From b0c023c85c9a1c675b6787c6292400c5fd229181 Mon Sep 17 00:00:00 2001
From: Felix Oghina <foghina@fb.com>
Date: Thu, 14 Jul 2016 13:27:11 -0700
Subject: [PATCH] fix removing views from ViewPagerAndroid

Summary:
Two things in this diff:

1. Implemented `getItemPosition` in our adapter; the default implementation always returns POSITION_UNCHANGED, which is incorrect, and causes `destroyItem` to never (sometimes?) be called.
2. Fix `destroyItem`: this never worked. `destroyItem` is always called by the ViewPager after a `notifyDataSetChanged()`, so after `removeViewAt`, which removes the view from `mViews`, causing `destroyItem` to throw `IndexOutOfBoundsException` when it tries to get the view. Since our item objects are just views, use that instead of checking `mViews`.

Reviewed By: ahmedre

Differential Revision: D3555427

fbshipit-source-id: 900c2696162d07f507e850517d483b943ce39a35
---
 .../facebook/react/views/viewpager/ReactViewPager.java | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/viewpager/ReactViewPager.java b/ReactAndroid/src/main/java/com/facebook/react/views/viewpager/ReactViewPager.java
index 8b86beb76..f53b84517 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/viewpager/ReactViewPager.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/viewpager/ReactViewPager.java
@@ -33,7 +33,7 @@ import com.facebook.react.uimanager.events.NativeGestureUtil;
 
   private class Adapter extends PagerAdapter {
 
-    private List<View> mViews = new ArrayList<>();
+    private final List<View> mViews = new ArrayList<>();
 
     void addView(View child, int index) {
       mViews.add(index, child);
@@ -67,6 +67,11 @@ import com.facebook.react.uimanager.events.NativeGestureUtil;
       return mViews.size();
     }
 
+    @Override
+    public int getItemPosition(Object object) {
+      return mViews.contains(object) ? mViews.indexOf(object) : POSITION_NONE;
+    }
+
     @Override
     public Object instantiateItem(ViewGroup container, int position) {
       View view = mViews.get(position);
@@ -76,8 +81,7 @@ import com.facebook.react.uimanager.events.NativeGestureUtil;
 
     @Override
     public void destroyItem(ViewGroup container, int position, Object object) {
-      View view = mViews.get(position);
-      container.removeView(view);
+      container.removeView((View) object);
     }
 
     @Override