So after being reached out too, I decided to create a fleshed out and optimized solution for this.
Draws in Lists and Arrays
Optimized, doesn’t use GUILayout
Customizable Spacing on the Inside and Outside of the border
Allows Nesting (but not nesting of parent objects, causes stack overflow)
Thanks to @laurentlavigne I had an idea to put backgrounds in the property drawer that layer on top of each other to clearly show children. This works brilliantly and I created 3 themes that you can change easily using an enum, HelpBox, Darken, Lighten and None.
To use it, put the ExpandableAttribute on a field that you want to be expandable:
[ExpandableAttribute]
public ScriptableObject child;
or:
[Expandable]
public ScriptableObject child;
And it will now appear as an expandable field. This also works on MonoBehaviour references, as you can see below I am referencing the Main Camera and I am getting all of the camera fields below.
The code for this solution is shown below. I will also be uploading this to the Asset Store at some point so Redistribute Privately so that I can fix the bugs. The Asset Store will allow me to publish updates to fix “self-nesting” issues, as there are currently issues with StackOverflowExceptions.
using System;
using UnityEngine;
#if UNITY_EDITOR
using System.Collections.Generic;
using UnityEditor;
#endif
/// <summary>
/// Use this property on a ScriptableObject type to allow the editors drawing the field to draw an expandable
/// area that allows for changing the values on the object without having to change editor.
/// </summary>
public class ExpandableAttribute : PropertyAttribute
{
public ExpandableAttribute ()
{
}
}
#if UNITY_EDITOR
/// <summary>
/// Draws the property field for any field marked with ExpandableAttribute.
/// </summary>
[CustomPropertyDrawer (typeof (ExpandableAttribute), true)]
public class ExpandableAttributeDrawer : PropertyDrawer
{
// Use the following area to change the style of the expandable ScriptableObject drawers;
#region Style Setup
private enum BackgroundStyles
{
None,
HelpBox,
Darken,
Lighten
}
/// <summary>
/// Whether the default editor Script field should be shown.
/// </summary>
private static bool SHOW_SCRIPT_FIELD = false;
/// <summary>
/// The spacing on the inside of the background rect.
/// </summary>
private static float INNER_SPACING = 6.0f;
/// <summary>
/// The spacing on the outside of the background rect.
/// </summary>
private static float OUTER_SPACING = 4.0f;
/// <summary>
/// The style the background uses.
/// </summary>
private static BackgroundStyles BACKGROUND_STYLE = BackgroundStyles.HelpBox;
/// <summary>
/// The colour that is used to darken the background.
/// </summary>
private static Color DARKEN_COLOUR = new Color (0.0f, 0.0f, 0.0f, 0.2f);
/// <summary>
/// The colour that is used to lighten the background.
/// </summary>
private static Color LIGHTEN_COLOUR = new Color (1.0f, 1.0f, 1.0f, 0.2f);
#endregion
/// <summary>
/// Cached editor reference.
/// </summary>
private Editor editor = null;
public override float GetPropertyHeight (SerializedProperty property, GUIContent label)
{
float totalHeight = 0.0f;
totalHeight += EditorGUIUtility.singleLineHeight;
if (property.objectReferenceValue == null)
return totalHeight;
if (!property.isExpanded)
return totalHeight;
if (editor == null)
Editor.CreateCachedEditor (property.objectReferenceValue, null, ref editor);
if (editor == null)
return totalHeight;
SerializedProperty field = editor.serializedObject.GetIterator ();
field.NextVisible (true);
if (SHOW_SCRIPT_FIELD)
{
totalHeight += EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;
}
while (field.NextVisible (true))
{
totalHeight += EditorGUI.GetPropertyHeight (field, true) + EditorGUIUtility.standardVerticalSpacing;
}
totalHeight += INNER_SPACING * 2;
totalHeight += OUTER_SPACING * 2;
return totalHeight;
}
public override void OnGUI (Rect position, SerializedProperty property, GUIContent label)
{
Rect fieldRect = new Rect (position);
fieldRect.height = EditorGUIUtility.singleLineHeight;
EditorGUI.PropertyField (fieldRect, property, label, true);
if (property.objectReferenceValue == null)
{
Debug.Log ("It's secretly null");
return;
}
property.isExpanded = EditorGUI.Foldout (fieldRect, property.isExpanded, GUIContent.none, true);
if (!property.isExpanded)
return;
if (editor == null)
Editor.CreateCachedEditor (property.objectReferenceValue, null, ref editor);
if (editor == null)
{
Debug.Log ("Couldn't fetch editor");
return;
}
#region Format Field Rects
List<Rect> propertyRects = new List<Rect> ();
Rect marchingRect = new Rect (fieldRect);
Rect bodyRect = new Rect (fieldRect);
bodyRect.xMin += EditorGUI.indentLevel * 18;
bodyRect.yMin += EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing
+ OUTER_SPACING;
SerializedProperty field = editor.serializedObject.GetIterator ();
field.NextVisible (true);
marchingRect.y += INNER_SPACING + OUTER_SPACING;
if (SHOW_SCRIPT_FIELD)
{
propertyRects.Add (marchingRect);
marchingRect.y += EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;
}
while (field.NextVisible (true))
{
marchingRect.y += marchingRect.height + EditorGUIUtility.standardVerticalSpacing;
marchingRect.height = EditorGUI.GetPropertyHeight (field, true);
propertyRects.Add (marchingRect);
}
marchingRect.y += INNER_SPACING;
bodyRect.yMax = marchingRect.yMax;
#endregion
DrawBackground (bodyRect);
#region Draw Fields
EditorGUI.indentLevel++;
int index = 0;
field = editor.serializedObject.GetIterator ();
field.NextVisible (true);
if (SHOW_SCRIPT_FIELD)
{
//Show the disabled script field
EditorGUI.BeginDisabledGroup (true);
EditorGUI.PropertyField (propertyRects[index], field, true);
EditorGUI.EndDisabledGroup ();
index++;
}
//Replacement for "editor.OnInspectorGUI ();" so we have more control on how we draw the editor
while (field.NextVisible (true))
{
try
{
EditorGUI.PropertyField (propertyRects[index], field, true);
}
catch (StackOverflowException)
{
field.objectReferenceValue = null;
Debug.LogError ("Detected self-nesting cauisng a StackOverflowException, avoid using the same " +
"object iside a nested structure.");
}
index++;
}
EditorGUI.indentLevel--;
#endregion
}
/// <summary>
/// Draws the Background
/// </summary>
/// <param name="rect">The Rect where the background is drawn.</param>
private void DrawBackground (Rect rect)
{
switch (BACKGROUND_STYLE) {
case BackgroundStyles.HelpBox:
EditorGUI.HelpBox (rect, "", MessageType.None);
break;
case BackgroundStyles.Darken:
EditorGUI.DrawRect (rect, DARKEN_COLOUR);
break;
case BackgroundStyles.Lighten:
EditorGUI.DrawRect (rect, LIGHTEN_COLOUR);
break;
}
}
}
/// <summary>
/// Required for the fetching of a default editor on MonoBehaviour objects.
/// </summary>
[CanEditMultipleObjects]
[CustomEditor(typeof(MonoBehaviour), true)]
public class MonoBehaviourEditor : Editor { }
/// <summary>
/// Required for the fetching of a default editor on ScriptableObject objects.
/// </summary>
[CanEditMultipleObjects]
[CustomEditor(typeof(ScriptableObject), true)]
public class ScriptableObjectEditor : Editor { }
#endif
