add fast scroller to library view

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryCategoryAdapter.kt

@@ -1,11 +1,11 @@
 package eu.kanade.tachiyomi.ui.library
 
 import eu.davidea.flexibleadapter.FlexibleAdapter
-import eu.kanade.tachiyomi.data.database.models.Manga
-import androidx.recyclerview.widget.RecyclerView
-import eu.davidea.flexibleadapter.SelectableAdapter
 import eu.davidea.flexibleadapter.items.IFlexible
+import eu.kanade.tachiyomi.data.database.models.Manga
 import eu.kanade.tachiyomi.ui.category.CategoryAdapter
+import java.util.*
+
 
 /**
  * Adapter storing a list of manga in a certain category.
@@ -51,4 +51,15 @@ class LibraryCategoryAdapter(view: LibraryCategoryView) :
         updateDataSet(mangas.filter { it.filter(s) })
     }
 
+    override fun onCreateBubbleText(position: Int): String {
+        return if (position < scrollableHeaders.size) {
+            "Top"
+        } else if (position >= itemCount - scrollableFooters.size) {
+            "Bottom"
+        } else { // Get and show the first character
+            val iFlexible: IFlexible<*>? = getItem(position)
+            (iFlexible as LibraryItem).manga.title.substring(0, 1).toUpperCase(Locale.US)
+        }
+    }
+
 }

app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryCategoryView.kt

@@ -86,6 +86,7 @@ class LibraryCategoryView @JvmOverloads constructor(context: Context, attrs: Att
         recycler.setHasFixedSize(true)
         recycler.adapter = adapter
         swipe_refresh.addView(recycler)
+        adapter.fastScroller = fast_scroller
 
         recycler.addOnScrollListener(object : RecyclerView.OnScrollListener() {
             override fun onScrollStateChanged(recycler: RecyclerView, newState: Int) {

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

@@ -1,14 +1,22 @@
 <?xml version="1.0" encoding="utf-8"?>
-<eu.kanade.tachiyomi.ui.library.LibraryCategoryView
-    xmlns:android="http://schemas.android.com/apk/res/android"
+<eu.kanade.tachiyomi.ui.library.LibraryCategoryView xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
 
     <androidx.swiperefreshlayout.widget.SwipeRefreshLayout
         android:id="@+id/swipe_refresh"
         android:layout_width="match_parent"
-        android:layout_height="match_parent">
+        android:layout_height="match_parent"
+        >
 
     </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
-
+    <eu.davidea.fastscroller.FastScroller
+        android:id="@+id/fast_scroller"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:layout_gravity="end"
+        app:fastScrollerBubbleEnabled="true"
+        tools:visibility="visible" />
 </eu.kanade.tachiyomi.ui.library.LibraryCategoryView>

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

@@ -1,7 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
+    xmlns:tools="http://schemas.android.com/tools"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
 
     <androidx.viewpager.widget.ViewPager
         android:layout_width="match_parent"
@@ -14,5 +16,4 @@
         android:layout_width="wrap_content"
         android:layout_gravity="center"
         android:layout_height="wrap_content"/>
-
 </FrameLayout>