ableton_link/lib.rs
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//! An overview of Link concepts can be found at
//! [http://ableton.github.io/link](http://ableton.github.io/link).
//!
//! Then see the doc of [Link](struct.Link.html) and
//! [SessionState](struct.SessionState.html).
//! Most of it is directly taken from the original Link docs.
//!
//! All i64 time values are in microseconds and should be used with the
//! [Clock](struct.Clock.html).
#[allow(non_camel_case_types)]
#[allow(non_snake_case)]
mod sys {
include!(concat!(env!("OUT_DIR"), "/link_rs.rs"));
}
use sys::*;
use std::os::raw::c_void;
/// # Represents a participant in a Link session.
///
/// Each Link instance has its own session state which
/// represents a beat timeline and a transport start/stop state. The
/// timeline starts running from beat 0 at the initial tempo when
/// constructed. The timeline always advances at a speed defined by
/// its current tempo, even if transport is stopped. Synchronizing to the
/// transport start/stop state of Link is optional for every peer.
/// The transport start/stop state is only shared with other peers when
/// start/stop synchronization is enabled.
///
/// A Link instance is initially disabled after construction, which
/// means that it will not communicate on the network. Once enabled,
/// a Link instance initiates network communication in an effort to
/// discover other peers. When peers are discovered, they immediately
/// become part of a shared Link session.
///
/// Each method of the Link type documents its thread-safety and
/// realtime-safety properties. When a method is marked thread-safe,
/// it means it is safe to call from multiple threads
/// concurrently. When a method is marked realtime-safe, it means that
/// it does not block and is appropriate for use in the thread that
/// performs audio IO.
///
/// Link provides one session state capture/commit method pair for use
/// in the audio thread and one for all other application contexts. In
/// general, modifying the session state should be done in the audio
/// thread for the most accurate timing results. The ability to modify
/// the session state from application threads should only be used in
/// cases where an application's audio thread is not actively running
/// or if it doesn't generate audio at all. Modifying the Link session
/// state from both the audio thread and an application thread
/// concurrently is not advised and will potentially lead to unexpected
/// behavior.
pub struct Link {
wlink: *mut WLink,
}
impl Drop for Link {
fn drop(&mut self) {
unsafe { Link_destroy(self.wlink) }
// println!("Link destroyed!")
}
}
impl Link {
/// Construct with an initial tempo.
pub fn new(bpm: f64) -> Link {
Link { wlink: unsafe { Link_create(bpm) } }
}
/// Is Link currently enabled?
/// * Thread-safe: yes
/// * Realtime-safe: yes
pub fn is_enabled(&self) -> bool {
unsafe { Link_isEnabled(self.wlink) }
}
/// Enable/disable Link.
/// * Thread-safe: yes
/// * Realtime-safe: no
pub fn enable(&mut self, enable: bool) {
unsafe { Link_enable(self.wlink, enable) }
}
/// Is start/stop synchronization enabled?
/// * Thread-safe: yes
/// * Realtime-safe: no
pub fn is_start_stop_sync_enabled(&self) -> bool {
unsafe { Link_isStartStopSyncEnabled(self.wlink) }
}
/// Enable start/stop synchronization.
/// * Thread-safe: yes
/// * Realtime-safe: no
pub fn enable_start_stop_sync(&mut self, enable: bool) {
unsafe { Link_enableStartStopSync(self.wlink, enable) }
}
/// How many peers are currently connected in a Link session?
/// * Thread-safe: yes
/// * Realtime-safe: yes
pub fn num_peers(&self) -> usize {
unsafe { Link_numPeers(self.wlink) }
}
/// Register a callback to be notified when the number of
/// peers in the Link session changes.
/// * Thread-safe: yes
/// * Realtime-safe: no
///
/// The callback is invoked on a Link-managed thread.
pub fn set_num_peers_callback(&mut self, callback: extern fn(usize)) {
unsafe {
let cb = callback as unsafe extern fn(usize);
Link_setNumPeersCallback(self.wlink, Some(cb));
}
}
/// Register a callback to be notified when the session tempo changes.
