driver: Remove the return value from RunWithoutMainLoop

internal/driver/ui.go

@@ -32,7 +32,7 @@ var RegularTermination = errors.New("regular termination")
 
 type UI interface {
 	Run(context UIContext) error
-	RunWithoutMainLoop(context UIContext) <-chan error
+	RunWithoutMainLoop(context UIContext)
 
 	DeviceScaleFactor() float64
 	CursorMode() CursorMode

internal/uidriver/glfw/ui.go

@@ -543,7 +543,7 @@ func (u *UserInterface) Run(uicontext driver.UIContext) error {
 	return <-ch
 }
 
-func (u *UserInterface) RunWithoutMainLoop(context driver.UIContext) <-chan error {
+func (u *UserInterface) RunWithoutMainLoop(context driver.UIContext) {
 	panic("glfw: RunWithoutMainLoop is not implemented")
 }
 

internal/uidriver/js/ui.go

@@ -425,7 +425,7 @@ func (u *UserInterface) Run(context driver.UIContext) error {
 	return nil
 }
 
-func (u *UserInterface) RunWithoutMainLoop(context driver.UIContext) <-chan error {
+func (u *UserInterface) RunWithoutMainLoop(context driver.UIContext) {
 	panic("js: RunWithoutMainLoop is not implemented")
 }
 

internal/uidriver/mobile/ui.go

@@ -47,6 +47,7 @@ var (
 
 	theUI = &UserInterface{
 		foreground: true,
+		errCh:      make(chan error),
 
 		// Give a default outside size so that the game can start without initializing them.
 		outsideWidth:  640,
@@ -64,12 +65,18 @@ func Get() *UserInterface {
 }
 
 // Update is called from mobile/ebitenmobileview.
-func (u *UserInterface) Update() {
+func (u *UserInterface) Update() error {
+	select {
+	case err := <-u.errCh:
+		return err
+	default:
+	}
+
 	u.m.Lock()
 	fg := u.foreground
 	u.m.Unlock()
 	if !fg {
-		return
+		return nil
 	}
 
 	renderCh <- struct{}{}
@@ -100,10 +107,11 @@ func (u *UserInterface) Update() {
 				break loop
 			}
 		}
-		return
+		return nil
 	} else {
 		u.t.Loop(ctx)
 	}
+	return nil
 }
 
 type UserInterface struct {
@@ -112,6 +120,7 @@ type UserInterface struct {
 
 	sizeChanged bool
 	foreground  bool
+	errCh       chan error
 
 	// Used for gomobile-build
 	gbuildWidthPx   int
@@ -221,17 +230,13 @@ func (u *UserInterface) Run(context driver.UIContext) error {
 	return nil
 }
 
-func (u *UserInterface) RunWithoutMainLoop(context driver.UIContext) <-chan error {
+func (u *UserInterface) RunWithoutMainLoop(context driver.UIContext) {
-	ch := make(chan error)
 	go func() {
-		defer close(ch)
 		// title is ignored?
 		if err := u.run(context, false); err != nil {
-			ch <- err
+			u.errCh <- err
 		}
 	}()
-
-	return ch
 }
 
 func (u *UserInterface) run(context driver.UIContext, mainloop bool) (err error) {

mobile/ebitenmobileview/mobile.go

@@ -36,9 +36,7 @@ import (
 var theState state
 
 type state struct {
-	game ebiten.Game
+	started bool
-
-	errorCh <-chan error
 
 	// m is a mutex required for each function.
 	// For example, on Android, Update can be called from a different thread:
@@ -47,18 +45,18 @@ type state struct {
 }
 
 func (s *state) isRunning() bool {
-	return s.game != nil && s.errorCh != nil
+	return s.started
 }
 
 func SetGame(game ebiten.Game) {
 	theState.m.Lock()
 	defer theState.m.Unlock()
 
-	if theState.game != nil {
+	if theState.started {
 		panic("ebitenmobileview: SetGame cannot be called twice or more")
 	}
-	theState.game = game
+	ebiten.RunGameWithoutMainLoop(game)
-	theState.errorCh = ebiten.RunGameWithoutMainLoop(theState.game)
+	theState.started = true
 }
 
 func Layout(viewWidth, viewHeight float64) {
@@ -75,21 +73,13 @@ func Update() error {
 
 	theState.m.Lock()
 	defer theState.m.Unlock()
-
+	if !theState.started {
-	if !theState.isRunning() {
 		// start is not called yet, but as update can be called from another thread, it is OK. Just ignore
 		// this.
 		return nil
 	}
 
-	select {
+	return mobile.Get().Update()
-	case err := <-theState.errorCh:
-		return err
-	default:
-	}
-
-	mobile.Get().Update()
-	return nil
 }
 
 func Suspend() {

run.go

@@ -243,11 +243,11 @@ func runGame(game Game, scale float64) error {
 //
 // Ebiten users should NOT call RunGameWithoutMainLoop.
 // Instead, functions in github.com/hajimehoshi/ebiten/mobile package calls this.
-func RunGameWithoutMainLoop(game Game) <-chan error {
+func RunGameWithoutMainLoop(game Game) {
 	game = &imageDumperGame{game: game}
 	fixWindowPosition(WindowSize())
 	theUIContext.set(game, 0)
-	return uiDriver().RunWithoutMainLoop(theUIContext)
+	uiDriver().RunWithoutMainLoop(theUIContext)
 }
 
 // ScreenSizeInFullscreen is deprecated as of 1.11.0-alpha.