Add scrollEnabled prop to Android ScrollView

Summary:
Perhaps there is a better way to do this, curious to hear it!

- If momentum scroll is active when `scrollEnabled` is toggled, the momentum scroll continues and the onMomentumScrollEnd event fires, which is the same as on iOS.
Closes https://github.com/facebook/react-native/pull/5656

Reviewed By: svcscm

Differential Revision: D2889897

Pulled By: dmmiller

fb-gh-sync-id: b2f44d2bcb48373f9945f6afd966447a118df717

Libraries/Components/ScrollView/ScrollView.js

@@ -227,7 +227,6 @@ var ScrollView = React.createClass({
     /**
      * When false, the content does not scroll.
      * The default value is true.
-     * @platform ios
      */
     scrollEnabled: PropTypes.bool,
     /**

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactHorizontalScrollView.java

@@ -31,13 +31,13 @@ public class ReactHorizontalScrollView extends HorizontalScrollView implements
 
   private final OnScrollDispatchHelper mOnScrollDispatchHelper = new OnScrollDispatchHelper();
 
-  private boolean mRemoveClippedSubviews;
-  private boolean mSendMomentumEvents;
+  private @Nullable Rect mClippingRect;
+  private boolean mDoneFlinging;
   private boolean mDragging;
   private boolean mFlinging;
-  private boolean mDoneFlinging;
-
-  private @Nullable Rect mClippingRect;
+  private boolean mRemoveClippedSubviews;
+  private boolean mScrollEnabled = true;
+  private boolean mSendMomentumEvents;
 
   public ReactHorizontalScrollView(Context context) {
     super(context);
@@ -61,6 +61,10 @@ public class ReactHorizontalScrollView extends HorizontalScrollView implements
     mSendMomentumEvents = sendMomentumEvents;
   }
 
+  public void setScrollEnabled(boolean scrollEnabled) {
+    mScrollEnabled = scrollEnabled;
+  }
+
   @Override
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     MeasureSpecAssertions.assertExplicitMeasureSpec(widthMeasureSpec, heightMeasureSpec);
@@ -95,6 +99,10 @@ public class ReactHorizontalScrollView extends HorizontalScrollView implements
 
   @Override
   public boolean onInterceptTouchEvent(MotionEvent ev) {
+    if (!mScrollEnabled) {
+      return false;
+    }
+
     if (super.onInterceptTouchEvent(ev)) {
       NativeGestureUtil.notifyNativeGestureStarted(this, ev);
       ReactScrollViewHelper.emitScrollBeginDragEvent(this);
@@ -107,6 +115,10 @@ public class ReactHorizontalScrollView extends HorizontalScrollView implements
 
   @Override
   public boolean onTouchEvent(MotionEvent ev) {
+    if (!mScrollEnabled) {
+      return false;
+    }
+
     int action = ev.getAction() & MotionEvent.ACTION_MASK;
     if (action == MotionEvent.ACTION_UP && mDragging) {
       ReactScrollViewHelper.emitScrollEndDragEvent(this);

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactHorizontalScrollViewManager.java

@@ -39,17 +39,21 @@ public class ReactHorizontalScrollViewManager
     return new ReactHorizontalScrollView(context);
   }
 
-  @ReactProp(name = ReactClippingViewGroupHelper.PROP_REMOVE_CLIPPED_SUBVIEWS)
-  public void setRemoveClippedSubviews(ReactHorizontalScrollView view, boolean removeClippedSubviews) {
-    view.setRemoveClippedSubviews(removeClippedSubviews);
+  @ReactProp(name = "scrollEnabled", defaultBoolean = true)
+  public void setScrollEnabled(ReactHorizontalScrollView view, boolean value) {
+    view.setScrollEnabled(value);
   }
 
-
   @ReactProp(name = "showsHorizontalScrollIndicator")
   public void setShowsHorizontalScrollIndicator(ReactHorizontalScrollView view, boolean value) {
     view.setHorizontalScrollBarEnabled(value);
   }
 
+  @ReactProp(name = ReactClippingViewGroupHelper.PROP_REMOVE_CLIPPED_SUBVIEWS)
+  public void setRemoveClippedSubviews(ReactHorizontalScrollView view, boolean removeClippedSubviews) {
+    view.setRemoveClippedSubviews(removeClippedSubviews);
+  }
+
   /**
    * Computing momentum events is potentially expensive since we post a runnable on the UI thread
    * to see when it is done.  We only do that if {@param sendMomentumEvents} is set to true.  This

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java

@@ -34,12 +34,13 @@ public class ReactScrollView extends ScrollView implements ReactClippingViewGrou
 
   private final OnScrollDispatchHelper mOnScrollDispatchHelper = new OnScrollDispatchHelper();
 
-  private boolean mRemoveClippedSubviews;
   private @Nullable Rect mClippingRect;
-  private boolean mSendMomentumEvents;
+  private boolean mDoneFlinging;
   private boolean mDragging;
   private boolean mFlinging;
-  private boolean mDoneFlinging;
+  private boolean mRemoveClippedSubviews;
+  private boolean mScrollEnabled = true;
+  private boolean mSendMomentumEvents;
 
   public ReactScrollView(Context context) {
     super(context);
@@ -49,6 +50,10 @@ public class ReactScrollView extends ScrollView implements ReactClippingViewGrou
     mSendMomentumEvents = sendMomentumEvents;
   }
 
+  public void setScrollEnabled(boolean scrollEnabled) {
+    mScrollEnabled = scrollEnabled;
+  }
+
   @Override
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     MeasureSpecAssertions.assertExplicitMeasureSpec(widthMeasureSpec, heightMeasureSpec);
@@ -99,6 +104,10 @@ public class ReactScrollView extends ScrollView implements ReactClippingViewGrou
 
   @Override
   public boolean onInterceptTouchEvent(MotionEvent ev) {
+    if (!mScrollEnabled) {
+      return false;
+    }
+
     if (super.onInterceptTouchEvent(ev)) {
       NativeGestureUtil.notifyNativeGestureStarted(this, ev);
       ReactScrollViewHelper.emitScrollBeginDragEvent(this);
@@ -111,6 +120,10 @@ public class ReactScrollView extends ScrollView implements ReactClippingViewGrou
 
   @Override
   public boolean onTouchEvent(MotionEvent ev) {
+    if (!mScrollEnabled) {
+      return false;
+    }
+
     int action = ev.getAction() & MotionEvent.ACTION_MASK;
     if (action == MotionEvent.ACTION_UP && mDragging) {
       ReactScrollViewHelper.emitScrollEndDragEvent(this);

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewManager.java

@@ -42,6 +42,11 @@ public class ReactScrollViewManager
     return new ReactScrollView(context);
   }
 
+  @ReactProp(name = "scrollEnabled", defaultBoolean = true)
+  public void setScrollEnabled(ReactScrollView view, boolean value) {
+    view.setScrollEnabled(value);
+  }
+
   @ReactProp(name = "showsVerticalScrollIndicator")
   public void setShowsVerticalScrollIndicator(ReactScrollView view, boolean value) {
     view.setVerticalScrollBarEnabled(value);