feat: event-stream event for when a screenshot is taken (#2565)

* feat: event-stream event for when a screenshot is taken

* ScreenshotTaken --> ScreenshotCaptured

* review comments

* fix: screenshot completion event path serializatation

* fixes

---------

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

niri-ipc/src/lib.rs

@@ -1483,6 +1483,14 @@ pub enum Event {
         /// For example, the config file couldn't be parsed.
         failed: bool,
     },
+    /// A screenshot was captured.
+    ScreenshotCaptured {
+        /// The file path where the screenshot was saved, if it was written to disk.
+        ///
+        /// If `None`, the screenshot was either only copied to the clipboard, or the path couldn't
+        /// be converted to a `String` (e.g. contained invalid UTF-8 bytes).
+        path: Option<String>,
+    },
 }
 
 impl FromStr for WorkspaceReferenceArg {

src/ipc/client.rs

@@ -481,6 +481,15 @@ pub fn handle_msg(mut msg: Msg, json: bool) -> anyhow::Result<()> {
                         };
                         println!("Config loaded {status}");
                     }
+                    Event::ScreenshotCaptured { path } => {
+                        let mut parts = vec![];
+                        parts.push("copied to clipboard".to_string());
+                        if let Some(path) = &path {
+                            parts.push(format!("saved to {path}"));
+                        }
+                        let description = parts.join(" and ");
+                        println!("Screenshot captured: {description}");
+                    }
                 }
             }
         }

src/ipc/server.rs

@@ -792,4 +792,15 @@ impl State {
         state.apply(event.clone());
         server.send_event(event);
     }
+
+    pub fn ipc_screenshot_taken(&mut self, path: Option<String>) {
+        let Some(server) = &self.niri.ipc_server else {
+            return;
+        };
+        let mut state = server.event_stream_state.borrow_mut();
+
+        let event = Event::ScreenshotCaptured { path };
+        state.apply(event.clone());
+        server.send_event(event);
+    }
 }

src/niri.rs

@@ -5643,6 +5643,17 @@ impl Niri {
             })
             .unwrap();
 
+        // Prepare to send screenshot completion event back to main thread.
+        let (event_tx, event_rx) = calloop::channel::sync_channel::<Option<String>>(1);
+        self.event_loop
+            .insert_source(event_rx, move |event, _, state| match event {
+                calloop::channel::Event::Msg(path) => {
+                    state.ipc_screenshot_taken(path);
+                }
+                calloop::channel::Event::Closed => (),
+            })
+            .unwrap();
+
         // Encode and save the image in a thread as it's slow.
         thread::spawn(move || {
             let mut buf = vec![];
@@ -5685,11 +5696,16 @@ impl Niri {
             }
 
             #[cfg(feature = "dbus")]
-            if let Err(err) = crate::utils::show_screenshot_notification(image_path) {
+            if let Err(err) = crate::utils::show_screenshot_notification(image_path.as_deref()) {
                 warn!("error showing screenshot notification: {err:?}");
             }
-            #[cfg(not(feature = "dbus"))]
-            drop(image_path);
+
+            // Send screenshot completion event.
+            let path_string = image_path
+                .as_ref()
+                .and_then(|p| p.to_str())
+                .map(|s| s.to_owned());
+            let _ = event_tx.send(path_string);
         });
 
         Ok(())

src/utils/mod.rs

@@ -461,7 +461,7 @@ pub fn baba_is_float_offset(now: Duration, view_height: f64) -> f64 {
 }
 
 #[cfg(feature = "dbus")]
-pub fn show_screenshot_notification(image_path: Option<PathBuf>) -> anyhow::Result<()> {
+pub fn show_screenshot_notification(image_path: Option<&Path>) -> anyhow::Result<()> {
     use std::collections::HashMap;
 
     use zbus::zvariant;