ndk: Add AMidi interface

ndk/src/lib.rs

@@ -16,6 +16,7 @@ pub mod hardware_buffer_format;
 pub mod input_queue;
 pub mod looper;
 pub mod media;
+pub mod midi;
 pub mod native_activity;
 pub mod native_window;
 pub mod surface_texture;

ndk/src/media/mod.rs

@@ -12,7 +12,7 @@ use std::{mem::MaybeUninit, ptr::NonNull};
 
 pub type Result<T, E = NdkMediaError> = std::result::Result<T, E>;
 
-fn construct<T>(with_ptr: impl FnOnce(*mut T) -> ffi::media_status_t) -> Result<T> {
+pub(crate) fn construct<T>(with_ptr: impl FnOnce(*mut T) -> ffi::media_status_t) -> Result<T> {
     let mut result = MaybeUninit::uninit();
     let status = with_ptr(result.as_mut_ptr());
     NdkMediaError::from_status(status).map(|()| unsafe { result.assume_init() })

ndk/src/midi.rs

@@ -0,0 +1,271 @@
+//! Bindings for [`AMidiDevice`], [`AMidiInputPort`], and [`AMidiOutputPort`]
+//!
+//! See [the NDK guide](https://developer.android.com/ndk/guides/audio/midi) for
+//! design and usage instructions, and [the NDK reference](https://developer.android.com/ndk/reference/group/midi)
+//! for an API overview.
+//!
+//! [`AMidiDevice`]: https://developer.android.com/ndk/reference/group/midi#amididevice
+//! [`AMidiInputPort`]: https://developer.android.com/ndk/reference/group/midi#amidiinputport
+//! [`AMidiOutputPort`]: https://developer.android.com/ndk/reference/group/midi#amidioutputport
+#![cfg(feature = "media")]
+
+pub use super::media::Result;
+use super::media::{construct, NdkMediaError};
+
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+use std::fmt;
+use std::marker::PhantomData;
+use std::os::raw::{c_int, c_uint};
+use std::ptr::NonNull;
+
+/// Result of [`MidiOutputPort::receive`].
+#[derive(Copy, Clone, Debug)]
+#[repr(u32)]
+pub enum MidiOpcode {
+    /// No MIDI messages are available.
+    NoMessage,
+    /// Received a MIDI message with the given length.
+    Data(usize),
+    /// Instructed to discard all pending MIDI data.
+    Flush,
+}
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[repr(u32)]
+pub enum MidiDeviceType {
+    Bluetooth = ffi::AMIDI_DEVICE_TYPE_BLUETOOTH,
+    USB = ffi::AMIDI_DEVICE_TYPE_USB,
+    Virtual = ffi::AMIDI_DEVICE_TYPE_VIRTUAL,
+}
+
+#[derive(Debug)]
+pub struct MidiDevice {
+    inner: NonNull<ffi::AMidiDevice>,
+}
+
+impl MidiDevice {
+    fn from_ptr(inner: NonNull<ffi::AMidiDevice>) -> Self {
+        Self { inner }
+    }
+
+    fn as_ptr(&self) -> *mut ffi::AMidiDevice {
+        self.inner.as_ptr()
+    }
+
+    /// Connects a native Midi Device object to the associated Java MidiDevice object.
+    ///
+    /// Use this AMidiDevice to access the rest of the native MIDI API.
+    pub fn from_java(
+        env: *mut jni_sys::JNIEnv,
+        midi_device_obj: jni_sys::jobject,
+    ) -> Result<MidiDevice> {
+        unsafe {
+            let ptr = construct(|res| ffi::AMidiDevice_fromJava(env, midi_device_obj, res))?;
+            Ok(Self::from_ptr(NonNull::new_unchecked(ptr)))
+        }
+    }
+
+    /// Gets the number of input (sending) ports available on the specified MIDI device.
+    pub fn get_num_input_ports(&self) -> Result<usize> {
+        let num_input_ports = unsafe { ffi::AMidiDevice_getNumInputPorts(self.as_ptr()) };
+        if num_input_ports >= 0 {
+            Ok(num_input_ports as usize)
+        } else {
+            NdkMediaError::from_status(ffi::media_status_t(num_input_ports as c_int)).map(|_| 0)
+        }
+    }
+
+    /// Gets the number of output (receiving) ports available on the specified MIDI device.
+    pub fn get_num_output_ports(&self) -> Result<usize> {
+        let num_output_ports = unsafe { ffi::AMidiDevice_getNumOutputPorts(self.as_ptr()) };
+        if num_output_ports >= 0 {
+            Ok(num_output_ports as usize)
+        } else {
+            Err(
+                NdkMediaError::from_status(ffi::media_status_t(num_output_ports as c_int))
+                    .unwrap_err(),
+            )
+        }
+    }
+
+    /// Gets the MIDI device type.
+    pub fn get_type(&self) -> Result<MidiDeviceType> {
+        let device_type = unsafe { ffi::AMidiDevice_getType(self.as_ptr()) };
+        if device_type >= 0 {
+            let device_type =
+                MidiDeviceType::try_from_primitive(device_type as u32).map_err(|e| {
+                    NdkMediaError::UnknownResult(ffi::media_status_t(e.number as c_int))
+                })?;
+            Ok(device_type)
+        } else {
+            Err(NdkMediaError::from_status(ffi::media_status_t(device_type)).unwrap_err())
+        }
+    }
+
+    /// Opens the input port so that the client can send data to it.
+    pub fn open_input_port(&self, port_number: i32) -> Result<MidiInputPort> {
+        unsafe {
+            let input_port =
+                construct(|res| ffi::AMidiInputPort_open(self.as_ptr(), port_number, res))?;
+            Ok(MidiInputPort::from_ptr(NonNull::new_unchecked(input_port)))
+        }
+    }
+
