melrōse musical expression player

package core import ( "math" "time" "github.com/emicklei/melrose/notify" ) // Beatmaster is a LoopController type Beatmaster struct { context Context beating bool bpmChanges chan float64 ticker *time.Ticker done chan bool schedule *BeatSchedule beats int64 // monotonic increasing number, starting at 0 biab int64 // current number of beats in a bar bpm float64 // current beats per minute settingNotifier func(LoopController) } func NewBeatmaster(ctx Context, bpm float64) *Beatmaster { return &Beatmaster{ context: ctx, beating: false, done: make(chan bool), bpmChanges: make(chan float64), schedule: NewBeatSchedule(), beats: 0, biab: 4, bpm: bpm} } func (b *Beatmaster) Reset() { b.Stop() // drain go func() { select { case <-b.bpmChanges: default: } }() b.schedule.Reset() b.Start() } func (b *Beatmaster) BPM() float64 { return b.bpm } func (b *Beatmaster) BIAB() int { return int(b.biab) } func (b *Beatmaster) BeatsAndBars() (int64, int64) { return b.beats, b.beats / b.biab } func (b *Beatmaster) SettingNotifier(handler func(LoopController)) { b.settingNotifier = handler } // Plan is part of LoopControl // bars is zero-based func (b *Beatmaster) Plan(bars int64, seq Sequenceable) { atBeats := b.beatsAtNextBar() + (b.biab * bars) if notify.IsDebug() { notify.Debugf("beat.schedule at beats: %d put: %s bars: %.2f", atBeats, Storex(seq), seq.S().Bars(int(b.biab))) } b.schedule.Schedule(atBeats, func(when time.Time) { d := b.context.Device() if d != nil { // TODO happens on testing; NEEDSFIX d.Play(NoCondition, seq, b.bpm, when) } }) } func (b *Beatmaster) beatsAtNextBar() int64 { if b.beats%b.biab == 0 { return b.beats } return (b.beats/b.biab + 1) * b.biab } // SetBPM will change the beats per minute at the next bar, unless the master is not started. func (b *Beatmaster) SetBPM(bpm float64) { if !b.beating { b.bpm = bpm b.notifySettingChanged() return } if b.bpm == bpm { return } if b.schedule.IsEmpty() { b.bpm = bpm b.notifySettingChanged() return } go func() { b.bpmChanges <- bpm }() } // TODO move checks to SetBIAB in control // SetBIAB will change the beats per bar, unless the master is not started. func (b *Beatmaster) SetBIAB(biab int) { if !b.beating { b.biab = int64(biab) return } if b.biab == int64(biab) { return } b.biab = int64(biab) b.notifySettingChanged() } func (b *Beatmaster) notifySettingChanged() { if b.settingNotifier == nil { return } b.settingNotifier(b) } func (b *Beatmaster) Start() { if b.beating { return } b.notifySettingChanged() b.beats = 0 b.ticker = time.NewTicker(beatTickerDuration(b.bpm)) b.beating = true go func() { if notify.IsDebug() { notify.Debugf("core.beatmaster: started bpm=%v tick=%v", b.bpm, beatTickerDuration(b.bpm)) } for { if b.beats%b.biab == 0 { // on a bar // abort ? select { case <-b.done: return // only change BPM on a bar case bpm := <-b.bpmChanges: if notify.IsDebug() { notify.Debugf("core.beatmaster: changed bpm=%v tick=%v", bpm, beatTickerDuration(bpm)) } b.bpm = bpm b.notifySettingChanged() b.ticker.Stop() b.ticker = time.NewTicker(beatTickerDuration(bpm)) default: } } // in between bars select { case <-b.done: return case now := <-b.ticker.C: if b.schedule.IsEmpty() { b.beats = 0 } else { actions := b.schedule.Unschedule(b.beats) for _, each := range actions { each(now) } b.beats++ } } } }() } func beatTickerDuration(bpm float64) time.Duration { return time.Duration(int(math.Round(float64(60*1000)/bpm))) * time.Millisecond } // Stop will stop the beats. Any Loops will continue to run. func (b *Beatmaster) Stop() { if !b.beating { return } b.beating = false b.ticker.Stop() b.done <- true if notify.IsDebug() { notify.Debugf("core.beatmaster: stopped") } } // NoLooper is a Beatmaster that does not loop var NoLooper = zeroBeat{} type zeroBeat struct{} func (s zeroBeat) Start() {} func (s zeroBeat) Stop() {} func (s zeroBeat) Reset() {} func (s zeroBeat) SetBPM(bpm float64) {} func (s zeroBeat) BPM() float64 { return 120.0 } func (s zeroBeat) SetBIAB(biab int) {} func (s zeroBeat) BIAB() int { return 4 } func (s zeroBeat) BeatsAndBars() (int64, int64) { return 0, 0 } func (s zeroBeat) Plan(bars int64, seq Sequenceable) {} func (s zeroBeat) SettingNotifier(handler func(LoopController)) {}