Version: 2023.2+
This example shows how to create a custom binding that binds USS selectors to a visual element.
This example creates a custom binding that assigns USS class selectors to each child element of a visual element based on the order of the child elements in the hierarchy. The first element always has the left round corner edge, while the last element always has the right round corner edge.
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 Toolkit, and C# scripting. Before you start, get familiar with the following:
Create a custom binding type that assigns USS classes based on the sibling index. The binding updates only when the sibling index changes.
Create a project in Unity with any template.
In the Assets
folder of your project, create a C# script named AddMenuUSSClass.cs
with the following content:
[!code-cs[(Modules/UIElements/Tests/UIElementsExamples/Assets/ui-toolkit-manual-code-examples/runtime-custom-binding/AddMenuUSSClass.cs)]
Generally speaking, you create a binding that binds to an existing property of the element. For demonstration purposes, this example creates a custom binding that binds to a property that doesn’t exist in the element. You must use UXML or C# to set up the binding that binds to a non-existing property. This example uses UXML to set up the binding.
In the Assets
folder of your project, create a USS file named CustomBinding.uss
with the following contents:
[!code-cs[(Modules/UIElements/Tests/UIElementsExamples/Assets/ui-toolkit-manual-code-examples/runtime-custom-binding/CustomBinding.uss)]
In the Assets
folder of your project, create a UXML file named CustomBinding.uxml
with the following contents:
[!code-cs[(Modules/UIElements/Tests/UIElementsExamples/Assets/ui-toolkit-manual-code-examples/runtime-custom-binding/CustomBinding.uxml)]
Double-click the CustomBinding.uxml
file to open it in UI Builder.
In the StyleSheet panel, select + > Add Existing USS, and then select the CustomBinding.uss
file.
Save your changes.
To test the binding, change the order of the button elements in the UI Builder and observe the changes in the UI Builder Viewport.
CustomBinding.uxml
file to open it in UI Builder.