How to provide custom descriptions for EditorGUI.EnumPopup?

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1

How can I specify custom descriptions for some enum values within a custom editor interface?

i.e.

public enum MyEnum {
   [Description("More detailed description for ABC")]
   ABC,
   [Description("More detailed description for DEF")]
   DEF,
}

1 Answer

1
2

Here is a custom control for editing enum fields where custom descriptions can be specified by decorating values with System.ComponentModel.DescriptionAttribute:

using UnityEngine;
using UnityEditor;

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;

public static class CustomGUI {
    // Cache of enum values.
    private static Dictionary<Type, int[]> s_EnumValueCache = new Dictionary<Type, int[]>();
    // Cache of enum descriptions/nicified values.
    private static Dictionary<Type, string[]> s_EnumDescriptionCache = new Dictionary<Type, string[]>();

    public static int[] GetEnumValues<T>() {
        if (!s_EnumValueCache.ContainsKey(typeof(T)))
            s_EnumValueCache[typeof(T)] = Enum.GetValues(typeof(T)).Cast<int>().ToArray();
        return s_EnumValueCache[typeof(T)];
    }

    public static string[] GetEnumDescriptions<T>() {
        if (!s_EnumDescriptionCache.ContainsKey(typeof(T))) {
            var list = new List<string>();
            foreach (var value in Enum.GetValues(typeof(T))) {
                var attribute = typeof(T).GetMember(value.ToString())[0].GetCustomAttributes(typeof(DescriptionAttribute), false).FirstOrDefault() as DescriptionAttribute;
                list.Add( attribute != null ? attribute.Description : ObjectNames.NicifyVariableName(value.ToString()) );
            }
            s_EnumDescriptionCache[typeof(T)] = list.ToArray();
        }
        return s_EnumDescriptionCache[typeof(T)];
    }

    public static int EnumPopup<T>(Rect position, int value) {
        var values = GetEnumValues<T>();
        int selectedIndex = EditorGUI.Popup(position, Array.IndexOf(values, value), GetEnumDescriptions<T>());
        return (selectedIndex >= 0 && selectedIndex < values.Length) ? values[selectedIndex] : value;
    }
}

Usage Example:

An enum can then be defined as follows:

using System.ComponentModel;

public enum MyEnum {
    [Description("More detailed description for ABC")]
    ABC,
    [Description("More detailed description for DEF")]
    DEF,
    LetUnityNicifyName,
}

Which can be presented within a custom GUI:

private MyEnum _selectedEnumValue = MyEnum.ABC;

private void OnGUI() {
    Rect position = GUILayoutUtility.GetRect(GUIContent.none, EditorStyles.popup);
    _selectedEnumValue = (MyEnum)CustomGUI.EnumPopup<MyEnum>(position, (int)_selectedEnumValue);
}