Model and history

TimelineModel

Holds the tracks and clips and records finished edits in a History. State objects are never changed in place, so comparing with === tells you whether something changed.

const model = new TimelineModel(state?, history?);

state	The current TimelineState
history	Its History
sources	Map of source id to { id, duration? }
peaks	Map of source id to Peaks
apply(label, edit)	Apply edit(state) => state as one undo step
draft(label, edit)	Show an edit in progress; each call starts again from the state before the draft
commit(label)	Finish the draft as one undo step
cancel()	Throw the draft away
load(state)	Replace everything without an undo step
setSource(source, peaks?)	Record a source's length and peaks

Events: change ({ state, label, final }) and source ({ id }).

History

const history = new History(limit = 200);

push({ label, undo, redo })	Record a step that has already been applied
undo() / redo()	Return false when there is nothing to do
clear()
canUndo / canRedo
info	{ canUndo, canRedo, undoLabel?, redoLabel? }

Event: change with info.

Grid

const grid = new Grid({ bpm: 120, meter: [4, 4], snap: 'beat' });

grid.beat; // seconds per beat of the meter
grid.bar; // seconds per bar
grid.step; // seconds between snap points, 0 when off
grid.round(1.37); // the nearest snap point
grid.position(5.5); // { bar: 3, beat: 4 }