Create a list view runtime UI

Version: 2021.3+

This example demonstrates how to create a list view runtime UI. This example uses the UXML and USS files directly to create the structure and style of the UI. If you are new to UI Toolkit and want to use UI Builder to create the UI, see Create an example UI with UI Builder.

Example overview

This example creates a simple character selection screen. When you click the name of a character from a list on the left, the detail of the character appears on the right.

You can find the completed files that this example creates in this GitHub repository.

先决条件

This guide is for developers familiar with the Unity Editor, UI Toolkit, and C# scripting. Before you start, get familiar with the following:

• UXML
• ListView
• Label
• PanelSettings
• UIDocument

Create the main UI Document

Create the main view UI Document and a USS file to style the visual elementsA node of a visual tree that instantiates or derives from the C# VisualElement class. You can style the look, define the behaviour, and display it on screen as part of the UI. More info
See in Glossary. Add two visual elements as containers in the UI Document: one that contains the list of character names and another that contains the selected character’s details.

1. Create a project in Unity with any template.

2. In the Project window, create a folder named UI to store all the UI Document and Style Sheet files.

3. In the UI folder, create a UI Document named MainView.uxml with the following content:

   <ui:UXML xmlns:ui="UnityEngine.UIElements" xmlns:uie="UnityEditor.UIElements" editor-extension-mode="False">
   <Style src="MainView.uss" />
   <ui:VisualElement name="background">
       <ui:VisualElement name="main-container">
           <ui:ListView focusable="true" name="character-list" />
           <ui:VisualElement name="right-container">
               <ui:VisualElement name="details-container">
                   <ui:VisualElement name="details">
                       <ui:VisualElement name="character-portrait" />
                   </ui:VisualElement>
                   <ui:Label text="Label" name="character-name" />
                   <ui:Label text="Label" display-tooltip-when-elided="true" name="character-class" />
               </ui:VisualElement>
           </ui:VisualElement>
       </ui:VisualElement>
   </ui:VisualElement>
   </ui:UXML>
   

4. In the UI folder, create a USS style sheet named MainView.uss with the following content:

       #background {
           flex-grow: 1;
           align-items: center;
           justify-content: center;
           background-color: rgb(115, 37, 38);
       }
   
       #main-container {
           flex-direction: row;
           height: 350px;
       }
   
       #character-list {
           width: 230px;
           border-color: rgb(49, 26, 17);
           border-width: 4px;
           background-color: rgb(110, 57, 37);
           border-radius: 15px;
           margin-right: 6px;
       }
   
       #character-name {
           -unity-font-style: bold;
           font-size: 18px;
       }
   
       #CharacterClass {
           margin-top: 2px;
           margin-bottom: 8px;
           padding-top: 0;
           padding-bottom: 0;
       }
   
       #right-container{
           justify-content: space-between; 
           align-items: flex-end;
       }
   
       #details-container{
           align-items: center; 
           background-color: rgb(170, 89, 57); 
           border-width: 4px; 
           border-color: rgb(49, 26, 17);
           border-radius: 15px;
           width: 252px; 
           justify-content: center; 
           padding: 8px;
           height: 163px;
       }
   
       #details{
           border-color: rgb(49, 26, 17); 
           border-width: 2px; 
           height: 120px; 
           width: 120px; 
           border-radius: 13px; 
           padding: 4px;
           background-color: rgb(255, 133, 84);
       }
   
       #character-portrait{
           flex-grow: 1; 
           -unity-background-scale-mode: scale-to-fit;
       }
   

Create a list entry UI Document

Create a UI Document and a Style Sheet for the individual entries in the list. The character list entry consists of a colored background frame and the character’s name.

