Detect mouse leaving the window (#1679)

* Detect mouse leaving the window

* Implement leave

* Use new API

* Fix mouse leave

* Fix mouse leave on Wayland

* Mouse leave on X11

* Detect mouse leaving window on macOS

* Fix example

refs:  #1434

wezterm-gui/src/termwindow/mod.rs

@@ -837,6 +837,10 @@ impl TermWindow {
                 self.mouse_event_impl(event, window);
                 Ok(true)
             }
+            WindowEvent::MouseLeave => {
+                self.mouse_leave_impl(window);
+                Ok(true)
+            }
             WindowEvent::Resized {
                 dimensions,
                 window_state,

wezterm-gui/src/termwindow/mouseevent.rs

@@ -199,6 +199,11 @@ impl super::TermWindow {
         }
     }
 
+    pub fn mouse_leave_impl(&mut self, context: &dyn WindowOps) {
+        self.current_mouse_event = None;
+        context.invalidate();
+    }
+
     fn drag_split(
         &mut self,
         mut item: UIItem,

window/examples/async.rs

@@ -80,7 +80,8 @@ impl MyWindow {
             WindowEvent::AppearanceChanged(_)
             | WindowEvent::AdviseDeadKeyStatus(_)
             | WindowEvent::Notification(_)
-            | WindowEvent::FocusChanged(_) => {}
+            | WindowEvent::FocusChanged(_)
+            | WindowEvent::MouseLeave => {}
         }
     }
 }

window/src/lib.rs

@@ -168,6 +168,7 @@ pub enum WindowEvent {
     KeyEvent(KeyEvent),
 
     MouseEvent(MouseEvent),
+    MouseLeave,
 
     AppearanceChanged(Appearance),
 

window/src/os/macos/window.rs

@@ -414,6 +414,7 @@ impl Window {
                 screen_changed: false,
                 gl_context_pair: None,
                 text_cursor_position: Rect::new(Point::new(0, 0), Size::new(0, 0)),
+                tracking_rect_tag: 0,
                 hscroll_remainder: 0.,
                 vscroll_remainder: 0.,
                 last_wheel: Instant::now(),
@@ -1045,6 +1046,7 @@ struct Inner {
     screen_changed: bool,
     gl_context_pair: Option<GlContextPair>,
     text_cursor_position: Rect,
+    tracking_rect_tag: NSInteger,
     hscroll_remainder: f64,
     vscroll_remainder: f64,
     last_wheel: Instant,
@@ -1679,6 +1681,35 @@ impl WindowView {
         }
     }
 
+    extern "C" fn update_tracking_areas(this: &mut Object, _sel: Sel) {
+        let frame = unsafe { NSView::frame(this as *mut _) };
+
+        if let Some(this) = Self::get_this(this) {
+            let mut inner = this.inner.borrow_mut();
+            if let Some(ref view) = inner.view_id {
+                let view = view.load();
+                if view.is_null() {
+                    return;
+                }
+
+                let tag = inner.tracking_rect_tag;
+                if tag != 0 {
+                    unsafe {
+                        let () = msg_send![*view, removeTrackingRect: tag];
+                    }
+                }
+
+                let rect = NSRect::new(
+                    NSPoint::new(0.0, 0.0),
+                    NSSize::new(frame.size.width, frame.size.height),
+                );
+                inner.tracking_rect_tag = unsafe {
+                    msg_send![*view, addTrackingRect: rect owner: *view userData: nil assumeInside: NO]
+                };
+            }
+        }
+    }
+
     extern "C" fn window_should_close(this: &mut Object, _sel: Sel, _id: id) -> BOOL {
         unsafe {
             let () = msg_send![this, setNeedsDisplay: YES];
@@ -1881,6 +1912,16 @@ impl WindowView {
         Self::mouse_common(this, nsevent, MouseEventKind::Move);
     }
 
