components/script/dom/css/fontfaceset.rs - main - githubmirror/servo

components/script/dom/css/fontfaceset.rs
366 строк14 KB
Simon Wülker
script: Handle CSS-connected font faces in `FontFaceSet::{Add, Delete}` (#46634)
19 июл 2026, 17:42
19 июл 2026, 17:4201b1501
/* 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/. */

use std::cell::RefCell;
use std::rc::Rc;

use dom_struct::dom_struct;
use fonts::FontFaceRuleWithOrigin;
use js::context::JSContext;
use js::gc::Handle;
use js::jsapi::Value;
use js::realm::CurrentRealm;
use js::rust::HandleObject;
use layout_api::{QueryMsg, ReflowGoal};
use script_bindings::cell::DomRefCell;
use script_bindings::codegen::GenericBindings::FontFaceBinding::{
    FontFaceLoadStatus, FontFaceMethods,
};
use script_bindings::like::Setlike;
use script_bindings::reflector::reflect_dom_object_with_proto;

use crate::dom::bindings::codegen::Bindings::FontFaceSetBinding::FontFaceSetMethods;
use crate::dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
use crate::dom::bindings::error::{Error, Fallible};
use crate::dom::bindings::refcounted::{Trusted, TrustedPromise};
use crate::dom::bindings::reflector::DomGlobal;
use crate::dom::bindings::root::{Dom, DomRoot};
use crate::dom::bindings::str::DOMString;
use crate::dom::eventtarget::EventTarget;
use crate::dom::fontface::FontFace;
use crate::dom::globalscope::GlobalScope;
use crate::dom::promise::Promise;
use crate::dom::promisenativehandler::Callback;
use crate::dom::types::PromiseNativeHandler;
use crate::dom::window::Window;
use crate::realms::enter_auto_realm;

/// <https://drafts.csswg.org/css-font-loading/#FontFaceSet-interface>
#[dom_struct]
pub(crate) struct FontFaceSet {
    target: EventTarget,

    /// <https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-readypromise-slot>
    #[conditional_malloc_size_of]
    promise: RefCell<Rc<Promise>>,

    set_entries: DomRefCell<Vec<Dom<FontFace>>>,
}

impl FontFaceSet {
    fn new_inherited(promise: Rc<Promise>) -> Self {
        FontFaceSet {
            target: EventTarget::new_inherited(),
            promise: promise.into(),
            set_entries: Default::default(),
        }
    }

    pub(crate) fn new(
        cx: &mut JSContext,
        global: &GlobalScope,
        proto: Option<HandleObject>,
    ) -> DomRoot<Self> {
        let promise = Promise::new(cx, global);
        reflect_dom_object_with_proto(
            cx,
            Box::new(FontFaceSet::new_inherited(promise)),
            global,
            proto,
        )
    }

    pub(super) fn handle_font_face_status_changed(&self, cx: &mut JSContext, font_face: &FontFace) {
        match font_face.Status() {
            FontFaceLoadStatus::Loading => {
                self.switch_to_loading(cx);
            },
            FontFaceLoadStatus::Loaded => {
                let Some(window) = DomRoot::downcast::<Window>(self.global()) else {
                    return;
                };

                let (family_name, template) = font_face
                    .template()
                    .expect("A loaded web font should have a template");
                window
                    .font_context()
                    .add_template_to_font_context(family_name, template);
                window.Document().dirty_all_nodes(cx.no_gc());
            },
            _ => {},
        }
    }

    /// Fulfill the font ready promise, returning true if it was not already fulfilled beforehand.
    pub(crate) fn fulfill_ready_promise_if_needed(&self, cx: &mut JSContext) -> bool {
        let promise = self.promise.borrow().clone();
        if promise.is_fulfilled() {
            return false;
        }
        promise.resolve_native(cx, self);
        true
    }

    pub(crate) fn waiting_to_fullfill_promise(&self) -> bool {
        !self.promise.borrow().is_fulfilled()
    }

    fn contains_face(&self, target: &FontFace) -> bool {
        self.set_entries
            .borrow()
            .iter()
            .any(|face| &**face == target)
    }

    /// Removes a face from the set's set entries.
    fn delete_face(&self, target: &FontFace) -> bool {
        let mut set_entries = self.set_entries.borrow_mut();
        let Some(index) = set_entries.iter().position(|face| &**face == target) else {
            return false;
        };
        set_entries.remove(index);
        true
    }

    /// <https://drafts.csswg.org/css-font-loading/#switch-the-fontfaceset-to-loading>
    pub(crate) fn switch_to_loading(&self, cx: &mut JSContext) {
        // Step 1. Let font face set be the given FontFaceSet.
        // Note: This is self.

