Configuration option to set theme to light/dark/auto

src/bridge/ui_commands.rs

@@ -117,6 +117,7 @@ pub enum ParallelCommand {
     FocusLost,
     FocusGained,
     DisplayAvailableFonts(Vec<String>),
+    SetBackground(String),
     #[cfg(windows)]
     RegisterRightClick,
     #[cfg(windows)]
@@ -148,6 +149,11 @@ impl ParallelCommand {
             ParallelCommand::FileDrop(path) => {
                 nvim.command(format!("e {path}").as_str()).await.ok();
             }
+            ParallelCommand::SetBackground(background) => {
+                nvim.command(format!("set background={}", background).as_str())
+                    .await
+                    .ok();
+            }
             ParallelCommand::DisplayAvailableFonts(fonts) => {
                 let mut content: Vec<String> = vec![
                     "What follows are the font names available for guifont. You can try any of them with <CR> in normal mode.",

src/settings/config.rs

@@ -38,6 +38,7 @@ pub struct Config {
     pub idle: Option<bool>,
     pub neovim_bin: Option<PathBuf>,
     pub frame: Option<Frame>,
+    pub theme: Option<String>,
 }
 
 impl Config {
@@ -72,6 +73,9 @@ impl Config {
         if let Some(neovim_bin) = &self.neovim_bin {
             env::set_var("NEOVIM_BIN", neovim_bin.to_string_lossy().to_string());
         }
+        if let Some(theme) = &self.theme {
+            env::set_var("NEOVIDE_THEME", theme);
+        }
     }
 
     fn load_from_path(path: &Path) -> Result<Self, Option<String>> {

src/window/mod.rs

@@ -16,7 +16,7 @@ use winit::{
     dpi::PhysicalSize,
     event::{Event, WindowEvent},
     event_loop::{ControlFlow, EventLoop},
-    window::{self, Fullscreen, Icon},
+    window::{self, Fullscreen, Icon, Theme},
 };
 
 #[cfg(target_os = "macos")]
@@ -85,6 +85,12 @@ pub struct WinitWindowWrapper {
     window_command_receiver: UnboundedReceiver<WindowCommand>,
 }
 
+pub fn set_background(background: &str) {
+    EVENT_AGGREGATOR.send(UiCommand::Parallel(ParallelCommand::SetBackground(
+        background.to_string(),
+    )));
+}
+
 impl WinitWindowWrapper {
     pub fn toggle_fullscreen(&mut self) {
         let window = self.windowed_context.window();
@@ -195,6 +201,19 @@ impl WinitWindowWrapper {
                     self.handle_focus_lost();
                 }
             }
+            Event::WindowEvent {
+                event: WindowEvent::ThemeChanged(theme),
+                ..
+            } => {
+                let settings = SETTINGS.get::<WindowSettings>();
+                if settings.theme.as_str() == "auto" {
+                    let background = match theme {
+                        Theme::Light => "light",
+                        Theme::Dark => "dark",
+                    };
+                    set_background(background);
+                }
+            }
             Event::RedrawRequested(..) | Event::WindowEvent { .. } => {
                 REDRAW_SCHEDULER.queue_next_frame()
             }
@@ -460,6 +479,19 @@ pub fn create_window() {
         renderer.grid_renderer.font_dimensions,
     );
 
+    println!("theme: {}", SETTINGS.get::<WindowSettings>().theme);
+
+    match SETTINGS.get::<WindowSettings>().theme.as_str() {
+        "light" => set_background("light"),
+        "dark" => set_background("dark"),
+        "auto" => match window.theme() {
+            Some(Theme::Light) => set_background("light"),
+            Some(Theme::Dark) => set_background("dark"),
+            None => {}
+        },
+        _ => {}
+    }
+
     let mut window_wrapper = WinitWindowWrapper {
         windowed_context,
         skia_renderer,

src/window/settings.rs

@@ -20,6 +20,7 @@ pub struct WindowSettings {
     pub padding_left: u32,
     pub padding_right: u32,
     pub padding_bottom: u32,
+    pub theme: String,
 }
 
 impl Default for WindowSettings {
@@ -43,6 +44,7 @@ impl Default for WindowSettings {
             padding_left: 0,
             padding_right: 0,
             padding_bottom: 0,
+            theme: "".to_string(),
         }
     }
 }

website/docs/configuration.md

@@ -272,6 +272,24 @@ sizes above 15.
 **Note**: This is currently glitchy, and leads to some underlines being clipped by the line of text
 below.
 
+#### Theme
+
+VimScript:
+
+```vim
+let g:neovide_theme = 'auto'
+```
+
+Lua:
+
+```lua
+vim.g.neovide_theme = 'auto'
+```
+
+Set the [`background`](https://neovim.io/doc/user/options.html#'background') option when Neovide
+starts. Possible values: _light_, _dark_, _auto_. On systems that support it, _auto_ will mirror the
+system theme, and will update `background` when the system theme changes.
+
 ### Functionality
 
 #### Refresh Rate