Bug 1707584 - part2 : implement :seeking pseudo class. r=media-playback-reviewers,firefox-style-system-reviewers,emilio,chunmin

alastor0325 · alastor0325 · commit 90eb82c617c1 · 2026-02-06T22:58:46.000Z
Per spec [1], :seeking should be set once `seeking attribute is true`, so the state needs to be setup in HTMLMediaElement::Seek() immediatley, so that the script can see the state applied right after updating the media's current time. [1] https://html.spec.whatwg.org/multipage/semantics-other.html#selector-seeking Differential Revision: https://phabricator.services.mozilla.com/D281038
diff --git a/dom/base/rust/lib.rs b/dom/base/rust/lib.rs
@@ -7,7 +7,7 @@
 use bitflags::bitflags;
 use malloc_size_of::malloc_size_of_is_0;
 
-pub const HEADING_LEVEL_OFFSET: usize = 53;
+pub const HEADING_LEVEL_OFFSET: usize = 54;
 
 bitflags! {
     /// Event-based element states.
@@ -146,6 +146,8 @@ bitflags! {
         const SUPPRESS_FOR_PRINT_SELECTION = 1u64 << 51;
         /// https://html.spec.whatwg.org/multipage/semantics-other.html#selector-paused
         const PAUSED = 1u64 << 52;
+        /// https://html.spec.whatwg.org/multipage/semantics-other.html#selector-seeking
+        const SEEKING = 1u64 << 53;
         /// https://drafts.csswg.org/selectors-5/#headings
         /// These 4 bits are used to pack the elements heading level into the element state
         /// Heading levels can be from 1-9 so 4 bits allows us to express the full range.
diff --git a/dom/media/mediaelement/HTMLMediaElement.cpp b/dom/media/mediaelement/HTMLMediaElement.cpp
@@ -2474,6 +2474,11 @@ void HTMLMediaElement::AbortExistingLoads() {
 
   if (mDecoder) {
     fireTimeUpdate = mDecoder->GetCurrentTime() != 0.0;
+    // When aborting during seeking, remove the seeking state since the decoder
+    // won't call SeekCompleted() or SeekAborted() after being shut down.
+    if (Seeking()) {
+      RemoveStates(ElementState::SEEKING);
+    }
     ShutdownDecoder();
   }
   if (mSrcStream) {
@@ -3555,6 +3560,7 @@ void HTMLMediaElement::Seek(double aTime, SeekTarget::Type aSeekType,
   // The media backend is responsible for dispatching the timeupdate
   // event if it changes the playback position as a result of the seek.
   LOG(LogLevel::Debug, ("%p SetCurrentTime(%f) starting seek", this, aTime));
+  AddStates(ElementState::SEEKING);
   mDecoder->Seek(aTime, aSeekType);
 
   // We changed whether we're seeking so we need to AddRemoveSelfReference.
@@ -6182,6 +6188,7 @@ void HTMLMediaElement::SeekCompleted() {
   // (Step 16)
   // TODO (bug 1688131): run these steps in a stable state.
   FireTimeUpdate(TimeupdateType::eMandatory);
+  RemoveStates(ElementState::SEEKING);
   QueueEvent(u"seeked"_ns);
   // We changed whether we're seeking so we need to AddRemoveSelfReference
   AddRemoveSelfReference();
@@ -6199,6 +6206,7 @@ void HTMLMediaElement::SeekCompleted() {
 }
 
 void HTMLMediaElement::SeekAborted() {
+  RemoveStates(ElementState::SEEKING);
   if (mSeekDOMPromise) {
     AbstractMainThread()->Dispatch(NS_NewRunnableFunction(
         __func__, [promise = std::move(mSeekDOMPromise)] {
diff --git a/servo/components/style/gecko/non_ts_pseudo_class_list.rs b/servo/components/style/gecko/non_ts_pseudo_class_list.rs
@@ -95,6 +95,7 @@ macro_rules! apply_non_ts_list {
                 // Media element pseudo classes
                 ("paused", Paused, PAUSED, _),
                 ("playing", Playing, PAUSED, _),
+                ("seeking", Seeking, SEEKING, _),
 
