io/input: deliver all observed events before deferring the rest

Even when a command defers event delivery to the next frame, the already
observed events must still be delivered in the current frame. This
matters for pointer events that hit more than one event handler.

Fixes: https://todo.sr.ht/~eliasnaur/gio/594
Signed-off-by: Elias Naur <mail@eliasnaur.com>

io/input/pointer_test.go

@@ -1086,6 +1086,33 @@ func TestPassCursor(t *testing.T) {
 	}
 }
 
+func TestPartialEvent(t *testing.T) {
+	var ops op.Ops
+	var r Router
+
+	rect := clip.Rect(image.Rect(0, 0, 100, 100))
+	background := rect.Push(&ops)
+	event.Op(&ops, 1)
+	background.Pop()
+
+	overlayPass := pointer.PassOp{}.Push(&ops)
+	overlay := rect.Push(&ops)
+	event.Op(&ops, 2)
+	overlay.Pop()
+	overlayPass.Pop()
+	assertEventSequence(t, events(&r, -1, pointer.Filter{Target: 1, Kinds: pointer.Press}))
+	assertEventSequence(t, events(&r, -1, pointer.Filter{Target: 2, Kinds: pointer.Press}))
+	r.Frame(&ops)
+	r.Queue(pointer.Event{
+		Kind: pointer.Press,
+	})
+	assertEventSequence(t, events(&r, -1, pointer.Filter{Target: 1, Kinds: pointer.Press}, key.FocusFilter{Target: 1}),
+		key.FocusEvent{}, pointer.Event{Kind: pointer.Press, Source: pointer.Mouse, Priority: pointer.Shared})
+	r.Source().Execute(key.FocusCmd{Tag: 1})
+	assertEventSequence(t, events(&r, -1, pointer.Filter{Target: 2, Kinds: pointer.Press}),
+		pointer.Event{Kind: pointer.Press, Source: pointer.Mouse, Priority: pointer.Foremost})
+}
+
 // offer satisfies io.ReadCloser for use in data transfers.
 type offer struct {
 	data   string

io/input/router.go

@@ -274,28 +274,29 @@ func (q *Router) Event(filters ...event.Filter) (event.Event, bool) {
 			}
 		}
 	}
-	if !q.deferring {
-		for i := range q.changes {
-			change := &q.changes[i]
-			for j, evt := range change.events {
-				match := false
-				switch e := evt.event.(type) {
-				case key.Event:
-					match = q.key.scratchFilter.Matches(change.state.keyState.focus, e, false)
-				default:
-					for _, tf := range q.scratchFilters {
-						if evt.tag == tf.tag && tf.filter.Matches(evt.event) {
-							match = true
-							break
-						}
+	for i := range q.changes {
+		if q.deferring && i > 0 {
+			break
+		}
+		change := &q.changes[i]
+		for j, evt := range change.events {
+			match := false
+			switch e := evt.event.(type) {
+			case key.Event:
+				match = q.key.scratchFilter.Matches(change.state.keyState.focus, e, false)
+			default:
+				for _, tf := range q.scratchFilters {
+					if evt.tag == tf.tag && tf.filter.Matches(evt.event) {
+						match = true
+						break
 					}
 				}
-				if match {
-					change.events = append(change.events[:j], change.events[j+1:]...)
-					// Fast forward state to last matched.
-					q.collapseState(i)
-					return evt.event, true
-				}
+			}
+			if match {
+				change.events = append(change.events[:j], change.events[j+1:]...)
+				// Fast forward state to last matched.
+				q.collapseState(i)
+				return evt.event, true
 			}
 		}
 	}