From b07a65b9d9fa4bc6d40283277df3dad5a25e3100 Mon Sep 17 00:00:00 2001
From: Samuel Susla <samuelsusla@fb.com>
Date: Thu, 13 Feb 2020 12:58:45 -0800
Subject: [PATCH] Fix ScrollView state not being set if scrollTo command was
 called

Summary:
# Problem
`UIManager::getRelativeLayoutMetrics`  returns incorrect `frame.origin.y` value.

Just quick reiteration how calculation of `frame.origin` works. We take frame of the target shadow node, travers hierarchy to the root and keep adding `frame.origin` of each ancestor to target shadow node's origin.

One more important piece of information, to calculate scroll view's `frame.origin`, we need to have its contentOffset which gets passed to Fabric core through state.

# So where does it go wrong?
Problem is that on Android, calling view command `scrollTo` doesn't set its internal state correctly. So when we calculate the layoutmetrics, scroll view's `frame.origin` is off by whatever value was used in `scrollTo`.

# The fix
In `ReactScrollView`, correctly set state after `scrollTo` is called on it.

Changelog: [Internal]

Reviewed By: JoshuaGross

Differential Revision: D19835549

fbshipit-source-id: d56e7b0b05023c0497e52c8b46fdcf58ca78b4a5
---
 .../react/views/scroll/ReactScrollView.java   | 30 ++++++++++++++++---
 .../views/scroll/ReactScrollViewManager.java  |  8 ++---
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java
index 48664a960ca..8004cc2ac63 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java
@@ -200,7 +200,7 @@ public class ReactScrollView extends ScrollView
   @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());
   }
 
   @Override
@@ -597,7 +597,7 @@ public class ReactScrollView extends ScrollView
     targetOffset = currentPage * interval;
     if (targetOffset != currentOffset) {
       mActivelyScrolling = true;
-      smoothScrollTo(getScrollX(), (int) targetOffset);
+      reactSmoothScrollTo(getScrollX(), (int) targetOffset);
     }
   }
 
@@ -715,7 +715,7 @@ public class ReactScrollView extends ScrollView
 
       postInvalidateOnAnimation();
     } else {
-      smoothScrollTo(getScrollX(), targetOffset);
+      reactSmoothScrollTo(getScrollX(), targetOffset);
     }
   }
 
@@ -768,6 +768,28 @@ public class ReactScrollView extends ScrollView
     mContentView = null;
   }
 
+  /**
+   * 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();
+  }
+
+  /**
+   * 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();
+  }
+
   /**
    * Called when a mContentView's layout has changed. Fixes the scroll position if it's too large
    * after the content resizes. Without this, the user would see a blank ScrollView when the scroll
@@ -791,7 +813,7 @@ public class ReactScrollView extends ScrollView
     int currentScrollY = getScrollY();
     int maxScrollY = getMaxScrollY();
     if (currentScrollY > maxScrollY) {
-      scrollTo(getScrollX(), maxScrollY);
+      reactScrollTo(getScrollX(), maxScrollY);
     }
   }
 
diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java
index d7fc393f4e4..d528caa2ea6 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java
@@ -201,9 +201,9 @@ public class ReactScrollViewManager extends ViewGroupManager<ReactScrollView>
   public void scrollTo(
       ReactScrollView 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);
     }
   }
 
@@ -275,9 +275,9 @@ public class ReactScrollViewManager extends ViewGroupManager<ReactScrollView>
     // ScrollView always has one child - the scrollable area
     int bottom = scrollView.getChildAt(0).getHeight() + scrollView.getPaddingBottom();
     if (data.mAnimated) {
-      scrollView.smoothScrollTo(scrollView.getScrollX(), bottom);
+      scrollView.reactSmoothScrollTo(scrollView.getScrollX(), bottom);
     } else {
-      scrollView.scrollTo(scrollView.getScrollX(), bottom);
+      scrollView.reactScrollTo(scrollView.getScrollX(), bottom);
     }
   }