Add feedback components 106-130; inert scope, focus return, two-step deploy

feedback/countup.go

@@ -0,0 +1,47 @@
+package feedback
+
+import (
+	"strconv"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type CountUpOptions struct {
+	// Scale is 1–4; zero means 1.
+	Scale int
+	Slot  pixel.Slot
+}
+
+type countKey struct{}
+
+// counting runs from one value to the next.
+type counting struct {
+	from, to int
+	at       time.Time
+}
+
+// CountUp counts to a new value in eight steps.
+func CountUp(c *ui.Context, value int, o CountUpOptions) *ui.Element {
+	k := pixel.K(c)
+	sc := pixel.Or("CountUp Scale", o.Scale, 1)
+	e := ui.Box(c).Role(ui.RoleText).Label(strconv.Itoa(value))
+	s := ui.Local(e, countKey{}, func() counting { return counting{from: value, to: value} })
+	shown := func() int {
+		step := 8
+		if !k.Reduce() {
+			step = since(c, k, s.at, 15, 8)
+		}
+		return s.from + (s.to-s.from)*step/8
+	}
+	if value != s.to {
+		s.from, s.to, s.at = shown(), value, k.Now()
+	}
+	n := strconv.Itoa(shown())
+	w := max(pixel.Measure(strconv.Itoa(s.from)), pixel.Measure(strconv.Itoa(s.to)))
+	return e.Size(k.D(w*sc), k.D(pixel.LineHeight*sc)).Draw(func(p *ui.Painter, r ui.Rect) {
+		k.Canvas(p, r).Text(0, 0, n, o.Slot, sc)
+	})
+}