Simple UI Toolkit workflow

If you perform a specific task often, you can use UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary Toolkit to create a dedicated UI for it. For example you can create a custom Editor window.

This guide describes the basic UI Toolkit workflow using a custom Editor window as an example. The example demonstrates how to create a custom Editor window and add UI controls into your custom Editor window using UI Builder, UXML, and C# script.

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

Prerequisites

This guide is for developers familiar with the Unity Editor and C# scripting, but new to UI Toolkit. Unity recommends that you have a basic understanding of the following concepts:

• UI Builder
• UXML
• Visual Tree
• Controls:
  • Label
  • Button
  • ToggleA checkbox that allows the user to switch an option on or off. More info
    See in Glossary

Create a custom Editor window

1. From the Project window, right-click and select Create > UI Toolkit > Editor Window.
2. In UI Toolkit Editor Window Creator, enter MyCustomEditor and disable USS.
3. Click Confirm.

This creates a custom Editor window with two labels. You can open the Editor window from the menu (Window > UI Toolkit > MyCustomEditor). You can find the source files for it in the Asset/Editor folder.

Add UI controls to the window

You can add UI controls into your window in the following ways:

• Use the UI Builder to visually add the UI controls
• Use an XML-like text file (UXML) to add the UI controls
• Use C# script to add the UI controls

You can use any of these methods individually, or combine. The following examples create three sets of labels, buttons, and toggles using a combination of these methods.

Use UI Builder to add UI controls

To visually add UI controls to your window, use UI Builder. The following example demonstrates how to add a button and a toggle into your custom Editor window in addition to the default label.

1. In the Editor folder, double-click MyCustomEditor.uxml to open the UI Builder.

2. In the UI Builder, drag Button and Toggle from Library > Controls into the Hierarchy or the window preview in the Viewport.

3. In Hierarchy, add some attributes to your controls:

   • Click the label, and then in the Text field of the InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
     See in Glossary, change the default text to These controls were created in UI Builder.
   • Click the button, and then in the Text field of the Inspector, enter This is button1. In the Name field of the Inspector, enter button1.
   • Click the toggle, and then in the Label field of the Inspector, enter Number?. In the Name field of the Inspector, enter toggle1.

4. Save and close the UI Builder window.

5. Open your custom Editor window. You should see the button and the toggle you just added in your window.

Use UXML to add UI controls

If you prefer define your UI in a text file, you can edit the UXML to add the UI controls. The example adds another set of label, button, and toggle into your window.

1. In the Editor folder, click Assets > Create > UI Toolkit > UI Document to create a UXML file called MyCustomEditor_UXML.uxml.

2. Open MyCustomEditor_UXML.uxml on a text editor.

   Tip: You can do so by clicking the arrow on MyCustomEditor_UXML.uxml in the Project windowA window that shows the contents of your Assets folder (Project tab) More info
   See in Glossary, and then double-clicking inlineStyle.

3. By default, the UXML document displays a single element with the engine:UXML tag. This is the root element of the XML tree. Within this element, you can add the UI controls with their attributes.

   Your finished MyCustomEditor_UXML.uxml file should look like the following:

   <?xml version="1.0" encoding="utf-8"?>
   <engine:UXML
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:engine="UnityEngine.UIElements"
       xmlns:editor="UnityEditor.UIElements"
       xsi:noNamespaceSchemaLocation="../../UIElementsSchema/UIElements.xsd"
   >
       <engine:Label text="These controls were created with UXML." />
       <engine:Button text="This is button2." name="button2"/>
       <engine:Toggle label="Number?" name="toggle2"/>
   </engine:UXML>
   

4. Open MyCustomEditor.cs.

5. Add a private VisualTreeAsset field called m_UXMLTree to the MyCustomEditor class. Put the attribute [SerializeField] above it:

   [SerializeField]
   private VisualTreeAsset m_UXMLTree;
   

6. Add the following line of code to the end of CreateGUI().

   rootVisualElement.Add(m_UXMLTree.Instantiate());
   

7. In the Project window, select MyCustomEditor.cs.

8. Drag MyCustomEditor_UXML.uxml from the Project window into the UXML Tree field in the Inspector. This assigns your UXML to the visual tree.

9. Open your custom Editor window. You should see three labels, two buttons, and two toggles in your window.

Use C# script to add UI controls

If you prefer coding, you can add UI Controls to your window using C# script. The following example adds another set of label, button, and toggle into your window.

