feat(volume-keys): capture on hardware volume buttons

Author: FreddyFunk

io.github.cosmic_utils.camera.yml

@@ -17,7 +17,10 @@ finish-args:
   - --socket=fallback-x11
   # Webcam access (currently no better option than this)
   # https://docs.flatpak.org/en/latest/sandbox-permissions.html#device-access
-  # Automatically includes GPU support since "dri" is part of "all"
+  # Automatically includes GPU support since "dri" is part of "all".
+  # Also exposes /dev/input/event*, which the haptic backend uses for
+  # vibration and the volume_keys backend reads as a shutter trigger on
+  # phones.
   - --device=all
   # Home directory access for saving photos/videos
   - --filesystem=xdg-pictures:rw

src/app/mod.rs

@@ -1588,6 +1588,43 @@ impl cosmic::Application for AppModel {
             )
         };
 
+        // Volume-key shutter on phones: the compositor swallows the keys
+        // for system audio so they never reach iced as keyboard events.
+        // The `volume_keys` backend reads `/dev/input/event*` directly,
+        // grabs each device exclusively while the window is focused
+        // (so the compositor doesn't *also* change the volume) and
+        // forwards presses as `Message::Capture` — same as the spacebar.
+        let volume_keys_sub = subscription_with_id(
+            "volume_keys",
+            cosmic::iced::stream::channel(8, async move |mut output| {
+                let mut rx = crate::backends::volume_keys::start();
+                while let Some(_key) = rx.recv().await {
+                    if output.send(Message::Capture).await.is_err() {
+                        break;
+                    }
+                }
+            }),
+        );
+
+        // Translate Wayland keyboard-focus transitions for the camera
+        // window into `WindowFocusChanged` messages; the update handler
+        // forwards them into the volume_keys backend so we only grab the
+        // hardware shutter buttons while the camera is in focus.
+        let window_focus_sub = subscription::filter_map("window_focus", |event| {
+            let subscription::Event::Interaction { event, .. } = event else {
+                return None;
+            };
+            match event {
+                cosmic::iced::Event::Window(cosmic::iced::window::Event::Focused) => {
+                    Some(Message::WindowFocusChanged(true))
+                }
+                cosmic::iced::Event::Window(cosmic::iced::window::Event::Unfocused) => {
+                    Some(Message::WindowFocusChanged(false))
+                }
+                _ => None,
+            }
+        });
+
         Subscription::batch([
             config_sub,
             camera_sub,
@@ -1602,6 +1639,8 @@ impl cosmic::Application for AppModel {
             audio_level_sub,
             portal_theme_sub,
             keybind_sub,
+            volume_keys_sub,
+            window_focus_sub,
         ])
     }
 

src/app/state.rs

@@ -1575,6 +1575,10 @@ pub enum Message {
     FitAnimationTick,
     /// Animation tick for the zoom-reset transition
     ZoomAnimationTick,
+    /// Wayland keyboard-focus changed for the app window. Toggles the
+    /// volume-key `EVIOCGRAB` and dispatch gate so we only consume the
+    /// hardware shutter buttons while the camera is in focus.
+    WindowFocusChanged(bool),
     /// Window control: close
     WindowClose,
     /// Window control: minimize

src/app/update.rs

@@ -215,6 +215,11 @@ impl AppModel {
                 self.zoom_animation.map(|a| a.start.elapsed()),
                 |s| s.zoom_animation = None,
             ),
+            Message::WindowFocusChanged(focused) => {
+                info!(focused, "WindowFocusChanged");
+                crate::backends::volume_keys::set_focused(focused);
+                Task::none()
+            }
             Message::WindowClose => self.handle_window_close(),
             Message::WindowMinimize => self.core.minimize(None),
             Message::WindowToggleMaximize => self.core.toggle_maximize(None),

src/backends/mod.rs

@@ -40,3 +40,4 @@ pub mod audio;
 pub mod camera;
 pub mod haptic;
 pub mod virtual_camera;
+pub mod volume_keys;