Unity uGUI ボタンを自作 & 拡張する

ButtonExtension.cs

using UnityEngine;
using UnityEngine.UI;
using UnityEngine.Events;
using UnityEngine.EventSystems;

[RequireComponent(typeof(Image))]
public class ButtonExtension : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IPointerEnterHandler, IPointerExitHandler
{
    [Header("押した瞬間")]
    public UnityEvent eventDown;
    [Header("離した瞬間")]
    public UnityEvent eventUp;
    [Header("押されている状態で入った瞬間")]
    public UnityEvent eventEnter;
    [Header("押されている状態で離れた瞬間")]
    public UnityEvent eventExit;


    bool isPush = false;
    bool isEnter = false;
    Image image;

    void Start()
    {
        #region test
        image = GetComponent<Image>();

        eventDown.AddListener(() => image.color = new Color(1f, 0f, 0f));
        eventUp.AddListener(() => image.color = new Color(1f, 1f, 1f));
        eventEnter.AddListener(() => image.color = new Color(1f, 0f, 0f));
        eventExit.AddListener(() => image.color = new Color(1f, 1f, 1f));
        #endregion
    }

    void OnEnable()
    {
        isPush = false;
        isEnter = false;
    }

    #region event
    public void OnPointerDown(PointerEventData eventData)
    {
        isPush = true;

        if (eventDown != null) eventDown.Invoke();
    }
    public void OnPointerUp(PointerEventData eventData)
    {
        isPush = false;
        if (!isEnter) return;  // オブジェクト内のみ有効

        if (eventUp != null) eventUp.Invoke();
    }
    public void OnPointerEnter(PointerEventData eventData)
    {
        isEnter = true;
        if (!isPush) return;

        if (eventEnter != null) eventEnter.Invoke();
    }
    public void OnPointerExit(PointerEventData eventData)
    {
        isEnter = false;
        if (!isPush) return;

        if (eventExit != null) eventExit.Invoke();
    }
    #endregion
}