Focus: optional rounded focus ring (FocusRingRadius/Width)

focus.go

@@ -34,6 +34,16 @@ type Focusable interface {
 // widgets simply do not embed it and stay non-focusable.
 type focusState struct {
 	focused bool
+	// FocusRingRadius, when > 0, draws the focus ring as a rounded rectangle of
+	// that corner radius (in device units) instead of the default 1-pixel square
+	// inset — for a widget whose body is a rounded field (a pill-shaped search
+	// box). Zero keeps the classic square ring, so every widget that does not set
+	// it renders byte-for-byte as before.
+	FocusRingRadius int
+	// FocusRingWidth is the rounded ring's stroke thickness; it applies only when
+	// FocusRingRadius > 0, and a value < 1 is treated as 1. Ignored for the square
+	// ring.
+	FocusRingWidth int
 }
 
 // SetFocused records whether this widget holds keyboard focus.
@@ -51,6 +61,14 @@ func (f *focusState) drawFocusRing(p painter.Painter, theme *Theme, r Rect) {
 	if !f.focused {
 		return
 	}
+	if f.FocusRingRadius > 0 {
+		w := f.FocusRingWidth
+		if w < 1 {
+			w = 1
+		}
+		p.StrokeRoundRect(painter.Rect{X: r.X, Y: r.Y, W: r.W, H: r.H}, f.FocusRingRadius, theme.Accent, w)
+		return
+	}
 	strokeRect(p, r.X+1, r.Y+1, r.W-2, r.H-2, theme.Accent)
 }
 

focus_test.go

@@ -4,7 +4,11 @@
 
 package toolkit
 
-import "testing"
+import (
+	"testing"
+
+	"github.com/go-widgets/painter"
+)
 
 // fakeFocusable is a minimal Focusable test double that records every
 // SetFocused call so tests can assert exactly when focus toggled.
@@ -267,3 +271,29 @@ func TestFocusRing_HandleKey(t *testing.T) {
 		t.Fatalf("unconsumed key must not move focus: Current() = %d, want 0", got)
 	}
 }
+
+func TestDrawFocusRingRounded(t *testing.T) {
+	th := DefaultLight()
+	r := Rect{X: 2, Y: 2, W: 16, H: 16}
+
+	// Unfocused: paints nothing (no accent anywhere).
+	buf := make([]byte, 4*20*20)
+	(&focusState{}).drawFocusRing(painter.NewPixelPainter(buf, 20, 20), th, r)
+	if hasColor(buf, 20, th.Accent) {
+		t.Fatal("an unfocused widget must paint no focus ring")
+	}
+
+	// Focused rounded ring (Radius > 0, Width < 1 -> defaults to 1): accent painted.
+	buf = make([]byte, 4*20*20)
+	(&focusState{focused: true, FocusRingRadius: 4}).drawFocusRing(painter.NewPixelPainter(buf, 20, 20), th, r)
+	if !hasColor(buf, 20, th.Accent) {
+		t.Fatal("a rounded focus ring should paint the accent")
+	}
+
+	// Focused square ring (Radius == 0): the classic branch also paints accent.
+	buf = make([]byte, 4*20*20)
+	(&focusState{focused: true}).drawFocusRing(painter.NewPixelPainter(buf, 20, 20), th, r)
+	if !hasColor(buf, 20, th.Accent) {
+		t.Fatal("the square focus ring should paint the accent")
+	}
+}