        // Step 2. Set the status attribute of font face set to "loading".
        // TODO: Implement the FontFaceSet status attribute.

        // Step 3. If font face set’s [[ReadyPromise]] slot currently holds a fulfilled
        // promise, replace it with a fresh pending promise.
        if self.promise.borrow().is_fulfilled() {
            *self.promise.borrow_mut() = Promise::new(cx, &self.global());
        }

        // Step 4. Queue a task to fire a font load event named loading at font face set.
        // TODO: Implement support for font loading events.
    }

    /// Runs the CSS cascade to ensure that new `@font-face` rules have
    /// an entry in this set.
    fn flush_author_font_set(&self, cx: &mut JSContext) {
        // FIXME: Use a new sort of ReflowGoal that only runs the CSS cascade without
        //        building a new box tree or running any sort of layout really.
        //        We query for the box area here, but we're not interested in the result.
        // FIXME: Figure out what to do for worker scopes.
        if let Some(window) = DomRoot::downcast::<Window>(self.global()) {
            let document = window.Document();
            if document.stylesheets_changed_since_last_reflow() {
                window.reflow(cx, ReflowGoal::LayoutQuery(QueryMsg::BoxArea));
            }
        }
    }

    /// Marks the entries corresponding to removed `@font-face` rules as not [css-connected].
    ///
    /// [css-connected]: https://drafts.csswg.org/css-font-loading/#css-connected
    pub(crate) fn notify_font_face_rules_removed(
        &self,
        removed_font_face_rules: &[FontFaceRuleWithOrigin],
    ) {
        let entries = self.set_entries.borrow_mut();
        for removed_font_face_rule in removed_font_face_rules {
            let Some(matching_font_face_object) = entries
                .iter()
                .find(|entry| entry.is_connected_to_font_face_rule(removed_font_face_rule))
            else {
                if cfg!(debug_assertions) {
                    unreachable!("Removed @font-face that was not previously present");
                }
                log::warn!("Removed @font-face that was not previously present");
                continue;
            };

            // https://drafts.csswg.org/css-font-loading/#font-face-css-connection:
            // > If a @font-face rule is removed from the document, its corresponding FontFace object is no longer CSS-connected.
            // > The connection is not restorable by any means.
            matching_font_face_object.disconnect_from_css();
        }
    }
}

impl FontFaceSetMethods<crate::DomTypeHolder> for FontFaceSet {
    /// <https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-ready>
    fn Ready(&self, cx: &mut JSContext) -> Rc<Promise> {
        if self.promise.borrow().is_fulfilled() {
            // There may be pending style changes that cause new web fonts to start loading,
            // re-initializing document.fonts.ready.
            self.flush_author_font_set(cx);
        }
        self.promise.borrow().clone()
    }

    /// <https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-add>
    fn Add(&self, cx: &mut JSContext, font_face: &FontFace) -> Fallible<DomRoot<FontFaceSet>> {
        // Step 1. If font is already in the FontFaceSet’s set entries,
        // skip to the last step of this algorithm immediately.
        if self.contains_face(font_face) {
            return Ok(DomRoot::from_ref(self));
        }

        // Step 2. If font is CSS-connected, throw an InvalidModificationError
        // exception and exit this algorithm immediately.
        if font_face.is_css_connected() {
            return Err(Error::InvalidModification(Some(
                "Cannot add CSS-connected FontFace to FontFaceSet".to_owned(),
            )));
        }

        // Step 3. Add the font argument to the FontFaceSet’s set entries.
        self.set_entries.borrow_mut().push(Dom::from_ref(font_face));
        font_face.set_associated_font_face_set(self);

        // Step 4. If font’s status attribute is "loading":
        // Step 4.1 If the FontFaceSet’s [[LoadingFonts]] list is empty, switch the FontFaceSet to loading.
        // Step 4.2 Append font to the FontFaceSet’s [[LoadingFonts]] list.
        self.handle_font_face_status_changed(cx, font_face);

        // Step 5. Return the FontFaceSet.
        Ok(DomRoot::from_ref(self))
    }

    /// <https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-delete>
    fn Delete(&self, to_delete: &FontFace) -> bool {
        // Step 1. If font is CSS-connected, return false and exit this algorithm immediately.
        if to_delete.is_css_connected() {
            return false;
        }

        // Step 2. Let deleted be the result of removing font from the FontFaceSet’s set entries.
        // TODO: Step 3. If font is present in the FontFaceSet’s [[LoadedFonts]], or [[FailedFonts]] lists, remove it.
        // TODO: Step 4. If font is present in the FontFaceSet’s [[LoadingFonts]] list, remove it. If font was the last
        // item in that list (and so the list is now empty), switch the FontFaceSet to loaded.
        // Step 5. Return deleted.
        self.delete_face(to_delete)
    }

