feat(theme): themes as files (theme crate: toml subset + ints, contrast check, wire); whimsy dark + light; display reads themes/, serves THEME/THEME_NAME, init SET_THEME -> THEME_CHANGED to all windows, bar themed; k-ui follows; settings appearance; init keeps choice in sealed users/<id>/settings/, reapplies at sign-in + display restart

crates/apps/settings/src/main.rs

@@ -1,5 +1,6 @@
 //! Settings: what each app may use (allow or revoke, through the
-//! permission manager), who is signed in, and signing out. A system app:
+//! permission manager), the theme (the display's list, kept per user by
+//! init), who is signed in, and signing out. A system app:
 //! `permissions` and `session` are only ever granted to apps on the system
 //! image.
 
@@ -29,6 +30,7 @@ enum Screen {
     Apps,
     /// One app, by its place in the list.
     App(usize),
+    Appearance,
     About,
 }
 
@@ -37,6 +39,8 @@ enum Event {
     Show(Screen),
     /// Allow or revoke this capability of the app on screen.
     Flip(Capability),
+    /// Use the display's `n`th theme.
+    Theme(usize),
     SignOut,
 }
 
@@ -54,6 +58,9 @@ struct Settings {
     rows: Vec<AppRow>,
     /// Who is signed in, and how.
     who: Option<(String, Role)>,
+    /// The display's themes, and which is in use.
+    themes: Vec<String>,
+    theme: usize,
     /// What went wrong last, shown until the next change.
     trouble: Option<String>,
 }
@@ -99,6 +106,23 @@ impl Settings {
         self.reload();
     }
 
+    fn appearance(&self) -> Element<Event> {
+        let rows = self.themes.iter().enumerate().map(|(i, name)| {
+            let item = list_item(name.clone(), Event::Theme(i));
+            if i == self.theme { item.subtitle("In use") } else { item }
+        });
+        let view = Self::hint(Self::heading("Appearance"), "Esc goes back").children(rows);
+        self.with_trouble(view).into()
+    }
+
+    fn choose_theme(&mut self, index: usize) {
+        let (Some(name), Some(session)) = (self.themes.get(index), libkos::start::session()) else { return };
+        match libkos::session::set_theme(session, name.as_bytes()) {
+            true => self.theme = index,
+            false => self.trouble = Some("That theme could not be kept.".to_string()),
+        }
+    }
+
     fn heading(title: &str) -> k_ui::element::FlexBuilder<Event> {
         column().padding(Spacing::Xl).gap(Spacing::Md).child(text(title).style(TextStyle::Heading))
     }
@@ -110,6 +134,7 @@ impl Settings {
     fn home(&self) -> Element<Event> {
         Self::heading("Settings")
             .child(list_item("Apps", Event::Show(Screen::Apps)).subtitle("What each app may use"))
+            .child(list_item("Appearance", Event::Show(Screen::Appearance)).subtitle("The theme everything is drawn in"))
             .child(list_item("About", Event::Show(Screen::About)).subtitle("Who is signed in, and this device"))
             .child(button("Sign out", Event::SignOut).variant(ButtonVariant::Destructive))
             .into()
@@ -176,7 +201,15 @@ impl App for Settings {
         let who = libkos::start::session()
             .and_then(|s| libkos::session::who(s, &mut name))
             .map(|(len, role)| (String::from_utf8_lossy(&name[..len]).into_owned(), role));
-        let mut s = Settings { screen: Screen::Home, apps, rows: Vec::new(), who, trouble: None };
+        let window = libkos::start::display();
+        let themes = window.map_or(Vec::new(), |w| {
+            (0..)
+                .map_while(|i| libkos::display::theme_name(w, i))
+                .map(|(n, len)| String::from_utf8_lossy(&n[..len]).into_owned())
+                .collect()
+        });
+        let theme = window.and_then(libkos::display::theme).map_or(0, |(i, _)| i);
+        let mut s = Settings { screen: Screen::Home, apps, rows: Vec::new(), who, themes, theme, trouble: None };
         s.reload();
         s
     }
@@ -195,6 +228,7 @@ impl App for Settings {
                     self.flip(i, cap);
                 }
             }
+            Event::Theme(i) => self.choose_theme(i),
             Event::SignOut => {
                 if let Some(s) = libkos::start::session() {
                     libkos::session::sign_out(s);
@@ -208,6 +242,7 @@ impl App for Settings {
             Screen::Home => self.home(),
             Screen::Apps => self.app_list(),
             Screen::App(i) => self.app(i),
+            Screen::Appearance => self.appearance(),
             Screen::About => self.about(),
         }
     }
@@ -217,7 +252,7 @@ impl App for Settings {
         self.screen = match self.screen {
             Screen::Home => return false,
             Screen::App(_) => Screen::Apps,
-            Screen::Apps | Screen::About => Screen::Home,
+            Screen::Apps | Screen::Appearance | Screen::About => Screen::Home,
         };
         true
     }
@@ -227,7 +262,8 @@ impl App for Settings {
             Screen::Home => 0,
             Screen::Apps => 1,
             Screen::About => 2,
-            Screen::App(i) => 3 + i,
+            Screen::Appearance => 3,
+            Screen::App(i) => 4 + i,
         }
     }
 }