/// * Thread-safe: yes
/// * Realtime-safe: no
///
/// The callback is invoked on a Link-managed thread.
pub fn set_tempo_callback(&mut self, callback: extern fn(f64)) {
unsafe {
let cb = callback as unsafe extern fn(f64);
Link_setTempoCallback(self.wlink, Some(cb));
}
}
/// Register a callback to be notified when the state of
/// start/stop isPlaying changes.
/// * Thread-safe: yes
/// * Realtime-safe: no
///
/// The callback is invoked on a Link-managed thread.
pub fn set_start_stop_callback(&mut self, callback: extern fn(bool)) {
unsafe {
let cb = callback as unsafe extern fn(bool);
Link_setStartStopCallback(self.wlink, Some(cb));
}
}
/// The clock used by Link.
/// * Thread-safe: yes
/// * Realtime-safe: yes
///
/// The Clock type is a platform-dependent
/// representation of the system clock. It exposes a `ticks()` method
/// that returns the current ticks of the system clock as well as
/// `micros()`, which is a normalized representation of the current system
/// time in std::chrono::microseconds. It also provides conversion
/// functions `ticksToMicros()` and `microsToTicks()` to faciliate
/// converting between these units.
pub fn clock(&self) -> Clock {
Clock { wc: unsafe { Link_clock(self.wlink) } }
}
// Capture the current Link Session State from the audio thread.
// * Thread-safe: no
// * Realtime-safe: yes
//
// This method should ONLY be called in the audio thread
// and must not be accessed from any other threads. The returned
// object stores a snapshot of the current Link Session State, so it
// should be captured and used in a local scope. Storing the
// Session State for later use in a different context is not advised
// because it will provide an outdated view.
// fn capture_audio_session_state(&self) -> SessionState {
// unimplemented!()
// }
/// Capture the current Link Session State from the audio thread.
/// * Thread-safe: no
/// * Realtime-safe: yes
///
/// This method should ONLY be called in the audio thread
/// and must not be accessed from any other threads. The closure
/// passes a snapshot of the current Link Session State, it
/// should only be used in the local scope. Storing the
/// Session State for later use in a different context is not advised
/// because it will provide an outdated view.
pub fn with_audio_session_state<F>(&self, f: F)
where F: FnMut(SessionState)
{
let user_data = &f as *const _ as *mut c_void;
unsafe {
Link_withAudioSessionState(self.wlink, Some(closure_wrapper::<F>), user_data);
}
extern fn closure_wrapper<F>(closure: *mut c_void, wss: *mut WSessionState)
where F: FnMut(SessionState)
{
let opt_closure = closure as *mut Option<F>;
unsafe {
let mut fnx = (*opt_closure).take().unwrap();
let ss = SessionState { wss };
fnx(ss);
}
}
}
/// Commit the given Session State to the Link session from the audio thread.
/// * Thread-safe: no
/// * Realtime-safe: yes
///
/// This method should ONLY be called in the audio
/// thread. The given Session State will replace the current Link
/// state. Modifications will be communicated to other peers in the
/// session.
pub fn commit_audio_session_state(&mut self, ss: SessionState) {
unsafe { Link_commitAudioSessionState(self.wlink, ss.wss) }
}
// Capture the current Link Session State from an application thread.
// * Thread-safe: yes
// * Realtime-safe: no
//
// Provides a mechanism for capturing the Link Session
// State from an application thread (other than the audio thread).
// The returned Session State stores a snapshot of the current Link
// state, so it should be captured and used in a local scope.
// Storing the it for later use in a different context is not
// advised because it will provide an outdated view.
// pub fn capture_app_session_state(&self) -> SessionState {
// let wss = unsafe { Link_captureAppSessionState(self.wlink) };
// SessionState { wss }
// }
/// Capture the current Link Session State from an application thread.
/// * Thread-safe: yes
/// * Realtime-safe: no
///
/// Provides a mechanism for capturing the Link Session
/// State from an application thread (other than the audio thread).
/// The closure passes a Session State that stores a snapshot of the current Link
/// state, it should only be used in the local scope.
