package widgets import ( "sync/atomic" "time" "github.com/gdamore/tcell" "git.sr.ht/~sircmpwn/aerc2/lib/ui" ) var ( frames = []string{ "[..] ", " [..] ", " [..] ", " [..] ", " [..]", " [..] ", " [..] ", " [..] ", } ) type Spinner struct { frame int64 // access via atomic onInvalidate func(d ui.Drawable) stop chan struct{} } func NewSpinner() *Spinner { spinner := Spinner{ stop: make(chan struct{}), frame: -1, } return &spinner } func (s *Spinner) Start() { if s.IsRunning() { return } atomic.StoreInt64(&s.frame, 0) go func() { for { select { case <-s.stop: atomic.StoreInt64(&s.frame, -1) s.stop <- struct{}{} return case <-time.After(200 * time.Millisecond): atomic.AddInt64(&s.frame, 1) s.Invalidate() } } }() } func (s *Spinner) Stop() { if !s.IsRunning() { return } s.stop <- struct{}{} <-s.stop s.Invalidate() } func (s *Spinner) IsRunning() bool { return atomic.LoadInt64(&s.frame) != -1 } func (s *Spinner) Draw(ctx *ui.Context) { if !s.IsRunning() { s.Start() } cur := int(atomic.LoadInt64(&s.frame) % int64(len(frames))) ctx.Fill(0, 0, ctx.Width(), ctx.Height(), ' ', tcell.StyleDefault) col := ctx.Width()/2 - len(frames[0])/2 + 1 ctx.Printf(col, 0, tcell.StyleDefault, "%s", frames[cur]) } func (s *Spinner) OnInvalidate(onInvalidate func(d ui.Drawable)) { s.onInvalidate = onInvalidate } func (s *Spinner) Invalidate() { if s.onInvalidate != nil { s.onInvalidate(s) } }