exp/textinput: change the return type of Start

exp/textinput/field.go

@@ -75,7 +75,7 @@ type Field struct {
 	selectionStartInBytes int
 	selectionEndInBytes   int
 
-	ch    chan State
+	ch    <-chan State
 	end   func()
 	state State
 	err   error

exp/textinput/textinput.go

@@ -50,7 +50,7 @@ type State struct {
 // Start is the low-level API. For most use cases, Field is easier to use.
 //
 // Start returns nil and nil if the current environment doesn't support this package.
-func Start(x, y int) (states chan State, close func()) {
+func Start(x, y int) (states <-chan State, close func()) {
 	cx, cy := ui.Get().LogicalPositionToClientPositionInNativePixels(float64(x), float64(y))
 	return theTextInput.Start(int(cx), int(cy))
 }

exp/textinput/textinput_darwin.go

@@ -33,7 +33,7 @@ type textInput struct {
 
 var theTextInput textInput
 
-func (t *textInput) Start(x, y int) (chan State, func()) {
+func (t *textInput) Start(x, y int) (<-chan State, func()) {
 	var session *session
 	ui.Get().RunOnMainThread(func() {
 		t.end()

exp/textinput/textinput_js.go

@@ -156,7 +156,7 @@ body.addEventListener("keyup", handler);`)
 	// TODO: What about other events like wheel?
 }
 
-func (t *textInput) Start(x, y int) (chan State, func()) {
+func (t *textInput) Start(x, y int) (<-chan State, func()) {
 	if !t.textareaElement.Truthy() {
 		return nil, nil
 	}

exp/textinput/textinput_noime.go

@@ -28,7 +28,7 @@ type textInput struct {
 
 var theTextInput textInput
 
-func (t *textInput) Start(x, y int) (chan State, func()) {
+func (t *textInput) Start(x, y int) (<-chan State, func()) {
 	// AppendInputChars is updated only when the tick is updated.
 	// If the tick is not updated, return nil immediately.
 	tick := ui.Get().Tick()

exp/textinput/textinput_windows.go

@@ -41,7 +41,7 @@ type textInput struct {
 
 var theTextInput textInput
 
-func (t *textInput) Start(x, y int) (chan State, func()) {
+func (t *textInput) Start(x, y int) (<-chan State, func()) {
 	if microsoftgdk.IsXbox() {
 		return nil, nil
 	}