Converts a UxmlAttribute type to and from a string.
Fields marked with UxmlAttributeAttribute are represented in UXML by a single string attribute,
however, to properly serialize these attributes, you must declare a UxmlAttributeConverter.
This converter converts the string attribute value into the appropriate data type for the marked field.
Note: The following types have native support and you can use them without declaring a UxmlAttributeConverter:
The following example creates a custom control that uses a class instance and a list of class instances as its attributes.
using System; using System.Collections.Generic; using UnityEngine.UIElements;
[Serializable] public class MyClassWithData { public int myInt; public float myFloat; }
[UxmlElement] public partial class MyElementWithData : VisualElement { [UxmlAttribute] public MyClassWithData someData;
[UxmlAttribute] public List<MyClassWithData> lotsOfData; }
To support the class, declare a converter:
using System; using System.Globalization; using UnityEditor.UIElements;
public class MyClassWithDataConverter : UxmlAttributeConverter<MyClassWithData> { public override MyClassWithData FromString(string value) { // Split using a | so that comma (,) can be used by the list. var split = value.Split('|');
return new MyClassWithData { myInt = int.Parse(split[0]), myFloat = float.Parse(split[1], CultureInfo.InvariantCulture) }; }
public override string ToString(MyClassWithData value) => FormattableString.Invariant($"{value.myInt}|{value.myFloat}"); }
Example UXML:
<ui:UXML xmlns:ui="UnityEngine.UIElements"> <MyElementWithData some-data="1|2.3" lots-of-data="1|2,3|4,5|6" /> </ui:UXML>
You can also use generic attribute converters. However, you must declare the attribute with the generic type. To use a type derived from a generic type, declare a new converter specifically for it. The following example uses a generic attribute converter and a custom property drawer to create a generic serialized dictionary:
using System; using System.Collections.Generic; using UnityEngine; using UnityEngine.UIElements;
[Serializable] public class SerializableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, ISerializationCallbackReceiver { [SerializeField] public List<TKey> keys = new List<TKey>(); [SerializeField] public List<TValue> values = new List<TValue>();
void ISerializationCallbackReceiver.OnAfterDeserialize() => TransferSerializedKeys(); void ISerializationCallbackReceiver.OnBeforeSerialize() { }
public void TransferSerializedKeys() { Clear();
for (var i = 0; i < Math.Min(keys.Count, values.Count); i++) { this[keys[i]] = values[i]; } } }
[UxmlElement] public partial class MyDictElement : VisualElement { [UxmlAttribute] public SerializableDictionary<int, string> dictionaryIntString;
[UxmlAttribute] public SerializableDictionary<int, int> dictionaryIntInt;
[UxmlAttribute] public SerializableDictionary<string, string> dictionaryStringString; }
Generic attribute converter:
using System; using System.Globalization; using System.Text; using UnityEditor.UIElements;
public class SerializableDictionaryConverter<TKey, TValue> : UxmlAttributeConverter<SerializableDictionary<TKey, TValue>> { static string ValueToString(object v) => Convert.ToString(v, CultureInfo.InvariantCulture);
public override string ToString(SerializableDictionary<TKey, TValue> source) { var sb = new StringBuilder(); foreach (var pair in source) { sb.Append($"{ValueToString(pair.Key)}|{ValueToString(pair.Value)},"); } return sb.ToString(); }
public override SerializableDictionary<TKey, TValue> FromString(string source) { var result = new SerializableDictionary<TKey, TValue>(); var items = source.Split(','); foreach (var item in items) { var fields = item.Split('|'); var key = (TKey)Convert.ChangeType(fields[0], typeof(TKey)); var value = (TValue)Convert.ChangeType(fields[1], typeof(TValue));
result.keys.Add(key); result.values.Add(value); } result.TransferSerializedKeys(); return result; } }
Custom property drawer:
using UnityEditor; using UnityEditor.UIElements; using UnityEngine.UIElements;
[CustomPropertyDrawer(typeof(SerializableDictionary<,>))] class SerializableDictionaryPropertyDrawer : PropertyDrawer { SerializedProperty m_Property; SerializedProperty m_Keys; SerializedProperty m_Values;
public override VisualElement CreatePropertyGUI(SerializedProperty property) { m_Property = property; m_Keys = property.FindPropertyRelative("keys"); m_Values = property.FindPropertyRelative("values");
var list = new ListView() { showAddRemoveFooter = true, showBorder = true, showAlternatingRowBackgrounds = AlternatingRowBackground.All, showFoldoutHeader = true, showBoundCollectionSize = false, reorderable = true, reorderMode = ListViewReorderMode.Animated, virtualizationMethod = CollectionVirtualizationMethod.DynamicHeight, headerTitle = property.displayName, bindingPath = m_Keys.propertyPath, overridingAddButtonBehavior = OnAddButton, bindItem = BindListItem, }; return list; }
void BindListItem(VisualElement item, int index) { item.Clear();
item.Add(new PropertyField(m_Keys.GetArrayElementAtIndex(index)) { label = "Key" }); item.Add(new PropertyField(m_Values.GetArrayElementAtIndex(index)) { label = "Value" }); item.Bind(m_Property.serializedObject); }
void OnAddButton(BaseListView baseListView, Button button) { m_Keys.InsertArrayElementAtIndex(m_Keys.arraySize); m_Values.InsertArrayElementAtIndex(m_Values.arraySize); m_Property.serializedObject.ApplyModifiedProperties(); } }
FromString | Provides a type converted from a string representation. |
ToString | Provides a string representation of a type. |