Add ability to disable scroll on android ViewPager

Summary: Similar to ScrollView, adds ability to set scrollEnabled={false}, which prevents dragging. Paging is still possible by updating initialPage.

Reviewed By: AaaChiuuu

Differential Revision: D3209743

fb-gh-sync-id: ce4140323a03f2257a9bb310c7285418b01abae7
fbshipit-source-id: ce4140323a03f2257a9bb310c7285418b01abae7

Author: Angela Hess

Libraries/Components/ViewPager/ViewPagerAndroid.android.js

@@ -123,6 +123,12 @@ var ViewPagerAndroid = React.createClass({
       'none', // default
       'on-drag',
     ]),
+
+    /**
+    * When false, the content does not scroll.
+    * The default value is true.
+    */
+    scrollEnabled: React.PropTypes.bool,
   },
 
   componentDidMount: function() {

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

@@ -125,6 +125,7 @@ public void onPageScrollStateChanged(int state) {
 
   private final EventDispatcher mEventDispatcher;
   private boolean mIsCurrentItemFromJs;
+  private boolean mScrollEnabled = true;
 
   public ReactViewPager(ReactContext reactContext) {
     super(reactContext);
@@ -141,19 +142,31 @@ public Adapter getAdapter() {
 
   @Override
   public boolean onInterceptTouchEvent(MotionEvent ev) {
-    if (super.onInterceptTouchEvent(ev)) {
+    if (mScrollEnabled && super.onInterceptTouchEvent(ev)) {
       NativeGestureUtil.notifyNativeGestureStarted(this, ev);
       return true;
     }
     return false;
   }
 
+  @Override
+  public boolean onTouchEvent(MotionEvent ev) {
+    if (!mScrollEnabled) {
+      return false;
+    }
+    return super.onTouchEvent(ev);
+  }
+
   public void setCurrentItemFromJs(int item, boolean animated) {
     mIsCurrentItemFromJs = true;
     setCurrentItem(item, animated);
     mIsCurrentItemFromJs = false;
   }
 
+  public void setScrollEnabled(boolean scrollEnabled) {
+    mScrollEnabled = scrollEnabled;
+  }
+
   /*package*/ void addViewToAdapter(View child, int index) {
     getAdapter().addView(child, index);
   }

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

@@ -43,6 +43,12 @@ protected ReactViewPager createViewInstance(ThemedReactContext reactContext) {
     return new ReactViewPager(reactContext);
   }
 
+
+  @ReactProp(name = "scrollEnabled", defaultBoolean = true)
+  public void setScrollEnabled(ReactViewPager viewPager, boolean value) {
+    viewPager.setScrollEnabled(value);
+  }
+
   @Override
   public boolean needsCustomLayoutForChildren() {
     return true;