Fix ViewPager behavior with Nodes

Summary: Add a batch addition operation for ViewPager.

Differential Revision: D3597840

fbshipit-source-id: 1c9c42e03da2492444298220e75f547b6567b4e5

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

@@ -9,15 +9,16 @@
 
 package com.facebook.react.uimanager;
 
-import android.view.View;
-import android.view.ViewGroup;
-
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.List;
 import java.util.WeakHashMap;
 
+import android.view.View;
+import android.view.ViewGroup;
+
 /**
  * Class providing children management API for view managers of classes extending ViewGroup.
  */
@@ -45,6 +46,19 @@ public void addView(T parent, View child, int index) {
     reorderChildrenByZIndex(parent);
   }
 
+  /**
+   * Convenience method for batching a set of addView calls
+   * Note that this adds the views to the beginning of the ViewGroup
+   *
+   * @param parent the parent ViewGroup
+   * @param views the set of views to add
+   */
+  public void addViews(T parent, List<View> views) {
+    for (int i = 0, size = views.size(); i < size; i++) {
+      addView(parent, views.get(i), i);
+    }
+  }
+
   public static void setViewZIndex(View view, int zIndex) {
     mZIndexHash.put(view, zIndex);
     // zIndex prop gets set BEFORE the view is added, so parent may be null.

ReactAndroid/src/main/java/com/facebook/react/views/viewpager/ReactViewPager.java

@@ -28,11 +28,12 @@
  * views to custom {@link PagerAdapter} instance which is used by {@link NativeViewHierarchyManager}
  * to add children nodes according to react views hierarchy.
  */
-/* package */ class ReactViewPager extends ViewPager {
+public class ReactViewPager extends ViewPager {
 
   private class Adapter extends PagerAdapter {
 
     private final List<View> mViews = new ArrayList<>();
+    private boolean mIsViewPagerInIntentionallyInconsistentState = false;
 
     void addView(View child, int index) {
       mViews.add(index, child);
@@ -57,6 +58,32 @@ void removeViewAt(int index) {
       setOffscreenPageLimit(mViews.size());
     }
 
+    /**
+     * Replace a set of views to the ViewPager adapter and update the ViewPager
+     */
+    void setViews(List<View> views) {
+      mViews.clear();
+      mViews.addAll(views);
+      notifyDataSetChanged();
+
+      // we want to make sure we return POSITION_NONE for every view here, since this is only
+      // called after a removeAllViewsFromAdapter
+      mIsViewPagerInIntentionallyInconsistentState = false;
+    }
+
+    /**
+     * Remove all the views from the adapter and de-parents them from the ViewPager
+     * After calling this, it is expected that notifyDataSetChanged should be called soon
+     * afterwards.
+     */
+    void removeAllViewsFromAdapter(ViewPager pager) {
+      mViews.clear();
+      pager.removeAllViews();
+      // set this, so that when the next addViews is called, we return POSITION_NONE for every
+      // entry so we can remove whichever views we need to and add the ones that we need to.
+      mIsViewPagerInIntentionallyInconsistentState = true;
+    }
+
     View getViewAt(int index) {
       return mViews.get(index);
     }
@@ -68,7 +95,9 @@ public int getCount() {
 
     @Override
     public int getItemPosition(Object object) {
-      return mViews.contains(object) ? mViews.indexOf(object) : POSITION_NONE;
+      // if we've removed all views, we want to return POSITION_NONE intentionally
+      return mIsViewPagerInIntentionallyInconsistentState || !mViews.contains(object) ?
+        POSITION_NONE : mViews.indexOf(object);
     }
 
     @Override
@@ -190,4 +219,12 @@ public void setScrollEnabled(boolean scrollEnabled) {
   /*package*/ View getViewFromAdapter(int index) {
     return getAdapter().getViewAt(index);
   }
+
+  public void setViews(List<View> views) {
+    getAdapter().setViews(views);
+  }
+
+  public void removeAllViewsFromAdapter() {
+    getAdapter().removeAllViewsFromAdapter(this);
+  }
 }