feat: enforce pointer constraints

compositor/src/input.rs

@@ -5,10 +5,11 @@ use smithay::{
     },
     input::{
         keyboard::FilterResult,
-        pointer::{AxisFrame, ButtonEvent, MotionEvent, RelativeMotionEvent},
+        pointer::{AxisFrame, ButtonEvent, MotionEvent, PointerHandle, RelativeMotionEvent},
     },
     reexports::wayland_server::protocol::wl_surface::WlSurface,
-    utils::{SERIAL_COUNTER, Serial},
+    utils::{Logical, Point, SERIAL_COUNTER, Serial},
+    wayland::pointer_constraints::{PointerConstraint, with_pointer_constraint},
 };
 
 use crate::Ferese;
@@ -36,6 +37,8 @@ impl Ferese {
                 };
                 let position = event.position_transformed(geometry.size) + geometry.loc.to_f64();
                 let pointer = self.seat.get_pointer().expect("seat has a pointer");
+                let position = self.constrain_pointer_position(&pointer, position);
+
                 pointer.motion(
                     self,
                     self.surface_under(position),
@@ -46,10 +49,12 @@ impl Ferese {
                     },
                 );
                 pointer.frame(self);
+                self.activate_focused_pointer_constraint(&pointer);
             }
             InputEvent::PointerMotion { event, .. } => {
                 let pointer = self.seat.get_pointer().expect("seat has a pointer");
                 let focus = self.surface_under(pointer.current_location());
+
                 pointer.relative_motion(
                     self,
                     focus,
@@ -64,9 +69,11 @@ impl Ferese {
             InputEvent::PointerButton { event, .. } => {
                 let pointer = self.seat.get_pointer().expect("seat has a pointer");
                 let serial = SERIAL_COUNTER.next_serial();
+
                 if event.state() == ButtonState::Pressed && !pointer.is_grabbed() {
                     self.focus_window_under_pointer(serial);
                 }
+
                 pointer.button(
                     self,
                     &ButtonEvent {
@@ -93,12 +100,14 @@ impl Ferese {
                         frame = frame.v120(Axis::Horizontal, value as i32);
                     }
                 }
+
                 if vertical != 0.0 {
                     frame = frame.value(Axis::Vertical, vertical);
                     if let Some(value) = event.amount_v120(Axis::Vertical) {
                         frame = frame.v120(Axis::Vertical, value as i32);
                     }
                 }
+
                 if source == AxisSource::Finger {
                     if event.amount(Axis::Horizontal) == Some(0.0) {
                         frame = frame.stop(Axis::Horizontal);
@@ -107,7 +116,9 @@ impl Ferese {
                         frame = frame.stop(Axis::Vertical);
                     }
                 }
+
                 let pointer = self.seat.get_pointer().expect("seat has a pointer");
+
                 pointer.axis(self, frame);
                 pointer.frame(self);
             }
@@ -118,6 +129,7 @@ impl Ferese {
     fn focus_window_under_pointer(&mut self, serial: Serial) {
         let pointer = self.seat.get_pointer().expect("seat has a pointer");
         let keyboard = self.seat.get_keyboard().expect("seat has a keyboard");
+
         if let Some((window, _)) = self.space.element_under(pointer.current_location()) {
             let window = window.clone();
             self.space.raise_element(&window, true);
@@ -130,10 +142,75 @@ impl Ferese {
         } else {
             keyboard.set_focus(self, Option::<WlSurface>::None, serial);
         }
+
         self.space.elements().for_each(|window| {
             if let Some(toplevel) = window.toplevel() {
                 toplevel.send_pending_configure();
             }
         });
     }
+
+    fn constrain_pointer_position(
+        &self,
+        pointer: &PointerHandle<Self>,
+        requested: Point<f64, Logical>,
+    ) -> Point<f64, Logical> {
+        let current = pointer.current_location();
+        let Some(focused_surface) = pointer.current_focus() else {
+            return requested;
+        };
+        let Some((surface, origin)) = self.surface_under(current) else {
+            return requested;
+        };
+        if surface != focused_surface {
+            return requested;
+        }
+
+        with_pointer_constraint(&surface, pointer, |constraint| {
+            let Some(constraint) = constraint.filter(|constraint| constraint.is_active()) else {
+                return requested;
+            };
+
+            match &*constraint {
+                PointerConstraint::Locked(_) => current,
+                PointerConstraint::Confined(_) => {
+                    let remains_on_surface = self
+                        .surface_under(requested)
+                        .is_some_and(|(candidate, _)| candidate == surface);
+                    let inside_region = constraint
+                        .region()
+                        .is_none_or(|region| region.contains((requested - origin).to_i32_round()));
+
+                    if remains_on_surface && inside_region {
+                        requested
+                    } else {
+                        current
+                    }
+                }
+            }
+        })
+    }
+
+    pub fn activate_focused_pointer_constraint(&self, pointer: &PointerHandle<Self>) {
+        let position = pointer.current_location();
+        let Some((surface, origin)) = self.surface_under(position) else {
+            return;
+        };
+        if pointer.current_focus().as_ref() != Some(&surface) {
+            return;
+        }
+
+        with_pointer_constraint(&surface, pointer, |constraint| {
+            let Some(constraint) = constraint else {
+                return;
+            };
+            let inside_region = constraint
+                .region()
+                .is_none_or(|region| region.contains((position - origin).to_i32_round()));
+
+            if !constraint.is_active() && inside_region {
+                constraint.activate();
+            }
+        });
+    }
 }