Migrate ScrollEvent to RCTModernEventEmitter

Summary:
Motivation: perf, simplicity, adhering to new SurfaceMountingManager APIs available to us. Backwards-compatible with events sent through old system or Fabric, to Fabric or non-Fabric Views.

Changelog: [Changed][Android] Old Native method to create ScrollEvent has been deprecated and will be removed at some point in the (distant) future

Reviewed By: mdvacca

Differential Revision: D26027105

fbshipit-source-id: b9dba5b56c2bfed3b8fc4488c54b271b85ab5fa0

Author: JoshuaGross

ReactAndroid/src/main/java/com/facebook/react/fabric/mounting/SurfaceMountingManager.java

@@ -43,6 +43,7 @@
 
 public class SurfaceMountingManager {
   public static final String TAG = SurfaceMountingManager.class.getSimpleName();
+
   private static final boolean SHOW_CHANGED_VIEW_HIERARCHIES = ReactBuildConfig.DEBUG && false;
   private static final long KEEPALIVE_MILLISECONDS = 1000;
 

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerHelper.java

@@ -150,6 +150,42 @@ public static ReactContext getReactContext(View view) {
     return (ReactContext) context;
   }
 
+  /**
+   * @return Get the ThemedReactContext associated with a View, if possible, and then call
+   *     getSurfaceId on it. See above (getReactContext) for additional context.
+   */
+  public static int getSurfaceId(View view) {
+    int reactTag = view.getId();
+
+    // In non-Fabric we don't have (or use) SurfaceId
+    if (getUIManagerType(reactTag) == UIManagerType.DEFAULT) {
+      return -1;
+    }
+
+    Context context = view.getContext();
+    if (!(context instanceof ThemedReactContext) && context instanceof ContextWrapper) {
+      context = ((ContextWrapper) context).getBaseContext();
+    }
+
+    int surfaceId = getSurfaceId(context);
+
+    // All Fabric-managed Views (should) have a ThemedReactContext attached.
+    if (surfaceId == -1) {
+      ReactSoftException.logSoftException(
+          "UIManagerHelper",
+          new IllegalStateException(
+              "Fabric View [" + reactTag + "] does not have SurfaceId associated with it"));
+    }
+    return surfaceId;
+  }
+
+  public static int getSurfaceId(Context context) {
+    if (context instanceof ThemedReactContext) {
+      return ((ThemedReactContext) context).getSurfaceId();
+    }
+    return -1;
+  }
+
   /**
    * @return the default padding used by Android EditText's. This method returns the padding in an
    *     array to avoid extra classloading during hot-path of RN Android.

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewHelper.java

@@ -81,9 +81,11 @@ private static void emitScrollEvent(
     }
 
     ReactContext reactContext = (ReactContext) scrollView.getContext();
+    int surfaceId = UIManagerHelper.getSurfaceId(reactContext);
     UIManagerHelper.getEventDispatcherForReactTag(reactContext, scrollView.getId())
         .dispatchEvent(
             ScrollEvent.obtain(
+                surfaceId,
                 scrollView.getId(),
                 scrollEventType,
                 scrollView.getScrollX(),

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ScrollEvent.java

@@ -15,6 +15,7 @@
 import com.facebook.react.uimanager.PixelUtil;
 import com.facebook.react.uimanager.events.Event;
 import com.facebook.react.uimanager.events.RCTEventEmitter;
+import com.facebook.react.uimanager.events.RCTModernEventEmitter;
 
 /** A event dispatched from a ScrollView scrolling. */
 public class ScrollEvent extends Event<ScrollEvent> {
@@ -33,6 +34,7 @@ public class ScrollEvent extends Event<ScrollEvent> {
   private @Nullable ScrollEventType mScrollEventType;
 
   public static ScrollEvent obtain(
+      int surfaceId,
       int viewTag,
       ScrollEventType scrollEventType,
       int scrollX,
@@ -48,6 +50,7 @@ public static ScrollEvent obtain(
       event = new ScrollEvent();
     }
     event.init(
+        surfaceId,
         viewTag,
         scrollEventType,
         scrollX,
@@ -69,6 +72,7 @@ public void onDispose() {
   private ScrollEvent() {}
 
   private void init(
+      int surfaceId,
       int viewTag,
       ScrollEventType scrollEventType,
       int scrollX,
@@ -79,7 +83,7 @@ private void init(
       int contentHeight,
       int scrollViewWidth,
       int scrollViewHeight) {
-    super.init(viewTag);
+    super.init(surfaceId, viewTag);
     mScrollEventType = scrollEventType;
     mScrollX = scrollX;
     mScrollY = scrollY;
@@ -116,6 +120,12 @@ public void dispatch(RCTEventEmitter rctEventEmitter) {
     rctEventEmitter.receiveEvent(getViewTag(), getEventName(), serializeEventData());
   }
 
+  @Override
+  public void dispatchV2(RCTModernEventEmitter rctEventEmitter) {
+    rctEventEmitter.receiveEvent(
+        getSurfaceId(), getViewTag(), getEventName(), serializeEventData());
+  }
+
   private WritableMap serializeEventData() {
     WritableMap contentInset = Arguments.createMap();
     contentInset.putDouble("top", 0);

ReactAndroid/src/main/java/com/facebook/react/views/textinput/ReactTextInputManager.java

@@ -1131,8 +1131,10 @@ public ReactScrollWatcher(ReactEditText editText) {
     @Override
     public void onScrollChanged(int horiz, int vert, int oldHoriz, int oldVert) {
       if (mPreviousHoriz != horiz || mPreviousVert != vert) {
+        int surfaceId = UIManagerHelper.getSurfaceId(mReactEditText);
         ScrollEvent event =
             ScrollEvent.obtain(
+                surfaceId,
                 mReactEditText.getId(),
                 ScrollEventType.SCROLL,
                 horiz,