feat(theme): per-app accent: pm gives window manifest accent before app runs (display ACCENT, refused after BUFFER); theme::with_accent keeps hue, shifts lightness until contrast passes, else theme accent; tally pink

crates/servers/display-server/src/tests/server.rs

@@ -232,3 +232,23 @@ fn init_switches_the_theme_and_every_window_hears_of_it() {
     let bogus = w::pack_name(b"Nope");
     assert_eq!(s.handle_call(0, [w::SET_THEME, bogus[0], bogus[1], bogus[2]], None).0[0], MALFORMED);
 }
+
+#[test]
+fn only_the_launcher_sets_an_accent_and_it_is_in_the_theme() {
+    let mut s = server();
+    let app = open(&mut s, 2, b"Tally");
+    let other = open(&mut s, 3, b"Snake");
+    let pink = 0xe91e63;
+    assert_eq!(s.handle_call(app, [w::ACCENT, pink, 0, 0], None).0[0], w::OK);
+    assert_eq!(s.handle_call(app, [w::ACCENT, 0x00ff00, 0, 0], None).0[0], MALFORMED, "once");
+    // The app starts: too late for it to choose one itself.
+    s.handle_call(other, [w::BUFFER, 0, 0, 0], None);
+    assert_eq!(s.handle_call(other, [w::ACCENT, pink, 0, 0], None).0[0], MALFORMED);
+    let accent = |s: &mut Srv, badge| {
+        let r = s.handle_call(badge, [w::THEME, 0, 0, 0], None).0;
+        // Colour 3, the top of the theme's second word.
+        theme::Rgba::rgb((r[3] >> 32) as u32 & 0xff_ffff)
+    };
+    assert_eq!(accent(&mut s, other), theme::Theme::WHIMSY_DARK.accent);
+    assert_eq!(accent(&mut s, app), theme::with_accent(theme::Theme::WHIMSY_DARK, theme::Rgba::rgb(pink as u32)).accent);
+}