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/sheet.go

@@ -0,0 +1,76 @@
+package overlay
+
+import (
+	"log/slog"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type SheetOptions struct {
+	// Height is in dots; zero means 120.
+	Height   int
+	Disabled bool
+}
+
+type SheetResult struct {
+	Element *ui.Element
+	// Closed is a drag down, Escape or a click outside.
+	Closed bool
+}
+
+type sheetKey struct{}
+
+// Sheet rises from the bottom; drag its bar down.
+func Sheet(c *ui.Context, text string, open *bool, o SheetOptions, content func()) SheetResult {
+	k := pixel.K(c)
+	h := pixel.Or("Sheet Height", o.Height, 120)
+	off := o.Disabled || pixel.Current(c).Inert
+	home := ui.Box(c)
+	pulled := ui.Local(home, sheetKey{}, func() float32 { return 0 })
+	rise := k.D(arriving(c, home, *open) * h / 4)
+	was := *open
+	var res SheetResult
+	res.Element = ui.DialogBase(c, open, func(back, panel *ui.Element) {
+		dim(k, back, pixel.Back, 8)
+		panel.Label(text).Focusable().FocusRing(false).Draw(func(p *ui.Painter, r ui.Rect) {
+			g := k.Canvas(p, r)
+			g.Frame(0, 0, g.W, g.H, pixel.Window, pixel.Face)
+		}).Children(func() {
+			pixel.Harbor(c, panel, func() {
+				bar := ui.Box(c).FillWidth().Height(k.D(10)).Role(ui.RoleNone)
+				_, dy, held := bar.Dragged()
+				switch {
+				case off:
+					*pulled = 0
+				case held:
+					*pulled = max(0, *pulled+dy)
+				case *pulled > 0:
+					if *pulled > k.D(h/3) {
+						// A release is no drag: build again, closed.
+						*open = false
+						c.Invalidate()
+					}
+					*pulled = 0
+				}
+				bar.Draw(func(p *ui.Painter, r ui.Rect) {
+					g := k.Canvas(p, r)
+					g.Rect((g.W-24)/2, 4, 24, 2, pixel.Shade)
+				})
+				ui.Column(c).Grow(1).Padding(0, k.D(8), k.D(8), k.D(8)).Children(func() { body(c, o.Disabled, content) })
+			})
+		})
+		// Placed after the bar, so a release lands at once.
+		drop := float32(int(*pulled/k.Dot())) * k.Dot()
+		panel.Absolute().Left(0).Right(0).Bottom(-rise - drop).Height(k.D(h))
+	})
+	res.Closed = was && !*open
+	if !*open {
+		*pulled = 0
+	}
+	if res.Closed {
+		slog.Debug("8bit: sheet closed", "label", text)
+	}
+	return res
+}