UXML element Foldout

C# class: Foldout
Namespace: UnityEngine.UIElements
Base class: BindableElement

Member attributes

This element has the following member attributes:

名称	类型	描述
text	string	This is the text of the toggle’s label.
value	boolean	This is the state of the Foldout’s toggle. It is true if the Foldout is open and its contents are visible, and false if the Foldout is closed, and its contents are hidden.

Inherited attributes

This element inherits the following attributes from its base class:

名称	类型	描述
binding-path	string	Path of the target property to be bound.
focusable	boolean	True if the element can be focused.
tabindex	int	An integer used to sort focusables in the focus ring. Must be greater than or equal to zero.

This element also inherits the following attributes from VisualElement:

名称	类型	描述
content-container	string	child elements are added to this element, usually this
name	string	The name of this VisualElement. Use this property to write USS selectors that target a specific element. The standard practice is to give an element a unique name.
picking-mode	UIElements.PickingMode	Determines if this element can be pick during mouseEvents or IPanel.Pick queries.
style	string	Reference to the style object of this element. Contains data computed from USS files or inline styles written to this object in C#.
tooltip	string	Text to display inside an information box after the user hovers the element for a small amount of time.
usage-hints	UIElements.UsageHints	A combination of hint values that specify high-level intended usage patterns for the VisualElement. This property can only be set when the VisualElement is not yet part of a Panel. Once part of a Panel, this property becomes effectively read-only, and attempts to change it will throw an exception. The specification of proper UsageHints drives the system to make better decisions on how to process or accelerate certain operations based on the anticipated usage pattern. Note that those hints do not affect behavioral or visual results, but only affect the overall performance of the panel and the elements within. It’s advised to always consider specifying the proper UsageHints, but keep in mind that some UsageHints might be internally ignored under certain conditions (e.g. due to hardware limitations on the target platform).
view-data-key	string	Used for view data persistence (ie. tree expanded states, scroll position, zoom level). This is the key used to save/load the view data from the view data store. Not setting this key will disable persistence for this VisualElement.

USS classes

The following table lists all the C# public property names and their related USS selector.

C# property	USS selector	描述
ussClassName	.unity-foldout	The USS class name for Foldout elements. Unity adds this USS class to every instance of a Foldout. Any styling applied to this class affects every Foldout located beside, or below the stylesheet in the visual tree.
toggleUssClassName	.unity-foldout__toggle	The USS class name of Toggle sub-elements in Foldout elements. Unity adds this USS class to the Toggle sub-element of every Foldout. Any styling applied to this class affects every Toggle sub-element located beside, or below the stylesheet in the visual tree.
contentUssClassName	.unity-foldout__content	The USS class name for the content element in a Foldout. Unity adds this USS class to the VisualElement that contains the elements to be shown or hidden. Any styling applied to this class affects every foldout container located beside, or below the stylesheet in the visual tree.
inputUssClassName	.unity-foldout__input	The USS class name for the Label element in a Foldout. Unity adds this USS class to the VisualElement that contains the Toggle input elements. Any styling applied to this class affects every foldout container located beside, or below the stylesheet in the visual tree.
checkmarkUssClassName	.unity-foldout__checkmark	The USS class name for the Label element in a Foldout. Unity adds this USS class to the VisualElement that represents the checkmark of the Toggle sub-element of every Foldout. Any styling applied to this class affects every foldout container located beside, or below the stylesheet in the visual tree.
textUssClassName	.unity-foldout__text	The USS class name for the Label element in a Foldout. Unity adds this USS class to the Label in the Toggle sub-element of every Foldout. Any styling applied to this class affects every foldout container located beside, or below the stylesheet in the visual tree.
disabledUssClassName	.unity-disabled	USS class name of local disabled elements.

You can also use the Matching Selectors section in the Inspector or the UI Toolkit Debugger to see which USS selectors affect the components of the visual element at every level of its hierarchy.

Create a Foldout

A Foldout has the following elements:

• Label: A label you can use as the name of the Foldout.
• Toggle: Click the toggle to expand or collapse the container sub-element. It is styled to look like an arrow rather than the default checkbox. When the container is collapsed, the arrow points right. When the container is expanded, the arrow points down.
• Container: A container contains the visual elements that you want to show or hide when you toggle the Foldout.

You can add elements to a Foldout’s container, and the show or hide function works automatically.

The following UI Document creates a Foldout with two buttons in its container. The two buttons show or hide when you toggle the Foldout.

<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">
    <ui:Foldout text="Foldout" name="MyFoldout" value="true">
        <ui:Button text="First item" />
        <ui:Button text="Second item" />
    </ui:Foldout>
</ui:UXML>

You can bind a Foldout to a Boolean variable or access its value through the INotifyValueChanged<bool> interface.

Respond to user actions

A Foldout and its Toggle sub-element respond to Change events. The Toggle hides or shows the Foldout container.

示例

The following C# code snippet creates a Foldout and checks whether the foldout is expanded:

// Create a new foldout, add two elements to it and add it to the container
var cSharpFoldout = new Foldout {text = "Elements"};
cSharpFoldout.Add(new Label("Indented Label"));
cSharpFoldout.Add(new Slider("Indented Slider", 0, 100));
container.Add(cSharpFoldout);

cSharpFoldout.RegisterValueChangedCallback(e =>
{
    // Check whether the foldout is expanded
    if (cSharpFoldout.value)
    {
        Debug.Log("Foldout is expanded");
    }
    else
    {
        Debug.Log("Foldout is collapsed");
    }
});

Additional resource

• UXML element Toggle