melrōse musical expression player

package core import ( "encoding/json" "fmt" "os" "time" "github.com/emicklei/melrose/notify" ) type NoteEvent struct { Start time.Time `json:"start"` End time.Time `json:"end"` Number int `json:"number"` Velocity int `json:"velocity"` } func (e NoteEvent) WithEnd(end time.Time) NoteEvent { return NoteEvent{Start: e.Start, Number: e.Number, Velocity: e.Velocity, End: end} } func NotesEventsToFile(events []NoteEvent, name string) { out, err := os.Create(name) if err != nil { notify.Errorf("NotesEventsToFile:%v", err) return } defer out.Close() enc := json.NewEncoder(out) enc.SetIndent("", "\t") if err := enc.Encode(events); err != nil { notify.Errorf("NotesEventsToFile:%v", err) } } func NoteEventsFromFile(name string) (list []NoteEvent) { in, err := os.Open(name) if err != nil { notify.Errorf("NoteEventsFromFile:%v", err) return } defer in.Close() dec := json.NewDecoder(in) if err := dec.Decode(&list); err != nil { notify.Errorf("NoteEventsFromFile:%v", err) } return } func NoteEventsToPeriods(events []NoteEvent) (list []NotePeriod) { for _, each := range events { list = append(list, NotePeriod{ startMs: each.Start.UnixMilli(), endMs: each.End.UnixMilli(), number: each.Number, velocity: each.Velocity, }) } return } type NoteEventStatistics struct { Start, End time.Time Lowest, Highest int } func NoteStatistics(list []NoteEvent) (stats NoteEventStatistics) { if len(list) == 0 { return stats } stats.Start = list[0].Start stats.End = list[len(list)-1].End stats.Lowest = 127 for _, each := range list { if each.Number < stats.Lowest { stats.Lowest = each.Number } if each.Number > stats.Highest { stats.Highest = each.Number } } return } const eventTimeFormat = "03:04:05.000000000" func (s NoteEventStatistics) String() string { return fmt.Sprintf("start=%s,end=%s,low=%d,high=%d", s.Start.Format(eventTimeFormat), s.End.Format(eventTimeFormat), s.Lowest, s.Highest) } type NoteChange struct { isOn bool note int64 velocity int64 } func (n NoteChange) Number() int { return int(n.note) } func (n NoteChange) Velocity() int { return int(n.velocity) } func (n NoteChange) IsOn() bool { return n.isOn } func (n NoteChange) NoteChangesDo(block func(NoteChange)) { block(n) } func NewNoteChange(isOn bool, midiNr int64, velocity int64) NoteChange { return NoteChange{ isOn: isOn, note: midiNr, velocity: velocity, } } func (n NoteChange) Handle(tim *Timeline, when time.Time) { // NOP }