Add scroll-to-top control for logs

app/src/main/java/se/ajpanton/notificationlog/ViewLogsFragment.kt

@@ -29,6 +29,12 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
         super.onViewCreated(view, savedInstanceState)
         binding = FragmentViewLogsBinding.bind(view)
         binding!!.logsRefresh.setOnRefreshListener(::loadLogs)
+        binding!!.logScroll.setOnScrollChangeListener { _, _, scrollY, _, _ ->
+            binding?.scrollToTop?.visibility = if (scrollY > dp(SCROLL_TO_TOP_THRESHOLD_DP)) View.VISIBLE else View.GONE
+        }
+        binding!!.scrollToTop.setOnClickListener {
+            binding?.logScroll?.smoothScrollTo(0, 0)
+        }
         loadLogs()
     }
 
@@ -236,5 +242,6 @@ class ViewLogsFragment : Fragment(R.layout.fragment_view_logs) {
     private companion object {
         const val LEFT_PILL_WEIGHT = 0.42f
         const val RIGHT_PILL_WEIGHT = 0.58f
+        const val SCROLL_TO_TOP_THRESHOLD_DP = 120
     }
 }

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

@@ -1,10 +1,15 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.swiperefreshlayout.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
         android:id="@+id/logs_refresh"
         android:layout_width="match_parent"
         android:layout_height="match_parent">
 
         <ScrollView
+            android:id="@+id/log_scroll"
             android:layout_width="match_parent"
             android:layout_height="match_parent">
 
@@ -29,3 +34,14 @@
             </LinearLayout>
         </ScrollView>
     </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
+
+    <com.google.android.material.floatingactionbutton.FloatingActionButton
+        android:id="@+id/scroll_to_top"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="end|bottom"
+        android:layout_margin="16dp"
+        android:contentDescription="Scroll to top"
+        android:visibility="gone"
+        android:src="@android:drawable/arrow_up_float" />
+</FrameLayout>