UXML element DropdownField

A DropdownField lets users choose a value from a list. When clicking on the control, it opens a drawer that presents multiple options, allowing users to select one. If you want to always display all the choices, use RadioButtonGroup.

Respond to user actions

A DropdownField responds to Change events.

You can bind a DropdownField to a string variable that holds the selected choice value.

Add options for a DropdownField in UI Builder

To add options for a DropdownField, in the Inspector of the DropdownField, enter the options separated by commas in Choices.

To set the default value, in the Inspector of the DropdownField, enter the numbering sequence of the option in Index, starting at 0.

Create a DropdownField in C# script

The following C# code snippets create a DropdownField with three options. The DropdownField selects the first option by default.

var dropdown = new DropdownField("Options", new List<string> { "Option 1", "Option 2", "Option 3" }, 0);
dropdown.RegisterValueChangedCallback(evt => Debug.Log(evt.newValue));
rootVisualElement.Add(dropdown);

Change styles for a DropdownField

Override the default Panel Settings fields in a USS file to change the styles of a DropdownField in Unity:

In the Hierarchy window, select your UI Document (.uxml).
Set Panel Settings as your Panel Settings asset. If you don’t have an existing Panel Settings asset, follow the instructions in the dialog to create one.
In your Panel Settings asset, assign a Theme Style Sheet.
In the Project window, select your TSS file.
Go to Style Sheets and select the Add (+) button.
Set your Style Sheet as your USS file.

예제

The best way to learn how to use DropdownField is to try an example. To see a DropdownField example, in Unity, select Window > UI Toolkit > Samples > DropdownField.

C# base class and namespace

C# class: DropdownField
Namespace: UnityEngine.UIElements
Base class: PopupField_1

Inherited UXML attributes

This element inherits the following attributes from its base class:

Name	타입	설명
`binding-path`	`string`	Path of the target property to be bound.
`choices`	`string`	The list of choices to display in the popup menu.
`focusable`	`boolean`	True if the element can be focused.
`index`	`int`	The currently selected index in the popup menu.
`label`	`string`	The string representing the label that will appear beside the field.
`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:

Name	타입	설명
`content-container`	`string`	Child elements are added to it, usually this is the same as the element itself.
`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. This is only supported in the Editor UI.
`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	설명
`ussClassName`	`.unity-popup-field`	USS class name of elements of this type.
`labelUssClassName`	`.unity-popup-field__label`	USS class name of labels in elements of this type.
`inputUssClassName`	`.unity-popup-field__input`	USS class name of input elements in elements of this type.
`ussClassName`	`.unity-base-popup-field`	USS class name of elements of this type.
`textUssClassName`	`.unity-base-popup-field__text`	USS class name of text elements in elements of this type.
`arrowUssClassName`	`.unity-base-popup-field__arrow`	USS class name of arrow indicators in elements of this type.
`labelUssClassName`	`.unity-base-popup-field__label`	USS class name of labels in elements of this type.
`inputUssClassName`	`.unity-base-popup-field__input`	USS class name of input elements in elements of this type.
`ussClassName`	`.unity-base-field`	USS class name of elements of this type.
`labelUssClassName`	`.unity-base-field__label`	USS class name of labels in elements of this type.
`inputUssClassName`	`.unity-base-field__input`	USS class name of input elements in elements of this type.
`noLabelVariantUssClassName`	`.unity-base-field--no-label`	USS class name of elements of this type, when there is no label.
`labelDraggerVariantUssClassName`	`.unity-base-field__label--with-dragger`	USS class name of labels in elements of this type, when there is a dragger attached on them.
`mixedValueLabelUssClassName`	`.unity-base-field__label--mixed-value`	USS class name of elements that show mixed values
`alignedFieldUssClassName`	`.unity-base-field__aligned`	USS class name of elements that are aligned in a inspector element
`disabledUssClassName`	`.unity-disabled`	USS class name of local disabled elements.

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