Hide edit event fab on scroll

app/src/main/java/app/insti/fragment/EventFragment.java

@@ -15,6 +15,7 @@ import android.os.Bundle;
 import android.support.design.widget.FloatingActionButton;
 import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentTransaction;
+import android.support.v4.widget.NestedScrollView;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.Toolbar;
@@ -230,10 +231,18 @@ public class EventFragment extends BackHandledFragment {
         });
         mShortAnimationDuration = getResources().getInteger(android.R.integer.config_shortAnimTime);
 
-        FloatingActionButton fab = (FloatingActionButton) getView().findViewById(R.id.edit_fab);
+        final FloatingActionButton fab = (FloatingActionButton) getView().findViewById(R.id.edit_fab);
 
         if (((MainActivity) getActivity()).editEventAccess(event)) {
             fab.setVisibility(View.VISIBLE);
+            NestedScrollView nsv = (NestedScrollView) getView().findViewById(R.id.event_scrollview);
+            nsv.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {
+                @Override
+                public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
+                    if (scrollY > oldScrollY) fab.hide();
+                    else fab.show();
+                }
+            });
         }
 
         fab.setOnClickListener(new View.OnClickListener() {

app/src/main/res/layout/fragment_event.xml

@@ -15,7 +15,8 @@
             android:layout_height="match_parent"
             android:orientation="vertical">
 
-            <ScrollView
+            <android.support.v4.widget.NestedScrollView
+                android:id="@+id/event_scrollview"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content">
 
@@ -213,7 +214,7 @@
                         android:layout_marginTop="10dp" />
 
                 </LinearLayout>
-            </ScrollView>
+            </android.support.v4.widget.NestedScrollView>
 
         </LinearLayout>