CrowdControl/Assets/Feel/MMTools/Editor/MMAttributes/MMConditionAttributeDrawer.cs

using UnityEngine;
using UnityEngine.UI;
using System.Collections;
using System;
#if UNITY_EDITOR
using UnityEditor;
#endif

namespace MoreMountains.Tools
{
	// original implementation by http://www.brechtos.com/hiding-or-disabling-inspector-properties-using-propertydrawers-within-unity-5/
	[CustomPropertyDrawer(typeof(MMConditionAttribute))]
	public class MMConditionAttributeDrawer : PropertyDrawer
	{
		#if  UNITY_EDITOR
		public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
		{
			MMConditionAttribute conditionAttribute = (MMConditionAttribute)attribute;
			bool enabled = GetConditionAttributeResult(conditionAttribute, property);
			bool previouslyEnabled = GUI.enabled;
			bool shouldDisplay = ShouldDisplay(conditionAttribute, enabled);
			if (shouldDisplay)
			{
				GUI.enabled = enabled;
				EditorGUI.PropertyField(position, property, label, true);
				GUI.enabled = previouslyEnabled;
			}
		}
		#endif
        
		private bool GetConditionAttributeResult(MMConditionAttribute conditionAttribute, SerializedProperty property)
		{
			bool enabled = true;
			string propertyPath = property.propertyPath; 
			string conditionPath = propertyPath.Replace(property.name, conditionAttribute.ConditionBoolean); 
			SerializedProperty sourcePropertyValue = property.serializedObject.FindProperty(conditionPath);

			if (sourcePropertyValue != null)
			{
				enabled = sourcePropertyValue.boolValue;
			}
			else
			{
				Debug.LogWarning("No matching boolean found for ConditionAttribute in object: " + conditionAttribute.ConditionBoolean);
			}
			if (conditionAttribute.Negative)
			{
				enabled = !enabled;
			}
			return enabled;
		}

		private bool ShouldDisplay(MMConditionAttribute conditionAttribute, bool result)
		{
			bool shouldDisplay = !conditionAttribute.Hidden || result;
			return shouldDisplay;
		}

		public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
		{
			MMConditionAttribute conditionAttribute = (MMConditionAttribute)attribute;
			bool enabled = GetConditionAttributeResult(conditionAttribute, property);

			bool shouldDisplay = ShouldDisplay(conditionAttribute, enabled);
			if (shouldDisplay)
			{
				return EditorGUI.GetPropertyHeight(property, label);
			}
			else
			{
				return -EditorGUIUtility.standardVerticalSpacing;
			}
		}
	}
}