Support scrollTo with RecycleViewBackedScrollView.

Differential Revision: D2581381

fb-gh-sync-id: 830f36f4d62a3097fdf3697a94a22441f11f93ef

ReactAndroid/src/main/java/com/facebook/react/views/recyclerview/RecyclerViewBackedScrollView.java

@@ -223,26 +223,37 @@ public class RecyclerViewBackedScrollView extends RecyclerView {
     }
   }
 
-  @Override
-  protected void onScrollChanged(int l, int t, int oldl, int oldt) {
-    super.onScrollChanged(l, t, oldl, oldt);
-
-    ReactListAdapter adapter = (ReactListAdapter) getAdapter();
-
+  private int calculateAbsoluteOffset() {
     int offsetY = 0;
     if (getChildCount() > 0) {
       View recyclerViewChild = getChildAt(0);
       int childPosition = getChildAdapterPosition(recyclerViewChild);
-      offsetY = adapter.getTopOffsetForItem(childPosition) - recyclerViewChild.getTop();
+      offsetY = ((ReactListAdapter) getAdapter()).getTopOffsetForItem(childPosition) -
+          recyclerViewChild.getTop();
     }
+    return offsetY;
+  }
+
+  /*package*/ void scrollTo(int scrollX, int scrollY, boolean animated) {
+    int deltaY = scrollY - calculateAbsoluteOffset();
+    if (animated) {
+      smoothScrollBy(0, deltaY);
+    } else {
+      scrollBy(0, deltaY);
+    }
+  }
+
+  @Override
+  protected void onScrollChanged(int l, int t, int oldl, int oldt) {
+    super.onScrollChanged(l, t, oldl, oldt);
 
     ScrollEvent event = new ScrollEvent(
         getId(),
         SystemClock.uptimeMillis(),
         0, /* offsetX = 0, horizontal scrolling only */
-        offsetY,
+        calculateAbsoluteOffset(),
         getWidth(),
-        adapter.getTotalChildrenHeight(),
+        ((ReactListAdapter) getAdapter()).getTotalChildrenHeight(),
         getWidth(),
         getHeight());
     ((ReactContext) getContext()).getNativeModule(UIManagerModule.class).getEventDispatcher()

ReactAndroid/src/main/java/com/facebook/react/views/recyclerview/RecyclerViewBackedScrollViewManager.java

@@ -2,16 +2,21 @@
 
 package com.facebook.react.views.recyclerview;
 
+import javax.annotation.Nullable;
+
 import android.view.View;
 
+import com.facebook.react.bridge.ReadableArray;
 import com.facebook.react.uimanager.ThemedReactContext;
 import com.facebook.react.uimanager.ViewGroupManager;
+import com.facebook.react.views.scroll.ReactScrollViewCommandHelper;
 
 /**
  * View manager for {@link RecyclerViewBackedScrollView}.
  */
 public class RecyclerViewBackedScrollViewManager extends
-    ViewGroupManager<RecyclerViewBackedScrollView> {
+    ViewGroupManager<RecyclerViewBackedScrollView>
+    implements ReactScrollViewCommandHelper.ScrollCommandHandler<RecyclerViewBackedScrollView> {
 
   private static final String REACT_CLASS = "AndroidRecyclerViewBackedScrollView";
 
@@ -46,4 +51,29 @@ public class RecyclerViewBackedScrollViewManager extends
   public void removeView(RecyclerViewBackedScrollView parent, View child) {
     parent.removeViewFromAdapter(child);
   }
+
+  /**
+   * Provides implementation of commands supported by {@link ReactScrollViewManager}
+   */
+  @Override
+  public void receiveCommand(
+      RecyclerViewBackedScrollView view,
+      int commandId,
+      @Nullable ReadableArray args) {
+    ReactScrollViewCommandHelper.receiveCommand(this, view, commandId, args);
+  }
+
+  @Override
+  public void scrollTo(
+      RecyclerViewBackedScrollView view,
+      ReactScrollViewCommandHelper.ScrollToCommandData data) {
+    view.scrollTo(data.mDestX, data.mDestY, true);
+  }
+
+  @Override
+  public void scrollWithoutAnimationTo(
+      RecyclerViewBackedScrollView view,
+      ReactScrollViewCommandHelper.ScrollToCommandData data) {
+    view.scrollTo(data.mDestX, data.mDestY, false);
+  }
 }