那些年我踩的坑——Unity编辑器SerializedProperty.enumValueIndex

Posted 2021-10-06 RaymondCL

这个是我自己的坑，自己挖的坑，然后自己跳了下去

首先上结论，以后别再犯同样的错误：
SerializedProperty.enumValueIndex得到的是当前枚举值在所有值中的排序索引，不是枚举值！！！是enumValueIndex，是Index！！！不是enumValue！

错误的写法：

public enum EventType
{
    None = 0,
    Test = 2,
    Attack = 1,
    Test3 = 3,
    Damage = 4,
}

[System.Serializable]
public class ActionEvent
{
    public EventType eventType;
    public float atkValue;
    public float damageValue;
}

public class Actor : MonoBehaviour
{
    public ActionEvent actionEvent;
}

[CustomPropertyDrawer(typeof(ActionEvent), true)]
public class ActionEventDrawer : PropertyDrawer
{
    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
    {
        using (new EditorGUI.PropertyScope(position, label, property))
        {
            SerializedProperty eventType = property.FindPropertyRelative("eventType");
            EditorGUI.PropertyField(position, eventType);
            position.y += EditorGUIUtility.singleLineHeight;
            //把enumValueIndex当成枚举值就是最大的错误
            switch (eventType.enumValueIndex)  
            {
                case (int)EventType.Attack:
                    EditorGUI.PropertyField(position, property.FindPropertyRelative("atkValue"));
                    break;
                case (int)EventType.Damage:
                    EditorGUI.PropertyField(position, property.FindPropertyRelative("damageValue"));
                    break;
            }
        }
    }
}

由于我的枚举被我从中间，删除了几个，导致枚举值不连续，因此最开始我使用Popup绘制时，一直以为是使用SerializedProperty.enumNames导致的问题，因为这个names是连续的数组，是对不上枚举值的，所以一直在这里改，一直没有注意到enumValueIndex的问题。

正确写法：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;
using System;
[CustomPropertyDrawer(typeof(ActionEvent), true)]
public class ActionEventDrawer : PropertyDrawer
{
    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
    {
        using (new EditorGUI.PropertyScope(position, label, property))
        {
            SerializedProperty eventType = property.FindPropertyRelative("eventType");
            EditorGUI.PropertyField(position, eventType);
            position.y += EditorGUIUtility.singleLineHeight;
            var eventTypeValue = Enum.GetValues(typeof(EventType)).GetValue(eventType.enumValueIndex);
            switch (eventTypeValue)  
            {
                case EventType.Attack:
                    EditorGUI.PropertyField(position, property.FindPropertyRelative("atkValue"));
                    break;
                case EventType.Damage:
                    EditorGUI.PropertyField(position, property.FindPropertyRelative("damageValue"));
                    break;
            }
        }
    }
}

我们在调试的窗口中可以看到枚举的值数组列：

var values = Enum.GetValues(typeof(FPSPlayerActionEventType));