 
                 // NOTE(emilio): Pseudo-classes below only depend on document state, and thus
diff --git a/servo/components/style/gecko/selector_parser.rs b/servo/components/style/gecko/selector_parser.rs
@@ -227,7 +227,7 @@ impl NonTSPseudoClass {
         if matches!(*self, Self::Heading(..)) {
             return static_prefs::pref!("layout.css.heading-selector.enabled");
         }
-        if matches!(*self, Self::Playing | Self::Paused) {
+        if matches!(*self, Self::Playing | Self::Paused | Self::Seeking) {
             return static_prefs::pref!("dom.media.pseudo-classes.enabled");
         }
         !self.has_any_flag(NonTSPseudoClassFlag::PSEUDO_CLASS_ENABLED_IN_UA_SHEETS_AND_CHROME)
diff --git a/servo/components/style/gecko/wrapper.rs b/servo/components/style/gecko/wrapper.rs
@@ -2085,7 +2085,8 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
             | NonTSPseudoClass::MozRevealed
             | NonTSPseudoClass::ActiveViewTransition
             | NonTSPseudoClass::MozValueEmpty
-            | NonTSPseudoClass::MozSuppressForPrintSelection => {
+            | NonTSPseudoClass::MozSuppressForPrintSelection
+            | NonTSPseudoClass::Seeking => {
                 self.state().intersects(pseudo_class.state_flag())
             },
             NonTSPseudoClass::Paused => self.is_html_media_element() && self.state().intersects(ElementState::PAUSED),
diff --git a/testing/web-platform/meta/css/selectors/invalidation/media-pseudo-classes-in-has.html.ini b/testing/web-platform/meta/css/selectors/invalidation/media-pseudo-classes-in-has.html.ini
@@ -1,7 +1,4 @@
 [media-pseudo-classes-in-has.html]
   prefs: [dom.media.pseudo-classes.enabled:true]
-  [Test :seeking pseudo-class]
-    expected: FAIL
-
   [Test :muted pseudo-class]
     expected: FAIL
diff --git a/testing/web-platform/meta/css/selectors/media/media-playback-state-timing.html.ini b/testing/web-platform/meta/css/selectors/media/media-playback-state-timing.html.ini
diff --git a/testing/web-platform/meta/css/selectors/media/media-playback-state.html.ini b/testing/web-platform/meta/css/selectors/media/media-playback-state.html.ini
diff --git a/testing/web-platform/tests/css/selectors/media/media-playback-state.html b/testing/web-platform/tests/css/selectors/media/media-playback-state.html
@@ -75,7 +75,7 @@
     }, "Test :seeking pseudo-class");
 
     test((t) => {
-      const pseudoClasses = [":playing", ":paused"];
+      const pseudoClasses = [":playing", ":paused", ":seeking"];
       const div = document.createElement("div");
       document.body.appendChild(div);
       t.add_cleanup(() => div.remove());
@@ -84,6 +84,6 @@
         assert_false(div.matches(pseudo));
         assert_true(div.matches(`:not(${pseudo})`));
       }
-    }, "Test that non-media elements do not match :playing or :paused");
+     }, "Test that non-media elements do not match :playing, :paused, or :seeking");
   </script>
 </body>

Original file line number	Diff line number	Diff line change
`@@ -227,7 +227,7 @@ impl NonTSPseudoClass {`
`227`	`227`	`if matches!(*self, Self::Heading(..)) {`
`228`	`228`	`return static_prefs::pref!("layout.css.heading-selector.enabled");`
`229`	`229`	`}`
`230`		`- if matches!(*self, Self::Playing \| Self::Paused) {`
	`230`	`+ if matches!(*self, Self::Playing \| Self::Paused \| Self::Seeking) {`
`231`	`231`	`return static_prefs::pref!("dom.media.pseudo-classes.enabled");`
`232`	`232`	`}`
`233`	`233`	`!self.has_any_flag(NonTSPseudoClassFlag::PSEUDO_CLASS_ENABLED_IN_UA_SHEETS_AND_CHROME)`