io/input,io/clipboard: [API] replace ReadOp with command

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

io/clipboard/clipboard.go

@@ -5,33 +5,20 @@ package clipboard
 import (
 	"io"
 
-	"gioui.org/internal/ops"
 	"gioui.org/io/event"
-	"gioui.org/op"
 )
 
-// Event is generated when the clipboard content is requested.
-type Event struct {
-	Text string
-}
-
 // WriteCmd copies Text to the clipboard.
 type WriteCmd struct {
 	Type string
 	Data io.ReadCloser
 }
 
-// ReadOp requests the text of the clipboard, delivered to
-// the current handler through an Event.
-type ReadOp struct {
+// ReadCmd requests the text of the clipboard, delivered to
+// the handler through an [io/transfer.DataEvent].
+type ReadCmd struct {
 	Tag event.Tag
 }
 
-func (h ReadOp) Add(o *op.Ops) {
-	data := ops.Write1(&o.Internal, ops.TypeClipboardReadLen, h.Tag)
-	data[0] = byte(ops.TypeClipboardRead)
-}
-
-func (Event) ImplementsEvent() {}
-
 func (WriteCmd) ImplementsCommand() {}
+func (ReadCmd) ImplementsCommand()  {}