Add layout background-color setting

niri-config/src/lib.rs

@@ -448,8 +448,8 @@ pub struct Output {
     pub variable_refresh_rate: Option<Vrr>,
     #[knuffel(child)]
     pub focus_at_startup: bool,
-    #[knuffel(child, default = DEFAULT_BACKGROUND_COLOR)]
-    pub background_color: Color,
+    #[knuffel(child)]
+    pub background_color: Option<Color>,
     #[knuffel(child)]
     pub backdrop_color: Option<Color>,
 }
@@ -479,7 +479,7 @@ impl Default for Output {
             position: None,
             mode: None,
             variable_refresh_rate: None,
-            background_color: DEFAULT_BACKGROUND_COLOR,
+            background_color: None,
             backdrop_color: None,
         }
     }
@@ -541,6 +541,8 @@ pub struct Layout {
     pub gaps: FloatOrInt<0, 65535>,
     #[knuffel(child, default)]
     pub struts: Struts,
+    #[knuffel(child, default = DEFAULT_BACKGROUND_COLOR)]
+    pub background_color: Color,
 }
 
 impl Default for Layout {
@@ -560,6 +562,7 @@ impl Default for Layout {
             gaps: FloatOrInt(16.),
             struts: Default::default(),
             preset_window_heights: Default::default(),
+            background_color: DEFAULT_BACKGROUND_COLOR,
         }
     }
 }
@@ -4279,12 +4282,14 @@ mod tests {
                             },
                         ),
                         focus_at_startup: true,
-                        background_color: Color {
-                            r: 0.09803922,
-                            g: 0.09803922,
-                            b: 0.4,
-                            a: 1.0,
-                        },
+                        background_color: Some(
+                            Color {
+                                r: 0.09803922,
+                                g: 0.09803922,
+                                b: 0.4,
+                                a: 1.0,
+                            },
+                        ),
                         backdrop_color: None,
                     },
                 ],
@@ -4501,6 +4506,12 @@ mod tests {
                         0.0,
                     ),
                 },
+                background_color: Color {
+                    r: 0.25,
+                    g: 0.25,
+                    b: 0.25,
+                    a: 1.0,
+                },
             },
             prefer_no_csd: true,
             cursor: Cursor {

src/niri.rs

@@ -15,7 +15,7 @@ use anyhow::{bail, ensure, Context};
 use calloop::futures::Scheduler;
 use niri_config::{
     Config, FloatOrInt, Key, Modifiers, OutputName, PreviewRender, TrackLayout,
-    WarpMouseToFocusMode, WorkspaceReference, DEFAULT_BACKGROUND_COLOR,
+    WarpMouseToFocusMode, WorkspaceReference,
 };
 use smithay::backend::allocator::Fourcc;
 use smithay::backend::input::Keycode;
@@ -1416,6 +1416,9 @@ impl State {
         if config.overview.backdrop_color != old_config.overview.backdrop_color {
             output_config_changed = true;
         }
+        if config.layout.background_color != old_config.layout.background_color {
+            output_config_changed = true;
+        }
 
         *old_config = config;
 
@@ -1529,8 +1532,8 @@ impl State {
             }
 
             let background_color = config
-                .map(|c| c.background_color)
-                .unwrap_or(DEFAULT_BACKGROUND_COLOR)
+                .and_then(|c| c.background_color)
+                .unwrap_or(full_config.layout.background_color)
                 .to_array_unpremul();
             let background_color = Color32F::from(background_color);
 
@@ -2725,8 +2728,8 @@ impl Niri {
             .unwrap_or(Transform::Normal);
 
         let background_color = c
-            .map(|c| c.background_color)
-            .unwrap_or(DEFAULT_BACKGROUND_COLOR)
+            .and_then(|c| c.background_color)
+            .unwrap_or(config.layout.background_color)
             .to_array_unpremul();
 
         let mut backdrop_color = c

wiki/Configuration:-Layout.md

@@ -11,6 +11,7 @@ layout {
     always-center-single-column
     empty-workspace-above-first
     default-column-display "tabbed"
+    background-color "#003300"
 
     preset-column-widths {
         proportion 0.33333
@@ -526,3 +527,18 @@ layout {
     }
 }
 ```
+
+### `background-color`
+
+<sup>Since: next release</sup>
+
+Set the default background color that niri draws for workspaces.
+This is visible when you're not using any background tools like swaybg.
+
+```kdl
+layout {
+    background-color "#003300"
+}
+```
+
+You can also set the color per-output [in the output config](./Configuration:-Outputs.md#background-color).

wiki/Configuration:-Outputs.md

@@ -210,7 +210,7 @@ output "HDMI-A-1" {
 Set the backdrop color that niri draws for this output.
 This is visible between workspaces or in the overview.
 
-The alpha channel for this color will be ignored.
+<sup>Until: next release</sup> The alpha channel for this color will be ignored.
 
 ```kdl
 output "HDMI-A-1" {

wiki/Overview.md

@@ -76,3 +76,27 @@ This will only work for *background* layer surfaces that ignore exclusive zones
 
 You can run two different wallpaper tools (like swaybg and swww), one for the backdrop and one for the normal workspace background.
 This way you could set the backdrop one to a blurred version of the wallpaper for a nice effect.
+
+You can also combine this with a transparent background color if you don't like the wallpaper moving together with workspaces:
+
+```kdl
+// Make the wallpaper stationary, rather than moving with workspaces.
+layer-rule {
+    // This is for swaybg; change for other wallpaper tools.
+    // Find the right namespace by running niri msg layers.
+    match namespace="^wallpaper$"
+    place-within-backdrop true
+}
+
+// Set transparent workspace background color.
+layout {
+    background-color "transparent"
+}
+
+// Optionally, disable the workspace shadows in the overview.
+overview {
+    workspace-shadow {
+        off
+    }
+}
+```