io/input,io/transfer: [API] replace OfferOp with command

Also delete two tests that are no longer relevant.

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

widget/dnd.go

@@ -77,12 +77,8 @@ func (d *Draggable) Update(gtx layout.Context) (mime string, requested bool) {
 
 // Offer the data ready for a drop. Must be called after being Requested.
 // The mime must be one in the requested list.
-func (d *Draggable) Offer(ops *op.Ops, mime string, data io.ReadCloser) {
-	transfer.OfferOp{
-		Tag:  &d.handle,
-		Type: mime,
-		Data: data,
-	}.Add(ops)
+func (d *Draggable) Offer(gtx layout.Context, mime string, data io.ReadCloser) {
+	gtx.Queue(transfer.OfferCmd{Tag: &d.handle, Type: mime, Data: data})
 }
 
 // Pos returns the drag position relative to its initial click position.

widget/dnd_test.go

@@ -51,12 +51,12 @@ func TestDraggable(t *testing.T) {
 		},
 	)
 	ofr := &offer{data: "hello"}
-	drag.Offer(gtx.Ops, "file", ofr)
+	drag.Offer(gtx, "file", ofr)
 	r.Frame(gtx.Ops)
 
 	evs := r.Events(drag)
-	if len(evs) != 1 {
-		t.Fatalf("expected 1 event, got %d", len(evs))
+	if len(evs) != 2 {
+		t.Fatalf("expected 2 event, got %d", len(evs))
 	}
 	ev := evs[0].(transfer.DataEvent)
 	ev.Open = nil

widget/example_test.go

@@ -94,7 +94,7 @@ func ExampleDraggable_Layout() {
 		// drag must respond with an Offer event when requested.
 		// Use the drag method for this.
 		if m, ok := drag.Update(gtx); ok {
-			drag.Offer(gtx.Ops, m, offer{Data: "hello world"})
+			drag.Offer(gtx, m, offer{Data: "hello world"})
 		}
 
 		// Setup the area for drops.