Implement `niri msg pick-window`

* feat: `niri msg pick-window`

* fixes

---------

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

6 files changed, 240 insertions, 1 deletions

diff --git a/src/cli.rs b/src/cli.rs
index 041b0343..9b106485 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -72,6 +72,8 @@ pub enum Msg {
     FocusedOutput,
     /// Print information about the focused window.
     FocusedWindow,
+    /// Pick a window with the mouse and print information about it.
+    PickWindow,
     /// Perform an action.
     Action {
         #[command(subcommand)]
diff --git a/src/input/mod.rs b/src/input/mod.rs
index 51555a96..8e22098c 100644
--- a/src/input/mod.rs
+++ b/src/input/mod.rs
@@ -48,6 +48,7 @@ use crate::utils::{center, get_monotonic_time, ResizeEdge};
 
 pub mod backend_ext;
 pub mod move_grab;
+pub mod pick_window_grab;
 pub mod resize_grab;
 pub mod scroll_tracker;
 pub mod spatial_movement_grab;
@@ -367,7 +368,6 @@ impl State {
             serial,
             time,
             |this, mods, keysym| {
-                let bindings = &this.niri.config.borrow().binds;
                 let key_code = event.key_code();
                 let modified = keysym.modified_sym();
                 let raw = keysym.raw_latin_sym_or_raw_current_sym();
@@ -383,6 +383,19 @@ impl State {
                     }
                 }
 