+    /// Opens the output port so that the client can receive data from it.
+    pub fn open_output_port(&self, port_number: i32) -> Result<MidiOutputPort> {
+        unsafe {
+            let output_port =
+                construct(|res| ffi::AMidiOutputPort_open(self.as_ptr(), port_number, res))?;
+            Ok(MidiOutputPort::from_ptr(NonNull::new_unchecked(
+                output_port,
+            )))
+        }
+    }
+}
+
+impl Drop for MidiDevice {
+    fn drop(&mut self) {
+        let status = unsafe { ffi::AMidiDevice_release(self.as_ptr()) };
+        NdkMediaError::from_status(status).unwrap();
+    }
+}
+
+pub struct MidiInputPort<'a> {
+    inner: NonNull<ffi::AMidiInputPort>,
+    _marker: PhantomData<&'a MidiDevice>,
+}
+
+impl<'a> fmt::Debug for MidiInputPort<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("MidiInputPort")
+            .field("inner", &self.inner)
+            .finish()
+    }
+}
+
+impl<'a> MidiInputPort<'a> {
+    fn from_ptr(inner: NonNull<ffi::AMidiInputPort>) -> Self {
+        Self {
+            inner,
+            _marker: PhantomData,
+        }
+    }
+
+    fn as_ptr(&self) -> *mut ffi::AMidiInputPort {
+        self.inner.as_ptr()
+    }
+
+    /// Sends data to the specified input port.
+    pub fn send(&self, buffer: &[u8]) -> Result<usize> {
+        let num_bytes_sent = unsafe {
+            ffi::AMidiInputPort_send(self.as_ptr(), buffer.as_ptr(), buffer.len() as ffi::size_t)
+        };
+        if num_bytes_sent >= 0 {
+            Ok(num_bytes_sent as usize)
+        } else {
+            Err(
+                NdkMediaError::from_status(ffi::media_status_t(num_bytes_sent as c_int))
+                    .unwrap_err(),
+            )
+        }
+    }
+
+    /// Sends a message with a 'MIDI flush command code' to the specified port.
+    ///
+    /// This should cause a receiver to discard any pending MIDI data it may have accumulated and
+    /// not processed.
+    pub fn send_flush(&self) -> Result<()> {
+        let result = unsafe { ffi::AMidiInputPort_sendFlush(self.as_ptr()) };
+        NdkMediaError::from_status(result)
+    }
+
+    pub fn send_with_timestamp(&self, buffer: &[u8], timestamp: i64) -> Result<usize> {
+        let num_bytes_sent = unsafe {
+            ffi::AMidiInputPort_sendWithTimestamp(
+                self.as_ptr(),
+                buffer.as_ptr(),
+                buffer.len() as ffi::size_t,
+                timestamp,
+            )
+        };
+        if num_bytes_sent >= 0 {
+            Ok(num_bytes_sent as usize)
+        } else {
+            Err(
+                NdkMediaError::from_status(ffi::media_status_t(num_bytes_sent as c_int))
+                    .unwrap_err(),
+            )
+        }
+    }
+}
+
+impl<'a> Drop for MidiInputPort<'a> {
+    fn drop(&mut self) {
+        unsafe { ffi::AMidiInputPort_close(self.as_ptr()) };
+    }
+}
+
+pub struct MidiOutputPort<'a> {
+    inner: NonNull<ffi::AMidiOutputPort>,
+    _marker: PhantomData<&'a MidiDevice>,
+}
+
+impl<'a> fmt::Debug for MidiOutputPort<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("MidiOutputPort")
+            .field("inner", &self.inner)
+            .finish()
+    }
+}
+
+impl<'a> MidiOutputPort<'a> {
+    fn from_ptr(inner: NonNull<ffi::AMidiOutputPort>) -> Self {
+        Self {
+            inner,
+            _marker: PhantomData,
+        }
+    }
+
+    fn as_ptr(&self) -> *mut ffi::AMidiOutputPort {
+        self.inner.as_ptr()
+    }
+
+    /// Receives the next pending MIDI message.
+    ///
+    /// To retrieve all pending messages, the client should repeatedly call this method until it
+    /// returns `Some(_)`.
+    ///
+    /// Note that this is a non-blocking call. If there are no Midi messages are available, the
+    /// function returns `None` immediately (for 0 messages received).
+    pub fn receive(&self, buffer: &mut [u8]) -> Result<(MidiOpcode, i64)> {
+        let mut opcode = 0i32;
+        let mut timestamp = 0i64;
+        let mut num_bytes_received: ffi::size_t = 0;
+        let result = unsafe {
+            ffi::AMidiOutputPort_receive(
+                self.as_ptr(),
+                &mut opcode,
+                buffer.as_mut_ptr(),
+                buffer.len() as ffi::size_t,
+                &mut num_bytes_received,
+                &mut timestamp,
+            )
+        };
+
+        if result < 0 {
+            Err(NdkMediaError::from_status(ffi::media_status_t(result as c_int)).unwrap_err())
+        } else if result == 0 {
+            Ok((MidiOpcode::NoMessage, timestamp))
+        } else if opcode as c_uint == ffi::AMIDI_OPCODE_DATA {
+            Ok((MidiOpcode::Data(num_bytes_received as usize), timestamp))
+        } else {
+            Ok((MidiOpcode::Flush, timestamp))
+        }
+    }
+}
+
+impl<'a> Drop for MidiOutputPort<'a> {
+    fn drop(&mut self) {
+        unsafe { ffi::AMidiOutputPort_close(self.as_ptr()) };
+    }
+}