title: ScrollController animateTo()
body: <p>I want the selected item in the horizontal listView to be centered, so I first calculate the position that should animate to (scroll to), and it is always calculated correctly, but when I select an item that is far from the currently selected one, the list doesn't scroll correctly to the calculated position.</p>
  
  <p>Code:</p>
  
  <pre><code>double _position =  index * (_width + 2 * _horizontalPadding)
                      + (_selectedWidth+_horizontalPadding);
  _scrollController.animateTo(
                    _position,
                    duration: Duration(milliseconds: 1000),
                    curve: Curves.ease);
  </code></pre>
  
  <p>where _width is the width of all elements but the selected one, as its width is _selectedWidth , and horizontal padding is constant .. and index is the index of the selected item</p>