Fix HorizontalScrollView not reporting its contentOffset

Summary:
# Problem

HorizontalScrollView was not reporting its `contentOffset` to Fabric, therefore `measure`  was returning wrong value.

# Solution

Copy over implementation of `updateState` from scrollView. I noticed that there is a lot of duplication between the two classes, that's why I decided to duplicate `updateState` as well.

Changelog: [Internal]

Reviewed By: JoshuaGross, mdvacca

Differential Revision: D20247552

fbshipit-source-id: 48b1eb0c11198a32531effe55301f8d554e92130

Author: sammy-SC

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

@@ -24,11 +24,15 @@
 import androidx.core.view.ViewCompat;
 import com.facebook.common.logging.FLog;
 import com.facebook.infer.annotation.Assertions;
+import com.facebook.react.bridge.WritableMap;
+import com.facebook.react.bridge.WritableNativeMap;
 import com.facebook.react.common.ReactConstants;
 import com.facebook.react.config.ReactFeatureFlags;
 import com.facebook.react.uimanager.MeasureSpecAssertions;
+import com.facebook.react.uimanager.PixelUtil;
 import com.facebook.react.uimanager.ReactClippingViewGroup;
 import com.facebook.react.uimanager.ReactClippingViewGroupHelper;
+import com.facebook.react.uimanager.StateWrapper;
 import com.facebook.react.uimanager.ViewProps;
 import com.facebook.react.uimanager.events.NativeGestureUtil;
 import com.facebook.react.views.view.ReactViewBackgroundManager;
@@ -43,6 +47,8 @@ public class ReactHorizontalScrollView extends HorizontalScrollView
 
   private static @Nullable Field sScrollerField;
   private static boolean sTriedToGetScrollerField = false;
+  private static final String CONTENT_OFFSET_LEFT = "contentOffsetLeft";
+  private static final String CONTENT_OFFSET_TOP = "contentOffsetTop";
 
   private final OnScrollDispatchHelper mOnScrollDispatchHelper = new OnScrollDispatchHelper();
   private final @Nullable OverScroller mScroller;
@@ -70,6 +76,7 @@ public class ReactHorizontalScrollView extends HorizontalScrollView
   private boolean mSnapToEnd = true;
   private ReactViewBackgroundManager mReactBackgroundManager;
   private boolean mPagedArrowScrolling = false;
+  private @Nullable StateWrapper mStateWrapper;
 
   private final Rect mTempRect = new Rect();
 
@@ -217,7 +224,7 @@ protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
   @Override
   protected void onLayout(boolean changed, int l, int t, int r, int b) {
     // Call with the present values in order to re-layout if necessary
-    scrollTo(getScrollX(), getScrollY());
+    reactScrollTo(getScrollX(), getScrollY());
   }
 
   /**
@@ -383,6 +390,8 @@ public boolean onTouchEvent(MotionEvent ev) {
     mVelocityHelper.calculateVelocity(ev);
     int action = ev.getAction() & MotionEvent.ACTION_MASK;
     if (action == MotionEvent.ACTION_UP && mDragging) {
+      updateStateOnScroll(getScrollX(), getScrollY());
+
       float velocityX = mVelocityHelper.getXVelocity();
       float velocityY = mVelocityHelper.getYVelocity();
       ReactScrollViewHelper.emitScrollEndDragEvent(this, velocityX, velocityY);
@@ -605,6 +614,8 @@ public void run() {
               ViewCompat.postOnAnimationDelayed(
                   ReactHorizontalScrollView.this, this, ReactScrollViewHelper.MOMENTUM_DELAY);
             } else {
+              updateStateOnScroll(getScrollX(), getScrollY());
+
               if (mPagingEnabled && !mSnappingToPage) {
                 // Only if we have pagingEnabled and we have not snapped to the page do we
                 // need to continue checking for the scroll.  And we cause that scroll by asking for
@@ -698,7 +709,7 @@ private void smoothScrollAndSnap(int velocity) {
     targetOffset = currentPage * interval;
     if (targetOffset != currentOffset) {
       mActivelyScrolling = true;
-      smoothScrollTo((int) targetOffset, getScrollY());
+      reactSmoothScrollTo((int) targetOffset, getScrollY());
     }
   }
 
@@ -834,7 +845,7 @@ private void flingAndSnap(int velocityX) {
 
       postInvalidateOnAnimation();
     } else {
-      smoothScrollTo(targetOffset, getScrollY());
+      reactSmoothScrollTo(targetOffset, getScrollY());
     }
   }
 