+    extern "C" fn mouse_exited(this: &mut Object, _sel: Sel, _nsevent: id) {
+        if let Some(myself) = Self::get_this(this) {
+            myself
+                .inner
+                .borrow_mut()
+                .events
+                .dispatch(WindowEvent::MouseLeave);
+        }
+    }
+
     fn key_common(this: &mut Object, nsevent: id, key_is_down: bool) {
         let is_a_repeat = unsafe { nsevent.isARepeat() == YES };
         let chars = unsafe { nsstring_to_str(nsevent.characters()) };
@@ -2443,6 +2484,10 @@ impl WindowView {
                 sel!(scrollWheel:),
                 Self::scroll_wheel as extern "C" fn(&mut Object, Sel, id),
             );
+            cls.add_method(
+                sel!(mouseExited:),
+                Self::mouse_exited as extern "C" fn(&mut Object, Sel, id),
+            );
 
             cls.add_method(
                 sel!(keyDown:),
@@ -2468,6 +2513,11 @@ impl WindowView {
                 Self::view_did_change_effective_appearance as extern "C" fn(&mut Object, Sel),
             );
 
+            cls.add_method(
+                sel!(updateTrackingAreas),
+                Self::update_tracking_areas as extern "C" fn(&mut Object, Sel),
+            );
+
             // NSTextInputClient
 
             cls.add_method(

window/src/os/wayland/pointer.rs

@@ -104,6 +104,7 @@ pub struct PendingMouse {
     surface_coords: Option<(f64, f64)>,
     button: Vec<(MousePress, ButtonState)>,
     scroll: Option<(f64, f64)>,
+    in_window: bool,
 }
 
 impl PendingMouse {
@@ -114,6 +115,7 @@ impl PendingMouse {
             button: vec![],
             scroll: None,
             surface_coords: None,
+            in_window: false,
         }))
     }
 
@@ -126,8 +128,15 @@ impl PendingMouse {
                     .lock()
                     .unwrap()
                     .update_last_serial(serial);
+                self.in_window = true;
                 false
             }
+            PointerEvent::Leave { .. } => {
+                let changed = self.in_window;
+                self.surface_coords = None;
+                self.in_window = false;
+                changed
+            }
             PointerEvent::Motion {
                 surface_x,
                 surface_y,
@@ -204,6 +213,10 @@ impl PendingMouse {
     pub fn scroll(pending: &Arc<Mutex<Self>>) -> Option<(f64, f64)> {
         pending.lock().unwrap().scroll.take()
     }
+
+    pub fn in_window(pending: &Arc<Mutex<Self>>) -> bool {
+        pending.lock().unwrap().in_window
+    }
 }
 
 impl PointerDispatcher {

window/src/os/wayland/window.rs

@@ -537,6 +537,11 @@ impl WaylandWindowInner {
                 self.events.dispatch(WindowEvent::MouseEvent(event));
             }
         }
+
+        if !PendingMouse::in_window(&pending_mouse) {
+            self.events.dispatch(WindowEvent::MouseLeave);
+            self.refresh_frame();
+        }
     }
 
     fn get_dpi_factor(&self) -> i32 {

window/src/os/windows/window.rs

@@ -61,6 +61,7 @@ pub(crate) struct WindowInner {
     in_size_move: bool,
     dead_pending: Option<(Modifiers, u32)>,
     saved_placement: Option<WINDOWPLACEMENT>,
+    track_mouse_leave: bool,
 
     keyboard_info: KeyboardLayoutInfo,
     appearance: Appearance,
@@ -415,6 +416,7 @@ impl Window {
             in_size_move: false,
             dead_pending: None,
             saved_placement: None,
+            track_mouse_leave: false,
             config: config.clone(),
         }));
 
