylist: &Stylist,
stylesheet: &Stylesheet,
guard: &SharedRwLockReadGuard)
{
debug!("StylesheetInvalidationSet::collect_invalidations_for");
if self.fully_invalid {
debug!(" > Fully invalid already");
return;
}
if stylesheet.disabled() ||
!stylesheet.is_effective_for_device(stylist.device(), guard) {
debug!(" > Stylesheet was not effective");
return; // Nothing to do here.
}
for rule in stylesheet.effective_rules(stylist.device(), guard) {
self.collect_invalidations_for_rule(rule, guard);
if self.fully_invalid {
self.invalid_scopes.clear();
break;
}
}
debug!(" > resulting invalidations: {:?}", self.invalid_scopes);
debug!(" > fully_invalid: {}", self.fully_invalid);
}
/// Clears the invalidation set, invalidating elements as needed if
/// `document_element` is provided.
pub fn flush<E>(&mut self, document_element: Option<E>)
where E: TElement,
{
if let Some(e) = document_element {
self.process_invalidations_in_subtree(e);
}
self.invalid_scopes.clear();
self.fully_invalid = false;
}
/// Process style invalidations in a given subtree, that is, look for all
/// the relevant scopes in the subtree, and mark as dirty only the relevant
/// ones.
///
/// Returns whether it invalidated at least one element's style.
#[allow(unsafe_code)]
fn process_invalidations_in_subtree<E>(&self, element: E) -> bool
where E: TElement,
{
let mut data = match element.mutate_data() {
Some(data) => data,
None => return false,
};
if !data.has_styles() {
return false;
}
if let Some(ref r) = data.get_restyle() {
if r.hint.contains_subtree() {
debug!("process_invalidations_in_subtree: {:?} was already invalid",
element);
return false;
}
}
if self.fully_invalid {
debug!("process_invalidations_in_subtree: fully_invalid({:?})",
element);
data.ensure_restyle().hint.insert(StoredRestyleHint::subtree());
return true;
}
for scope in &self.invalid_scopes {
if scope.matches(element) {
debug!("process_invalidations_in_subtree: {:?} matched {:?}",
element, scope);
data.ensure_restyle().hint.insert(StoredRestyleHint::subtree());
return true;
}
}
let mut any_children_invalid = false;
for child in element.as_node().traversal_children() {
let child = match child.as_element() {
Some(e) => e,
None => continue,
};
any_children_invalid |= self.process_invalidations_in_subtree(child);
}
if any_children_invalid {
debug!("Children of {:?} changed, setting dirty descendants",
element);
unsafe { element.set_dirty_descendants() }
}
return any_children_invalid
}
fn scan_component(
component: &Component<SelectorImpl>,
scope: &mut Option<InvalidationScope>)
{
match *component {
Component::Class(ref class) => {
if scope.as_ref().map_or(true, |s| !s.is_id()) {
*scope = Some(InvalidationScope::Class(class.clone()));
}
}
Component::ID(ref id) => {
if scope.is_none() {
*scope = Some(InvalidationScope::ID(id.clone()));
}
}
_ => {
// Ignore everything else, at least for now.
}
}
}
/// Collect a style scopes for a given selector.
///
/// We look at the outermost class or id selector to the left of an ancestor
/// combinator, in order to restyle only a given subtree.
///
/// We prefer id scopes to class scopes, and outermost scopes to innermost
/// scopes (to reduce the amount of traversal we need to do).
fn collect_scopes(&mut self, selector: &Selector<SelectorImpl>) {
debug!("StylesheetInvalidationSet::collect_scopes({:?})", selector);
let mut scope: Option<InvalidationScope> = None;
let mut scan = true;
let mut iter = selector.iter();
loop {
for component in &mut iter {
if scan {
Self::scan_component(component, &mut scope);
}
}
match iter.next_sequence() {
None => break,
Some(combinator) => {
scan = combinator.is_ancestor();
}
}
}
match scope {
Some(s) => {
debug!(" > Found scope: {:?}", s);
self.invalid_scopes.insert(s);
}
None => {
debug!(" > Scope not found");
// If we didn't find a scope, any element could match this, so
// let's just bail out.
self.fully_invalid = true;
}
}
}
/// Collects invalidations for a given CSS rule.
fn collect_invalidations_for_rule(
&mut self,
rule: &CssRule,
guard: &SharedRwLockReadGuard)
{
use stylesheets::CssRule::*;
debug!("StylesheetInvalidationSet::collect_invalidations_for_rule");
debug_assert!(!self.fully_invalid, "Not worth to be here!");
match *rule {
Style(ref lock) => {
let style_rule = lock.read_with(guard);
for selector_and_hashes in &style_rule.selectors.0 {
self.collect_scopes(&selector_and_hashes.selector);
if self.fully_invalid {
return;
}
}
}
Document(..) |
Namespace(..) |
Import(..) |
Media(..) |
Supports(..) => {
// Do nothing, relevant nested rules are visited as part of the
// iteration.
}
FontFace(..) |
CounterStyle(..) |
Keyframes(..) |
Page(..) |
Viewport(..) => {
debug!(" > Found unsupported rule, marking the whole subtree \
invalid.");
// TODO(emilio): Can we do better here?
//
// At least in `@page`, we could check the relevant media, I
// guess.
self.fully_invalid = true;
}
}
}
}