/// Storing it for later use in a different context is not
/// advised because it will provide an outdated view.
pub fn with_app_session_state<F>(&self, f: F)
where F: FnMut(SessionState)
{
let user_data = &f as *const _ as *mut c_void;
unsafe {
Link_withAppSessionState(self.wlink, Some(closure_wrapper::<F>), user_data);
}
extern fn closure_wrapper<F>(closure: *mut c_void, wss: *mut WSessionState)
where F: FnMut(SessionState)
{
let opt_closure = closure as *mut Option<F>;
unsafe {
let mut fnx = (*opt_closure).take().unwrap();
let ss = SessionState { wss };
fnx(ss);
}
}
}
/// Commit the given Session State to the Link session from an
/// application thread.
/// * Thread-safe: yes
/// * Realtime-safe: no
///
/// The given Session State will replace the current Link
/// Session State. Modifications of the Session State will be
/// communicated to other peers in the session.
pub fn commit_app_session_state(&mut self, ss: SessionState) {
unsafe { Link_commitAppSessionState(self.wlink, ss.wss) }
}
}
/// # Representation of a timeline and the start/stop state
///
/// A SessionState object is intended for use in a local scope within
/// a single thread - none of its methods are thread-safe. All of its methods are
/// non-blocking, so it is safe to use from a realtime thread.
/// It provides functions to observe and manipulate the timeline and start/stop
/// state.
///
/// The timeline is a representation of a mapping between time and beats for varying
/// quanta.
///
/// The start/stop state represents the user intention to start or stop transport at
/// a specific time. Start stop synchronization is an optional feature that allows to
/// share the user request to start or stop transport between a subgroup of peers in
/// a Link session. When observing a change of start/stop state, audio playback of a
/// peer should be started or stopped the same way it would have happened if the user
/// had requested that change at the according time locally. The start/stop state can
/// only be changed by the user. This means that the current local start/stop state
/// persists when joining or leaving a Link session. After joining a Link session
/// start/stop change requests will be communicated to all connected peers.
pub struct SessionState {
wss: *mut WSessionState,
}
// impl Drop for SessionState {
// fn drop(&mut self) {
// unsafe { SessionState_destroy(self.wss) }
// }
// }
impl SessionState {
/// The tempo of the timeline, in bpm.
pub fn tempo(&self) -> f64 {
unsafe { SessionState_tempo(self.wss) }
}
/// Set the timeline tempo to the given bpm value, taking
/// effect at the given time.
pub fn set_tempo(&mut self, bpm: f64, at_time: i64) {
unsafe { SessionState_setTempo(self.wss, bpm, at_time) }
}
/// Get the beat value corresponding to the given time
/// for the given quantum.
///
/// The magnitude of the resulting beat value is
/// unique to this Link instance, but its phase with respect to
/// the provided quantum is shared among all session
/// peers. For non-negative beat values, the following
/// property holds: fmod(beatAtTime(t, q), q) == phaseAtTime(t, q)
pub fn beat_at_time(&self, time: i64, quantum: f64) -> f64 {
unsafe { SessionState_beatAtTime(self.wss, time, quantum) }
}
/// Get the session phase at the given time for the given quantum.
///
/// The result is in the interval [0, quantum). The
/// result is equivalent to fmod(beatAtTime(t, q), q) for
/// non-negative beat values. This method is convenient if the
/// client is only interested in the phase and not the beat
/// magnitude. Also, unlike fmod, it handles negative beat values
/// correctly.
pub fn phase_at_time(&self, time: i64, quantum: f64) -> f64 {
unsafe { SessionState_phaseAtTime(self.wss, time, quantum) }
}
/// Get the time at which the given beat occurs for the
/// given quantum.
///
/// The inverse of beatAtTime, assuming a constant
/// tempo. beatAtTime(timeAtBeat(b, q), q) === b.
pub fn time_at_beat(&self, beat: f64, quantum: f64) -> i64 {
unsafe { SessionState_timeAtBeat(self.wss, beat, quantum) }
}
/// Attempt to map the given beat to the given time in the
/// context of the given quantum.
///
/// This method behaves differently depending on the
/// state of the session. If no other peers are connected,
/// then this instance is in a session by itself and is free to
/// re-map the beat/time relationship whenever it pleases. In this
/// case, beatAtTime(time, quantum) == beat after this method has
/// been called.