1. In the UI folder, create a UI Document named ListEntry.uxml with the following content:

   <ui:UXML xmlns:ui="UnityEngine.UIElements" xmlns:uie="UnityEditor.UIElements" editor-extension-mode="False">
   <Style src="ListEntry.uss" />
   <ui:VisualElement name="list-entry">
       <ui:Label text="Label" display-tooltip-when-elided="true" name="character-name" />
   </ui:VisualElement>
   </ui:UXML>
   

2. In the UI folder, create a Style Sheet file named ListEntry.uss with the following content:

       #list-entry {
           height: 41px;
           align-items: flex-start;
           justify-content: center;
           padding-left: 10px;
           background-color: rgb(170, 89, 57);
           border-color: rgb(49, 26, 17);
           border-width: 2px;
           border-radius: 15px;
       }
   
       #character-name {
           -unity-font-style: bold;
           font-size: 18px;
           color: rgb(49, 26, 17);
       }
   

Create sample data to display

Create sample data to fill the character list in the UI. For the character list, create a class that holds a character name, class, and a portrait image.

1. In the Asset folder, create a folder named Scripts to store your C# scripts.

2. In the Scripts folder, create a C# script named CharacterData.cs with the following content:

   using UnityEngine;
   
   public enum ECharacterClass
   {
       Knight, Ranger, Wizard
   }
   
   [CreateAssetMenu] //This adds an entry to the **Create** menu
   public class CharacterData : ScriptableObject
   {
       public string CharacterName;
       public ECharacterClass Class;
       public Sprite PortraitImage;
   }
   

   This creates a Character Data item in the Assets > Create menu.

3. In the Assets folder, create a folder named Resources.

4. In the Resources folder, create a folder named Characters to store all your sample character data.

5. In the Characters folder, right-click and select Create > Character Data to create an instance of the ScriptableObject.

6. Create more CharacterData instances and fill them with placeholder data.

Set up the scene

Create a UIDocument GameObject in the SampleScene and add the UI Document as the source asset.

1. In the SampleScene, select GameObject > UI Toolkit > UI Document.
2. Select the UIDocument GameObject in the Hierarchy window.
3. Drag MainView.uxml from your Project window to the Source Asset field of the UI Document component in the Inspector window. This references the source asset to the UXML file.

Create controllers for the list entry and the main view

Create two C# scripts with the following classes:

• A CharacterListEntryController class to display the data of a character instance in the UI of the list entry. It needs to access the label for the character name and set it to display the name of the given character instance.
• A CharacterListController class for the character list in the main view, and a MonoBehaviour script that instantiates and assigns it to the visual treeAn object graph, made of lightweight nodes, that holds all the elements in a window or panel. It defines every UI you build with the UI Toolkit.
  See in Glossary.

Note: The CharacterListEntryController class isn’t a MonoBehaviour. Since the visual elements in UI Toolkit aren’t GameObjects, you can’t attach components to them. Instead, you attach the class to the userData property in the CharacterListController class.

1. In the Scripts folder, create a C# script named CharacterListEntryController.cs with the following contents:

   using UnityEngine.UIElements;
   
   public class CharacterListEntryController
   {
       Label NameLabel;
   
       //This function retrieves a reference to the 
       //character name label inside the UI element.
   
       public void SetVisualElement(VisualElement visualElement)
       {
           NameLabel = visualElement.Q<Label>("character-name");
       }
   
       //This function receives the character whose name this list 
       //element displays. Since the elements listed 
       //in a `ListView` are pooled and reused, it's necessary to 
       //have a `Set` function to change which character's data to display.
   
       public void SetCharacterData(CharacterData characterData)
       {
           NameLabel.text = characterData.CharacterName;
       }
   }
   

2. In the Scripts folder, create a C# script named CharacterListController.cs with the following content:

   using System.Collections.Generic;
   using UnityEngine;
   using UnityEngine.UIElements;
   
   public class CharacterListController
   {
       // UXML template for list entries
       VisualTreeAsset ListEntryTemplate;
   
       // UI element references
       ListView CharacterList;
       Label CharClassLabel;
       Label CharNameLabel;
       VisualElement CharPortrait;
   
       public void InitializeCharacterList(VisualElement root, VisualTreeAsset listElementTemplate)
       {
           EnumerateAllCharacters();
   
