io/input: discard pointer reset event if filter doesn't match

New handlers receive reset events the first time Source.Event is called.
However, in case the filter doesn't match a reset event it shouldn't be
reported.

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

io/input/pointer_test.go

@@ -19,6 +19,16 @@ import (
 	"gioui.org/op/clip"
 )
 
+func TestFilterReset(t *testing.T) {
+	r := new(Router)
+	if _, ok := r.Event(pointer.Filter{}); ok {
+		t.Fatal("empty filter matched reset event")
+	}
+	if _, ok := r.Event(pointer.Filter{Kinds: pointer.Cancel}); ok {
+		t.Fatal("second call to Event matched reset event")
+	}
+}
+
 func TestPointerNilTarget(t *testing.T) {
 	r := new(Router)
 	r.Event(pointer.Filter{Kinds: pointer.Press})

io/input/router.go

@@ -255,7 +255,7 @@ func (q *Router) Event(filters ...event.Filter) (event.Event, bool) {
 				break
 			}
 			h := q.stateFor(f.Target)
-			if reset, ok := h.pointer.ResetEvent(); ok {
+			if reset, ok := h.pointer.ResetEvent(); ok && h.filter.pointer.Matches(reset) {
 				return reset, true
 			}
 		}