audio-processor-traits 1.0.0-alpha.7

// Augmented Audio: Audio libraries and applications
// Copyright (c) 2022 Pedro Tacla Yamada
//
// The MIT License (MIT)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// THE SOFTWARE.
/// Represents an "Event" type for audio processors. Due to how events are forwarded to processors,
/// the list of events received might contain non-MIDI events.
pub trait MidiMessageLike {
    fn is_midi(&self) -> bool;
    fn bytes(&self) -> Option<&[u8]>;
}

/// A MIDI event processor
pub trait MidiEventHandler {
    /// MIDI messages. May contain invalid events (of a different type) which should be skipped.
    fn process_midi_events<Message: MidiMessageLike>(&mut self, midi_messages: &[Message]);
}

pub struct NoopMidiEventHandler {}

impl Default for NoopMidiEventHandler {
    fn default() -> Self {
        Self::new()
    }
}

impl NoopMidiEventHandler {
    pub fn new() -> Self {
        Self {}
    }
}

impl MidiEventHandler for NoopMidiEventHandler {
    fn process_midi_events<Message: MidiMessageLike>(&mut self, _midi_messages: &[Message]) {}
}

/// `rust-vst` compatibility for the MidiMessageLike trait
#[cfg(feature = "vst_support")]
pub mod vst {
    use ::vst::api::{Event, EventType, MidiEvent};

    use super::*;

    /// Cast the VST `Events` struct onto a `MidiMessageLike` slice you can pass into processors
    pub fn midi_slice_from_events(events: &::vst::api::Events) -> &[*mut Event] {
        unsafe {
            std::slice::from_raw_parts(
                &events.events[0] as *const *mut _,
                events.num_events as usize,
            )
        }
    }

    impl MidiMessageLike for *mut Event {
        fn is_midi(&self) -> bool {
            unsafe { matches!((**self).event_type, EventType::Midi) }
        }

        fn bytes(&self) -> Option<&[u8]> {
            unsafe {
                if matches!((**self).event_type, EventType::Midi) {
                    let midi_event = *self as *const MidiEvent;
                    Some(&(*midi_event).midi_data)
                } else {
                    None
                }
            }
        }
    }

    impl MidiMessageLike for *const Event {
        fn is_midi(&self) -> bool {
            unsafe { matches!((**self).event_type, EventType::Midi) }
        }

        fn bytes(&self) -> Option<&[u8]> {
            unsafe {
                match (**self).event_type {
                    EventType::Midi => {
                        let midi_event = *self as *const MidiEvent;
                        Some(&(*midi_event).midi_data)
                    }
                    _ => None,
                }
            }
        }
    }
}