Animation in Viewpager tab change fadein / fadeout as like Linkedin introduction screen

Question

I want to implement same kind of animation such as linked in does in android application for its Introduction(Login / register) screen.

I am using view pager for In

Answer 1

This is a lag free one and also handles the Buttons

Main Idea:

1) first create transparent background for your fragments.

2) Create LayerDrawable and add background image of each fragment as an item. Then add your LayerDrawable as a background of your viewpager.

3) in onCreate method set alpha of each layer correctly so just upper one has alpha value of 255.

4) set for each view of your FragmentStatPagerAdapter a tag that corresponds to drawable index that you declared in the LayerDrawable. for example when you open the app FragmentA is showing so its tag must correspond to upper drawable that is 2 (beginning from 0). last page tag must be 0 corresponds to lowest drawable.

5) change drawable of each view at the function transformPage

6) for adding the button use RelativeLayout. In order to place buttons on top of all views use RelativeLayout. Later children are placing higher on the Z axis. You can see it in the code:

now lets see code:

MainActivity

public class MainActivity extends FragmentActivity {

    ViewPager viewPager=null;
    int numberOfViewPagerChildren = 3;
    int lastIndexOfViewPagerChildren = numberOfViewPagerChildren - 1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewPager = (ViewPager) findViewById(R.id.pager);
        viewPager.setAdapter(new MyAdapter(getSupportFragmentManager()));

        final LayerDrawable background = (LayerDrawable) viewPager.getBackground();

        background.getDrawable(0).setAlpha(0); // this is the lowest drawable
        background.getDrawable(1).setAlpha(0);
        background.getDrawable(2).setAlpha(255); // this is the upper one 

        viewPager.setPageTransformer(true, new ViewPager.PageTransformer() {
            @Override
            public void transformPage(View view, float position) {

                int index = (Integer) view.getTag();
                Drawable currentDrawableInLayerDrawable;
                currentDrawableInLayerDrawable = background.getDrawable(index);

                if(position <= -1 || position >= 1) {
                    currentDrawableInLayerDrawable.setAlpha(0);
                } else if( position == 0 ) {
                    currentDrawableInLayerDrawable.setAlpha(255);
                } else { 
                    currentDrawableInLayerDrawable.setAlpha((int)(255 - Math.abs(position*255)));
                }

            }
        });


        }
    class MyAdapter extends FragmentStatePagerAdapter
    {

        public MyAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int i) {
            Fragment fragment=null;
            if(i==0)
            {
                fragment=new FragmentA();
            }
            if(i==1)
            {
                fragment=new FragmentB();
            }
            if(i==2)
            {
                fragment=new FragmentC();
            }
            return fragment;
        }

        @Override
        public int getCount() {
            return numberOfViewPagerChildren;
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {
            if(object instanceof FragmentA){
                view.setTag(2);
            }
            if(object instanceof FragmentB){
                view.setTag(1);
            }
            if(object instanceof FragmentC){
                view.setTag(0);
            }
            return super.isViewFromObject(view, object);
        }        
    }

}

activity_main.xml

LayerDrawable

for lazy people who just do not want to declare fragments:

FragmentA

public class FragmentA extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_a,container,false);

        return v;
    }
}

fragment_a.xml