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/libkos/src/display.rs

@@ -50,10 +50,67 @@ pub fn subscribe(window: CapSlot, notify: CapSlot, badge: types::badge::Badge) -
     sent.is_ok_and(|r| r.words()[0] == w::OK)
 }
 
+/// What a window hears.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Event {
+    Input(crate::input::InputEvent),
+    /// Ask for the theme again (`theme`).
+    ThemeChanged,
+}
+
+/// `window`'s next event, if one is waiting; ones not known here are
+/// skipped.
+pub fn poll(window: CapSlot) -> Option<Event> {
+    loop {
+        let words = syscall::request(window, [w::POLL, 0, 0, 0]).ok()?;
+        match words[0] {
+            0 => return None,
+            w::THEME_CHANGED => return Some(Event::ThemeChanged),
+            _ => {
+                if let Some(e) = crate::input::decode(words) {
+                    return Some(Event::Input(e));
+                }
+            }
+        }
+    }
+}
+
 /// `window`'s next input event, if one is waiting.
 pub fn poll_input(window: CapSlot) -> Option<crate::input::InputEvent> {
-    let words = syscall::request(window, [w::POLL, 0, 0, 0]).ok()?;
-    crate::input::decode(words)
+    loop {
+        if let Event::Input(e) = poll(window)? {
+            return Some(e);
+        }
+    }
+}
+
+/// The theme in use, as `theme::wire` words it, and its place in the
+/// display's list (`theme_name`).
+pub fn theme(window: CapSlot) -> Option<(usize, [usize; w::THEME_WORDS])> {
+    // A switch mid-read is seen and read again; a few in a row, given up.
+    for _ in 0..3 {
+        let mut words = [0; w::THEME_WORDS];
+        let mut first = None;
+        let mut torn = false;
+        for part in 0..w::THEME_WORDS / 2 {
+            let r = syscall::request(window, [w::THEME, part, 0, 0]).ok()?;
+            if r[0] != w::OK {
+                return None;
+            }
+            torn |= *first.get_or_insert(r[1]) != r[1];
+            words[part * 2..part * 2 + 2].copy_from_slice(&r[2..]);
+        }
+        if !torn {
+            return first.map(|head| (head >> 32, words));
+        }
+    }
+    None
+}
+
+/// The name of the display's `index`th theme, if it has that many.
+pub fn theme_name(window: CapSlot, index: usize) -> Option<([u8; w::NAME_BYTES], usize)> {
+    let r = syscall::request(window, [w::THEME_NAME, index, 0, 0]).ok()?;
+    (r[0] == w::OK).then(|| w::unpack_name([r[1], r[2], r[3]]))
 }
 
 /// A changed area, as corners.

crates/libkos/src/session.rs

@@ -31,3 +31,10 @@ pub fn who(session: CapSlot, name: &mut [u8; types::name::BYTES]) -> Option<(usi
 pub fn sign_out(session: CapSlot) -> bool {
     syscall::send_msg(session, [SIGN_OUT, 0, 0, 0], None).is_ok()
 }
+
+/// Makes the theme named `name` the signed-in user's (kept, and shown at
+/// once); whether init took it.
+pub fn set_theme(session: CapSlot, name: &[u8]) -> bool {
+    let [a, b, c] = types::name::pack(name);
+    syscall::request(session, [types::spawn::SET_THEME, a, b, c]).is_ok_and(|r| r[0] == types::spawn::reply::OK)
+}