This should have been several separate commits

backends/x/window.go

@@ -1,6 +1,5 @@
 package x
 
-import "io"
 import "image"
 import "errors"
 import "github.com/jezek/xgb/xproto"
@@ -34,7 +33,7 @@ type window struct {
 	theme  theme.Theme
 	config config.Config
 
-	selectionRequest func (io.Reader, error)
+	selectionRequest *selectionRequest
 
 	metrics struct {
 		width  int
@@ -286,75 +285,26 @@ func (window *window) Copy (data data.Data) {
 	// TODO
 }
 
-func (window *window) Paste (accept data.Mime, callback func (io.Reader, error)) {
+func (window *window) Paste (callback func (data.Data, error), accept ...data.Mime) {
 	// Follow:
 	// https://tronche.com/gui/x/icccm/sec-2.html#s-2.4
-
-	die := func (err error) {
-		window.selectionRequest = nil
-		callback(nil, err)
-	}
+	die := func (err error) { callback(nil, err) }
 	if window.selectionRequest != nil {
 		// TODO: add the request to a queue and take care of it when the
 		// current selection has completed
 		die(errors.New("there is already a selection request"))
+		return
 	}
 
 	selectionName := "CLIPBOARD"
 	propertyName  := "TOMO_SELECTION"
-	targetName    := accept.String()
-	if accept == data.M("text", "plain") {
-		targetName = "UTF8_STRING"
-	}
-
-	// get atoms
 	selectionAtom, err := xprop.Atm(window.backend.connection, selectionName)
 	if err != nil { die(err); return }
-	targetAtom, err := xprop.Atm(window.backend.connection, targetName)
-	if err != nil { die(err); return }
 	propertyAtom, err := xprop.Atm(window.backend.connection, propertyName)
 	if err != nil { die(err); return }
 
-	// The requestor should set the property argument to the name of a
-	// property that the owner can use to report the value of the selection.
-	// Requestors should ensure that the named property does not exist on
-	// the window before issuing the ConvertSelection. The exception to this
-	// rule is when the requestor intends to pass parameters with the
-	// request. Some targets may be defined such that requestors can pass
-	// parameters along with the request. If the requestor wishes to provide
-	// parameters to a request, they should be placed in the specified
-	// property on the requestor window before the requestor issues the
-	// ConvertSelection request, and this property should be named in the
-	// request.
-	err = xproto.DeletePropertyChecked (
-		window.backend.connection.Conn(),
-		window.xWindow.Id,
-		propertyAtom).Check()
-	if err != nil { die(err); return }
-
-	// The selection argument specifies the particular selection involved,
-	// and the target argument specifies the required form of the
-	// information. For information about the choice of suitable atoms to
-	// use, see section 2.6. The requestor should set the requestor argument
-	// to a window that it created; the owner will place the reply property
-	// there. The requestor should set the time argument to the timestamp on
-	// the event that triggered the request for the selection value. Note
-	// that clients should not specify CurrentTime*.
-	err = xproto.ConvertSelectionChecked (
-		window.backend.connection.Conn(),
-		window.xWindow.Id,
-		selectionAtom,
-		targetAtom,
-		propertyAtom,
-		// TODO: *possibly replace this zero with an actual timestamp
-		// received from the server. this is non-trivial as we cannot
-		// rely on the timestamp of the last received event, because
-		// there is a possibility that this method is invoked
-		// asynchronously from within tomo.Do().
-		0).Check()
-	if err != nil { die(err); return }
-
-	window.selectionRequest = callback
+	window.selectionRequest = window.newSelectionRequest (
+		selectionAtom, propertyAtom, callback, accept...)
 	return
 }