[Unity] UIScrollToSelection.cs

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
using UnityEngine.EventSystems;

public class UIScrollToSelection : MonoBehaviour {

//*** ATTRIBUTES ***//
    [Header("[ Settings ]")]
    [SerializeField]
    private float scrollSpeed = 10f;

//*** PROPERTIES ***//
    // REFERENCES
    protected RectTransform LayoutListGroup {
        get {return TargetScrollRect != null ? TargetScrollRect.content : null;}
    }

    // SETTINGS
    protected float ScrollSpeed {
        get {return scrollSpeed;}
    }

    // VARIABLES
    protected RectTransform TargetScrollObject {get; set;}
    protected RectTransform ScrollWindow {get; set;}
    protected ScrollRect TargetScrollRect {get; set;}

//*** METHODS - PUBLIC ***//


//*** METHODS - PROTECTED ***//
    protected virtual void Awake (){
        TargetScrollRect = GetComponent<ScrollRect>();
        ScrollWindow = TargetScrollRect.GetComponent<RectTransform>();
    }

    protected virtual void Start (){

    }

    protected virtual void Update (){
        ScrollRectToLevelSelection();
    }

//*** METHODS - PRIVATE ***//
    private void ScrollRectToLevelSelection (){
        // check main references
        bool referencesAreIncorrect = (TargetScrollRect == null || LayoutListGroup == null || ScrollWindow == null);

        if (referencesAreIncorrect == true){
            return;
        }

        // get calculation references
        EventSystem events = EventSystem.current;
        RectTransform selection =
            events.currentSelectedGameObject != null ?
            events.currentSelectedGameObject.GetComponent<RectTransform>() :
            null;

        // check if scrolling is possible
        if (selection == null ||
            selection.transform.parent != LayoutListGroup.transform)
        {
            return;
        }

        // move the current scroll rect to correct position
        float selectionPos = -selection.anchoredPosition.y;

        float elementHeight = LayoutListGroup.rect.height / LayoutListGroup.transform.childCount;
        float maskHeight = ScrollWindow.rect.height;
        float listPixelAnchor = LayoutListGroup.anchoredPosition.y;

        // get the element offset value depending on the cursor move direction
        float offlimitsValue = 0;

        if (selectionPos < listPixelAnchor){
            offlimitsValue = listPixelAnchor - selectionPos;
        } else if (selectionPos + elementHeight > listPixelAnchor + maskHeight){
            offlimitsValue = (listPixelAnchor + maskHeight) - (selectionPos + elementHeight);
        }

        // move the target scroll rect
        TargetScrollRect.verticalNormalizedPosition +=
            (offlimitsValue / LayoutListGroup.rect.height) * Time.deltaTime * scrollSpeed;

        // save last object we were "heading to" to prevent blocking
        TargetScrollObject = selection;
    }
}