DropdownField
UnityEngine.UIElements.DropdownField
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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.
참고
To align an element with other fields in an Inspector window, simply apply the USS class to it. For more information, refer to .
.unity-base-field__alignedBaseFieldCreate a DropdownField
You can create a DropdownField with UI Builder, UXML, or C#.
UI Builder
To add options for a DropdownField in UI Builder, in the Inspector panel of the DropdownField, set the options in the Choices field.
To set the default value, in the Inspector of the DropdownField, enter the numbering sequence of the option in Index, starting at .
0C#
The following C# example create a DropdownField with three options. The DropdownField selects the first option by default but you can change the default value by setting the property.
indexvar dropdown = new DropdownField(new List<string> { "Option 1", "Option 2", "Option 3" }, 0); // Add another option. dropdown.choices.Add("Option 4"); // To return int value instead of string. dropdown.index = 1; // Option 2 dropdown.value = "Option 3"; // Set to an existing value // Assert that the index is set correctly. Assert.IsTrue(dropdown.index == 2); // Register to the value changed callback. dropdown.RegisterValueChangedCallback(evt => Debug.Log(evt.newValue)); // Style the dropdown. dropdown.style.width = 200; dropdown.style.height = 50;
The UI looks like this:
DropdownField Example
Change styles for a DropdownField
You can override the default Panel Settings fields in a USS file to change the styles of a DropdownField:
- 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.
Examples
The following UXML example creates a DropdownField:
<UXML xmlns="UnityEngine.UIElements" xmlns:uie="UnityEditor.UIElements"> <DropdownField label="UXML Field" name="the-uxml-field" /></UXML>
The following USS example styles the DropdownField:
.some-styled-field { -unity-font-style: bold;}
The following C# example illustrates some of the customizable functionalities of the DropdownField:
// You can provide the list of choices by code, or by comma separated values in UXML // <DropdownField .... choices="Option 1,Option 2,Option 3" .... /> var choices = new List<string> { "Option 1", "Option 2", "Option 3" }; // Get a reference to the dropdown field from UXML and assign a value to it. var uxmlField = container.Q<DropdownField>("the-uxml-field"); uxmlField.choices = choices; uxmlField.value = choices[0]; // Create a new dropdown with the same choices, disable it, and give it a style class. var csharpField = new DropdownField("C# Field", choices, 0); csharpField.SetEnabled(false); csharpField.AddToClassList("some-styled-field"); container.Add(csharpField); // Mirror the value of the UXML field into the C# field. uxmlField.RegisterCallback<ChangeEvent<string>>((evt) => { csharpField.value = evt.newValue; });
To try this example live in Unity, go to Window > UI Toolkit > Samples.
C# base class and namespace
C# class:
DropdownFieldNamespace:
UnityEngine.UIElementsBase class:
PopupField_1Inherited UXML attributes
This element inherits the following attributes from its base class:
Name | Type | Description |
|---|---|---|
| | Path of the target property to be bound. |
| | The list of choices to display in the popup menu. |
| | Whether an element can potentially receive focus. If false, the element can't receive focus. If true, the element receives focus only when its |
| | The currently selected index in the popup menu. Setting the index updates the |
| | The string representing the label that will appear beside the field. If the string is empty, the label element is removed from the hierarchy. If the string is not empty, the label element is added to the hierarchy. |
| | An integer used to sort focusable elements in the focus ring. Must be greater than or equal to zero. Setting the |
| | The currently selected value in the popup menu. |
This element also inherits the following attributes from :
VisualElementName | Type | Description |
|---|---|---|
| | Logical container where child elements are added. If a child is added to this element, the child is added to this element's content container instead. When iterating over the If the content container is the same as the element itself, child elements are added directly to the element. This is true for most elements but can be overridden by more complex types. The |
| | Assigns a data source to this VisualElement which overrides any inherited data source. This data source is inherited by all children. |
| | Path from the data source to the value. |
| | The possible type of data source assignable to this VisualElement. This information is only used by the UI Builder as a hint to provide some completion to the data source path field when the effective data source cannot be specified at design time. |
| | Returns true if the This flag isn't changed if the VisualElement is disabled implicitly by one of its parents. To verify this, use |
| | Indicates the directionality of the element's text. The value will propagate to the element's children. |
| | 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. |
| | Determines if this element can be the target of pointer events or picked by Elements can not be picked if: - They are invisible- Their Elements with a picking mode of |
| | Sets the style values on a The returned style data, computed from USS files or inline styles written to this object in C#, doesn't represent the fully resolved styles, such as the final height and width of a VisualElement. To access these fully resolved styles, use For information about how to use this property and all the supported USS properties, refer to the Apply styles in C# scripts and USS properties reference manual pages. |
| | 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. |
| | A combination of hint values that specify high-level intended usage patterns for the |
| | Used for view data persistence, such as tree expanded states, scroll position, or zoom level. This key is used to save and load the view data from the view data store. If you don't set this key, the persistence is disabled for the associated |
USS classes
The following table lists all the C# public property names and their related USS selector.
C# property | USS selector | Description |
|---|---|---|
| | USS class name of elements of this type. |
| | USS class name of labels in elements of this type. |
| | USS class name of input elements in elements of this type. |
| | USS class name of elements of this type. |
| | USS class name of text elements in elements of this type. |
| | USS class name of arrow indicators in elements of this type. |
| | USS class name of labels in elements of this type. |
| | USS class name of input elements in elements of this type. |
| | USS class name of elements of this type. |
| | USS class name of labels in elements of this type. |
| | USS class name of input elements in elements of this type. |
| | USS class name of elements of this type, when there is no label. |
| | USS class name of labels in elements of this type, when there is a dragger attached on them. |
| | USS class name of elements that show mixed values |
| | USS class name of elements that are aligned in a inspector element |
| | 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 at every level of its hierarchy.
VisualElement