tab indicator: Add corner-radius setting

niri-config/src/lib.rs

@@ -697,6 +697,8 @@ pub struct TabIndicator {
     pub position: TabIndicatorPosition,
     #[knuffel(child, unwrap(argument), default = Self::default().gaps_between_tabs)]
     pub gaps_between_tabs: FloatOrInt<0, 65535>,
+    #[knuffel(child, unwrap(argument), default = Self::default().corner_radius)]
+    pub corner_radius: FloatOrInt<0, 65535>,
     #[knuffel(child)]
     pub active_color: Option<Color>,
     #[knuffel(child)]
@@ -720,6 +722,7 @@ impl Default for TabIndicator {
             },
             position: TabIndicatorPosition::Left,
             gaps_between_tabs: FloatOrInt(0.),
+            corner_radius: FloatOrInt(0.),
             active_color: None,
             inactive_color: None,
             active_gradient: None,
@@ -1234,6 +1237,17 @@ impl From<CornerRadius> for [f32; 4] {
     }
 }
 
+impl From<f32> for CornerRadius {
+    fn from(value: f32) -> Self {
+        Self {
+            top_left: value,
+            top_right: value,
+            bottom_right: value,
+            bottom_left: value,
+        }
+    }
+}
+
 #[derive(knuffel::DecodeScalar, Debug, Clone, Copy, PartialEq, Eq)]
 pub enum BlockOutFrom {
     Screencast,

src/layout/tab_indicator.rs

@@ -180,6 +180,11 @@ impl TabIndicator {
         self.shaders.resize_with(count, Default::default);
         self.shader_locs.resize_with(count, Default::default);
 
+        let position = self.config.position;
+        let radius = self.config.corner_radius.0 as f32;
+        let shared_rounded_corners = self.config.gaps_between_tabs.0 == 0.;
+        let mut tabs_left = tab_count;
+
         let rects = self.tab_rects(area, count, scale);
         for ((shader, loc), (tab, rect)) in zip(
             zip(&mut self.shaders, &mut self.shader_locs),
@@ -200,6 +205,50 @@ impl TabIndicator {
                 color_to *= 0.5;
             }
 
+            let radius = if shared_rounded_corners && tab_count > 1 {
+                if tabs_left == tab_count {
+                    // First tab.
+                    match position {
+                        TabIndicatorPosition::Left | TabIndicatorPosition::Right => CornerRadius {
+                            top_left: radius,
+                            top_right: radius,
+                            bottom_right: 0.,
+                            bottom_left: 0.,
+                        },
+                        TabIndicatorPosition::Top | TabIndicatorPosition::Bottom => CornerRadius {
+                            top_left: radius,
+                            top_right: 0.,
+                            bottom_right: 0.,
+                            bottom_left: radius,
+                        },
+                    }
+                } else if tabs_left == 1 {
+                    // Last tab.
+                    match position {
+                        TabIndicatorPosition::Left | TabIndicatorPosition::Right => CornerRadius {
+                            top_left: 0.,
+                            top_right: 0.,
+                            bottom_right: radius,
+                            bottom_left: radius,
+                        },
+                        TabIndicatorPosition::Top | TabIndicatorPosition::Bottom => CornerRadius {
+                            top_left: 0.,
+                            top_right: radius,
+                            bottom_right: radius,
+                            bottom_left: 0.,
+                        },
+                    }
+                } else {
+                    // Tab in the middle.
+                    CornerRadius::default()
+                }
+            } else {
+                // Separate tabs, or the only tab.
+                CornerRadius::from(radius)
+            };
+            let radius = radius.fit_to(rect.size.w as f32, rect.size.h as f32);
+            tabs_left -= 1;
+
             shader.update(
                 rect.size,
                 gradient_area,
@@ -209,7 +258,7 @@ impl TabIndicator {
                 ((tab.gradient.angle as f32) - 90.).to_radians(),
                 Rectangle::from_size(rect.size),
                 0.,
-                CornerRadius::default(),
+                radius,
                 scale as f32,
                 1.,
             );

wiki/Configuration:-Layout.md

@@ -63,6 +63,7 @@ layout {
         length total-proportion=1.0
         position "right"
         gaps-between-tabs 2
+        corner-radius 8
         active-color "red"
         inactive-color "gray"
         // active-gradient from="#80c8ff" to="#bbddff" angle=45
@@ -439,6 +440,9 @@ It can be `left`, `right`, `top`, or `bottom`.
 
 `gaps-between-tabs` controls the gap between individual tabs in logical pixels.
 
+`corner-radius` sets the rounded corner radius for tabs in the indicator in logical pixels.
+When `gaps-between-tabs` is zero, only the first and the last tabs have rounded corners, otherwise all tabs do.
+
 `active-color`, `inactive-color`, `active-gradient`, `inactive-gradient` let you override the colors for the tabs.
 They have the same semantics as the border and focus ring colors and gradients.