How to implement joystick?

Joystick will not implement and the game will pause everytime I try to move the joystick?

CODE:

using UnityEngine; using System.Collections;

using UnityEngine.EventSystems;

using UnityEngine.UI; using System;

public class VirtualJoystick : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler { public RectTransform thumb;

 private Vector2 originalPosition;
 private Vector2 originalThumbPosition;

 void Start()
 {
     originalPosition = this.GetComponent<RectTransform>().localPosition;
     originalThumbPosition = thumb.localPosition;

     thumb.gameObject.SetActive(false);

     delta = Vector2.zero;
 }
 public Vector2 delta;

 void OnBeginDrag(PointerEventData eventData)
 {
     thumb.gameObject.SetActive(true);

     Vector3 worldPoint = new Vector3();
     RectTransformUtility.ScreenPointToWorldPointInRectangle(
         this.transform as RectTransform,
         eventData.position,
         eventData.enterEventCamera,
         out worldPoint);

     this.GetComponent<RectTransform>().position = worldPoint;

     thumb.localPosition = originalThumbPosition;
 }
         void OnMouseDrag (PointerEventData eventData)
         {
             Vector3 worldPoint = new Vector3();
             RectTransformUtility.ScreenPointToWorldPointInRectangle(
                 this.transform as RectTransform,
                 eventData.position,
                 eventData.enterEventCamera,
                 out worldPoint);

             thumb.position = new Vector3();

             var size = GetComponent<RectTransform>().rect.size;

             delta = thumb.localPosition;

             delta.x /= size.x / 2.0f;
             delta.y /= size.y / 2.0f;

             delta.x = Mathf.Clamp(delta.x, -1.0f, 1.0f);
             delta.y = Mathf.Clamp(delta.y, -1.0f, 1.0f);

         }
         void OnEndDrag (PointerEventData eventData)
         {
             this.GetComponent<RectTransform>().localPosition = originalPosition;

             delta = Vector2.zero;

             thumb.gameObject.SetActive(false);
         }


 public void OnDrag(PointerEventData eventData)
 {
     throw new NotImplementedException();
 }

 void IEndDragHandler.OnEndDrag(PointerEventData eventData)
 {
     throw new NotImplementedException();
 }

 void IBeginDragHandler.OnBeginDrag(PointerEventData eventData)
 {
     throw new NotImplementedException();
 }

}