mapbox-sdk/Unity/Editor/AddMonoBehavioursModifierDrawer.cs

namespace Mapbox.Editor
{
	using Mapbox.Unity.MeshGeneration.Modifiers;
	using UnityEditor;
	using UnityEngine;

	[CustomPropertyDrawer(typeof(AddMonoBehavioursModifierType))]
	class AddMonoBehavioursModifierDrawer : PropertyDrawer
	{
		const int _offset = 40;
		MonoScript _monoscript;

		public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
		{
			EditorGUI.BeginProperty(position, label, property);

			position = EditorGUI.PrefixLabel(position, GUIUtility.GetControlID(FocusType.Passive), label);
			var scriptRect = new Rect(position.x, position.y, position.width, position.height - _offset);
			var helpRect = new Rect(position.x, position.y + _offset / 2, position.width, _offset);
			var typeStringProperty = property.FindPropertyRelative("_typeString");
			var monoscriptProperty = property.FindPropertyRelative("_script");

			EditorGUI.BeginChangeCheck();

			_monoscript = monoscriptProperty.objectReferenceValue as MonoScript;
			_monoscript = EditorGUI.ObjectField(scriptRect, _monoscript, typeof(MonoScript), false) as MonoScript;

			if (EditorGUI.EndChangeCheck())
			{
				var type = _monoscript.GetClass();
				if (type != null && type.IsSubclassOf(typeof(MonoBehaviour)))
				{
					monoscriptProperty.objectReferenceValue = _monoscript;
					typeStringProperty.stringValue = _monoscript.GetClass().ToString();
				}
				else
				{
					monoscriptProperty.objectReferenceValue = null;
					typeStringProperty.stringValue = "";
				}
			}

			if (monoscriptProperty.objectReferenceValue == null)
			{
				EditorGUI.HelpBox(helpRect, "Selected object is not a MonoBehaviour!", MessageType.Error);
			}

			EditorGUI.EndProperty();
		}

		public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
		{
			return base.GetPropertyHeight(property, label) + _offset;
		}
	}
}