+                if pressed && raw == Some(Keysym::Escape) && this.niri.pick_window.is_some() {
+                    // We window picking state so the pick window grab must be active.
+                    // Unsetting it cancels window picking.
+                    this.niri
+                        .seat
+                        .get_pointer()
+                        .unwrap()
+                        .unset_grab(this, serial, time);
+                    this.niri.suppressed_keys.insert(key_code);
+                    return FilterResult::Intercept(None);
+                }
+
+                let bindings = &this.niri.config.borrow().binds;
                 should_intercept_key(
                     &mut this.niri.suppressed_keys,
                     bindings,
diff --git a/src/input/pick_window_grab.rs b/src/input/pick_window_grab.rs
new file mode 100644
index 00000000..9a3b22ae
--- /dev/null
+++ b/src/input/pick_window_grab.rs
@@ -0,0 +1,167 @@
+use smithay::backend::input::ButtonState;
+use smithay::input::pointer::{
+    AxisFrame, ButtonEvent, CursorImageStatus, GestureHoldBeginEvent, GestureHoldEndEvent,
+    GesturePinchBeginEvent, GesturePinchEndEvent, GesturePinchUpdateEvent, GestureSwipeBeginEvent,
+    GestureSwipeEndEvent, GestureSwipeUpdateEvent, GrabStartData as PointerGrabStartData,
+    MotionEvent, PointerGrab, PointerInnerHandle, RelativeMotionEvent,
+};
+use smithay::input::SeatHandler;
+use smithay::utils::{Logical, Point};
+
+use crate::niri::State;
+use crate::window::Mapped;
+
+pub struct PickWindowGrab {
+    start_data: PointerGrabStartData<State>,
+}
+
+impl PickWindowGrab {
+    pub fn new(start_data: PointerGrabStartData<State>) -> Self {
+        Self { start_data }
+    }
+
+    fn on_ungrab(&mut self, state: &mut State) {
+        if let Some(tx) = state.niri.pick_window.take() {
+            let _ = tx.send_blocking(None);
+        }
+        state
+            .niri
+            .cursor_manager
+            .set_cursor_image(CursorImageStatus::default_named());
+        // Redraw to update the cursor.
+        state.niri.queue_redraw_all();
+    }
+}
+
+impl PointerGrab<State> for PickWindowGrab {
+    fn motion(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        _focus: Option<(<State as SeatHandler>::PointerFocus, Point<f64, Logical>)>,
+        event: &MotionEvent,
+    ) {
+        handle.motion(data, None, event);
+    }
+
+    fn relative_motion(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        _focus: Option<(<State as SeatHandler>::PointerFocus, Point<f64, Logical>)>,
+        event: &RelativeMotionEvent,
+    ) {
+        handle.relative_motion(data, None, event);
+    }
+
+    fn button(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &ButtonEvent,
+    ) {
+        if event.state == ButtonState::Pressed {
+            if let Some(tx) = data.niri.pick_window.take() {
+                let _ = tx.send_blocking(
+                    data.niri
+                        .window_under(handle.current_location())
+                        .map(Mapped::id),
+                );
+            }
+            handle.unset_grab(self, data, event.serial, event.time, true);
+        }
+    }
+
+    fn axis(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        details: AxisFrame,
+    ) {
+        handle.axis(data, details);
+    }
+
+    fn frame(&mut self, data: &mut State, handle: &mut PointerInnerHandle<'_, State>) {
+        handle.frame(data);
+    }
+
+    fn gesture_swipe_begin(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &GestureSwipeBeginEvent,
+    ) {
+        handle.gesture_swipe_begin(data, event);
+    }
+
+    fn gesture_swipe_update(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &GestureSwipeUpdateEvent,
+    ) {
+        handle.gesture_swipe_update(data, event);
+    }
+
+    fn gesture_swipe_end(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &GestureSwipeEndEvent,
+    ) {
+        handle.gesture_swipe_end(data, event);
+    }
+
+    fn gesture_pinch_begin(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &GesturePinchBeginEvent,
+    ) {
+        handle.gesture_pinch_begin(data, event);
+    }
+
+    fn gesture_pinch_update(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &GesturePinchUpdateEvent,
+    ) {
+        handle.gesture_pinch_update(data, event);
+    }
+
+    fn gesture_pinch_end(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &GesturePinchEndEvent,
+    ) {
+        handle.gesture_pinch_end(data, event);
+    }
+
+    fn gesture_hold_begin(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &GestureHoldBeginEvent,
+    ) {
+        handle.gesture_hold_begin(data, event);
+    }
+
+    fn gesture_hold_end(
+        &mut self,
+        data: &mut State,
+        handle: &mut PointerInnerHandle<'_, State>,
+        event: &GestureHoldEndEvent,
+    ) {
+        handle.gesture_hold_end(data, event);
+    }
+
+    fn start_data(&self) -> &PointerGrabStartData<State> {
+        &self.start_data
+    }
+
+    fn unset(&mut self, data: &mut State) {
+        self.on_ungrab(data);
+    }
+}
diff --git a/src/ipc/client.rs b/src/ipc/client.rs
index 8682d8d3..66cdaf7d 100644
--- a/src/ipc/client.rs
+++ b/src/ipc/client.rs
@@ -19,6 +19,7 @@ pub fn handle_msg(msg: Msg, json: bool) -> anyhow::Result<()> {
         Msg::Outputs => Request::Outputs,
         Msg::FocusedWindow => Request::FocusedWindow,
         Msg::FocusedOutput => Request::FocusedOutput,
+        Msg::PickWindow => Request::PickWindow,
         Msg::Action { action } => Request::Action(action.clone()),
         Msg::Output { output, action } => Request::Output {
             output: output.clone(),
@@ -252,6 +253,23 @@ pub fn handle_msg(msg: Msg, json: bool) -> anyhow::Result<()> {
                 println!("No output is focused.");
             }
         }
+        Msg::PickWindow => {
+            let Response::PickedWindow(window) = response else {
+                bail!("unexpected response: expected PickedWindow, got {response:?}");
+            };
+
+            if json {
+                let window = serde_json::to_string(&window).context("error formatting response")?;
+                println!("{window}");
+                return Ok(());
+            }
+
+            if let Some(window) = window {
+                print_window(&window);
+            } else {
+                println!("No window selected.");
+            }
+        }
         Msg::Action { .. } => {
             let Response::Handled = response else {
                 bail!("unexpected response: expected Handled, got {response:?}");
diff --git a/src/ipc/server.rs b/src/ipc/server.rs
index 6706928a..c8f8edcf 100644
--- a/src/ipc/server.rs
+++ b/src/ipc/server.rs
@@ -18,12 +18,17 @@ use niri_config::OutputName;
 use niri_ipc::state::{EventStreamState, EventStreamStatePart as _};
 use niri_ipc::{Event, KeyboardLayouts, OutputConfigChanged, Reply, Request, Response, Workspace};
 use smithay::desktop::layer_map_for_output;
+use smithay::input::pointer::{
+    CursorIcon, CursorImageStatus, Focus, GrabStartData as PointerGrabStartData,
+};
 use smithay::reexports::calloop::generic::Generic;
 use smithay::reexports::calloop::{Interest, LoopHandle, Mode, PostAction};
 use smithay::reexports::rustix::fs::unlink;
+use smithay::utils::SERIAL_COUNTER;
 use smithay::wayland::shell::wlr_layer::{KeyboardInteractivity, Layer};
 
