Unity3d property drawer for automatically making enums flags into mask fields in the inspector.

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Unity3d property drawer for automatically making enums flags into mask fields in the inspector.

Usage: Put the .cs files somewhere in your project. When you have an enum field you want to turn into a mask field in the inspector, add the EnumFlag attribute over the field. Eg:

[EnumFlag]
MyCustomEnum thisEnum;
// This lets you give the field a custom name in the inspector.
[EnumFlag("Custom Inspector Name")]
MyCustomEnum anotherEnum;

EnumFlagAttribute.cs

using UnityEngine;

public class EnumFlagAttribute : PropertyAttribute
{
	public string enumName;

	public EnumFlagAttribute() {}

	public EnumFlagAttribute(string name)
	{
		enumName = name;
	}
}

EnumFlagDrawer.cs

using System;
using System.Reflection;
using UnityEditor;
using UnityEngine;

[CustomPropertyDrawer(typeof(EnumFlagAttribute))]
public class EnumFlagDrawer : PropertyDrawer {
	public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
	{
		EnumFlagAttribute flagSettings = (EnumFlagAttribute)attribute;
		Enum targetEnum = GetBaseProperty<Enum>(property);

		string propName = flagSettings.enumName;
		if (string.IsNullOrEmpty(propName))
			propName = property.name;

		EditorGUI.BeginProperty(position, label, property);
		Enum enumNew = EditorGUI.EnumMaskField(position, propName, targetEnum);
		property.intValue = (int) Convert.ChangeType(enumNew, targetEnum.GetType());
		EditorGUI.EndProperty();
	}

	static T GetBaseProperty<T>(SerializedProperty prop)
	{
		// Separate the steps it takes to get to this property
		string[] separatedPaths = prop.propertyPath.Split('.');
		
		// Go down to the root of this serialized property
		System.Object reflectionTarget = prop.serializedObject.targetObject as object;
		// Walk down the path to get the target object
		foreach (var path in separatedPaths)
		{
			FieldInfo fieldInfo = reflectionTarget.GetType().GetField(path);
			reflectionTarget = fieldInfo.GetValue(reflectionTarget);
		}
		return (T) reflectionTarget;
	}
}

i would use the label if no propName is set:

public override void OnGUI (Rect position, SerializedProperty property, GUIContent label)
{
    EnumFlagAttribute flagSettings = (EnumFlagAttribute)attribute;
    Enum targetEnum = GetBaseProperty<Enum> (property);
    EditorGUI.BeginProperty (position, label, property);
    Enum enumNew;
    string propName = flagSettings.enumName;
    if (string.IsNullOrEmpty (propName)) {
        enumNew = EditorGUI.EnumMaskField (position, label, targetEnum);
    } else {
        enumNew = EditorGUI.EnumMaskField (position, propName, targetEnum); 
    }
    property.intValue = (int)Convert.ChangeType (enumNew, targetEnum.GetType ());
    EditorGUI.EndProperty ();
}

Hey man, thank you so much for providing this snippet. I managed to make it shown in inspector even if the attribute is private or protected. I just had to change this line:

FieldInfo fieldInfo = reflectionTarget.GetType().GetField(path);

To this:

FieldInfo fieldInfo = reflectionTarget.GetType().GetField(path, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);

// This is how it looks
[SerializeField, EnumFlag]
private Axis _axis;

[SerializeField, EnumFlag]
protected Axis _axis;

When the propertyPath contains an array it breaks for me,
my enum property is contained in a serializable class named Route
my monobehaviour has a List which breaks this method.

Fixed it in my fork

It definitely breaks when multiple objects are selected. This would overwrite the values :(

Found a workaround for your problem nicekei:

                EditorGUI.BeginChangeCheck(); //new line
		EditorGUI.BeginProperty(position, label, property);
		Enum enumNew = EditorGUI.EnumMaskField(position, propName, targetEnum);
                if (!property.hasMultipleDifferentValues || EditorGUI.EndChangeCheck()) //new line
		             property.intValue = (int) Convert.ChangeType(enumNew, targetEnum.GetType());
		EditorGUI.EndProperty();

Forked it

You don't neeed this in modern Unity if you use the '[System.Flags]` attribute as Unity will use a mask field for any enum serialized with this attribute.