Cursor active notes

[rvilarl]

The cursor, on each movement, fires an event including the active notes. At present there is no way to differentiate if:

• a note activated some steps behind but still active (from a piano perspective keep the associted keys pressed)
• a note activated some steps but reactivated (from a piano perspective release and press the associated keys again)

Please note that there is a variant of the second sceenario where notes can be tied (from a piano perspective keep the keys pressed) In chords, ties can affect specific pitches meaning that it could be that some keys are to be kept pressed and others are to be re-pressed.

[jaredjj3]

@rvilarl, thanks for the issue!

Ultimately, I think the second bullet shows that the current SequenceEntry abstraction is not sufficient for describing all the different changes during playback.

vexml/src/playback/types.ts

Lines 5 to 10 in fd2e539

	export type SequenceEntry = {
	anchorElement: PlaybackElement;
	activeElements: PlaybackElement[];
	durationRange: DurationRange;
	xRange: NumberRange;
	};

Every score element actually has a lifecycle, and that's not communicated well here. I'll prototype some ideas for the next iteration of SequenceEntry when I can. Feel free to interject, list more requirements, or provide some ideas.

[rvilarl]

An idea could be: for the active elements, keep the ms when it was activated.

Another challenging topic for the cursors are the grace notes, they are played either before or after the associated note is hit.