Implement is-window-cast-target window rule matcher

niri-config/src/lib.rs

@@ -1210,6 +1210,8 @@ pub struct Match {
     #[knuffel(property)]
     pub is_floating: Option<bool>,
     #[knuffel(property)]
+    pub is_window_cast_target: Option<bool>,
+    #[knuffel(property)]
     pub at_startup: Option<bool>,
 }
 
@@ -3948,6 +3950,7 @@ mod tests {
                         is_focused: None,
                         is_active_in_column: None,
                         is_floating: None,
+                        is_window_cast_target: None,
                         at_startup: None,
                     }],
                     excludes: vec![
@@ -3958,6 +3961,7 @@ mod tests {
                             is_focused: None,
                             is_active_in_column: None,
                             is_floating: None,
+                            is_window_cast_target: None,
                             at_startup: None,
                         },
                         Match {
@@ -3967,6 +3971,7 @@ mod tests {
                             is_focused: Some(false),
                             is_active_in_column: None,
                             is_floating: None,
+                            is_window_cast_target: None,
                             at_startup: None,
                         },
                     ],

src/niri.rs

@@ -642,13 +642,18 @@ impl State {
         self.niri.refresh_idle_inhibit();
         self.refresh_pointer_contents();
         foreign_toplevel::refresh(self);
+
+        #[cfg(feature = "xdp-gnome-screencast")]
+        self.niri.refresh_mapped_cast_outputs();
+        // Should happen before refresh_window_rules(), but after anything that can start or stop
+        // screencasts.
+        #[cfg(feature = "xdp-gnome-screencast")]
+        self.niri.refresh_mapped_cast_window_rules();
+
         self.niri.refresh_window_rules();
         self.refresh_ipc_outputs();
         self.ipc_refresh_layout();
         self.ipc_refresh_keyboard_layout_index();
-
-        #[cfg(feature = "xdp-gnome-screencast")]
-        self.niri.refresh_mapped_cast_outputs();
     }
 
     fn notify_blocker_cleared(&mut self) {
@@ -3256,6 +3261,20 @@ impl Niri {
         }
     }
 
+    #[cfg(feature = "xdp-gnome-screencast")]
+    pub fn refresh_mapped_cast_window_rules(&mut self) {
+        // O(N^2) but should be fine since there aren't many casts usually.
+        self.layout.with_windows_mut(|mapped, _| {
+            let id = mapped.id().get();
+            // Find regardless of cast.is_active.
+            let value = self
+                .casts
+                .iter()
+                .any(|cast| cast.target == (CastTarget::Window { id }));
+            mapped.set_is_window_cast_target(value);
+        });
+    }
+
     #[cfg(feature = "xdp-gnome-screencast")]
     pub fn refresh_mapped_cast_outputs(&mut self) {
         use std::collections::hash_map::Entry;

src/window/mapped.rs

@@ -80,6 +80,9 @@ pub struct Mapped {
     /// Whether this window is floating.
     is_floating: bool,
 
+    /// Whether this window is a target of a window cast.
+    is_window_cast_target: bool,
+
     /// Whether this window should ignore opacity set through window rules.
     ignore_opacity_window_rule: bool,
 
@@ -188,6 +191,7 @@ impl Mapped {
             is_focused: false,
             is_active_in_column: true,
             is_floating: false,
+            is_window_cast_target: false,
             ignore_opacity_window_rule: false,
             block_out_buffer: RefCell::new(SolidColorBuffer::new((0., 0.), [0., 0., 0., 1.])),
             animate_next_configure: false,
@@ -260,6 +264,10 @@ impl Mapped {
         self.is_floating
     }
 
+    pub fn is_window_cast_target(&self) -> bool {
+        self.is_window_cast_target
+    }
+
     pub fn toggle_ignore_opacity_window_rule(&mut self) {
         self.ignore_opacity_window_rule = !self.ignore_opacity_window_rule;
     }
@@ -273,6 +281,15 @@ impl Mapped {
         self.need_to_recompute_rules = true;
     }
 
+    pub fn set_is_window_cast_target(&mut self, value: bool) {
+        if self.is_window_cast_target == value {
+            return;
+        }
+
+        self.is_window_cast_target = value;
+        self.need_to_recompute_rules = true;
+    }
+
     fn render_snapshot(&self, renderer: &mut GlesRenderer) -> LayoutElementRenderSnapshot {
         let _span = tracy_client::span!("Mapped::render_snapshot");
 

src/window/mod.rs

@@ -146,6 +146,13 @@ impl<'a> WindowRef<'a> {
             WindowRef::Mapped(mapped) => mapped.is_floating(),
         }
     }
+
+    pub fn is_window_cast_target(self) -> bool {
+        match self {
+            WindowRef::Unmapped(_) => false,
+            WindowRef::Mapped(mapped) => mapped.is_window_cast_target(),
+        }
+    }
 }
 
 impl ResolvedWindowRules {
@@ -446,5 +453,11 @@ fn window_matches(window: WindowRef, role: &XdgToplevelSurfaceRoleAttributes, m:
         }
     }
 
+    if let Some(is_window_cast_target) = m.is_window_cast_target {
+        if window.is_window_cast_target() != is_window_cast_target {
+            return false;
+        }
+    }
+
     true
 }

wiki/Configuration:-Window-Rules.md

@@ -34,6 +34,7 @@ window-rule {
     match is-focused=false
     match is-active-in-column=true
     match is-floating=true
+    match is-window-cast-target=true
     match at-startup=true
 
     // Properties that apply once upon window opening.
@@ -239,6 +240,42 @@ window-rule {
 }
 ```
 
+#### `is-window-cast-target`
+
+<sup>Since: next release</sup>
+
+Can be `true` or `false`.
+Matches `true` for windows that are target of an ongoing window screencast.
+
+```kdl
+// Indicate screencasted windows with red colors.
+window-rule {
+    match is-window-cast-target=true
+
+    focus-ring {
+        active-color "#f38ba8"
+        inactive-color "#7d0d2d"
+    }
+
+    border {
+        inactive-color "#7d0d2d"
+    }
+
+    shadow {
+        color "#7d0d2d70"
+    }
+
+    tab-indicator {
+        active-color "#f38ba8"
+        inactive-color "#7d0d2d"
+    }
+}
+```
+
+Example:
+
+![](https://github.com/user-attachments/assets/375b381e-3a87-4e94-8676-44404971d893)
+
 #### `at-startup`
 
 <sup>Since: 0.1.6</sup>