1 files changed, 250 insertions, 0 deletions
diff --git a/third_party/rust/midir/src/backend/webmidi/mod.rs b/third_party/rust/midir/src/backend/webmidi/mod.rs
new file mode 100644
index 0000000000..b76f0b3617
--- /dev/null
+++ b/third_party/rust/midir/src/backend/webmidi/mod.rs
@@ -0,0 +1,250 @@
+//! 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)
+
+extern crate js_sys;
+extern crate wasm_bindgen;
+extern crate web_sys;
+
+use self::js_sys::{Map, Promise, Uint8Array};
+use self::wasm_bindgen::prelude::*;
+use self::wasm_bindgen::JsCast;
+use self::web_sys::{MidiAccess, MidiOptions, MidiMessageEvent};
+
+use std::cell::RefCell;
+use std::sync::{Arc, Mutex};
+
+use ::errors::*;
+use ::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,
+}
+
+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<::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(::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,
+}
+
+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<::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(::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"))
+    }
+}