You can write to style to set style values to an element. However, to get the actually rendered styles of an element, read from resolvedStyle.
In a C# script, you can set styles directly to the style properties of a visual elementA 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. For example, the following code sets the background color of a button to red:
button.style.backgroundColor = Color.red
You can also add a Unity style sheet (USS) to any visual element. Unity represents USS files as StyleSheet objects in 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.
To add style sheets to a visual element:
StyleSheet objects with standard Unity APIs, such as AssetDatabase.Load() or Resources.Load().styleSheets property of a visual element to add the StyleSheet object.For example, given a style sheet in the local variable styleSheet and an element in the local variable element, the following example adds the style sheet to the element:
element.styleSheets.Add(styleSheet);
Note: Style rules apply to the visual element and all its descendants, but don’t apply to the parent or siblings of the element. Any change to the USS file automatically refreshes the UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary that uses this style sheet.
Style values on an element are computed from various sources, including multiple applied classes, inheritance from ancestors, and inline styles from UXML or C# code. These values might change from frame to frame. The style only holds the inline styles for the element and doesn’t reflect other sources. The resolvedStyle has the final calculated values, considering all sources on the current frame.
For example, when you use the inline style to set the height for an element, both the style and resolvedStyle start with the same value. When the element is added to the hierarchy, resolvedStyle.height can be NaN until the layout updates. If you define the height in a class as a percentage, the computed width relies on parent properties such as border-height and padding. Although style.height might give a relative value, such as for transitions that can change the value, resolvedStyle.height gives the actual rendered height.
To get the resolved style when the geometry changes, you can use the GeometryChangedEvent event. This event is triggered when the layout of a VisualElement changes, which includes changes in size and position. You can register a callback for this event and in the callback, you can access the resolvedStyle property of the VisualElement to get the final computed styles.
The following example creates a custom Editor window and logs the resolved height of an element. The height of the element changes if you resize the window:
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;
public class ResolvedStyles : EditorWindow
{
[MenuItem("Window/UI Toolkit/ResolvedStyles")]
public static void ShowExample()
{
GetWindow<ResolvedStyles>();
}
private void OnEnable()
{
titleContent = new GUIContent("Resolved Styles");
}
public void CreateGUI()
{
VisualElement root = rootVisualElement;
// Element that is tracked.
// When you resize the Editor window, the inner content is not necessarily updated
// during the drag operation. The resolved height field is updated whenever the drag
// operation is complete.
var element = new VisualElement
{
style =
{
flexGrow = 1,
backgroundColor = Color.red
}
};
root.Add(element);
// Register a callback for the GeometryChangedEvent
element.RegisterCallback<GeometryChangedEvent>(OnGeometryChanged);
}
// Callback for the GeometryChangedEvent
public void OnGeometryChanged(GeometryChangedEvent evt)
{
// Get the VisualElement that triggered the event
VisualElement element = evt.target as VisualElement;
// Get the resolved style of the VisualElement
float height = element.resolvedStyle.height;
// Log the resolved of the VisualElement
Debug.Log("Resolved height: " + height);
}
}
If the element’s geometry doesn’t change, you can add a scheduler to periodically check the resolved style of the element:
element.schedule.Execute(() =>
{
Debug.Log(element.resolvedStyle.height);
}).Every(100);