Version: 2021.3+
This example demonstrates how to create a simple custom control with two attributes.
This example creates a custom control called MyElement
with two attributes and exposes it to UXML and UI Builder. This example also shows how to add the custom control to a UI in the UI Builder.
You can find the completed files that this example creates in this GitHub repository.
This guide is for developers who are familiar with Unity, UI Toolkit, and C# scripting. Before you start, get familiar with the following:
To create a new custom control class in C#, inherit it from the VisualElement
class. This allows you to create and use this element in C#, but won’t automatically expose it in UXML and UI Builder. To expose it, define a traits class derived from UxmlTraits
and override the Init()
.
Create a Unity project with any template.
In the Assets
folder, create a C# script named MyElement.cs
with the following content:
using UnityEngine;
using UnityEngine.UIElements;
class MyElement : VisualElement
{
public new class UxmlFactory : UxmlFactory<MyElement, UxmlTraits> { }
// Add the two custom UXML attributes.
public new class UxmlTraits : VisualElement.UxmlTraits
{
UxmlStringAttributeDescription m_String =
new UxmlStringAttributeDescription { name = "my-string", defaultValue = "default_value" };
UxmlIntAttributeDescription m_Int =
new UxmlIntAttributeDescription { name = "my-int", defaultValue = 2 };
public override void Init(VisualElement ve, IUxmlAttributes bag, CreationContext cc)
{
base.Init(ve, bag, cc);
var ate = ve as MyElement;
ate.myString = m_String.GetValueFromBag(bag, cc);
ate.myInt = m_Int.GetValueFromBag(bag, cc);
}
}
// Must expose your element class to a { get; set; } property that has the same name
// as the name you set in your UXML attribute description with the camel case format
public string myString { get; set; }
public int myInt { get; set; }
}
Create a UXML file with any name you want.
Double-click the UXML file to open it in the UI Builder.
In the Library section of the UI Builder, select Project > Custom Controls (C#) > MyElement.
Drag MyElement to the Hierarchy window.
To see the custom attributes for MyElement, go to the Inspector window of MyElement:
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