 use crate::backend::IpcOutputMap;
+use crate::input::pick_window_grab::PickWindowGrab;
 use crate::layout::workspace::WorkspaceId;
 use crate::niri::State;
 use crate::utils::{version, with_toplevel_role};
@@ -322,6 +327,35 @@ async fn process(ctx: &ClientCtx, request: Request) -> Reply {
             let window = windows.values().find(|win| win.is_focused).cloned();
             Response::FocusedWindow(window)
         }
+        Request::PickWindow => {
+            let (tx, rx) = async_channel::bounded(1);
+            ctx.event_loop.insert_idle(move |state| {
+                let pointer = state.niri.seat.get_pointer().unwrap();
+                let start_data = PointerGrabStartData {
+                    focus: None,
+                    button: 0,
+                    location: pointer.current_location(),
+                };
+                let grab = PickWindowGrab::new(start_data);
+                // The `WindowPickGrab` ungrab handler will cancel the previous ongoing pick, if
+                // any.
+                pointer.set_grab(state, grab, SERIAL_COUNTER.next_serial(), Focus::Clear);
+                state.niri.pick_window = Some(tx);
+                state
+                    .niri
+                    .cursor_manager
+                    .set_cursor_image(CursorImageStatus::Named(CursorIcon::Crosshair));
+                // Redraw to update the cursor.
+                state.niri.queue_redraw_all();
+            });
+            let result = rx.recv().await;
+            let id = result.map_err(|_| String::from("error getting picked window info"))?;
+            let window = id.and_then(|id| {
+                let state = ctx.event_stream_state.borrow();
+                state.windows.windows.get(&id.get()).cloned()
+            });
+            Response::PickedWindow(window)
+        }
         Request::Action(action) => {
             let (tx, rx) = async_channel::bounded(1);
 
diff --git a/src/niri.rs b/src/niri.rs
index b013927b..f3b6d3c2 100644
--- a/src/niri.rs
+++ b/src/niri.rs
@@ -159,6 +159,7 @@ use crate::utils::{
     center, center_f64, expand_home, get_monotonic_time, ipc_transform_to_smithay, logical_output,
     make_screenshot_path, output_matches_name, output_size, send_scale_transform, write_png_rgba8,
 };
+use crate::window::mapped::MappedId;
 use crate::window::{InitialConfigureState, Mapped, ResolvedWindowRules, Unmapped, WindowRef};
 
 const CLEAR_COLOR_LOCKED: [f32; 4] = [0.3, 0.1, 0.1, 1.];
@@ -356,6 +357,8 @@ pub struct Niri {
     pub hotkey_overlay: HotkeyOverlay,
     pub exit_confirm_dialog: Option<ExitConfirmDialog>,
 
+    pub pick_window: Option<async_channel::Sender<Option<MappedId>>>,
+
     pub debug_draw_opaque_regions: bool,
     pub debug_draw_damage: bool,
 
@@ -2172,6 +2175,8 @@ impl Niri {
             hotkey_overlay,
             exit_confirm_dialog,
 
+            pick_window: None,
+
             debug_draw_opaque_regions: false,
             debug_draw_damage: false,