    /// <https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-clear>
    fn Clear(&self, cx: &mut JSContext) {
        self.flush_author_font_set(cx);

        // Step 1. Remove all non-CSS-connected items from the FontFaceSet’s set entries,
        // its [[LoadedFonts]] list, and its [[FailedFonts]] list.
        self.set_entries.borrow_mut().clear();

        // TODO Step 2. If the FontFaceSet’s [[LoadingFonts]] list is non-empty, remove all items from it,
        // then switch the FontFaceSet to loaded.
    }

    /// <https://drafts.csswg.org/css-font-loading/#dom-fontfaceset-load>
    fn Load(&self, cx: &mut JSContext, _font: DOMString, _text: DOMString) -> Rc<Promise> {
        // Step 1. Let font face set be the FontFaceSet object this method was called on. Let
        // promise be a newly-created promise object.
        let load_promise = Promise::new(cx, &self.global());

        // Step 3. Find the matching font faces from font face set using the font and text
        // arguments passed to the function, and let font face list be the return value (ignoring
        // the found faces flag). If a syntax error was returned, reject promise with a SyntaxError
        // exception and terminate these steps.
        //
        // TODO: Implement this.

        #[derive(MallocSizeOf, JSTraceable)]
        struct LoadPromiseFulfillmentHandler {
            #[conditional_malloc_size_of]
            load_promise: Rc<Promise>,
        }
        impl Callback for LoadPromiseFulfillmentHandler {
            fn callback(&self, cx: &mut CurrentRealm, _: Handle<Value>) {
                self.load_promise
                    .resolve_native(cx, &Vec::<&FontFace>::new());
            }
        }

        // Step 4. Queue a task to run the following steps synchronously:
        let trusted_this = Trusted::new(self);
        let trusted_load_promise = TrustedPromise::new(load_promise.clone());
        self.global()
            .task_manager()
            .font_loading_task_source()
            .queue(task!(resolve_font_face_set_load_task: move |cx| {
                let load_promise = trusted_load_promise.root();
                let this = trusted_this.root();

                // Step 4.1. For all of the font faces in the font face list, call their load()
                // method.
                // Step 4.2. Resolve promise with the result of waiting for all of the
                // [[FontStatusPromise]]s of each font face in the font face list, in order.
                //
                // TODO: These steps are not implemented. Instead we wait until all fonts
                // are loaded by resolving the returned promise when
                // `document.fonts.ready` is resolved. The return list of fonts will not
                // be correct, but any code that waits on the promise will have
                // conservatively consistent behavior. This is important for preventing
                // intermittent results in WPT tests.
                let global = this.global();
                let handler = PromiseNativeHandler::new(
                    cx,
                    &global,
                    Some(Box::new(LoadPromiseFulfillmentHandler {
                        load_promise,
                    })),
                    None,
                );

                let ready_promise = this.Ready(cx);
                let mut realm = enter_auto_realm(cx, &*global);
                ready_promise.append_native_handler(&mut realm.current_realm(), &handler);
            }));

        // Step 2. Return promise. Complete the rest of these steps asynchronously.
        load_promise
    }

    /// <https://html.spec.whatwg.org/multipage/#customstateset>
    fn Size(&self, cx: &mut JSContext) -> u32 {
        self.size(cx)
    }
}

impl Setlike for FontFaceSet {
    type Key = DomRoot<FontFace>;

    #[inline(always)]
    fn get_index(&self, cx: &mut JSContext, index: u32) -> Option<Self::Key> {
        self.flush_author_font_set(cx);
        self.set_entries
            .borrow()
            .get(index as usize)
            .map(|face| face.as_rooted())
    }

    #[inline(always)]
    fn size(&self, cx: &mut JSContext) -> u32 {
        self.flush_author_font_set(cx);
        self.set_entries.borrow().len() as u32
    }

    #[inline(always)]
    fn add(&self, _cx: &mut JSContext, face: Self::Key) {
        self.set_entries.borrow_mut().push(face.as_traced());
    }

    #[inline(always)]
    fn has(&self, cx: &mut JSContext, target: Self::Key) -> bool {
        self.flush_author_font_set(cx);
        self.contains_face(&target)
    }

    #[inline(always)]
    fn clear(&self, cx: &mut JSContext) {
        self.flush_author_font_set(cx);
        self.set_entries.borrow_mut().clear();
    }

    #[inline(always)]
    fn delete(&self, cx: &mut JSContext, to_delete: Self::Key) -> bool {
        self.flush_author_font_set(cx);
        self.delete_face(&to_delete)
    }
}