Add loading spinner

1 files changed, 80 insertions, 0 deletions

diff --git a/widgets/spinner.go b/widgets/spinner.go
new file mode 100644
index 0000000..2e7e367
--- /dev/null
+++ b/widgets/spinner.go
@@ -0,0 +1,80 @@
+package widgets
+
+import (
+	"time"
+
+	"github.com/gdamore/tcell"
+
+	"git.sr.ht/~sircmpwn/aerc2/lib/ui"
+)
+
+var (
+	frames = []string{
+		"[..]    ",
+		" [..]   ",
+		"  [..]  ",
+		"   [..] ",
+		"    [..]",
+		"   [..] ",
+		"  [..]  ",
+		" [..]   ",
+	}
+)
+
+type Spinner struct {
+	frame        int
+	onInvalidate func(d ui.Drawable)
+	stop         chan interface{}
+}
+
+func NewSpinner() *Spinner {
+	spinner := Spinner{
+		stop:  make(chan interface{}),
+		frame: -1,
+	}
+	return &spinner
+}
+
+func (s *Spinner) Start() {
+	s.frame = 0
+	go func() {
+		for {
+			select {
+			case <-s.stop:
+				return
+			case <-time.After(200 * time.Millisecond):
+				s.frame++
+				if s.frame >= len(frames) {
+					s.frame = 0
+				}
+				s.Invalidate()
+			}
+		}
+	}()
+}
+
+func (s *Spinner) Stop() {
+	s.stop <- nil
+	s.frame = -1
+	s.Invalidate()
+}
+
+func (s *Spinner) IsRunning() bool {
+	return s.frame != -1
+}
+
+func (s *Spinner) Draw(ctx *ui.Context) {
+	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[s.frame])
+}
+
+func (s *Spinner) OnInvalidate(onInvalidate func(d ui.Drawable)) {
+	s.onInvalidate = onInvalidate
+}
+
+func (s *Spinner) Invalidate() {
+	if s.onInvalidate != nil {
+		s.onInvalidate(s)
+	}
+}