Add overlay components 176-195; pixel Harbor and Kit.Cue

Dialogs on DialogBase with focusable panels that harbor parked focus,
popovers on PopoverBase, bubbles, drawers, sheets, a lightbox, an RPG
dialogue box, notifications, a pause menu and a dithered title card.
Kit.Cue moves from feedback to pixel.

overlay/overlay.go

@@ -0,0 +1,135 @@
+// Package overlay floats windows, bubbles and veils over the view.
+package overlay
+
+import (
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+// dim checkers the backdrop of a dialog.
+func dim(k pixel.Kit, back *ui.Element, s pixel.Slot, level int) {
+	back.Draw(func(p *ui.Painter, r ui.Rect) {
+		g := k.Canvas(p, r)
+		g.Veil(0, 0, g.W, g.H, s, level)
+	})
+}
+
+// dark puts the deeper of Ink and Back first.
+func dark(k pixel.Kit) (dark, light pixel.Slot) {
+	if k.Palette().Night {
+		return pixel.Back, pixel.Ink
+	}
+	return pixel.Ink, pixel.Back
+}
+
+// choose lists items under a hand; digits pick 1–9.
+func choose(c *ui.Context, text string, items []string, cur *int, digits, off bool) int {
+	k := pixel.K(c)
+	n := len(items)
+	*cur = max(0, min(*cur, n-1))
+	off = off || pixel.Current(c).Inert
+	box := ui.Column(c).FocusRing(false).Role(ui.RoleList).Label(text)
+	if !off {
+		box.Focusable().AutoFocus()
+	}
+	pixel.Park(c, box, off)
+	picked := -1
+	if off {
+		box.Description(k.Msg("disabled"))
+	}
+	if box.Shortcut(0, ui.KeyDown) {
+		*cur = (*cur + 1) % n
+	}
+	if box.Shortcut(0, ui.KeyUp) {
+		*cur = (*cur + n - 1) % n
+	}
+	enter, space := box.Shortcut(0, ui.KeyEnter), box.Shortcut(0, ui.KeySpace)
+	if enter || space {
+		picked = *cur
+	}
+	for i := range min(9, n) {
+		if digits && box.Shortcut(0, ui.Key1+ui.Key(i)) {
+			*cur, picked = i, i
+		}
+	}
+	box.Children(func() {
+		for i, it := range items {
+			row := ui.Row(c).Height(k.D(pixel.LineHeight)).MinWidth(k.D(pixel.Measure(it) + 16)).Role(ui.RoleListItem).Label(it)
+			if !off && row.Clicked() {
+				*cur, picked = i, i
+			}
+			row.Draw(func(p *ui.Painter, r ui.Rect) {
+				g := k.Canvas(p, r)
+				if i == *cur {
+					g.Sprite(g.Step(4)%2, (g.H-pixel.Hand.H)/2, pixel.Hand, 0, pixel.Edge, 1)
+				}
+				g.Text(14, 0, it, pixel.Ink, 1)
+			})
+		}
+	})
+	if !off {
+		box.Description(items[*cur])
+	}
+	return picked
+}
+
+// body builds content, inert while off.
+func body(c *ui.Context, off bool, content func()) {
+	if !off {
+		content()
+		return
+	}
+	s := pixel.Current(c)
+	s.Inert = true
+	pixel.Scope(c, s, content)
+}
+
+type hintKey struct{}
+
+// hinting is when hover began, and a press-given focus.
+type hinting struct {
+	since   time.Time
+	pressed bool
+}
+
+// hint holds after resting wait, or on keyboard focus.
+func hint(c *ui.Context, e *ui.Element, wait time.Duration) bool {
+	k := pixel.K(c)
+	s := ui.Local(e, hintKey{}, func() hinting { return hinting{} })
+	_, _, over := e.PointerPosition()
+	hovered, focus := e.Hovered(), e.FocusWithin()
+	switch {
+	case over && !hovered:
+		// A press inside: its focus is not the keyboard's.
+		s.pressed = true
+	case !focus:
+		s.pressed = false
+	}
+	rested := false
+	if hovered {
+		if s.since.IsZero() {
+			s.since = k.Now()
+		}
+		steps := int(wait / (100 * time.Millisecond))
+		rested = k.Since(c, s.since, 10, steps) >= steps
+	} else {
+		s.since = time.Time{}
+	}
+	return rested || focus && !s.pressed
+}
+
+// arriving counts the steps, of four, a panel still slides.
+func arriving(c *ui.Context, home *ui.Element, open bool) int {
+	k := pixel.K(c)
+	on := 0
+	if open {
+		on = 1
+	}
+	if k.Reduce() {
+		return 0
+	}
+	return 4 - k.Since(c, k.Cue(home, on), 15, 4)
+}