Create a tabbed menu for runtime

Tabbed menus are common in video games and application UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary. You can use UI Toolkit to create a tabbed menu for a custom Editor window or runtime. This example demonstrates how to create a tabbed menu in the sample sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary.

Example overview

This example adds a menu in the sample scene. The menu has three tabs. Each tab presents certain content. When you click a tab, only the content associated with that tab is displayed.

To create tabbed content, you need to define the menu elements, styles, and logic.

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

Prerequisites

This guide is for developers who are familiar with Unity, UI Toolkit, Flexbox, and C# scripting.

This guide references the following concepts:

Define the tabbed menu elements

Create two sections in your menu using the UI Builder, one for tabs and one for the content of tabs. In these sections, create three tab elements and three tab content elements.

Create a project in Unity Editor using any template.
Click GameObject > UI Toolkit > UI Document to add a UI Document in the sample scene.
Create a folder in Assets called TabbedMenu to store all your files.
In the TabbedMenu folder, create a UI Document called TabbedMenu.uxml.
Add the UXML to your UI Document by selecting the UIDocument in the SampleScene and dragging TabbedMenu.uxml to Source Asset in the UI Document section in 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.
Open TabbedMenu.uxml using the UI Builder.
Add two VisualElements called tabs and tabContent under the root.
Under tabs, add three Label controls and give them the following Label texts:
- London
- Paris
- Ottawa
Under tabContent, add three Label controls and give them the following Label texts:
- London is the capital city of England
- Paris is the capital of France
- Ottawa is the capital of Canada
To associate the tab content with the tab, this example uses the same prefixes but different suffixes for the Label names. Each tab name has the Tab suffix and each tab content has the Content suffix. Set the tab Label names and content Label names to the following:
- LondonTab
- ParisTab
- OttawaTab
- LondonContent
- ParisContent
- OttawaContent

Your UI Builder Hierarchy should look like the following:

Define the tabbed menu styles

Define the layout for tabs and tab content using USS. You can style the tabs and the tab content the way you like. This example arranges tabs in a row and on top of the tab content. It adds a background color for the selected tab and hides the un-selected tab content.

In the TabbedMenu folder, create a stylesheet called TabbedMenu.uss.

Open TabbedMenu.uss and add the following styling rules:

/* Style for tabs */
#tabs {
    flex-basis: 10%;
    flex-direction: row;
    background-color: rgb(229, 223, 223);
    font-size: 12px;
    -unity-font-style: bold;
    font-size: 14px;
}

/* Sets each label in tabs to have the same size. */
.tab {
    flex-grow: 1;
}

/* Adds background color for the selected tab */
.currentlySelectedTab {
    background-color: rgb(173, 166, 166);
}

/* Style for tabContent */
#tabContent {
    flex-basis: 90%;
    background-color: rgb(255, 255, 255);
    font-size: 20px;
}

/* Hides the unselected tab content */
.unselectedContent {
    display: none;
}

Open TabbedMenu.uxml in UI Builder.
Click Add Existing USS and select TabbedMenu.uss.
Apply your styles to the UI controls:
- Apply .tab to each label under tabs
- Apply .currentlySelectedTab to LondonTab
- Apply .unselectedContent to ParisContent and OttawaContent

The finished TabbedMenu.uxml should look like the following:

<ui:UXML xmlns:ui="UnityEngine.UIElements" xmlns:uie="UnityEditor.UIElements" xsi="http://www.w3.org/2001/XMLSchema-instance" engine="UnityEngine.UIElements" editor="UnityEditor.UIElements" noNamespaceSchemaLocation="../../../UIElementsSchema/UIElements.xsd" editor-extension-mode="False">
   /* Your src might look different. If you save your UXML in UI Builder, USS file is referenced by the file location, fileID and guid. */
   <Style src="TabbedMenu-style.uss" />
   <ui:VisualElement name="tabs">
      <ui:Label name="LondonTab" text="London" class="tab currentlySelectedTab" />
      <ui:Label name="ParisTab" text="Paris" class="tab" />
      <ui:Label name="OttawaTab" text="Ottawa" class="tab" />
   </ui:VisualElement>
   <ui:VisualElement name="tabContent">
      <ui:Label text="London is the capital city of England" name="LondonContent" />
      <ui:Label text="Paris is the capital of France" name="ParisContent" class="unselectedContent" />
      <ui:Label text="Ottawa is the capital of Canada" name="OttawaContent" class="unselectedContent" />
   </ui:VisualElement>
</ui:UXML>

Define the tabbed menu logic

Create the C# scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary that change the displayed tab content. When a user clicks a tab, the tab’s content displays and the current content hides.

