Quelle  mod.rs

//! Web MIDI Backend.
//!
//! Reference:
//! * [W3C Editor's Draft](https://webaudio.github.io/web-midi-api/)
//! * [MDN web docs](https://developer.mozilla.org/en-US/docs/Web/API/MIDIAccess)

use js_sys::{Map, Promise, Uint8Array};
use wasm_bindgen::prelude::*;
use wasm_bindgen::JsCast;
use web_sys::{MidiAccess, MidiMessageEvent, MidiOptions};

use std::cell::RefCell;
use std::sync::{Arc, Mutex};

use crate::errors::*;
use crate::Ignore;

thread_local! {
    static STATIC : RefCell<Static> = RefCell::new(Static::new());
}

struct Static {
    pub access: Option<MidiAccess>,
    pub request: Option<Promise>,
    pub ever_requested: bool,

    pub on_ok: Closure<dyn FnMut(JsValue)>,
    pub on_err: Closure<dyn FnMut(JsValue)>,
}

impl Static {
    pub fn new() -> Self {
        let mut s = Self {
            access: None,
            request: None,
            ever_requested: false,

            on_ok: Closure::wrap(Box::new(|access| {
                STATIC.with(|s| {
                    let mut s = s.borrow_mut();
                    let access: MidiAccess = access.dyn_into().unwrap();
                    s.request = None;
                    s.access = Some(access);
                });
            })),
            on_err: Closure::wrap(Box::new(|_error| {
                STATIC.with(|s| {
                    let mut s = s.borrow_mut();
                    s.request = None;
                });
            })),
        };
        // Some notes on sysex behavior:
        //  1) Some devices (but not all!) may work without sysex
        //  2) Chrome will only prompt the end user to grant permission if they requested sysex permissions for now...
        //      but that's changing soon for "security reasons" (reduced fingerprinting? poorly tested drivers?):
        //      https://www.chromestatus.com/feature/5138066234671104
        //
        //  I've chosen to hardcode sysex=true here, since that'll be compatible with more devices, *and* should change
        //  less behavior when Chrome's changes land.
        s.request_midi_access(true);
        s
    }

    fn request_midi_access(&mut self, sysex: bool) {
        self.ever_requested = true;
        if self.access.is_some() {
            return;
        } // Already have access
        if self.request.is_some() {
            return;
        } // Mid-request already
        let window = if let Some(w) = web_sys::window() {
            w
        } else {
            return;
        };

        let _request = match window
            .navigator()
            .request_midi_access_with_options(MidiOptions::new().sysex(sysex))
        {
            Ok(p) => {
                self.request = Some(p.then2(&self.on_ok, &self.on_err));
            }
            Err(_) => {
                return;
            } // node.js? brower doesn't support webmidi? other?
        };
    }
}

#[derive(Clone, PartialEq)]
pub struct MidiInputPort {
    input: web_sys::MidiInput,
}

impl MidiInputPort {
    pub fn id(&self) -> String {
        self.input.id()
    }
}

pub struct MidiInput {
    ignore_flags: Ignore,
}

impl MidiInput {
    pub fn new(_client_name: &str) -> Result<Self, InitError> {
        STATIC.with(|_| {});
        Ok(MidiInput {
            ignore_flags: Ignore::None,
        })
    }

    pub(crate) fn ports_internal(&self) -> Vec<crate::common::MidiInputPort> {
        STATIC.with(|s| {
            let mut v = Vec::new();
            let s = s.borrow();
            if let Some(access) = s.access.as_ref() {
                let inputs: Map = access.inputs().unchecked_into();
                inputs.for_each(&mut |value, _| {
                    v.push(crate::common::MidiInputPort {
                        imp: MidiInputPort {
                            input: value.dyn_into().unwrap(),
                        },
                    });
                });
            }
            v
        })
    }

    pub fn ignore(&mut self, flags: Ignore) {
        self.ignore_flags = flags;
    }

    pub fn port_count(&self) -> usize {
        STATIC.with(|s| {
            let s = s.borrow();
            s.access
                .as_ref()
                .map(|access| access.inputs().unchecked_into::<Map>().size() as usize)
                .unwrap_or(0)
        })
    }

    pub fn port_name(&self, port: &MidiInputPort) -> Result<String, PortInfoError> {
        Ok(port.input.name().unwrap_or_else(|| port.input.id()))
    }

    pub fn connect<F, T: Send + 'static>(
        self,
        port: &MidiInputPort,
        _port_name: &str,
        mut callback: F,
        data: T,
    ) -> Result<MidiInputConnection<T>, ConnectError<MidiInput>>
    where
        F: FnMut(u64, &[u8], &mut T) + Send + 'static,
    {
        let input = port.input.clone();
        let _ = input.open(); // NOTE: asyncronous!

