Bug fix: ui.Main should be suspended when error occurs in the loop

image_test.go

@@ -30,11 +30,14 @@ import (
 func TestMain(m *testing.M) {
 	code := 0
 	// Run an Ebiten process so that (*Image).At is available.
+	regularTermination := errors.New("regular termination")
 	f := func(screen *Image) error {
 		code = m.Run()
-		return errors.New("regular termination")
+		return regularTermination
+	}
+	if err := Run(f, 320, 240, 1, "Test"); err != nil && err != regularTermination {
+		panic(err)
 	}
-	Run(f, 320, 240, 1, "Test")
 	os.Exit(code)
 }
 

internal/loop/run.go

@@ -86,7 +86,7 @@ type GraphicsContext interface {
 	UpdateAndDraw(context *opengl.Context, updateCount int) error
 }
 
-func Run(g GraphicsContext, width, height int, scale float64, title string, fps int) error {
+func Run(g GraphicsContext, width, height int, scale float64, title string, fps int) (err error) {
 	if currentRunContext != nil {
 		return errors.New("loop: The game is already running")
 	}
@@ -100,7 +100,12 @@ func Run(g GraphicsContext, width, height int, scale float64, title string, fps
 		return err
 	}
 	// TODO: Use the error value
-	defer ui.CurrentUI().Terminate()
+	defer func() {
+		if err != nil {
+			return
+		}
+		err = ui.CurrentUI().Terminate()
+	}()
 
 	n := now()
 	currentRunContext.lastUpdated = n

internal/ui/ui_glfw.go

@@ -76,14 +76,19 @@ func initialize() error {
 	return nil
 }
 
-func Main() error {
+func Main(ch <-chan error) error {
-	return currentUI.main()
+	return currentUI.main(ch)
 }
 
-func (u *userInterface) main() error {
+func (u *userInterface) main(ch <-chan error) error {
 	// TODO: Check this is done on the main thread.
-	for f := range u.funcs {
+	for {
+		select {
+		case f := <-u.funcs:
 			f()
+		case err := <-ch:
+			return err
+		}
 	}
 	return nil
 }

internal/ui/ui_js.go

@@ -278,9 +278,8 @@ func devicePixelRatio() float64 {
 	return ratio
 }
 
-func Main() error {
+func Main(ch <-chan error) error {
-	// Do nothing
+	return <-ch
-	return nil
 }
 
 func (u *userInterface) Start(width, height int, scale float64, title string) error {

internal/ui/ui_mobile.go

@@ -24,7 +24,7 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/graphics/opengl"
 )
 
-func Main() error {
+func Main(ch <-chan error) error {
 	return errors.New("ui: don't call this: use RunWithoutMainLoop instead of Run")
 }
 

run.go

@@ -81,10 +81,11 @@ func Run(f func(*Image) error, width, height int, scale float64, title string) e
 		}
 		close(ch)
 	}()
-	if err := ui.Main(); err != nil {
+	// TODO: Use context in Go 1.7?
+	if err := ui.Main(ch); err != nil {
 		return err
 	}
-	return <-ch
+	return nil
 }
 
 // RunWithoutMainLoop runs the game, but don't call the loop on the main (UI) thread.