Stop animations when window is hidden (API + UWP)

components/compositing/lib.rs

@@ -110,6 +110,8 @@ pub enum ConstellationMsg {
     ExitFullScreen(TopLevelBrowsingContextId),
     /// Media session action.
     MediaSessionAction(MediaSessionActionType),
+    /// Toggle browser visibility.
+    ChangeBrowserVisibility(TopLevelBrowsingContextId, bool),
 }
 
 impl fmt::Debug for ConstellationMsg {
@@ -141,6 +143,7 @@ impl fmt::Debug for ConstellationMsg {
             DisableProfiler => "DisableProfiler",
             ExitFullScreen(..) => "ExitFullScreen",
             MediaSessionAction(..) => "MediaSessionAction",
+            ChangeBrowserVisibility(..) => "ChangeBrowserVisibility",
         };
         write!(formatter, "ConstellationMsg::{}", variant)
     }

components/compositing/windowing.rs

@@ -105,6 +105,8 @@ pub enum WindowEvent {
     /// Sent when the user triggers a media action through the UA exposed media UI
     /// (play, pause, seek, etc.).
     MediaSessionAction(MediaSessionActionType),
+    /// Set browser visibility. A hidden browser will not tick the animations.
+    ChangeBrowserVisibility(TopLevelBrowsingContextId, bool),
 }
 
 impl Debug for WindowEvent {
@@ -136,6 +138,7 @@ impl Debug for WindowEvent {
             WindowEvent::ToggleSamplingProfiler(..) => write!(f, "ToggleSamplingProfiler"),
             WindowEvent::ExitFullScreen(..) => write!(f, "ExitFullScreen"),
             WindowEvent::MediaSessionAction(..) => write!(f, "MediaSessionAction"),
+            WindowEvent::ChangeBrowserVisibility(..) => write!(f, "ChangeBrowserVisibility"),
         }
     }
 }

components/constellation/constellation.rs

@@ -1681,6 +1681,9 @@ where
             FromCompositorMsg::MediaSessionAction(action) => {
                 self.handle_media_session_action_msg(action);
             },
+            FromCompositorMsg::ChangeBrowserVisibility(top_level_browsing_context_id, visible) => {
+                self.handle_change_browser_visibility(top_level_browsing_context_id, visible);
+            },
         }
     }
 
@@ -4276,6 +4279,32 @@ where
         }
     }
 
+    fn handle_change_browser_visibility(
+        &mut self,
+        top_level_browsing_context_id: TopLevelBrowsingContextId,
+        visible: bool,
+    ) {
+        let browsing_context_id = BrowsingContextId::from(top_level_browsing_context_id);
+        let pipeline_id = match self.browsing_contexts.get(&browsing_context_id) {
+            Some(browsing_context) => browsing_context.pipeline_id,
+            None => {
+                return warn!(
+                    "Browsing context {} got visibility change event after closure.",
+                    browsing_context_id
+                );
+            },
+        };
+        match self.pipelines.get(&pipeline_id) {
+            None => {
+                return warn!(
+                    "Pipeline {} got visibility change event after closure.",
+                    pipeline_id
+                )
+            },
+            Some(pipeline) => pipeline.notify_visibility(visible),
+        };
+    }
+
     fn notify_history_changed(&self, top_level_browsing_context_id: TopLevelBrowsingContextId) {
         // Send a flat projection of the history to embedder.
         // The final vector is a concatenation of the LoadData of the past

components/servo/lib.rs

@@ -735,6 +735,19 @@ where
                     );
                 }
             },
+
+            WindowEvent::ChangeBrowserVisibility(top_level_browsing_context_id, visible) => {
+                let msg = ConstellationMsg::ChangeBrowserVisibility(
+                    top_level_browsing_context_id,
+                    visible,
+                );
+                if let Err(e) = self.constellation_chan.send(msg) {
+                    warn!(
+                        "Sending ChangeBrowserVisibility to constellation failed ({:?}).",
+                        e
+                    );
+                }
+            },
         }
     }
 

ports/libsimpleservo/api/src/lib.rs

@@ -487,6 +487,17 @@ impl ServoGlue {
         self.process_event(WindowEvent::MediaSessionAction(action))
     }
 
+    pub fn change_visibility(&mut self, visible: bool) -> Result<(), &'static str> {
+        info!("change_visibility");
+        if let Ok(id) = self.get_browser_id() {
+            let event = WindowEvent::ChangeBrowserVisibility(id, visible);
+            self.process_event(event)
+        } else {
+            // Ignore visibility change if no browser has been created yet.
+            Ok(())
+        }
+    }
+
     fn process_event(&mut self, event: WindowEvent) -> Result<(), &'static str> {
         self.events.push(event);
         if !self.batch_mode {

ports/libsimpleservo/capi/src/lib.rs

@@ -686,6 +686,14 @@ pub extern "C" fn media_session_action(action: CMediaSessionActionType) {
     });
 }
 
+#[no_mangle]
+pub extern "C" fn change_visibility(visible: bool) {
+    catch_any_panic(|| {
+        debug!("change_visibility");
+        call(|s| s.change_visibility(visible));
+    });
+}
+
 pub struct WakeupCallback(extern "C" fn());
 
 impl WakeupCallback {

support/hololens/ServoApp/BrowserPage.cpp

@@ -71,6 +71,10 @@ void BrowserPage::BindServoEvents() {
                 ? Visibility::Collapsed
                 : Visibility::Visible);
       });
+  Window::Current().VisibilityChanged(
+      [=](const auto &, const VisibilityChangedEventArgs &args) {
+        servoControl().ChangeVisibility(args.Visible());
+      });
 }
 
 void BrowserPage::OnURLFocused(Windows::Foundation::IInspectable const &) {

support/hololens/ServoApp/ServoControl/Servo.h

@@ -56,6 +56,7 @@ public:
   void Reload() { capi::reload(); }
   void Stop() { capi::stop(); }
   bool LoadUri(hstring uri) { return capi::load_uri(*hstring2char(uri)); }
+  void ChangeVisibility(bool visible) { capi::change_visibility(visible); }
   bool IsUriValid(hstring uri) {
     return capi::is_uri_valid(*hstring2char(uri));
   }

support/hololens/ServoApp/ServoControl/ServoControl.cpp

@@ -247,6 +247,9 @@ void ServoControl::GoForward() {
 void ServoControl::Reload() {
   RunOnGLThread([=] { mServo->Reload(); });
 }
+void ServoControl::ChangeVisibility(bool visible) {
+  RunOnGLThread([=] { mServo->ChangeVisibility(visible); });
+}
 void ServoControl::Stop() {
   RunOnGLThread([=] { mServo->Stop(); });
 }

support/hololens/ServoApp/ServoControl/ServoControl.h

@@ -13,6 +13,7 @@ struct ServoControl : ServoControlT<ServoControl>, public servo::ServoDelegate {
   void GoForward();
   void Reload();
   void Stop();
+  void ChangeVisibility(bool);
   void Shutdown();
   hstring LoadURIOrSearch(hstring);
   void SendMediaSessionAction(int32_t);

support/hololens/ServoApp/ServoControl/ServoControl.idl

@@ -14,6 +14,7 @@ namespace ServoApp {
       void SetTransientMode(Boolean transient);
       void SetArgs(String args);
       void Shutdown();
+      void ChangeVisibility(Boolean visible);
       void SendMediaSessionAction(UInt32 action);
       event EventDelegate OnLoadStarted;
       event EventDelegate OnLoadEnded;