ASIO: open control panel

CHANGELOG.md

@@ -43,6 +43,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **ALSA**: `Debug` implementations for `Host`, `Device`, `Stream`, and internal types.
 - **ALSA**: Example demonstrating ALSA error suppression during enumeration.
 - **ALSA**: Support for native DSD playback.
+- **ASIO**: Extension trait for ASIO devices, which allows opening the control panel.
 - **WASAPI**: Enable as-necessary resampling in the WASAPI server process.
 
 ### Changed

asio-sys/build.rs

@@ -238,6 +238,7 @@ fn create_bindings(cpal_asio_dir: &PathBuf) {
         .allowlist_function("ASIOStart")
         .allowlist_function("ASIOStop")
         .allowlist_function("ASIODisposeBuffers")
+        .allowlist_function("ASIOControlPanel")
         .allowlist_function("ASIOExit")
         .allowlist_function("load_asio_driver")
         .allowlist_function("remove_current_driver")

asio-sys/src/bindings/mod.rs

@@ -788,6 +788,11 @@ impl Driver {
         let mut mcb = MESSAGE_CALLBACKS.lock().unwrap();
         mcb.retain(|&(id, _)| id != rem_id);
     }
+
+    /// Opens the ASIO driver's control panel window.
+    pub fn open_control_panel(&self) -> Result<(), AsioError> {
+        unsafe { asio_result!(ai::ASIOControlPanel()) }
+    }
 }
 
 impl DriverState {

src/host/asio/mod.rs

@@ -25,7 +25,7 @@ mod stream;
 ///
 /// ASIO only supports loading a single driver at a time globally, so all Host instances
 /// must share the same underlying sys::Asio wrapper to properly coordinate driver access.
-static GLOBAL_ASIO: OnceLock<Arc<sys::Asio>> = OnceLock::new();
+pub(crate) static GLOBAL_ASIO: OnceLock<Arc<sys::Asio>> = OnceLock::new();
 
 /// The host for ASIO.
 #[derive(Debug)]

src/platform/asio.rs

@@ -0,0 +1,83 @@
+//! Implementations for ASIO-specific device functionality.
+
+use crate::BackendSpecificError;
+use crate::Device;
+
+/// Extension trait for ASIO-specific device functionality.
+pub trait AsioDeviceExt {
+    /// Returns `true` if this device is an ASIO device.
+    fn is_asio_device(&self) -> bool;
+
+    /// Opens the ASIO driver's control panel window.
+    ///
+    /// This provides access to device-specific settings like buffer size,
+    /// sample rate, input/output routing, and hardware-specific features.
+    ///
+    /// # Blocking Behavior
+    ///
+    /// **WARNING**: This call may block until the user closes the control panel.
+    /// Consider spawning a thread to avoid blocking the main thread.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error if this device is not an ASIO device.
+    fn asio_open_control_panel(&self) -> Result<(), BackendSpecificError>;
+}
+
+#[cfg(all(target_os = "windows", feature = "asio"))]
+impl AsioDeviceExt for Device {
+    fn is_asio_device(&self) -> bool {
+        matches!(self.as_inner(), crate::platform::DeviceInner::Asio(_))
+    }
+
+    fn asio_open_control_panel(&self) -> Result<(), BackendSpecificError> {
+        use crate::host::asio::GLOBAL_ASIO;
+        use crate::platform::DeviceInner;
+
+        if let DeviceInner::Asio(ref asio_device) = self.as_inner() {
+            let description = asio_device
+                .description()
+                .map_err(|e| BackendSpecificError {
+                    description: format!("Could not get device name: {:?}", e),
+                })?;
+
+            let driver = GLOBAL_ASIO
+                .get()
+                .ok_or(BackendSpecificError {
+                    description: "ASIO not initialized.".into(),
+                })?
+                .load_driver(description.name())
+                .map_err(|e| BackendSpecificError {
+                    description: format!("Failed to load driver: {:?}", e),
+                })?;
+
+            driver
+                .open_control_panel()
+                .map_err(|e| BackendSpecificError {
+                    description: format!("Failed to open control panel: {:?}", e),
+                })
+        } else {
+            Err(BackendSpecificError {
+                description: "Not an ASIO device".to_string(),
+            })
+        }
+    }
+}
+
+#[cfg(not(all(target_os = "windows", feature = "asio")))]
+impl AsioDeviceExt for Device {
+    fn is_asio_device(&self) -> bool {
+        false
+    }
+
+    fn asio_open_control_panel(&self) -> Result<(), BackendSpecificError> {
+        Err(not_available())
+    }
+}
+
+#[cfg(not(all(target_os = "windows", feature = "asio")))]
+fn not_available() -> BackendSpecificError {
+    BackendSpecificError {
+        description: "ASIO is not available on this platform".to_string(),
+    }
+}

src/platform/mod.rs

@@ -10,6 +10,8 @@ pub use self::platform_impl::*;
 #[cfg(feature = "custom")]
 pub use crate::host::custom::{Device as CustomDevice, Host as CustomHost, Stream as CustomStream};
 
+pub mod asio;
+
 /// A macro to assist with implementing a platform's dynamically dispatched [`Host`] type.
 ///
 /// These dynamically dispatched types are necessary to allow for users to switch between hosts at