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

feedback/busyoverlay.go

@@ -0,0 +1,54 @@
+package feedback
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type BusyOverlayOptions struct{}
+
+type busyKey struct{}
+
+// BusyOverlay veils busy content, whose controls then take no input.
+func BusyOverlay(c *ui.Context, busy bool, o BusyOverlayOptions, content func()) *ui.Element {
+	k := pixel.K(c)
+	outer := ui.Box(c)
+	// held is whether the veil had the focus last frame.
+	held := ui.Local(outer, busyKey{}, func() bool { return false })
+	if !busy && *held {
+		// From the root, parked controls inside take it back.
+		c.Root().Focus()
+		*held = false
+	}
+	if busy {
+		// Busy content is one Tab stop: the veil.
+		outer.FocusGroup(ui.Vertical)
+	}
+	return outer.Children(func() {
+		s := pixel.Current(c)
+		s.Inert = s.Inert || busy
+		before := c.Root().Focused()
+		var body *ui.Element
+		pixel.Scope(c, s, func() { body = ui.Box(c).Children(content) })
+		if !busy {
+			return
+		}
+		veil := ui.Box(c).Absolute().Left(0).Top(0).Right(0).Bottom(0).Focusable().FocusRing(false).Role(ui.RoleProgress).Label(k.Msg("wait"))
+		if body.FocusWithin() || !before && c.Root().Focused() {
+			veil.Focus()
+		}
+		*held = veil.Focused()
+		focus := veil.FocusVisible()
+		veil.Draw(func(p *ui.Painter, r ui.Rect) {
+			g := k.Canvas(p, r)
+			g.Checker(0, 0, g.W, g.H, pixel.Back)
+			// The spinner doubles in size where it fits.
+			sc := max(1, min(2, min(g.W, g.H)/14))
+			beads(g, (g.W-12*sc)/2, (g.H-12*sc)/2, sc)
+			if focus {
+				g.FocusMark(0, 0, g.W, g.H)
+			}
+		})
+	})
+}