Version: 2023.2+
You can bind to a list without ListView. To do so, bind each element to an item in the array of the serialized object and track the value of the array size. The array size might change in certain situations, such as an undo or reset operation.
This example demonstrates how to bind to a list without ListView.
This example creates a list of TexturePreviewElements and binds the list to an underlying list of Texture2D objects.
You can find the completed files that this example creates in this GitHub repository.
This guide is for developers familiar with the Unity Editor, UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary Toolkit, and C# scripting. Before you start, get familiar with the following:
BindProperty()
TrackPropertyValue
ScrollView
Create a C# class that contains a list. This list is the target of the binding.
Assets
folder (Project tab) More infobind-to-list-without-ListView
to store all your files.TexturePackAsset.cs
and replace its contents with the following:using System.Collections.Generic; using UnityEngine; namespace UIToolkitExamples { [CreateAssetMenu(menuName = "UIToolkitExamples/TexturePackAsset")] public class TexturePackAsset : ScriptableObject { public List<Texture2D> textures; public void Reset() { textures = new() { null, null, null, null }; } } }
Create a custom control with C# that represents a reference to a 2D texture asset, and style it with USS.
Editor
.TexturePreviewElement.cs
.TexturePreviewElement.cs
with the following:using System; using UnityEditor.UIElements; using UnityEngine; using UnityEngine.UIElements; using Object = UnityEngine.Object; namespace UIToolkitExamples { [UxmlElement] public partial class TexturePreviewElement : BindableElement, INotifyValueChanged<Object> { public static readonly string ussClassName = "texture-preview-element"; Image m_Preview; ObjectField m_ObjectField; Texture2D m_Value; public TexturePreviewElement() { AddToClassList(ussClassName); // Create a preview image. m_Preview = new Image(); Add(m_Preview); // Create an ObjectField, set its object type, and register a callback when its value changes. m_ObjectField = new ObjectField(); m_ObjectField.objectType = typeof(Texture2D); m_ObjectField.RegisterValueChangedCallback(OnObjectFieldValueChanged); Add(m_ObjectField); styleSheets.Add(Resources.Load<StyleSheet>("texture_preview_element")); } void OnObjectFieldValueChanged(ChangeEvent<Object> evt) { value = evt.newValue; } public void SetValueWithoutNotify(Object newValue) { if (newValue == null || newValue is Texture2D) { // Update the preview Image and update the ObjectField. m_Value = newValue as Texture2D; m_Preview.image = m_Value; // Notice that this line calls the ObjectField's SetValueWithoutNotify() method instead of just setting // m_ObjectField.value. This is very important; you don't want m_ObjectField to send a ChangeEvent. m_ObjectField.SetValueWithoutNotify(m_Value); } else throw new ArgumentException($"Expected object of type {typeof(Texture2D)}"); } public Object value { get => m_Value; // The setter is called when the user changes the value of the ObjectField, which calls // OnObjectFieldValueChanged(), which calls this. set { if (value == this.value) return; var previous = this.value; SetValueWithoutNotify(value); using (var evt = ChangeEvent<Object>.GetPooled(previous, value)) { evt.target = this; SendEvent(evt); } } } } }
Resources
.texture_preview_element.uss
and replace its contents with the following:.texture-preview-element { width: 200px; height: 200px; } .texture-preview-element > .unity-image { flex-grow: 1; }
Create the custom Editor with a C# script that creates the asset.
To change the size of the textures list when the number of TexturePreviewElements
in the UI changes, call the SetupList()
method and walk through the list of entries in the serialized list.
To bind each TexturePreviewElement
to the list of textures, call BindProperty()
with the property name of TexturePackAsset.textures
.
TexturePackEditor.cs
and replace its contents with the following:using UnityEditor; using UnityEditor.UIElements; using UnityEngine; using UnityEngine.UIElements; namespace UIToolkitExamples { [CustomEditor(typeof(TexturePackAsset))] public class TexturePackEditor : Editor { [SerializeField] VisualTreeAsset m_VisualTreeAsset; public override VisualElement CreateInspectorGUI() { var editor = m_VisualTreeAsset.CloneTree(); var container = editor.Q(className: "preview-container"); SetupList(container); // Watch the array size to handle the list being changed var propertyForSize = serializedObject.FindProperty(nameof(TexturePackAsset.textures) + ".Array"); propertyForSize.Next(true); // Expand to obtain array size editor.TrackPropertyValue(propertyForSize, prop => SetupList(container)); editor.Q<Button>("add-button").RegisterCallback<ClickEvent>(OnClick); return editor; } void SetupList(VisualElement container) { var property = serializedObject.FindProperty(nameof(TexturePackAsset.textures) + ".Array"); var endProperty = property.GetEndProperty(); property.NextVisible(true); // Expand the first child. var childIndex = 0; // Iterate each property under the array and populate the container with preview elements do { // Stop if we've reached the end of the array if (SerializedProperty.EqualContents(property, endProperty)) break; // Skip the array size property if (property.propertyType == SerializedPropertyType.ArraySize) continue; TexturePreviewElement element; // Find an existing element or create one if (childIndex < container.childCount) { element = (TexturePreviewElement)container[childIndex]; } else { element = new TexturePreviewElement(); container.Add(element); } element.BindProperty(property); ++childIndex; } while (property.NextVisible(false)); // Never expand children. // Remove excess elements if the array is now smaller while (childIndex < container.childCount) { container.RemoveAt(container.childCount - 1); } } void OnClick(ClickEvent evt) { var property = serializedObject.FindProperty(nameof(TexturePackAsset.textures)); property.arraySize += 1; serializedObject.ApplyModifiedProperties(); } } }
texture_pack_editor.uxml
and replace its contents with the following:<ui:UXML xmlns:ui="UnityEngine.UIElements" xmlns:uie="UnityEditor.UIElements" xmlns="UnityEngine.UIElements" example="UIToolkitExamples" editor-extension-mode="True"> <ui:ScrollView> <ui:VisualElement class="preview-container" style="flex-wrap: wrap; flex-direction: row; justify-content: space-around;" /> </ui:ScrollView> <ui:Button name="add-button" text="Add" /> </ui:UXML>
TexturePackAsset.textures
object changes.Tip: To import some textures and assign them to the different entries in the list, try this free Playground asset store plugin.
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