Hide FAB on scroll

app/src/main/java/org/solovyev/android/calculator/view/PagerViewFabBehavior.java

@@ -0,0 +1,60 @@
+package org.solovyev.android.calculator.view;
+
+import android.content.Context;
+import android.support.design.widget.CoordinatorLayout;
+import android.support.design.widget.FloatingActionButton;
+import android.support.v4.view.ViewCompat;
+import android.support.v4.view.ViewPager;
+import android.support.v7.widget.RecyclerView;
+import android.util.AttributeSet;
+import android.view.View;
+
+public class PagerViewFabBehavior extends FloatingActionButton.Behavior {
+
+    public PagerViewFabBehavior() {
+        super();
+    }
+
+    public PagerViewFabBehavior(Context context, AttributeSet attributeSet) {
+        super();
+    }
+
+    @Override
+    public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout,
+            FloatingActionButton child, View directTargetChild, View target, int nestedScrollAxes) {
+        switch (nestedScrollAxes) {
+            case ViewCompat.SCROLL_AXIS_HORIZONTAL:
+                return target instanceof ViewPager;
+            case ViewCompat.SCROLL_AXIS_VERTICAL:
+                return target instanceof RecyclerView;
+            default:
+                return false;
+        }
+    }
+
+    @Override
+    public void onNestedScroll(CoordinatorLayout coordinatorLayout, FloatingActionButton child,
+            View target, int dxConsumed, int dyConsumed, int dxUnconsumed, int dyUnconsumed) {
+        onScroll(child, dxConsumed, dyConsumed);
+    }
+
+    @Override
+    public boolean onNestedFling(CoordinatorLayout coordinatorLayout, FloatingActionButton child,
+            View target, float velocityX, float velocityY, boolean consumed) {
+        return onScroll(child, velocityX, velocityY);
+    }
+
+    private boolean onScroll(FloatingActionButton child, float scrollX, float scrollY) {
+        if (scrollY > 0 && child.getVisibility() == View.VISIBLE) {
+            child.hide();
+            return true;
+        } else if (scrollY < 0 && child.getVisibility() != View.VISIBLE) {
+            child.show();
+            return true;
+        } else if (scrollX != 0 && child.getVisibility() != View.VISIBLE) {
+            child.show();
+            return true;
+        }
+        return false;
+    }
+}

app/src/main/res/layout-land/activity_tabs.xml

@@ -59,6 +59,7 @@
     </android.support.design.widget.AppBarLayout>
 
     <android.support.design.widget.FloatingActionButton
+        app:layout_behavior="org.solovyev.android.calculator.view.PagerViewFabBehavior"
         android:id="@+id/fab"
         style="@style/CppFab" />
 

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

@@ -58,6 +58,7 @@
     </android.support.design.widget.AppBarLayout>
 
     <android.support.design.widget.FloatingActionButton
+        app:layout_behavior="org.solovyev.android.calculator.view.PagerViewFabBehavior"
         android:id="@+id/fab"
         style="@style/CppFab"/>