popover: Show overlays as selected

src/manager.rs

@@ -1,4 +1,5 @@
 /*! Procedures relating to the management of the switching of layouts */
+use ::util;
 
 pub mod c {
     use std::os::raw::{c_char, c_void};
@@ -14,5 +15,20 @@ pub mod c {
             manager: Manager,
             name: *const c_char,
         );
+
+        pub fn eekboard_context_service_get_overlay(
+            manager: Manager,
+        ) -> *const c_char;
     }
 }
+
+/// Returns the overlay name.
+/// The result lifetime is "as long as the C copy lives"
+pub fn get_overlay(manager: c::Manager) -> Option<String> {
+    let raw_str = unsafe {
+        c::eekboard_context_service_get_overlay(manager)
+    };
+    // this string is generated from Rust, should never be invalid
+    util::c::as_str(&raw_str).unwrap()
+        .map(String::from)
+}