io/pointer,io/router,gesture: add pointer.Foremost priority

Replace the pointer.Scroll special case with a new priority that
indicates the foremost handler, checked in gesture.Scroll.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

io/pointer/pointer.go

@@ -113,6 +113,9 @@ const (
 	// Shared priority is for handlers that
 	// are part of a matching set larger than 1.
 	Shared Priority = iota
+	// Foremost priority is like Shared, but the
+	// handler is the foremost of the matching set.
+	Foremost
 	// Grabbed is used for matching sets of size 1.
 	Grabbed
 )
@@ -199,6 +202,8 @@ func (p Priority) String() string {
 	switch p {
 	case Shared:
 		return "Shared"
+	case Foremost:
+		return "Foremost"
 	case Grabbed:
 		return "Grabbed"
 	default:

io/router/pointer.go

@@ -262,29 +262,34 @@ func (q *pointerQueue) Push(e pointer.Event, events *handlerEvents) {
 }
 
 func (q *pointerQueue) deliverEvent(p *pointerInfo, events *handlerEvents, e pointer.Event) {
+	foremost := true
 	for _, k := range p.handlers {
 		h := q.handlers[k]
 		e := e
 		if p.pressed && len(p.handlers) == 1 {
 			e.Priority = pointer.Grabbed
+		} else if foremost {
+			e.Priority = pointer.Foremost
 		}
+
 		e.Position = h.transform.Invert().Transform(e.Position)
 
-		addPointerEvent(events, k, e, h.types)
-
-		// Only deliver scroll events to the foremost handler.
-		if e.Type == pointer.Scroll && e.Type&h.types != 0 {
-			return
+		if e.Type&h.types == e.Type {
+			foremost = false
+			events.Add(k, e)
 		}
 	}
 }
 
 func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, events *handlerEvents, e pointer.Event) {
+	foremost := true
 	for _, k := range p.handlers {
 		h := q.handlers[k]
 		e := e
 		if p.pressed && len(p.handlers) == 1 {
 			e.Priority = pointer.Grabbed
+		} else if foremost {
+			e.Priority = pointer.Foremost
 		}
 
 		// Hit-test to deliver Enter/Leave events. Consider non-mouse
@@ -304,18 +309,16 @@ func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, events *handlerEv
 		case !hit && entered != -1:
 			p.entered = append(p.entered[:entered], p.entered[entered+1:]...)
 			e.Type = pointer.Leave
-			addPointerEvent(events, k, e, h.types)
 		case hit && entered == -1:
 			p.entered = append(p.entered, k)
 			e.Type = pointer.Enter
-			addPointerEvent(events, k, e, h.types)
+		default:
+			continue
+		}
+		if e.Type&h.types == e.Type {
+			foremost = false
+			events.Add(k, e)
 		}
-	}
-}
-
-func addPointerEvent(events *handlerEvents, k event.Tag, e pointer.Event, types pointer.Type) {
-	if e.Type&types == e.Type {
-		events.Add(k, e)
 	}
 }
 

io/router/pointer_test.go

@@ -125,7 +125,7 @@ func TestPointerTypes(t *testing.T) {
 	assertEventSequence(t, r.Events(handler), pointer.Cancel, pointer.Press, pointer.Release)
 }
 
-func TestPointerScroll(t *testing.T) {
+func TestPointerPriority(t *testing.T) {
 	handler1 := new(int)
 	handler2 := new(int)
 	var ops op.Ops
@@ -139,7 +139,7 @@ func TestPointerScroll(t *testing.T) {
 	var r Router
 	r.Frame(&ops)
 	r.Add(
-		// Hit handler 2.
+		// Hit both handlers.
 		pointer.Event{
 			Type: pointer.Scroll,
 			Position: f32.Point{
@@ -164,8 +164,12 @@ func TestPointerScroll(t *testing.T) {
 			},
 		},
 	)
-	assertEventSequence(t, r.Events(handler1), pointer.Cancel, pointer.Scroll)
-	assertEventSequence(t, r.Events(handler2), pointer.Cancel, pointer.Scroll)
+	hev1 := r.Events(handler1)
+	hev2 := r.Events(handler2)
+	assertEventSequence(t, hev1, pointer.Cancel, pointer.Scroll, pointer.Scroll)
+	assertEventSequence(t, hev2, pointer.Cancel, pointer.Scroll)
+	assertEventPriorities(t, hev1, pointer.Shared, pointer.Shared, pointer.Foremost)
+	assertEventPriorities(t, hev2, pointer.Shared, pointer.Foremost)
 }
 
 func TestPointerEnterLeave(t *testing.T) {
@@ -463,7 +467,7 @@ func pointerTypes(events []event.Event) []pointer.Type {
 	return types
 }
 
-// assertEventSequence ensures that the provided actualEvents match the expected event types
+// assertEventSequence checks that the provided events match the expected pointer event types
 // in the provided order.
 func assertEventSequence(t *testing.T, events []event.Event, expected ...pointer.Type) {
 	t.Helper()
@@ -473,6 +477,20 @@ func assertEventSequence(t *testing.T, events []event.Event, expected ...pointer
 	}
 }
 
+// assertEventPriorities checks that the pointer.Event priorities of events match prios.
+func assertEventPriorities(t *testing.T, events []event.Event, prios ...pointer.Priority) {
+	t.Helper()
+	var got []pointer.Priority
+	for _, e := range events {
+		if e, ok := e.(pointer.Event); ok {
+			got = append(got, e.Priority)
+		}
+	}
+	if !reflect.DeepEqual(got, prios) {
+		t.Errorf("expected priorities %v, got %v", prios, got)
+	}
+}
+
 func BenchmarkRouterAdd(b *testing.B) {
 	// Set this to the number of overlapping handlers that you want to
 	// evaluate performance for. Typical values for the example applications