1 files changed, 64 insertions, 0 deletions
diff --git a/crates/core/src/manager/input_pin.rs b/crates/core/src/manager/input_pin.rs
new file mode 100644
index 0000000..e3a7fbf
--- /dev/null
+++ b/crates/core/src/manager/input_pin.rs
@@ -0,0 +1,64 @@
+//! Requesting a virtual-pointer pin to a specific window - Phase 2 of
+//! this project's own multi-cursor plan (see `docs/TODO.md`'s "Multi-
+//! cursor Phase 2" entry, and `crates/wayland/src/virtual_pointer.rs`'s
+//! own module doc comment for the full design). Split out the same way
+//! `lock.rs` is: everything here is plain `impl WindowManager` methods:
+//! see `super` (`mod.rs`) for `WindowManager`'s field definitions.
+
+use super::*;
+
+impl WindowManager {
+    /// Queues a request to pin (`window` is `Some`) or unpin (`None`)
+    /// every virtual pointer object owned by the client with process id
+    /// `pid` - the only caller today is the IPC `"pin_input"` dispatch,
+    /// the compositor-agnostic side of `srd dispatch pin input`/`unpin
+    /// input`. Core has no real Wayland protocol object to reach into
+    /// itself (that's backend-owned, same as `output_position_requests`);
+    /// the Wayland backend drains and applies this on its own next poll.
+    ///
+    /// Replaces (not accumulates) any still-pending request for the same
+    /// `pid`, the same "last write wins" semantics `request_output_
+    /// position` already has - only the *latest* requested pin for a
+    /// given pid matters if several arrive before the backend's next
+    /// drain.
+    pub fn request_pin_input(&mut self, pid: i32, window: Option<WindowId>) {
+        self.pin_input_requests.retain(|(existing, _)| *existing != pid);
+        self.pin_input_requests.push((pid, window));
+    }
+
+    /// Takes every currently-queued pin-input request, leaving the queue
+    /// empty. The backend calls this once per poll, same as `drain_
+    /// output_position_requests`.
+    pub fn drain_pin_input_requests(&mut self) -> Vec<(i32, Option<WindowId>)> {
+        std::mem::take(&mut self.pin_input_requests)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn a_pin_request_is_reported_once_then_the_queue_is_empty() {
+        let mut wm = WindowManager::new();
+        assert!(wm.drain_pin_input_requests().is_empty());
+        wm.request_pin_input(1234, Some(7));
+        assert_eq!(wm.drain_pin_input_requests(), vec![(1234, Some(7))]);
+        assert!(wm.drain_pin_input_requests().is_empty());
+    }
+
+    #[test]
+    fn a_second_request_for_the_same_pid_replaces_the_first_before_a_drain() {
+        let mut wm = WindowManager::new();
+        wm.request_pin_input(1234, Some(7));
+        wm.request_pin_input(1234, Some(9));
+        assert_eq!(wm.drain_pin_input_requests(), vec![(1234, Some(9))]);
+    }
+
+    #[test]
+    fn unpinning_is_a_real_queued_request_too_not_a_no_op() {
+        let mut wm = WindowManager::new();
+        wm.request_pin_input(1234, None);
+        assert_eq!(wm.drain_pin_input_requests(), vec![(1234, None)]);
+    }
+}