ebiten: update the comment for CursorPosition

CursorPosition should return a mouse cursor position on browsers
even in mobiles.

Closes #3087

cmd/ebitenmobile/_files/EbitenSurfaceView.java

@@ -59,12 +59,13 @@ class EbitenSurfaceView extends GLSurfaceView implements Renderer {
 
         @Override
         public void onSurfaceCreated(GL10 gl, EGLConfig config) {
-            if (!onceSurfaceCreated_) {
-                onceSurfaceCreated_ = true;
+            // As EbitenSurfaceView can be recreated anytime, this flag for strict context restoration must be checked every time.
+            if (Ebitenmobileview.usesStrictContextRestoration()) {
+                Ebitenmobileview.onContextLost();
                 return;
             }
-            if (hasStrictContextRestoration()) {
-                Ebitenmobileview.onContextLost();
+            if (!onceSurfaceCreated_) {
+                onceSurfaceCreated_ = true;
                 return;
             }
             contextLost_ = true;
@@ -81,8 +82,6 @@ class EbitenSurfaceView extends GLSurfaceView implements Renderer {
         }
     }
 
-    private boolean strictContextRestoration_ = false;
-
     public EbitenSurfaceView(Context context) {
         super(context);
         initialize();
@@ -96,8 +95,8 @@ class EbitenSurfaceView extends GLSurfaceView implements Renderer {
     private void initialize() {
         setEGLContextClientVersion(3);
         setEGLConfigChooser(8, 8, 8, 8, 0, 0);
-        // setRenderer must be called before setRenderRequester.
-        // Or, the application crashes.
+        setPreserveEGLContextOnPause(true);
+        // setRenderer must be called before setRenderer. Or, setRenderMode in setExplicitRenderingMode will crash.
         setRenderer(new EbitenRenderer());
 
         Ebitenmobileview.setRenderer(this);
@@ -115,6 +114,8 @@ class EbitenSurfaceView extends GLSurfaceView implements Renderer {
 
     @Override
     public synchronized void setExplicitRenderingMode(boolean explicitRendering) {
+        // TODO: Remove this logic when FPSModeVsyncOffMinimum is removed.
+        // This doesn't work when EbitenSurfaceView is recreated anyway.
         if (explicitRendering) {
             setRenderMode(RENDERMODE_WHEN_DIRTY);
         } else {
@@ -122,16 +123,6 @@ class EbitenSurfaceView extends GLSurfaceView implements Renderer {
         }
     }
 
-    @Override
-    public synchronized void setStrictContextRestoration(boolean strictContextRestoration) {
-        strictContextRestoration_ = strictContextRestoration;
-        setPreserveEGLContextOnPause(!strictContextRestoration);
-    }
-
-    private synchronized boolean hasStrictContextRestoration() {
-        return strictContextRestoration_;
-    }
-
     @Override
     public synchronized void requestRenderIfNeeded() {
         if (getRenderMode() == RENDERMODE_WHEN_DIRTY) {

cmd/ebitenmobile/_files/EbitenViewController.m

@@ -364,10 +364,6 @@
   }
 }
 
-- (void)setStrictContextRestoration:(BOOL)strictContextRestoration {
-  // Do nothing.
-}
-
 - (void)setExplicitRenderingMode:(BOOL)explicitRendering {
   @synchronized(self) {
     explicitRendering_ = explicitRendering;

input.go

@@ -79,7 +79,7 @@ func KeyName(key Key) string {
 //
 // CursorPosition returns (0, 0) before the main loop on desktops and browsers.
 //
-// CursorPosition always returns (0, 0) on mobiles.
+// CursorPosition always returns (0, 0) on mobile native applications.
 //
 // CursorPosition is concurrent-safe.
 func CursorPosition() (x, y int) {

internal/ui/ui_mobile.go

@@ -101,7 +101,7 @@ type userInterfaceImpl struct {
 	fpsMode  atomic.Int32
 	renderer Renderer
 
-	strictContextRestoration     bool
+	strictContextRestoration     atomic.Bool
 	strictContextRestorationOnce sync.Once
 
 	m sync.RWMutex
@@ -156,11 +156,11 @@ func (u *UserInterface) runMobile(game Game, options *RunOptions) (err error) {
 	u.graphicsDriver = g
 	u.setGraphicsLibrary(lib)
 	close(u.graphicsLibraryInitCh)
-	u.strictContextRestoration = options.StrictContextRestoration
-	if !u.strictContextRestoration {
+	if options.StrictContextRestoration {
+		u.strictContextRestoration.Store(true)
+	} else {
 		restorable.Disable()
 	}
-	u.renderer.SetStrictContextRestoration(u.strictContextRestoration)
 
 	for {
 		if err := u.update(); err != nil {
@@ -312,7 +312,6 @@ func (u *UserInterface) UpdateInput(keys map[Key]struct{}, runes []rune, touches
 
 type Renderer interface {
 	SetExplicitRenderingMode(explicitRendering bool)
-	SetStrictContextRestoration(strictContextRestoration bool)
 	RequestRenderIfNeeded()
 }
 
@@ -331,6 +330,10 @@ func (u *UserInterface) updateIconIfNeeded() error {
 	return nil
 }
 
+func (u *UserInterface) UsesStrictContextRestoration() bool {
+	return u.strictContextRestoration.Load()
+}
+
 func IsScreenTransparentAvailable() bool {
 	return false
 }

mobile/ebitenmobileview/mobile.go

@@ -132,3 +132,7 @@ func SetRenderer(renderer Renderer) {
 func SetSetGameNotifier(setGameNotifier SetGameNotifier) {
 	theState.setSetGameNotifier(setGameNotifier)
 }
+
+func UsesStrictContextRestoration() bool {
+	return ui.Get().UsesStrictContextRestoration()
+}

run.go

@@ -302,17 +302,20 @@ type RunGameOptions struct {
 	//
 	// StrictContextRestration is available only on Android. Otherwise, StrictContextRestration is ignored.
 	//
-	// When StrictContextRestration is false, Ebitengine tries to rely on the OS to restore the context.
 	// In Android, Ebitengien uses `GLSurfaceView`'s `setPreserveEGLContextOnPause(true)`.
 	// This works in most cases, but it is still possible that the context is lost in some minor cases.
-	// With StrictContextRestration false, the activity's launch mode should be singleInstance,
-	// or the activity no longer works correctly after the context is lost.
 	//
-	// When StrictContextRestration is true, Ebitengine tries to restore the context more strictly.
-	// This is useful when you want to restore the context in any case.
+	// When StrictContextRestration is true, Ebitengine tries to restore the context more strictly
+	// for such minor cases.
 	// However, this might cause a performance issue since Ebitengine tries to keep all the information
 	// to restore the context.
 	//
+	// When StrictContextRestration is false, Ebitengine does nothing special to restore the context and
+	// relies on the OS's behavior.
+	//
+	// As a side note, especially when StrictContextRestration is false, the activity's launch mode should
+	// be singleInstance, or the activity no longer works correctly after the context is lost.
+	//
 	// The default (zero) value is false.
 	StrictContextRestration bool
 }