Struct helgoboss_midi::PollingParameterNumberMessageScanner

pub struct PollingParameterNumberMessageScanner { /* private fields */ }

Scanner for detecting (N)RPN messages in a stream of short messages with polling.

Supports the following message sequences (x and y represent the bytes that make up the parameter number, MSB represents either a data entry MSB or an increment/decrement value):

• [x, y, MSB]: Interpreted as 7-bit data entry or increment/decrement message.
• [x, y, MSB, LSB]: Interpreted as 14-bit data entry message.
• [x, y, LSB, MSB]: Interpreted as 14-bit data entry message.
• [x, y, MSB, MSB, ...]: Interpreted as 7-bit data entry or increment/decrement messages.
• [x, y, MSB, LSB, MSB, LSB, ...]: Interpreted as 14-bit data entry messages.
• [x, y, MSB, LSB, LSB, ...]: Interpreted as 14-bit data entry messages.

Please note that this requires invoking the poll method on a regular basis because a timeout is used to wait for potentially relevant messages that might arrive a bit later.

Example

use helgoboss_midi::test_util::{control_change, channel, u7, u14};
use helgoboss_midi::{ParameterNumberMessage, PollingParameterNumberMessageScanner};
use std::time::Duration;

let mut scanner = PollingParameterNumberMessageScanner::new(Duration::from_millis(0));

let result_1 = scanner.feed(&control_change(2, 99, 3));
let result_2 = scanner.feed(&control_change(2, 98, 37));
let result_3 = scanner.feed(&control_change(2, 6, 126));
let result_4 = scanner.poll(channel(2));
assert_eq!(result_1, [None, None]);
assert_eq!(result_2, [None, None]);
assert_eq!(result_3, [None, None]);
assert_eq!(
    result_4,
    Some(ParameterNumberMessage::non_registered_7_bit(
        channel(2),
        u14(421),
        u7(126)
    ))
);

Implementations

impl PollingParameterNumberMessageScanner

pub fn new(timeout: Duration) -> PollingParameterNumberMessageScanner

Creates a new scanner.

The timeout determines how long to wait for the second value byte.

pub fn feed(
    &mut self,
    msg: &impl ShortMessage
) -> [Option<ParameterNumberMessage>; 2]

Feeds the scanner a single short message.

Returns zero, one or two (N)RPN messages. Two if the scanner was currently waiting for a data entry LSB (after receiving an MSB) and encountering a data increment or decrement. In this case we have two complete messages to emit.

pub fn poll(&mut self, channel: Channel) -> Option<ParameterNumberMessage>

Returns the (N)RPN message as soon as the timeout of waiting for the second value message has been exceeded.

pub fn reset(&mut self)

Resets the scanner discarding all intermediate scanning progress.

Trait Implementations

impl Clone for PollingParameterNumberMessageScanner

fn clone(&self) -> PollingParameterNumberMessageScanner

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PollingParameterNumberMessageScanner

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for PollingParameterNumberMessageScanner

fn default() -> PollingParameterNumberMessageScanner

Returns the “default value” for a type.

impl PartialEq<PollingParameterNumberMessageScanner> for PollingParameterNumberMessageScanner

fn eq(&self, other: &PollingParameterNumberMessageScanner) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &PollingParameterNumberMessageScanner) -> bool

This method tests for !=.

impl Copy for PollingParameterNumberMessageScanner

impl Eq for PollingParameterNumberMessageScanner

impl StructuralEq for PollingParameterNumberMessageScanner

impl StructuralPartialEq for PollingParameterNumberMessageScanner