launchy 0.4.1

Low-level bindings and high-level abstractions for the Novation Launchpad MIDI devices
Documentation 
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pub use crate::protocols::query::*;

use super::Button;

/// A Launchpad S input message
#[derive(Debug, Eq, PartialEq, Hash, Clone)]
pub enum Message {
    /// A button was pressed
    Press { button: Button },
    /// A button was released
    Release { button: Button },
    /// Emitted after a text scroll was initiated
    TextEndedOrLooped,
    /// Every once in a while, the device randomly spews out a weird undocumented MIDI message.
    /// I have no idea what that is about. It comes relatively regularly though, so I don't want
    /// to discard those messages either.
    UnknownShortMessage { bytes: [u8; 3] },
    /// The response to a [device inquiry request](super::Output::request_device_inquiry)
    DeviceInquiry(DeviceInquiry),
    /// The response to a [version inquiry request](super::Output::request_version_inquiry)
    VersionInquiry(VersionInquiry),
}

fn decode_grid_button(btn: u8) -> Button {
    Button::GridButton {
        x: btn % 16,
        y: btn / 16,
    }
}

/// The Launchpad S input connection creator.
pub struct Input;

impl crate::InputDevice for Input {
    const MIDI_CONNECTION_NAME: &'static str = "Launchy S input";
    const MIDI_DEVICE_KEYWORD: &'static str = "Launchpad S";
    type Message = Message;

    fn decode_message(_timestamp: u64, data: &[u8]) -> Message {
        if let Some(device_inquiry) = parse_device_query(data) {
            return Message::DeviceInquiry(device_inquiry);
        }

        if let Some(version_inquiry) = parse_version_query(data) {
            return Message::VersionInquiry(version_inquiry);
        }

        // first byte of a launchpad midi message is the message type
        match data {
            // Note on
            &[0x90, button, velocity] => {
                let button = decode_grid_button(button);

                match velocity {
                    0 => Message::Release { button },
                    127 => Message::Press { button },
                    other => panic!("Unexpected grid note-on velocity {}", other),
                }
            }
            // Controller change
            &[0xB0, number @ 104..=111, velocity] => {
                let button = Button::ControlButton {
                    index: number - 104,
                };

                match velocity {
                    0 => Message::Release { button },
                    127 => Message::Press { button },
                    other => panic!("Unexpected control note-on velocity {}", other),
                }
            }
            &[0xB0, 0, 3] => Message::TextEndedOrLooped,
            &[a, b, c] => Message::UnknownShortMessage { bytes: [a, b, c] },
            // YES we have no note off message handler here because it's not used by the launchpad.
            // It sends zero-velocity note-on messages instead.
            other => panic!("Unexpected midi message: {:?}", other),
        }
    }
}