Account for border in contents_under()

Fixes pointer clicks going through window borders to a layer surface below,
also fixes window not getting activated in all cases from a border click.

4 files changed, 63 insertions, 41 deletions

diff --git a/src/layout/mod.rs b/src/layout/mod.rs
index 01122177..593279b7 100644
--- a/src/layout/mod.rs
+++ b/src/layout/mod.rs
@@ -450,6 +450,20 @@ pub enum AddWindowTarget<'a, W: LayoutElement> {
     NextTo(&'a W::Id),
 }
 
+/// Type of the window hit from `window_under()`.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum HitType {
+    /// The hit is within a window's input region and can be used for sending events to it.
+    Input {
+        /// Position of the window's buffer.
+        win_pos: Point<f64, Logical>,
+    },
+    /// The hit can activate a window, but it is not in the input region so cannot send events.
+    ///
+    /// For example, this could be clicking on a tile border outside the window.
+    Activate,
+}
+
 impl<W: LayoutElement> InteractiveMoveState<W> {
     fn moving(&self) -> Option<&InteractiveMoveData<W>> {
         match self {
@@ -485,6 +499,16 @@ impl ActivateWindow {
     }
 }
 
+impl HitType {
+    pub fn offset_win_pos(mut self, offset: Point<f64, Logical>) -> Self {
+        match &mut self {
+            HitType::Input { win_pos } => *win_pos += offset,
+            HitType::Activate => (),
+        }
+        self
+    }
+}
+
 impl Options {
     fn from_config(config: &Config) -> Self {
         let layout = &config.layout;
@@ -2155,18 +2179,12 @@ impl<W: LayoutElement> Layout<W> {
         mon.active_window().map(|win| (win, &mon.output))
     }
 
-    /// Returns the window under the cursor and the position of its toplevel surface within the
-    /// output.
-    ///
-    /// `Some((w, Some(p)))` means that the cursor is within the window's input region and can be
-    /// used for delivering events to the window. `Some((w, None))` means that the cursor is within
-    /// the window's activation region, but not within the window's input region. For example, the
-    /// cursor may be on the window's server-side border.
+    /// Returns the window under the cursor and the hit type.
     pub fn window_under(
         &self,
         output: &Output,
         pos_within_output: Point<f64, Logical>,
-    ) -> Option<(&W, Option<Point<f64, Logical>>)> {
+    ) -> Option<(&W, HitType)> {
         let MonitorSet::Normal { monitors, .. } = &self.monitor_set else {
             return None;
         };
@@ -2177,9 +2195,9 @@ impl<W: LayoutElement> Layout<W> {
 
             if move_.tile.is_in_input_region(pos_within_tile) {
                 let win_pos = tile_pos + move_.tile.buf_loc();
-                return Some((move_.tile.window(), Some(win_pos)));
+                return Some((move_.tile.window(), HitType::Input { win_pos }));
             } else if move_.tile.is_in_activation_region(pos_within_tile) {
-                return Some((move_.tile.window(), None));
+                return Some((move_.tile.window(), HitType::Activate));
             }
 
             return None;
diff --git a/src/layout/monitor.rs b/src/layout/monitor.rs
index ebafad17..53bf5377 100644
--- a/src/layout/monitor.rs
+++ b/src/layout/monitor.rs
@@ -14,7 +14,7 @@ use super::tile::Tile;
 use super::workspace::{
     OutputId, Workspace, WorkspaceAddWindowTarget, WorkspaceId, WorkspaceRenderElement,
 };
-use super::{ActivateWindow, LayoutElement, Options};
+use super::{ActivateWindow, HitType, LayoutElement, Options};
 use crate::animation::{Animation, Clock};
 use crate::input::swipe_tracker::SwipeTracker;
 use crate::render_helpers::renderer::NiriRenderer;
@@ -1007,13 +1007,10 @@ impl<W: LayoutElement> Monitor<W> {
         Some((ws, bounds.loc))
     }
 
-    pub fn window_under(
-        &self,
-        pos_within_output: Point<f64, Logical>,
-    ) -> Option<(&W, Option<Point<f64, Logical>>)> {
+    pub fn window_under(&self, pos_within_output: Point<f64, Logical>) -> Option<(&W, HitType)> {
         let (ws, offset) = self.workspace_under(pos_within_output)?;
-        let (win, win_pos) = ws.window_under(pos_within_output - offset)?;
-        Some((win, win_pos.map(|p| p + offset)))
+        let (win, hit) = ws.window_under(pos_within_output - offset)?;
+        Some((win, hit.offset_win_pos(offset)))
     }
 
     pub fn resize_edges_under(&self, pos_within_output: Point<f64, Logical>) -> Option<ResizeEdge> {
diff --git a/src/layout/workspace.rs b/src/layout/workspace.rs
index f005577d..165ae750 100644
--- a/src/layout/workspace.rs
+++ b/src/layout/workspace.rs
@@ -19,7 +19,9 @@ use super::scrolling::{
     ScrollingSpaceRenderElement,
 };
 use super::tile::{Tile, TileRenderSnapshot};
-use super::{ActivateWindow, InteractiveResizeData, LayoutElement, Options, RemovedTile, SizeFrac};
+use super::{
+    ActivateWindow, HitType, InteractiveResizeData, LayoutElement, Options, RemovedTile, SizeFrac,
+};
 use crate::animation::Clock;
 use crate::niri_render_elements;
 use crate::render_helpers::renderer::NiriRenderer;
@@ -1459,10 +1461,7 @@ impl<W: LayoutElement> Workspace<W> {
             .start_close_animation_for_tile(renderer, snapshot, tile_size, tile_pos, blocker);
     }
 
