Fix VirtualViewExperimental alignment for empty cases (#53519)

Summary:
Pull Request resolved: #53519

Changelog: [Internal] - Remove empty checks on the target rects and early return for empty ScrollView rects -- aligning the implementation with v1 of VirtualView

Reviewed By: yungsters

Differential Revision: D81247994

fbshipit-source-id: 4fda9f90e18d736944fe4236a4b79f0681e1564c

Author: lunaleaps

packages/react-native/React/Fabric/Mounting/ComponentViews/ScrollView/RCTVirtualViewContainerState.mm

@@ -161,10 +161,7 @@ - (void)_updateModes:(id<RCTVirtualViewProtocol>)virtualView
     RCTVirtualViewMode mode = RCTVirtualViewModeHidden;
     CGRect thresholdRect = _emptyRect;
 
-    if (CGRectIsEmpty(rect)) {
-      mode = RCTVirtualViewModeHidden;
-      thresholdRect = _emptyRect;
-    } else if (CGRectOverlaps(rect, visibleRect)) {
+    if (CGRectOverlaps(rect, visibleRect)) {
       thresholdRect = visibleRect;
       mode = RCTVirtualViewModeVisible;
     } else if (CGRectOverlaps(rect, _prerenderRect)) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/scroll/VirtualViewContainer.kt

@@ -104,6 +104,15 @@ internal class VirtualViewContainerState {
 
   private fun updateModes(virtualView: VirtualView? = null) {
     scrollView.getDrawingRect(visibleRect)
+
+    // This happens because ScrollView content isn't ready yet. The danger here is if ScrollView
+    // intentionally goes but curently ScrollView and v1 Fling use this check to determine if
+    // "content ready"
+    if (visibleRect.isEmpty()) {
+      debugLog("updateModes", { "scrollView visibleRect is empty" })
+      return
+    }
+
     prerenderRect.set(visibleRect)
     prerenderRect.inset(
         (-prerenderRect.width() * prerenderRatio).toInt(),
@@ -117,7 +126,6 @@ internal class VirtualViewContainerState {
       var mode = VirtualViewMode.Hidden
       var thresholdRect = emptyRect
       when {
-        rect.isEmpty -> {}
         rectsOverlap(rect, visibleRect) -> {
           thresholdRect = visibleRect
           if (onWindowFocusChangeListener != null) {

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/virtual/viewexperimental/ReactVirtualViewExperimental.kt

@@ -129,6 +129,9 @@ public class ReactVirtualViewExperimental(context: Context) :
     }
 
   override fun onModeChange(newMode: VirtualViewMode, thresholdRect: Rect) {
+    modeChangeEmitter ?: return
+    scrollView ?: return
+
     if (newMode == mode) {
       return
     }