From 30989dd24ac8a7754b4ecd5c3d976065da478cf7 Mon Sep 17 00:00:00 2001
From: Andrei Coman <andreic@fb.com>
Date: Tue, 27 Sep 2016 04:22:59 -0700
Subject: [PATCH] Fix ReactSwipeRefreshLayout

Summary:
`ReactSwipeRefreshLayout` extends `SwipeRefreshLayout` which does not play nice with Android's touch handling system.
There are two problems:
1. `SwipeRefreshLayout` overrides and swallows `requestDisallowInterceptTouchEvent`, which means that Views underneath the `SwipeRefreshLayout` will not interact correctly with parent Views of
`SwipeRefreshLayout`. We've seen this in practice by H-ScrollViews having their touches intercepted by an enclosing ViewPager. This is fixed by passing `requestDisallowInterceptTouchEvent` up to the parents of `SwipeRefreshLayout`.
2. `SwipeRefreshLayout` overrides `onInterceptTouchEvent` and never calls `super.onInterceptTouchEvent`, therefore ignoring the value of `disallowIntercept`. That means that it will intercept some touches when it
shouldn't. One such case is again the H-ScrollView, which should receive all horizontal scrolls and stop `SwipeRefreshLayout` from intercepting any touch events after scrolling. Currently, after the H-ScrollView starts scrolling, it is still possible to get the `SwipeRefreshLayout` to detect and emit refresh events. This is fixed by checking and blocking on horizontal scrolls.

Reviewed By: foghina

Differential Revision: D3929893

fbshipit-source-id: e6f8050fb554e53318a7ca564c49c20cb5137df9
---
 .../swiperefresh/ReactSwipeRefreshLayout.java | 49 +++++++++++++++++--
 1 file changed, 45 insertions(+), 4 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/swiperefresh/ReactSwipeRefreshLayout.java b/ReactAndroid/src/main/java/com/facebook/react/views/swiperefresh/ReactSwipeRefreshLayout.java
index d16e58de1b8..9f8ede6537c 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/views/swiperefresh/ReactSwipeRefreshLayout.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/views/swiperefresh/ReactSwipeRefreshLayout.java
@@ -11,10 +11,11 @@ package com.facebook.react.views.swiperefresh;
 
 import android.support.v4.widget.SwipeRefreshLayout;
 import android.view.MotionEvent;
+import android.view.ViewConfiguration;
 
 import com.facebook.react.bridge.ReactContext;
-import com.facebook.react.uimanager.events.NativeGestureUtil;
 import com.facebook.react.uimanager.PixelUtil;
+import com.facebook.react.uimanager.events.NativeGestureUtil;
 
 /**
  * Basic extension of {@link SwipeRefreshLayout} with ReactNative-specific functionality.
@@ -24,13 +25,15 @@ public class ReactSwipeRefreshLayout extends SwipeRefreshLayout {
   private static final float DEFAULT_CIRCLE_TARGET = 64;
 
   private boolean mDidLayout = false;
-
   private boolean mRefreshing = false;
   private float mProgressViewOffset = 0;
-
+  private int mTouchSlop;
+  private float mPrevTouchX;
+  private boolean mIntercepted;
 
   public ReactSwipeRefreshLayout(ReactContext reactContext) {
     super(reactContext);
+    mTouchSlop = ViewConfiguration.get(reactContext).getScaledTouchSlop();
   }
 
   @Override
@@ -71,12 +74,50 @@ public class ReactSwipeRefreshLayout extends SwipeRefreshLayout {
     }
   }
 
+  /**
+   * {@link SwipeRefreshLayout} overrides {@link ViewGroup#requestDisallowInterceptTouchEvent} and
+   * swallows it. This means that any component underneath SwipeRefreshLayout will now interact
+   * incorrectly with Views that are above SwipeRefreshLayout. We fix that by transmitting the call
+   * to this View's parents.
+   */
+  @Override
+  public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
+    if (getParent() != null) {
+      getParent().requestDisallowInterceptTouchEvent(disallowIntercept);
+    }
+  }
+
   @Override
   public boolean onInterceptTouchEvent(MotionEvent ev) {
-    if (super.onInterceptTouchEvent(ev)) {
+    if (shouldInterceptTouchEvent(ev) && super.onInterceptTouchEvent(ev)) {
       NativeGestureUtil.notifyNativeGestureStarted(this, ev);
       return true;
     }
     return false;
   }
+
+  /**
+   * {@link SwipeRefreshLayout} completely bypasses ViewGroup's "disallowIntercept" by overriding
+   * {@link ViewGroup#onInterceptTouchEvent} and never calling super.onInterceptTouchEvent().
+   * This means that horizontal scrolls will always be intercepted, even though they shouldn't, so
+   * we have to check for that manually here.
+   */
+  private boolean shouldInterceptTouchEvent(MotionEvent ev) {
+    switch (ev.getAction()) {
+      case MotionEvent.ACTION_DOWN:
+        mPrevTouchX = ev.getX();
+        mIntercepted = false;
+        break;
+
+      case MotionEvent.ACTION_MOVE:
+        final float eventX = ev.getX();
+        final float xDiff = Math.abs(eventX - mPrevTouchX);
+
+        if (mIntercepted || xDiff > mTouchSlop) {
+          mIntercepted = true;
+          return false;
+        }
+    }
+    return true;
+  }
 }