@@ -857,7 +868,7 @@ private void smoothScrollToNextPage(int direction) {
       page = 0;
     }
 
-    smoothScrollTo(page * width, getScrollY());
+    reactSmoothScrollTo(page * width, getScrollY());
     handlePostTouchScrolling(0, 0);
   }
 
@@ -885,4 +896,45 @@ public void setBorderRadius(float borderRadius, int position) {
   public void setBorderStyle(@Nullable String style) {
     mReactBackgroundManager.setBorderStyle(style);
   }
+
+  /**
+   * Calls `smoothScrollTo` and updates state.
+   *
+   * <p>`smoothScrollTo` changes `contentOffset` and we need to keep `contentOffset` in sync between
+   * scroll view and state. Calling raw `smoothScrollTo` doesn't update state.
+   */
+  public void reactSmoothScrollTo(int x, int y) {
+    smoothScrollTo(x, y);
+    updateStateOnScroll(x, y);
+  }
+
+  /**
+   * Calls `reactScrollTo` and updates state.
+   *
+   * <p>`reactScrollTo` changes `contentOffset` and we need to keep `contentOffset` in sync between
+   * scroll view and state. Calling raw `reactScrollTo` doesn't update state.
+   */
+  public void reactScrollTo(int x, int y) {
+    scrollTo(x, y);
+    updateStateOnScroll(x, y);
+  }
+
+  public void updateState(@Nullable StateWrapper stateWrapper) {
+    mStateWrapper = stateWrapper;
+  }
+
+  /**
+   * Called on any stabilized onScroll change to propagate content offset value to a Shadow Node.
+   */
+  private void updateStateOnScroll(int scrollX, int scrollY) {
+    if (mStateWrapper == null) {
+      return;
+    }
+
+    WritableMap map = new WritableNativeMap();
+    map.putDouble(CONTENT_OFFSET_LEFT, PixelUtil.toDIPFromPixel(scrollX));
+    map.putDouble(CONTENT_OFFSET_TOP, PixelUtil.toDIPFromPixel(scrollY));
+
+    mStateWrapper.updateState(map);
+  }
 }

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

@@ -16,7 +16,9 @@
 import com.facebook.react.uimanager.DisplayMetricsHolder;
 import com.facebook.react.uimanager.PixelUtil;
 import com.facebook.react.uimanager.ReactClippingViewGroupHelper;
+import com.facebook.react.uimanager.ReactStylesDiffMap;
 import com.facebook.react.uimanager.Spacing;
+import com.facebook.react.uimanager.StateWrapper;
 import com.facebook.react.uimanager.ThemedReactContext;
 import com.facebook.react.uimanager.ViewGroupManager;
 import com.facebook.react.uimanager.ViewProps;
@@ -62,6 +64,15 @@ public ReactHorizontalScrollView createViewInstance(ThemedReactContext context)
     return new ReactHorizontalScrollView(context, mFpsListener);
   }
 
+  @Override
+  public Object updateState(
+      ReactHorizontalScrollView view,
+      ReactStylesDiffMap props,
+      @Nullable StateWrapper stateWrapper) {
+    view.updateState(stateWrapper);
+    return null;
+  }
+
   @ReactProp(name = "scrollEnabled", defaultBoolean = true)
   public void setScrollEnabled(ReactHorizontalScrollView view, boolean value) {
     view.setScrollEnabled(value);
@@ -179,9 +190,9 @@ public void flashScrollIndicators(ReactHorizontalScrollView scrollView) {
   public void scrollTo(
       ReactHorizontalScrollView scrollView, ReactScrollViewCommandHelper.ScrollToCommandData data) {
     if (data.mAnimated) {
-      scrollView.smoothScrollTo(data.mDestX, data.mDestY);
+      scrollView.reactSmoothScrollTo(data.mDestX, data.mDestY);
     } else {
-      scrollView.scrollTo(data.mDestX, data.mDestY);
+      scrollView.reactScrollTo(data.mDestX, data.mDestY);
     }
   }
 
@@ -192,9 +203,9 @@ public void scrollToEnd(
     // ScrollView always has one child - the scrollable area
     int right = scrollView.getChildAt(0).getWidth() + scrollView.getPaddingRight();
     if (data.mAnimated) {
-      scrollView.smoothScrollTo(right, scrollView.getScrollY());
+      scrollView.reactSmoothScrollTo(right, scrollView.getScrollY());
     } else {
-      scrollView.scrollTo(right, scrollView.getScrollY());
+      scrollView.reactScrollTo(right, scrollView.getScrollY());
     }
   }