FastScroll

A ListView-like FastScroller for Androids RecyclerView.

FastScroll brings the popular fast scrolling and section indexing features of Androids ListView to the RecyclerView with a Lollipop styled scrollbar and section bubble view. The scrollbar provides a handle for quickly navigating a list while the bubble view displays the currently visible section index.

FastScroll was inspired by this Styling Android blog post.

Download

Gradle:

dependencies {
    implementation "io.github.l4digital:fastscroll:2.1.0"
}

Maven:

<dependency>
  <groupId>io.github.l4digital</groupId>
  <artifactId>fastscroll</artifactId>
  <version>2.1.0</version>
</dependency>

Usage

There are a few ways to implement the FastScroll library:

• The FastScrollRecyclerView is a RecyclerView that creates and adds the FastScroller to its parent ViewGroup.

• The FastScrollView is a layout that creates and manages a RecyclerView with a FastScroller. FastScrollView is particularly useful when the parent ViewGroup requires a single child view, for example a SwipeRefreshLayout.

FastScrollRecyclerView:

Add the FastScrollRecyclerView to your xml layout and set your customizations using attributes.

The parent ViewGroup must be a ConstraintLayout, CoordinatorLayout, FrameLayout, or RelativeLayout in order for the FastScroller to be properly displayed on top of the RecyclerView.

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.l4digital.fastscroll.FastScrollRecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:bubbleColor="#00bb00"
        app:bubbleTextColor="#ffffff"
        app:handleColor="#999999" />

</FrameLayout>

FastScrollRecyclerView extends Android's RecyclerView and can be setup the same way.

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_example)

    findViewById<FastScrollRecyclerView>(R.id.recycler_view).apply {
        layoutManager = LinearLayoutManager(context)
        adapter = ExampleAdapter()
    }
}

Implement the FastScroller.SectionIndexer interface in your RecyclerView Adapter and override getSectionText().

class ExampleAdapter : RecyclerView.Adapter<ExampleAdapter.ViewHolder>(), FastScroller.SectionIndexer {

    // ...

    override fun getSectionText(position: Int) = getItem(position).getSectionIndex()
}

FastScrollView:

Add the FastScrollView to your xml layout and set your customizations using attributes.

<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.l4digital.fastscroll.FastScrollView
        android:id="@+id/fastscroll_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:bubbleColor="#00bb00"
        app:bubbleTextColor="#ffffff"
        app:handleColor="#999999" />

</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>

FastScrollView contains a RecyclerView and a FastScroller that can be accessed with public methods.

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_example)

    findViewById<FastScrollView>(R.id.fastscroll_view).apply {
        setLayoutManager(LinearLayoutManager(context))
        setAdapter(ExampleAdapter())
    }
}

Implement the FastScroller.SectionIndexer interface in your RecyclerView Adapter and override getSectionText().

class ExampleAdapter : RecyclerView.Adapter<ExampleAdapter.ViewHolder>(), FastScroller.SectionIndexer {

    // ...

    override fun getSectionText(position: Int) = getItem(position).getSectionIndex()
}

Alternative Usage:

If you are unable to use the FastScrollRecyclerView or FastScrollView, you can add a FastScroller to your layout and implement with any RecyclerView. See this github issue for an example.

FastScrollListener:

An optional FastScrollListener can be added to receive events when fast scrolling starts or stops.

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_example)

    findViewById<FastScrollRecyclerView>(R.id.recycler_view).apply {
        setFastScrollListener(object : FastScroller.FastScrollListener {
            override fun onFastScrollStart(fastScroller: FastScroller) {
                // fast scroll started
            }

            override fun onFastScrollStop(fastScroller: FastScroller) {
                // fast scroll stopped
            }
        })
    }
}

Customization

The following attributes can be set to customize the visibility and appearance of the elements within the FastScroller view:

• app:hideScrollbar=["true" | "false"] Hides the scrollbar when not scrolling
• app:showBubble=["true" | "false"] Shows the section bubble while fast scrolling
• app:showBubbleAlways=["true" | "false"] Shows the section bubble while scrolling
• app:showTrack=["true" | "false"] Shows the scroll track while scrolling
• app:handleColor=["#rrggbb" | "@color"] Sets the color of the scroll handle
• app:trackColor=["#rrggbb" | "@color"] Sets the color of the scroll track
• app:bubbleColor=["#rrggbb" | "@color"] Sets the background color of the section bubble
• app:bubbleSize=["normal" | "small"] Sets the size of the section bubble
• app:bubbleTextColor=["#rrggbb" | "@color"] Sets the text color of the section bubble
• app:bubbleTextSize=["sp" | "@dimen"] Sets the scaled pixel text size of the section bubble

License

Copyright 2022 Randy Webster. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.