@@ -1133,6 +1135,21 @@ unsafe fn mouse_button(hwnd: HWND, msg: UINT, wparam: WPARAM, lparam: LPARAM) ->
 
 unsafe fn mouse_move(hwnd: HWND, _msg: UINT, wparam: WPARAM, lparam: LPARAM) -> Option<LRESULT> {
     if let Some(inner) = rc_from_hwnd(hwnd) {
+        let mut inner = inner.borrow_mut();
+
+        if !inner.track_mouse_leave {
+            inner.track_mouse_leave = true;
+
+            let mut trk = TRACKMOUSEEVENT {
+                cbSize: std::mem::size_of::<TRACKMOUSEEVENT>() as u32,
+                dwFlags: TME_LEAVE,
+                hwndTrack: hwnd,
+                dwHoverTime: 0,
+            };
+
+            inner.track_mouse_leave = TrackMouseEvent(&mut trk) == winapi::shared::minwindef::TRUE;
+        }
+
         let (modifiers, mouse_buttons) = mods_and_buttons(wparam);
         let coords = mouse_coords(lparam);
         let event = MouseEvent {
@@ -1143,10 +1160,20 @@ unsafe fn mouse_move(hwnd: HWND, _msg: UINT, wparam: WPARAM, lparam: LPARAM) ->
             modifiers,
         };
 
-        inner
-            .borrow_mut()
-            .events
-            .dispatch(WindowEvent::MouseEvent(event));
+        inner.events.dispatch(WindowEvent::MouseEvent(event));
+        Some(0)
+    } else {
+        None
+    }
+}
+
+unsafe fn mouse_leave(hwnd: HWND, _msg: UINT, _wparam: WPARAM, _lparam: LPARAM) -> Option<LRESULT> {
+    if let Some(inner) = rc_from_hwnd(hwnd) {
+        let mut inner = inner.borrow_mut();
+
+        inner.track_mouse_leave = false;
+        inner.events.dispatch(WindowEvent::MouseLeave);
+
         Some(0)
     } else {
         None
@@ -2000,6 +2027,7 @@ unsafe fn do_wnd_proc(hwnd: HWND, msg: UINT, wparam: WPARAM, lparam: LPARAM) ->
         WM_SETTINGCHANGE => apply_theme(hwnd),
         WM_IME_COMPOSITION => ime_composition(hwnd, msg, wparam, lparam),
         WM_MOUSEMOVE => mouse_move(hwnd, msg, wparam, lparam),
+        WM_MOUSELEAVE => mouse_leave(hwnd, msg, wparam, lparam),
         WM_MOUSEHWHEEL | WM_MOUSEWHEEL => mouse_wheel(hwnd, msg, wparam, lparam),
         WM_LBUTTONDBLCLK | WM_RBUTTONDBLCLK | WM_MBUTTONDBLCLK | WM_LBUTTONDOWN | WM_LBUTTONUP
         | WM_RBUTTONDOWN | WM_RBUTTONUP | WM_MBUTTONDOWN | WM_MBUTTONUP => {

window/src/os/x11/connection.rs

@@ -138,6 +138,10 @@ fn window_id_from_event(event: &xcb::GenericEvent) -> Option<xcb::xproto::Window
             let msg: &xcb::FocusOutEvent = unsafe { xcb::cast_event(event) };
             Some(msg.event())
         }
+        xcb::LEAVE_NOTIFY => {
+            let msg: &xcb::LeaveNotifyEvent = unsafe { xcb::cast_event(event) };
+            Some(msg.event())
+        }
         _ => None,
     }
 }

window/src/os/x11/window.rs

@@ -414,6 +414,9 @@ impl XWindowInner {
                 log::trace!("Calling focus_change(false)");
                 self.events.dispatch(WindowEvent::FocusChanged(false));
             }
+            xcb::LEAVE_NOTIFY => {
+                self.events.dispatch(WindowEvent::MouseLeave);
+            }
             _ => {
                 eprintln!("unhandled: {:x}", r);
             }
@@ -825,6 +828,7 @@ impl XWindow {
                             | xcb::EVENT_MASK_BUTTON_PRESS
                             | xcb::EVENT_MASK_BUTTON_RELEASE
                             | xcb::EVENT_MASK_POINTER_MOTION
+                            | xcb::EVENT_MASK_LEAVE_WINDOW
                             | xcb::EVENT_MASK_BUTTON_MOTION
                             | xcb::EVENT_MASK_KEY_RELEASE
                             | xcb::EVENT_MASK_PROPERTY_CHANGE