io/router: fix focused key event propagation

When a key.InputOp is focused, keypresses that it does not explicitly
include in its key set should check for ancestor clip areas that are
interested in them. Previously this check only included ancestors of
the final clip area in the hit tree, and could fail to find ancestors
of the focused key.InputOp because they were in a different branch.

This commit also adds a test to lock in the new behavior.

This can likely be made more efficient by adding a rapid way to map
from the focused key tag to its index in the hit tree. I wasn't sure
whether the complexity was warranted, but I'm happy to do that if
it's desired.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

io/router/key_test.go

@@ -321,37 +321,65 @@ func TestNoFocus(t *testing.T) {
 }
 
 func TestKeyRouting(t *testing.T) {
-	handlers := make([]int, 3)
+	handlers := make([]int, 5)
 	ops := new(op.Ops)
+	macroOps := new(op.Ops)
 	r := new(Router)
 
 	rect := clip.Rect{Max: image.Pt(10, 10)}
 
+	macro := op.Record(macroOps)
 	key.InputOp{Tag: &handlers[0], Keys: "A"}.Add(ops)
 	cl1 := rect.Push(ops)
 	key.InputOp{Tag: &handlers[1], Keys: "B"}.Add(ops)
 	key.InputOp{Tag: &handlers[2], Keys: "A"}.Add(ops)
 	cl1.Pop()
+	cl2 := rect.Push(ops)
+	key.InputOp{Tag: &handlers[3], Keys: "B"}.Add(ops)
+	key.InputOp{Tag: &handlers[4], Keys: "A"}.Add(ops)
+	cl2.Pop()
+	call := macro.Stop()
+	call.Add(ops)
 
 	r.Frame(ops)
 
 	A, B := key.Event{Name: "A"}, key.Event{Name: "B"}
 	r.Queue(A, B)
 
-	assertKeyEvent(t, r.Events(&handlers[2]), false, A)
-	assertKeyEvent(t, r.Events(&handlers[1]), false, B)
+	// With no focus, the events should traverse the final branch of the hit tree
+	// searching for handlers.
+	assertKeyEvent(t, r.Events(&handlers[4]), false, A)
+	assertKeyEvent(t, r.Events(&handlers[3]), false, B)
+	assertKeyEvent(t, r.Events(&handlers[2]), false)
+	assertKeyEvent(t, r.Events(&handlers[1]), false)
 	assertKeyEvent(t, r.Events(&handlers[0]), false)
+
+	r2 := new(Router)
+
+	call.Add(ops)
+	key.FocusOp{Tag: &handlers[2]}.Add(ops)
+	r2.Frame(ops)
+
+	r2.Queue(A, B)
+
+	// With focus, the events should traverse the branch of the hit tree
+	// containing the focused element.
+	assertKeyEvent(t, r2.Events(&handlers[4]), false)
+	assertKeyEvent(t, r2.Events(&handlers[3]), false)
+	assertKeyEvent(t, r2.Events(&handlers[2]), true, A)
+	assertKeyEvent(t, r2.Events(&handlers[1]), false, B)
+	assertKeyEvent(t, r2.Events(&handlers[0]), false)
 }
 
-func assertKeyEvent(t *testing.T, events []event.Event, expected bool, expectedInputs ...event.Event) {
+func assertKeyEvent(t *testing.T, events []event.Event, expectedFocus bool, expectedInputs ...event.Event) {
 	t.Helper()
 	var evtFocus int
 	var evtKeyPress int
 	for _, e := range events {
 		switch ev := e.(type) {
 		case key.FocusEvent:
-			if ev.Focus != expected {
-				t.Errorf("focus is expected to be %v, got %v", expected, ev.Focus)
+			if ev.Focus != expectedFocus {
+				t.Errorf("focus is expected to be %v, got %v", expectedFocus, ev.Focus)
 			}
 			evtFocus++
 		case key.Event, key.EditEvent:

io/router/router.go

@@ -183,12 +183,19 @@ func rangeNorm(r key.Range) key.Range {
 
 func (q *Router) queueKeyEvent(e key.Event) {
 	kq := &q.key.queue
-	if f := q.key.queue.focus; f != nil && kq.Accepts(f, e) {
+	f := q.key.queue.focus
+	if f != nil && kq.Accepts(f, e) {
 		q.handlers.Add(f, e)
 		return
 	}
 	pq := &q.pointer.queue
 	idx := len(pq.hitTree) - 1
+	if f != nil {
+		// If there is a focused tag, traverse its ancestry through the
+		// hit tree to search for handlers.
+		for ; pq.hitTree[idx].ktag != f; idx-- {
+		}
+	}
 	for idx != -1 {
 		n := &pq.hitTree[idx]
 		idx = n.next