A ViewPager and PagerAdapter combination that support auto scroll

LoopingViewPager

A ViewPager and PagerAdapter combination that support auto scroll, infinite loop and page indicators.

A ViewPager and a PagerAdapter that can:

AutoScroll (On/Off able)
Infinite Loop (On/Off able)
ViewPager's height can be wrap_content / an aspect ratio
Adjustable auto scroll interval
Won't scroll nor loop if there is only 1 item
Works well with notifyDataSetChanged()
Supports page indicators
Supports different view types

Demo Effect

Why this library

Although there are already quite a number of similar libraries out there,
I cannot find one that fits all of the below requirements:

Sufficient documentation
Last updated in less than 3 years
Good infinite looping effect
Configurable auto-scroll
ViewPager that supports fixed aspect ratio (Or wrap_content)
Good support with Page Indicators

Especially for 6, even some of them supports, they provide built-in indicators only; or does not tell user how to implement their own indicator.
I wrote this library to tackle all of these problems I faced after trying a whole day with other libraries.

Usage

Add to Project

First make sure jcenter() is included as a repository in your project's build.gradle:

allprojects {
    repositories {
        jcenter()
    }
}

And then add the below to your app's build.gradle:

    implementation 'com.asksira.android:loopingviewpager:1.1.2'

Step 1: Create LoopingViewPager in XML

    <com.asksira.loopingviewpager.LoopingViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:isInfinite="true"
        app:autoScroll="true"
        app:scrollInterval="5000"
        app:viewpagerAspectRatio="1.33"/>

Attribute Name	Default	Allowed Values
isInfinite	false	true / false
autoScroll	false	true / false
viewpagerAspectRatio	0	any float (width / height)
wrap_content	true	true / false
scrollInterval	5000	any integer (represents ms)

viewpagerAspectRatio 0 means does not apply aspectRatio.
That means, default LoopingViewPager has no aspect ratio and wrap_content is true.
Once aspect ratio is set, wrap_content will be overrided (meaningless).

In most cases, you should set an aspect ratio.

If you wonder why you need to set app:wrap_content="true", take a look at this Stackoverflow post.

Step 2: Create your PagerAdapter that extends LoopingPagerAdapter

You should

Specify the data type in the generic (<DataType>)
Create your own constructor according to this DataType
override inflateView() and bindView()

public class DemoInfiniteAdapter extends LoopingPagerAdapter<Integer> {

    public DemoInfiniteAdapter(Context context, ArrayList<Integer> itemList, boolean isInfinite) {
        super(context, itemList, isInfinite);
    }

    //This method will be triggered if the item View has not been inflated before.
    @Override
    protected View inflateView(int viewType, ViewGroup container, int listPosition) {
        return LayoutInflater.from(context).inflate(R.layout.item_pager, container, false);
    }

    //Bind your data with your item View here.
    //Below is just an example in the demo app.
    //You can assume convertView will not be null here.
    //You may also consider using a ViewHolder pattern.
    @Override
    protected void bindView(View convertView, int listPosition, int viewType) {
        convertView.findViewById(R.id.image).setBackgroundColor(context.getResources().getColor(getBackgroundColor(listPosition)));
        TextView description = convertView.findViewById(R.id.description);
        description.setText(String.valueOf(itemList.get(listPosition)));
    }
}

Step 3: Bind LoopingViewPager with your Adapter

        adapter = new DemoInfiniteAdapter(context, dataItems, true);
        viewPager.setAdapter(adapter);

Step 4: Resume and Pause autoScroll in your Activity (If you need autoScroll)

    @Override
    protected void onResume() {
        super.onResume();
        viewPager.resumeAutoScroll();
    }

    @Override
    protected void onPause() {
        viewPager.pauseAutoScroll();
        super.onPause();
    }

Handling dataSet change

If you have new data to update to your adapter, simply call:

adapter.setItemList(newItemList);
viewPager.reset(); //In order to reset the current page position

How do I implement different View types?