///
/// If there are other peers in the session, this instance
/// should not abruptly re-map the beat/time relationship in the
/// session because that would lead to beat discontinuities among
/// the other peers. In this case, the given beat will be mapped
/// to the next time value greater than the given time with the
/// same phase as the given beat.
///
/// This method is specifically designed to enable the concept of
/// "quantized launch" in client applications. If there are no other
/// peers in the session, then an event (such as starting
/// transport) happens immediately when it is requested. If there
/// are other peers, however, we wait until the next time at which
/// the session phase matches the phase of the event, thereby
/// executing the event in-phase with the other peers in the
/// session. The client only needs to invoke this method to
/// achieve this behavior and should not need to explicitly check
/// the number of peers.
pub fn request_beat_at_time(&mut self, beat: f64, time: i64, quantum: f64) {
unsafe { SessionState_requestBeatAtTime(self.wss, beat, time, quantum) }
}
/// Rudely re-map the beat/time relationship for all peers
/// in a session.
///
/// DANGER: This method should only be needed in
/// certain special circumstances. Most applications should not
/// use it. It is very similar to requestBeatAtTime except that it
/// does not fall back to the quantizing behavior when it is in a
/// session with other peers. Calling this method will
/// unconditionally map the given beat to the given time and
/// broadcast the result to the session. This is very anti-social
/// behavior and should be avoided.
///
/// One of the few legitimate uses of this method is to
/// synchronize a Link session with an external clock source. By
/// periodically forcing the beat/time mapping according to an
/// external clock source, a peer can effectively bridge that
/// clock into a Link session. Much care must be taken at the
/// application layer when implementing such a feature so that
/// users do not accidentally disrupt Link sessions that they may
/// join.
pub fn force_beat_at_time(&mut self, beat: f64, time: i64, quantum: f64) {
unsafe { SessionState_forceBeatAtTime(self.wss, beat, time, quantum) }
}
/// Set if transport should be playing or stopped, taking effect
/// at the given time.
pub fn set_is_playing(&mut self, is_playing: bool, time: i64) {
unsafe { SessionState_setIsPlaying(self.wss, is_playing, time) }
}
/// Is transport playing?
pub fn is_playing(&self) -> bool {
unsafe { SessionState_isPlaying(self.wss) }
}
/// Get the time at which a transport start/stop occurs.
pub fn time_for_is_playing(&self) -> i64 {
unsafe { SessionState_timeForIsPlaying(self.wss) }
}
/// Convenience function to attempt to map the given beat to the time
/// when transport is starting to play in context of the given quantum.
/// This function evaluates to a no-op if isPlaying() equals false.
pub fn request_beat_at_start_playing_time(&mut self, beat: f64, quantum: f64) {
unsafe { SessionState_requestBeatAtStartPlayingTime(self.wss, beat, quantum) }
}
/// Convenience function to start or stop transport at a given time and
/// attempt to map the given beat to this time in context of the given quantum.
pub fn set_is_playing_and_request_beat_at_time(&mut self,
is_playing: bool, time: i64, beat: f64, quantum: f64) {
unsafe { SessionState_setIsPlayingAndRequestBeatAtTime(self.wss,
is_playing, time, beat, quantum) }
}
}
pub struct Clock {
wc: *mut WClock,
}
impl Drop for Clock{
fn drop(&mut self) {
unsafe { Clock_destroy(self.wc) }
}
}
impl Clock {
#[cfg(target_os = "macos")]
pub fn ticks_to_micros(&self, ticks: u64) -> i64 {
unsafe { Clock_ticksToMicros(self.wc, ticks) }
}
#[cfg(target_os = "macos")]
pub fn micros_to_ticks(&self, micros: i64) -> u64 {
unsafe { Clock_microsToTicks(self.wc, micros) }
}
#[cfg(target_os = "macos")]
pub fn ticks(&self) -> u64 {
unsafe { Clock_ticks(self.wc) }
}
pub fn micros(&self) -> i64 {
unsafe { Clock_micros(self.wc) }
}
}
#[cfg(test)]
mod tests {
#[test]
fn it_works() {
assert_eq!(2 + 2, 4);
}
}