ScrollView .scrollTo not working? Saving ScrollView position on rotation

Question

Ok.. I must be overlooking something real simple here, but i think i\'m trying to do something fairly basic.. Simply retain the scrollbar position of a ScrollView on orienta

Answer 1

You should start scroll before components are drawn, since scroll does not work untill components are not created:

@Override
public void onWindowFocusChanged(boolean hasFocus) {
    scrollView.scrollTo(.... 

Answer 2

onRestoreInstanceState() is just to early to scroll the view. That's why posting new Runnable helps, but not always. Sometimes one even have to use postDelayed() to let it work. For Fragment one can use onViewCreated() instead :

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    sViewX = savedInstanceState.getInt("sViewX");   
    sViewY = savedInstanceState.getInt("sViewY");
    sView.scrollTo(sViewX, sViewY);
}

Answer 3

For MVVMCross:

protected override void OnSaveInstanceState(Bundle outState)
{
    base.OnSaveInstanceState(outState);

    ScrollView sv = FindViewById<ScrollView>(Resource.Id.dispatchScrollView);
    int posY = sv.ScrollY;

    outState.PutInt("scrollY", posY);
}

protected override void OnRestoreInstanceState(Bundle savedInstanceState)
{
    base.OnRestoreInstanceState(savedInstanceState);

    ScrollView sv = FindViewById<ScrollView>(Resource.Id.dispatchScrollView);
    int posY = savedInstanceState.GetInt("scrollY");

    sv.Post(new Runnable(new Action(() => sv.ScrollTo(0, posY))));
}

Answer 4

Instead of sending scroll action to next run-loop, you can scroll your view in global layout callback:

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    sView.getViewTreeObserver().addOnGlobalLayoutListener(
        new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                sView.scrollTo(sViewX, sViewY);
            }
        }
    );
}

Answer 5

I figured it out.

Since I'm using setText to TextViews in my onCreate, calling .scrollTo won't work.

So now I'm using the following:

sView.post(new Runnable() {
    @Override
    public void run() {
        sView.scrollTo(sViewX, sViewY);
    } 
});

Answer 6

This is working for me

@Override
protected void onSaveInstanceState(Bundle outState) {
    outState.putInt(SystemGlobal.SCROLL_Y, mRelativeLayoutMain.getTop());
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onRestoreInstanceState(savedInstanceState);
    mRelativeLayoutMain.scrollTo(0, savedInstanceState.getInt(SystemGlobal.SCROLL_Y));
}