-    pub fn window_under(
-        &self,
-        pos: Point<f64, Logical>,
-    ) -> Option<(&W, Option<Point<f64, Logical>>)> {
+    pub fn window_under(&self, pos: Point<f64, Logical>) -> Option<(&W, HitType)> {
         self.tiles_with_render_positions()
             .find_map(|(tile, tile_pos, visible)| {
                 if !visible {
@@ -1473,9 +1472,9 @@ impl<W: LayoutElement> Workspace<W> {
 
                 if tile.is_in_input_region(pos_within_tile) {
                     let win_pos = tile_pos + tile.buf_loc();
-                    return Some((tile.window(), Some(win_pos)));
+                    return Some((tile.window(), HitType::Input { win_pos }));
                 } else if tile.is_in_activation_region(pos_within_tile) {
-                    return Some((tile.window(), None));
+                    return Some((tile.window(), HitType::Activate));
                 }
 
                 None
diff --git a/src/niri.rs b/src/niri.rs
index 7e1884be..a7fc872f 100644
--- a/src/niri.rs
+++ b/src/niri.rs
@@ -128,7 +128,7 @@ use crate::layer::mapped::LayerSurfaceRenderElement;
 use crate::layer::MappedLayer;
 use crate::layout::tile::TileRenderElement;
 use crate::layout::workspace::WorkspaceId;
-use crate::layout::{Layout, LayoutElement as _, MonitorRenderElement};
+use crate::layout::{HitType, Layout, LayoutElement as _, MonitorRenderElement};
 use crate::niri_render_elements;
 use crate::protocols::foreign_toplevel::{self, ForeignToplevelManagerState};
 use crate::protocols::gamma_control::GammaControlManagerState;
@@ -450,6 +450,9 @@ pub struct PointContents {
     // Output under point.
     pub output: Option<Output>,
     // Surface under point and its location in the global coordinate space.
+    //
+    // Can be `None` even when `window` is set, for example when the pointer is over the niri
+    // border around the window.
     pub surface: Option<(WlSurface, Point<f64, Logical>)>,
     // If surface belongs to a window, this is that window.
     pub window: Option<Window>,
@@ -2693,7 +2696,7 @@ impl Niri {
                             )
                         })
                 })
-                .map(|(s, l)| (s, (None, Some(l.clone()))))
+                .map(|(s, l)| (Some(s), (None, Some(l.clone()))))
         };
 
         let layer_toplevel_under = |layer| layer_surface_under(layer, false);
@@ -2702,18 +2705,22 @@ impl Niri {
         let window_under = || {
             self.layout
                 .window_under(output, pos_within_output)
-                .and_then(|(mapped, win_pos_within_output)| {
-                    let win_pos_within_output = win_pos_within_output?;
+                .map(|(mapped, hit)| {
                     let window = &mapped.window;
-                    window
-                        .surface_under(
-                            pos_within_output - win_pos_within_output,
-                            WindowSurfaceType::ALL,
-                        )
-                        .map(|(s, pos_within_window)| {
-                            (s, pos_within_window.to_f64() + win_pos_within_output)
-                        })
-                        .map(|s| (s, (Some(window.clone()), None)))
+                    let surface_and_pos = if let HitType::Input { win_pos } = hit {
+                        let win_pos_within_output = win_pos;
+                        window
+                            .surface_under(
+                                pos_within_output - win_pos_within_output,
+                                WindowSurfaceType::ALL,
+                            )
+                            .map(|(s, pos_within_window)| {
+                                (s, pos_within_window.to_f64() + win_pos_within_output)
+                            })
+                    } else {
+                        None
+                    };
+                    (surface_and_pos, (Some(window.clone()), None))
                 })
         };
 
@@ -2744,14 +2751,15 @@ impl Niri {
                 .or_else(|| layer_toplevel_under(Layer::Background));
         }
 
-        let Some(((surface, surface_pos_within_output), (window, layer))) = under else {
+        let Some((mut surface_and_pos, (window, layer))) = under else {
             return rv;
         };
 
-        let surface_loc_in_global_space =
-            surface_pos_within_output + output_pos_in_global_space.to_f64();
+        if let Some((_, surface_pos)) = &mut surface_and_pos {
+            *surface_pos += output_pos_in_global_space.to_f64();
+        }
 
-        rv.surface = Some((surface, surface_loc_in_global_space));
+        rv.surface = surface_and_pos;
         rv.window = window;
         rv.layer = layer;
         rv