io/router: deduplicate pointer handlers

When the same handler is added several times
and that handler sets pointer.Grabbed, it gets lost.

Signed-off-by: Pierre Curto <pierre.curto@gmail.com>

io/router/pointer.go

@@ -214,7 +214,7 @@ func (q *pointerQueue) opHit(handlers *[]event.Tag, pos f32.Point) {
 		}
 		if n.tag != nil {
 			if _, exists := q.handlers[n.tag]; exists {
-				*handlers = append(*handlers, n.tag)
+				*handlers = addHandler(*handlers, n.tag)
 			}
 		}
 	}
@@ -473,6 +473,16 @@ func searchTag(tags []event.Tag, tag event.Tag) (int, bool) {
 	return 0, false
 }
 
+// addHandler adds tag to the slice if not present.
+func addHandler(tags []event.Tag, tag event.Tag) []event.Tag {
+	for _, t := range tags {
+		if t == tag {
+			return tags
+		}
+	}
+	return append(tags, tag)
+}
+
 func opDecodeFloat32(d []byte) float32 {
 	return float32(int32(binary.LittleEndian.Uint32(d)))
 }

io/router/pointer_test.go

@@ -114,6 +114,38 @@ func TestPointerGrab(t *testing.T) {
 	assertEventSequence(t, r.Events(handler3), pointer.Cancel)
 }
 
+func TestPointerGrabSameHandlerTwice(t *testing.T) {
+	handler1 := new(int)
+	handler2 := new(int)
+	var ops op.Ops
+
+	types := pointer.Press | pointer.Release
+
+	pointer.InputOp{Tag: handler1, Types: types, Grab: true}.Add(&ops)
+	pointer.InputOp{Tag: handler1, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler2, Types: types}.Add(&ops)
+
+	var r Router
+	r.Frame(&ops)
+	r.Queue(
+		pointer.Event{
+			Type:     pointer.Press,
+			Position: f32.Pt(50, 50),
+		},
+	)
+	assertEventSequence(t, r.Events(handler1), pointer.Cancel, pointer.Press)
+	assertEventSequence(t, r.Events(handler2), pointer.Cancel, pointer.Press)
+	r.Frame(&ops)
+	r.Queue(
+		pointer.Event{
+			Type:     pointer.Release,
+			Position: f32.Pt(50, 50),
+		},
+	)
+	assertEventSequence(t, r.Events(handler1), pointer.Release)
+	assertEventSequence(t, r.Events(handler2), pointer.Cancel)
+}
+
 func TestPointerMove(t *testing.T) {
 	handler1 := new(int)
 	handler2 := new(int)