1. Open MyCustomEditor.cs.

2. Unity uses UnityEngine.UIElements for basic UI controls like label, button, and toggle. To work with UI controls, you must add the following declaration if it’s not already present.

   using UnityEngine.UIElements;
   

3. Change the text of the existing label from "Hello World! From C#" to "These controls were created using C# code.".

4. The EditorWindow class has a property called rootVisualElement. To add the UI controls to your window, first instantiate the element class with some attributes, and then use the Add methods of the rootVisualElement.

   Your finished CreateGUI() method should look like the following:

   public void CreateGUI()
   {
       // Each editor window contains a root VisualElement object
       VisualElement root = rootVisualElement;
   
       // VisualElements objects can contain other VisualElements following a tree hierarchy.
       Label label = new Label("These controls were created using C# code.");
       root.Add(label);
   
       Button button = new Button();
       button.name = "button3";
       button.text = "This is button3.";
       rootVisualElement.Add(button);
   
       Toggle toggle = new Toggle();
       toggle.name = "toggle3";
       toggle.label = "Number?";
       rootVisualElement.Add(toggle);
   
       // Import UXML
       var visualTree = AssetDatabase.LoadAssetAtPath<VisualTreeAsset>("Assets/Editor/MyCustomEditor.uxml");
       VisualElement labelFromUXML = visualTree.Instantiate();
       root.Add(labelFromUXML);
   
       rootVisualElement.Add(m_UXMLTree.Instantiate());
   }
   

5. Go to the Editor and open your custom Editor window. You should see three labels, three buttons, and three toggles in your window.

Define the behavior of your UI controls

You can set up event handlers for your UI controls so that when you click the button, and select or clear the toggle, your UI controls perform some tasks.

The code below shows example event handlers that do the following:

• When a button is clicked, the Editor Console displays a message.
• When a toggle is selected, the Console shows how many times the buttons have been clicked.

using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;

public class MyCustomEditor : EditorWindow
{
    [MenuItem("Window/UI Toolkit/MyCustomEditor")]
    public static void ShowExample()
    {
        MyCustomEditor wnd = GetWindow<MyCustomEditor>();
        wnd.titleContent = new GUIContent("MyCustomEditor");
    }

    [SerializeField]
    private VisualTreeAsset m_UXMLTree;

    private int m_ClickCount = 0;

    private const string m_ButtonPrefix = "button";

    public void CreateGUI()
    {
        // Each editor window contains a root VisualElement object
        VisualElement root = rootVisualElement;

        // VisualElements objects can contain other VisualElements following a tree hierarchy.
        Label label = new Label("These controls were created using C# code.");
        root.Add(label);

        Button button = new Button();
        button.name = "button3";
        button.text = "This is button3.";
        rootVisualElement.Add(button);

        Toggle toggle = new Toggle();
        toggle.name = "toggle3";
        toggle.label = "Number?";
        rootVisualElement.Add(toggle);

        // Import UXML
        var visualTree = AssetDatabase.LoadAssetAtPath<VisualTreeAsset>("Assets/Editor/MyCustomEditor.uxml");
        VisualElement labelFromUXML = visualTree.Instantiate();
        root.Add(labelFromUXML);

        rootVisualElement.Add(m_UXMLTree.Instantiate());

        //Call the event handler
        SetupButtonHandler();
    }

    //Functions as the event handlers for your button click and number counts 
    private void SetupButtonHandler()
    {
        var buttons = rootVisualElement.Query<Button>();
        buttons.ForEach(RegisterHandler);
    }

    private void RegisterHandler(Button button)
    {
        button.RegisterCallback<ClickEvent>(PrintClickMessage);
    }

    private void PrintClickMessage(ClickEvent evt)
    {
        ++m_ClickCount;

        //Because of the names we gave the buttons and toggles, we can use the
        //button name to find the toggle name.
        Button button = evt.currentTarget as Button;
        string buttonNumber = button.name.Substring(m_ButtonPrefix.Length);
        string toggleName = "toggle" + buttonNumber;
        Toggle toggle = rootVisualElement.Q<Toggle>(toggleName);

        Debug.Log("Button was clicked!" +
            (toggle.value ? " Count: " + m_ClickCount : ""));
    }
}

Additional resources

• Create a custom Editor window

• UI Toolkit simple workflow added in Unity 2021.2 NewIn20212