sked/Assets/Script/Common/Editor/OnlyReadDrawer.cs

using UnityEditor;
using UnityEngine;

[CustomPropertyDrawer(typeof(OnlyReadAttribute))]
public class OnlyReadDrawer : PropertyDrawer
{
    public override void OnGUI(Rect position, SerializedProperty prop, GUIContent label)
    {
        string valueStr;

        switch (prop.propertyType)
        {
            case SerializedPropertyType.Integer:
                valueStr = $"{prop.intValue}";
                break;
            case SerializedPropertyType.Boolean:
                valueStr = $"{prop.boolValue}";
                break;
            case SerializedPropertyType.Float:
                valueStr = $"{prop.floatValue}";
                break;
            case SerializedPropertyType.String:
                valueStr = $"{prop.stringValue}";
                break;
            case SerializedPropertyType.Enum:
                valueStr = $"{prop.enumNames[prop.enumValueIndex]}";
                break;
            case SerializedPropertyType.Vector2:
                valueStr = $"{prop.vector2Value}";
                break;
            default:
                valueStr = "(not supported)";
                break;
        }

        EditorGUI.LabelField(position, label.text, valueStr);
    }
}