        let ignore_flags = self.ignore_flags;
        let user_data = Arc::new(Mutex::new(Some(data)));

        let closure = {
            let user_data = user_data.clone();

            let closure = Closure::wrap(Box::new(move |event: MidiMessageEvent| {
                let time = (event.time_stamp() * 1000.0) as u64; // ms -> us
                let buffer = event.data().unwrap();

                let status = buffer[0];
                if !(status == 0xF0 && ignore_flags.contains(Ignore::Sysex)
                    || status == 0xF1 && ignore_flags.contains(Ignore::Time)
                    || status == 0xF8 && ignore_flags.contains(Ignore::Time)
                    || status == 0xFE && ignore_flags.contains(Ignore::ActiveSense))
                {
                    callback(
                        time,
                        &buffer[..],
                        user_data.lock().unwrap().as_mut().unwrap(),
                    );
                }
            }) as Box<dyn FnMut(MidiMessageEvent)>);

            input.set_onmidimessage(Some(closure.as_ref().unchecked_ref()));

            closure
        };

        Ok(MidiInputConnection {
            ignore_flags,
            input,
            user_data,
            closure,
        })
    }
}

pub struct MidiInputConnection<T> {
    ignore_flags: Ignore,
    input: web_sys::MidiInput,
    user_data: Arc<Mutex<Option<T>>>,
    #[allow(dead_code)] // Must be kept alive until we decide to unregister from input
    closure: Closure<dyn FnMut(MidiMessageEvent)>,
}

impl<T> MidiInputConnection<T> {
    pub fn close(self) -> (MidiInput, T) {
        let Self {
            ignore_flags,
            input,
            user_data,
            ..
        } = self;

        input.set_onmidimessage(None);
        let mut user_data = user_data.lock().unwrap();

        (MidiInput { ignore_flags }, user_data.take().unwrap())
    }
}

#[derive(Clone, PartialEq)]
pub struct MidiOutputPort {
    output: web_sys::MidiOutput,
}

impl MidiOutputPort {
    pub fn id(&self) -> String {
        self.output.id()
    }
}

pub struct MidiOutput {}

impl MidiOutput {
    pub fn new(_client_name: &str) -> Result<Self, InitError> {
        STATIC.with(|_| {});
        Ok(MidiOutput {})
    }

    pub(crate) fn ports_internal(&self) -> Vec<crate::common::MidiOutputPort> {
        STATIC.with(|s| {
            let mut v = Vec::new();
            let s = s.borrow();
            if let Some(access) = s.access.as_ref() {
                access
                    .outputs()
                    .unchecked_into::<Map>()
                    .for_each(&mut |value, _| {
                        v.push(crate::common::MidiOutputPort {
                            imp: MidiOutputPort {
                                output: value.dyn_into().unwrap(),
                            },
                        });
                    });
            }
            v
        })
    }

    pub fn port_count(&self) -> usize {
        STATIC.with(|s| {
            let s = s.borrow();
            s.access
                .as_ref()
                .map(|access| access.outputs().unchecked_into::<Map>().size() as usize)
                .unwrap_or(0)
        })
    }

    pub fn port_name(&self, port: &MidiOutputPort) -> Result<String, PortInfoError> {
        Ok(port.output.name().unwrap_or_else(|| port.output.id()))
    }

    pub fn connect(
        self,
        port: &MidiOutputPort,
        _port_name: &str,
    ) -> Result<MidiOutputConnection, ConnectError<MidiOutput>> {
        let _ = port.output.open(); // NOTE: asyncronous!
        Ok(MidiOutputConnection {
            output: port.output.clone(),
        })
    }
}

pub struct MidiOutputConnection {
    output: web_sys::MidiOutput,
}

impl MidiOutputConnection {
    pub fn close(self) -> MidiOutput {
        let _ = self.output.close(); // NOTE: asyncronous!
        MidiOutput {}
    }

    pub fn send(&mut self, message: &[u8]) -> Result<(), SendError> {
        self.output
            .send(unsafe { Uint8Array::view(message) }.as_ref())
            .map_err(|_| SendError::Other("JavaScript exception"))
    }
}