Add datetime components 196-215; Kit.At; inert stepper arrows

Calendars, date and time inputs, pickers, clocks, timers, a sun dial,
a season wheel, an agenda and a day schedule. Kit.At rebuilds at a
moment (relative times, midnight). Stepper and NumberInput arrows stop
under Inert. DateInput parks a popup focus as its own.

datetime/timeinput.go

@@ -0,0 +1,121 @@
+package datetime
+
+import (
+	"fmt"
+	"log/slog"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type TimeInputOptions struct {
+	Disabled bool
+}
+
+type TimeInputResult struct {
+	Element *ui.Element
+	Changed bool
+}
+
+type timeKey struct{}
+
+// timing is the segment edited, and a first digit typed.
+type timing struct {
+	seg, first int
+}
+
+// TimeInput edits HH:MM; Up and Down step, digits type.
+func TimeInput(c *ui.Context, text string, tm *time.Time, o TimeInputOptions) TimeInputResult {
+	k := pixel.K(c)
+	old := *tm
+	shell, base, st := pixel.Shell(c, func() *ui.Element {
+		return ui.Box(c).Focusable().Role(ui.RoleTextField).Label(text).Disabled(o.Disabled)
+	})
+	s := ui.Local(base, timeKey{}, func() timing { return timing{first: -1} })
+	h, m := tm.Hour(), tm.Minute()
+	set := func(hour, minute int) {
+		*tm = time.Date(tm.Year(), tm.Month(), tm.Day(), hour, minute, 0, 0, tm.Location())
+		h, m = hour, minute
+	}
+	step := func(d int) {
+		if s.seg == 0 {
+			set((h+d+24)%24, m)
+		} else {
+			set(h, (m+d+60)%60)
+		}
+		s.first = -1
+	}
+	if base.Shortcut(0, ui.KeyUp) {
+		step(1)
+	}
+	if base.Shortcut(0, ui.KeyDown) {
+		step(-1)
+	}
+	for _, mv := range []struct {
+		key ui.Key
+		seg int
+	}{{ui.KeyLeft, 0}, {ui.KeyRight, 1}} {
+		if base.Shortcut(0, mv.key) {
+			s.seg, s.first = mv.seg, -1
+		}
+	}
+	for d := range 10 {
+		if !base.Shortcut(0, ui.Key0+ui.Key(d)) {
+			continue
+		}
+		top := 23
+		if s.seg == 1 {
+			top = 59
+		}
+		v := d
+		if s.first >= 0 && s.first*10+d <= top {
+			v = s.first*10 + d
+		}
+		if s.seg == 0 {
+			set(v, m)
+		} else {
+			set(h, v)
+		}
+		// A second digit ends a segment; hours pass to minutes.
+		if s.first >= 0 {
+			s.first, s.seg = -1, 1
+		} else {
+			s.first = d
+		}
+	}
+	// Enter and Space are taken, so clicks come from pointers.
+	base.Shortcut(0, ui.KeyEnter)
+	base.Shortcut(0, ui.KeySpace)
+	if base.Clicked() {
+		x, _, _ := base.PointerPosition()
+		s.seg, s.first = 0, -1
+		if int(x/k.Dot()) >= 4+pixel.Measure("00:") {
+			s.seg = 1
+		}
+	}
+	shown := fmt.Sprintf("%02d:%02d", h, m)
+	base.Description(shown)
+	seg := s.seg
+	shell.Size(k.D(pixel.Measure("00:00")+10), k.D(pixel.LineHeight+6)).Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		g.Frame(0, 0, g.W, g.H, pixel.Sunken, pixel.Well)
+		hh, mm, at := shown[:2], shown[3:], 5
+		for i, part := range []string{hh, ":", mm} {
+			ink, w := pixel.Ink, pixel.Measure(part)
+			if st.Focus && (i == 0 && seg == 0 || i == 2 && seg == 1) {
+				g.Rect(at-1, 2, w+2, g.H-4, pixel.Accent)
+				ink = pixel.AccentInk
+			}
+			g.Text(at, 3, part, ink, 1)
+			at += w
+		}
+		g.Finish(st)
+	})
+	res := TimeInputResult{Element: shell, Changed: !tm.Equal(old)}
+	if res.Changed {
+		slog.Debug("8bit: time input", "label", text, "time", shown)
+	}
+	return res
+}