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November 14, 2022 18:03
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A relative simple way to get the instance object from a custom property drawer that draws a serialized class inside a component
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using UnityEngine; | |
using System.Collections; | |
public class Example : MonoBehaviour | |
{ | |
public ExampleClass example; | |
void Start() {} | |
void Update() {} | |
} |
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using UnityEngine; | |
using System; | |
[Serializable] | |
public class ExampleClass | |
{ | |
public string field = "example string"; | |
public void Print() | |
{ | |
Debug.Log("ExampleClass.field: " + field); | |
} | |
} |
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using UnityEngine; | |
using UnityEditor; | |
[CustomPropertyDrawer (typeof(ExampleClass))] | |
public class ExampleProperty : NestablePropertyDrawer | |
{ | |
protected new ExampleClass propertyObject { get { return (ExampleClass)base.propertyObject; } } | |
private SerializedProperty stringField = null; | |
protected override void Initialize(SerializedProperty prop) | |
{ | |
base.Initialize(prop); | |
if (stringField == null) | |
stringField = prop.FindPropertyRelative("field"); | |
} | |
public override void OnGUI(Rect position, SerializedProperty prop, GUIContent label) | |
{ | |
base.OnGUI(position, prop, label); | |
EditorGUI.BeginProperty(position, label, prop); | |
EditorGUI.BeginChangeCheck(); | |
EditorGUI.PropertyField(position, stringField); | |
if (EditorGUI.EndChangeCheck()) | |
{ | |
stringField.serializedObject.ApplyModifiedProperties(); | |
propertyObject.Print(); | |
} | |
EditorGUI.EndProperty(); | |
} | |
} |
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using UnityEngine; | |
using UnityEditor; | |
using System; | |
using System.Collections; | |
using System.Reflection; | |
using System.Text.RegularExpressions; | |
public class NestablePropertyDrawer : PropertyDrawer | |
{ | |
private bool initialized = false; | |
protected object propertyObject = null; | |
protected Type objectType = null; | |
private static readonly Regex matchArrayElement = new Regex(@"^data\[(\d+)\]$"); | |
protected virtual void Initialize(SerializedProperty prop) | |
{ | |
if (initialized) | |
return; | |
SerializedObject serializedObject = prop.serializedObject; | |
string path = prop.propertyPath; | |
propertyObject = serializedObject == null || serializedObject.targetObject == null ? null : serializedObject.targetObject; | |
objectType = propertyObject == null ? null : propertyObject.GetType(); | |
if (!string.IsNullOrEmpty(path) && propertyObject != null) | |
{ | |
string[] splitPath = path.Split('.'); | |
Type fieldType = null; | |
//work through the given property path, node by node | |
for (int i = 0; i < splitPath.Length; i++) | |
{ | |
string pathNode = splitPath[i]; | |
//both arrays and lists implement the IList interface | |
if (fieldType != null && typeof(IList).IsAssignableFrom(fieldType)) | |
{ | |
//IList items are serialized like this: `Array.data[0]` | |
Debug.AssertFormat(pathNode.Equals("Array", StringComparison.Ordinal), serializedObject.targetObject, "Expected path node 'Array', but found '{0}'", pathNode); | |
//just skip the `Array` part of the path | |
pathNode = splitPath[++i]; | |
//match the `data[0]` part of the path and extract the IList item index | |
Match elementMatch = matchArrayElement.Match(pathNode); | |
int index; | |
if (elementMatch.Success && int.TryParse(elementMatch.Groups[1].Value, out index)) | |
{ | |
IList objectArray = (IList)propertyObject; | |
bool validArrayEntry = objectArray != null && index < objectArray.Count; | |
propertyObject = validArrayEntry ? objectArray[index] : null; | |
objectType = fieldType.IsArray | |
? fieldType.GetElementType() //only set for arrays | |
: fieldType.GenericTypeArguments[0]; //type of `T` in List<T> | |
} | |
else | |
{ | |
Debug.LogErrorFormat(serializedObject.targetObject, "Unexpected path format for array item: '{0}'", pathNode); | |
} | |
//reset fieldType, so we don't end up in the IList branch again next iteration | |
fieldType = null; | |
} | |
else | |
{ | |
FieldInfo field; | |
Type instanceType = objectType; | |
BindingFlags fieldBindingFlags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.FlattenHierarchy; | |
do | |
{ | |
field = instanceType.GetField(pathNode, fieldBindingFlags); | |
//b/c a private, serialized field of a subclass isn't directly retrievable, | |
fieldBindingFlags = BindingFlags.Instance | BindingFlags.NonPublic; | |
//if neccessary, work up the inheritance chain until we find it. | |
instanceType = instanceType.BaseType; | |
} | |
while (field == null && instanceType != typeof(object)); | |
//store object info for next iteration or to return | |
propertyObject = field == null || propertyObject == null ? null : field.GetValue(propertyObject); | |
fieldType = field == null ? null : field.FieldType; | |
objectType = fieldType; | |
} | |
} | |
} | |
initialized = true; | |
} | |
public override void OnGUI(Rect position, SerializedProperty prop, GUIContent label) | |
{ | |
Initialize(prop); | |
} | |
} |
Yeah, I remember doing a similar thing for a project at some point. I think in my case it was about multi object editing, which also reuses the same drawer instance. But I guess I'll not update this gist to support that.
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I think it is the 2nd case. I put them in a reorderable list so there will be multiple instances on the same game object. It is surprisingly troublesome to make it right. But actually I think even if they are not on the same game object, they will still share the same drawer. My final approach to reduce reflection was to have a Dictionary<int, Dictionary<string, Entry>> where the int is instance id (kind of an id for the component containing the property), and string is the property path, Entry is a struct containing initialization status, the referenced property instance, and everything else that is prominent. I had to invalidate this cache when there is a change to the reorderable list.