EventTriggerListener

using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;
public class EventTriggerListener : UnityEngine.EventSystems.EventTrigger{
	public delegate void VoidDelegate (GameObject go);
	public delegate void VoidDelegateData (GameObject go, PointerEventData eventData);
	public VoidDelegate onClick;
	public VoidDelegate onDown;
	public VoidDelegate onEnter;
	public VoidDelegate onExit;
	public VoidDelegate onUp;
	public VoidDelegate onSelect;

	public VoidDelegateData onDrag;
	public VoidDelegate onBeginDrag;
	public VoidDelegate onEndDrag;

	public VoidDelegate onUpdateSelect;
	
	static public EventTriggerListener Get (GameObject go)
	{
		EventTriggerListener listener = go.GetComponent<EventTriggerListener>();
		if (listener == null) listener = go.AddComponent<EventTriggerListener>();
		return listener;
	}
	public override void OnPointerClick(PointerEventData eventData)
	{
		if(onClick != null) 	onClick(gameObject);
	}
	public override void OnPointerDown (PointerEventData eventData){
		if(onDown != null) onDown(gameObject);
	}
	public override void OnPointerEnter (PointerEventData eventData){
		if(onEnter != null) onEnter(gameObject);
	}
	public override void OnPointerExit (PointerEventData eventData){
		if(onExit != null) onExit(gameObject);
	}
	public override void OnPointerUp (PointerEventData eventData){
		if(onUp != null) onUp(gameObject);
	}
	public override void OnSelect (BaseEventData eventData){
		if(onSelect != null) onSelect(gameObject);
	}
	public override void OnUpdateSelected (BaseEventData eventData){
		if(onUpdateSelect != null) onUpdateSelect(gameObject);
	}

	public override void OnDrag (PointerEventData eventData){
		if(onDrag != null) onDrag(gameObject,eventData);
	}
	public override void OnBeginDrag (PointerEventData eventData){
		if(onBeginDrag != null) onBeginDrag(gameObject);
	}
	public override void OnEndDrag (PointerEventData eventData){
		if(onEndDrag != null) onEndDrag(gameObject);
	}
}

uGUIJoystick

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

public class uGUIJoystick : MonoBehaviour {
	private RectTransform m_JoystickControoler;
	private Vector3 startPos;
	public float joystickX;
	public float joystickY;
	private float clampPos;
	private float fixPos;
	// Use this for initialization
	void Start () {
		m_JoystickControoler = transform.Find("Controller").GetComponent<RectTransform>();
		startPos = m_JoystickControoler.position;

		clampPos = GetComponent<RectTransform>().sizeDelta.x/2;
		fixPos = 1/GetComponent<RectTransform>().sizeDelta.x*2;

		EventTriggerListener.Get(m_JoystickControoler.gameObject).onDrag = OnDrag;
		EventTriggerListener.Get(m_JoystickControoler.gameObject).onEndDrag = OnEndDrag;
	}
	
	// DragController
	public void OnDrag (GameObject go,PointerEventData eventData) {
		// Set ControllerPos by MousePos
		m_JoystickControoler.position = eventData.position;
		// Clamp ControllerPos(LocalPos)
		m_JoystickControoler.localPosition = Vector3.ClampMagnitude( m_JoystickControoler.localPosition, clampPos);
		joystickX = m_JoystickControoler.localPosition.x * fixPos;
		joystickY = m_JoystickControoler.localPosition.y * fixPos;
		//Debug.Log(eventData.pointerId);
	}
	// EndDragController
	public void OnEndDrag (GameObject go) {
		m_JoystickControoler.position = startPos;
		joystickX = 0;
		joystickY = 0;
	}
}