           // Store a reference to the template for the list entries
           ListEntryTemplate = listElementTemplate;
   
           // Store a reference to the character list element
           CharacterList = root.Q<ListView>("character-list");
   
           // Store references to the selected character info elements
           CharClassLabel = root.Q<Label>("character-class");
           CharNameLabel = root.Q<Label>("character-name");
           CharPortrait = root.Q<VisualElement>("character-portrait");
   
           FillCharacterList();
   
           // Register to get a callback when an item is selected
           CharacterList.onSelectionChange += OnCharacterSelected;
       }
   
       List<CharacterData> AllCharacters;
   
       void EnumerateAllCharacters()
       {
           AllCharacters = new List<CharacterData>();
           AllCharacters.AddRange(Resources.LoadAll<CharacterData>("Characters"));
       }
   
       void FillCharacterList()
       {
           // Set up a make item function for a list entry
           CharacterList.makeItem = () =>
           {
               // Instantiate the UXML template for the entry
               var newListEntry = ListEntryTemplate.Instantiate();
   
               // Instantiate a controller for the data
               var newListEntryLogic = new CharacterListEntryController();
   
               // Assign the controller script to the visual element
               newListEntry.userData = newListEntryLogic;
   
               // Initialize the controller script
               newListEntryLogic.SetVisualElement(newListEntry);
   
               // Return the root of the instantiated visual tree
               return newListEntry;
           };
   
           // Set up bind function for a specific list entry
           CharacterList.bindItem = (item, index) =>
           {
               (item.userData as CharacterListEntryController).SetCharacterData(AllCharacters[index]);
           };
   
           // Set a fixed item height
           CharacterList.fixedItemHeight = 45;
   
           // Set the actual item's source list/array
           CharacterList.itemsSource = AllCharacters;
       }
   
       void OnCharacterSelected(IEnumerable<object> selectedItems)
       {
           // Get the currently selected item directly from the ListView
           var selectedCharacter = CharacterList.selectedItem as CharacterData;
   
           // Handle none-selection (Escape to deselect everything)
           if (selectedCharacter == null)
           {
               // Clear
               CharClassLabel.text = "";
               CharNameLabel.text = "";
               CharPortrait.style.backgroundImage = null;
   
               return;
           }
   
           // Fill in character details
           CharClassLabel.text = selectedCharacter.Class.ToString();
           CharNameLabel.text = selectedCharacter.CharacterName;
           CharPortrait.style.backgroundImage = new StyleBackground(selectedCharacter.PortraitImage);
       }
   }
   

Attach the controller script to the main view

The CharacterListController isn’t a MonoBehaviour, so it must be attached to the visual tree. Create a MonoBehaviour script that you can attach to the same GameObject as the UIDocument. It instantiates the CharacterListController and attaches it to the Visual Tree.

1. In the Scripts folder, create a C# script named MainView.cs with the following content:

   using UnityEngine;
   using UnityEngine.UIElements;
   
   public class MainView : MonoBehaviour
   {
       [SerializeField]
       VisualTreeAsset ListEntryTemplate;
   
       void OnEnable()
       {
           // The UXML is already instantiated by the UIDocument component
           var uiDocument = GetComponent<UIDocument>();
   
           // Initialize the character list controller
           var characterListController = new CharacterListController();
           characterListController.InitializeCharacterList(uiDocument.rootVisualElement, ListEntryTemplate);
       }
   }
   

2. In the SampleScene, select UIDocument.

3. Drag MainView.cs to Add Component in the Inspector window.

4. Drag ListEntry.uxml to the ListEntry Template field.

5. Enter Play mode to see your UI displayed in the game view.

Additional resource

• UXML element ListView
• Get started with runtime UI
• Render UI in the Game view
• The Panel Settings asset
• Runtime event system