In the TabbedMenu folder, create the following two C# script files:
- TabbedMenu.cs: Attaches the tabbed menu logic to the game.
- TabbedMenuController.cs: Defines the tab selection logic.
Add TabbedMenu.cs as a component to the UI Document by selecting the UIDocument in the SampleScene and dragging TabbedMenu.cs to Add Component button in the Inspector.

Open TabbedMenu.cs and replace with the following code:

using UnityEngine;
using UnityEngine.UIElements;

//Inherits from class `MonoBehaviour`. This makes it attachable to a game object as a component.
public class TabbedMenu : MonoBehaviour
{
    private TabbedMenuController controller;

    private void OnEnable()
    {
        UIDocument menu = GetComponent<UIDocument>();
        VisualElement root = menu.rootVisualElement;

        controller = new(root);

        controller.RegisterTabCallbacks();
    }
}

Open TabbedMenuController.cs and replace with the following code:

using UnityEngine.UIElements;

public class TabbedMenuController
{
    /* Define member variables*/
    private const string tabClassName = "tab";
    private const string currentlySelectedTabClassName = "currentlySelectedTab";
    private const string unselectedContentClassName = "unselectedContent";
    // Tab and tab content have the same prefix but different suffix
    // Define the suffix of the tab name
    private const string tabNameSuffix = "Tab";
    // Define the suffix of the tab content name
    private const string contentNameSuffix = "Content";

    private readonly VisualElement root;

    public TabbedMenuController(VisualElement root)
    {
        this.root = root;
    }

    public void RegisterTabCallbacks()
    {
        UQueryBuilder<Label> tabs = GetAllTabs();
        tabs.ForEach((Label tab) => {
            tab.RegisterCallback<ClickEvent>(TabOnClick);
        });
    }

    /* Method for the tab on-click event: 

       - If it is not selected, find other tabs that are selected, unselect them 
       - Then select the tab that was clicked on
    */
    private void TabOnClick(ClickEvent evt)
    {
        Label clickedTab = evt.currentTarget as Label;
        if (!TabIsCurrentlySelected(clickedTab))
        {
            GetAllTabs().Where(
                (tab) => tab != clickedTab && TabIsCurrentlySelected(tab)
            ).ForEach(UnselectTab);
            SelectTab(clickedTab);
        }
    }
    //Method that returns a Boolean indicating whether a tab is currently selected
    private static bool TabIsCurrentlySelected(Label tab)
    {
        return tab.ClassListContains(currentlySelectedTabClassName);
    }

    private UQueryBuilder<Label> GetAllTabs()
    {
        return root.Query<Label>(className: tabClassName);
    }

    /* Method for the selected tab: 
       -  Takes a tab as a parameter and adds the currentlySelectedTab class
       -  Then finds the tab content and removes the unselectedContent class */
    private void SelectTab(Label tab)
    {
        tab.AddToClassList(currentlySelectedTabClassName);
        VisualElement content = FindContent(tab);
        content.RemoveFromClassList(unselectedContentClassName);
    }

    /* Method for the unselected tab: 
       -  Takes a tab as a parameter and removes the currentlySelectedTab class
       -  Then finds the tab content and adds the unselectedContent class */
    private void UnselectTab(Label tab)
    {
        tab.RemoveFromClassList(currentlySelectedTabClassName);
        VisualElement content = FindContent(tab);
        content.AddToClassList(unselectedContentClassName);
    }

    // Method to generate the associated tab content name by for the given tab name
    private static string GenerateContentName(Label tab) =>
        tab.name.Replace(tabNameSuffix, contentNameSuffix);

    // Method that takes a tab as a parameter and returns the associated content element
    private VisualElement FindContent(Label tab)
    {
        return root.Q(GenerateContentName(tab));
    }
}

Go back to Unity and enter Play mode. You should see the content change when you click a new tab.

Tabbed menu example added in Unity 2021.2 NewIn20212

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