Simple! Override one more method in your Adapter:

    @Override
    protected int getItemViewType(int listPosition) {
        //Return your own view type, same as what you did when using RecyclerView
    }

And then, of course, according to the viewtype parameter passed to you in inflateView() and bindView(), differentiate what you need to inflate or bind.

You may also refer to the demo app for a complete example.

How do I integrate a Page Indicator?

I don't provide a built-in page indicator because:

ViewPager and Indicator are logically separated
I want to make this library adaptable to all page indicators

With that said, I personally suggest using this PageIndicatorView.
I create this demo and tested using this library.

Principle

There are 2 callbacks in LoopingViewPager that are designed to tell a PageIndicator 2 things:

I am now being scrolled to a new page, please update your indicator transition position;
I am now being selected to a new page, please update your indicator selected position.

And a public method getIndicatorCount() that can tell the indicator how many indicators(dots) should it show.

Example

And here is an example using PageIndicatorView:

        //Do not bind IndicatorView directly with ViewPager.
        //Below is how we achieve the effect by binding manually.

        //Tell the IndicatorView that how many indicators should it display:
        indicatorView.setCount(viewPager.getIndicatorCount());

        //Set IndicatorPageChangeListener on LoopingViewPager.
        //When the methods are called, update the Indicator accordingly.
        viewPager.setIndicatorPageChangeListener(new LoopingViewPager.IndicatorPageChangeListener() {
            @Override
            public void onIndicatorProgress(int selectingPosition, float progress) {
            }

            @Override
            public void onIndicatorPageChange(int newIndicatorPosition) {
                indicatorView.setSelection(newIndicatorPosition);
            }
        });

Don't forget to update the indicator counts if you updated items in adapter:

indicatorView.setCount(viewPager.getIndicatorCount());

By implementing this way, you can basically use any indicators you like, as long as that indicator allows you to configure programmatically (1) The number of indicators; (2) Which indicator is selected. And even, if it supports, (3) The progress of indicator transition effect.

Advanced: Interactive Indicator Animation

You may have already noticed, there is an interactive effect - where the indicator position follows the swipe action of user, as shown in the second GIF in the demo section.

If you want to do this, use the below instead:

        viewPager.setIndicatorPageChangeListener(new LoopingViewPager.IndicatorPageChangeListener() {
            @Override
            public void onIndicatorProgress(int selectingPosition, float progress) {
                indicatorView.setProgress(selectingPosition, progress);
            }

            @Override
            public void onIndicatorPageChange(int newIndicatorPosition) {
            }
        });

In my demo, I am using the PageIndicatorView.
This PageIndicatorView expects you to handle the indicator progress solely by yourself, i.e. The indicator will not finish its animation if you call setSelection() on it.
e.g. I scrolled to 50% from page 1 to page 2. Then I released by finger. PageIndicatorView expects you to continue calling setProgress() from 0.5, 0.6, all the way to 0.99, 1.0; instead of calling setCurrentItem() the moment you released your finger.
I call this type of indicator non-smart. Default handling of LoopingViewPager treats indicator as non-smart.

If you have another IndicatorView which is smart (i.e. It will finish the animation by itself if you call setSelection() the moment user released his finger), do the following:

        viewPager.setIndicatorSmart(true);

By setting this, LoopingViewPager will call onIndicatorProgress() only when user is dragging, but not after he released his finger.
Therefore you should call indicatorView.setSelection(newIndicatorPosition) in onIndicatorPageChange().

However, I have to warn you that, up to the current release, the effect of onIndicatorProgress() is still imperfect on non-smart indicators.
As far as I can find out, I noticed the below problems:

If user swipes very fastly, i.e. before ViewPager reaches SCROLL_STATE_IDLE, directly from SCROLL_STATE_SETTLING to SCROLL_STATE_DRAGGING, the indicator will not move until user released his finger again. This is not obvious unless user is attempting to test this indicator effect.
If user skip pages very fastly, e.g. from page 1 to page 6 and then to page 3 quickly, the indicator may appears in a wrong position for a short moment.

if you cannot accept these minor defects, I suggest you use onIndicatorPageChange() only.