Version: 2022.3
Language : English
Migrate from Unity UI (uGUI) to UI Toolkit
Unity UI

Migrate from Immediate Mode GUI (IMGUI) to UI Toolkit

This guide is for developers experienced with Immediate Mode GUI (IMGUI) to migrate to UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary
Toolkit. This guide focuses on the Editor UI, but its information can also apply to the runtime UI as well.

Key differences

Code-driven versus UI-driven

IMGUI is code-driven by calls to the OnGUI function in an C# script which implements it. UI Toolkit provides more options for Editor UI creation. With UI Toolkit, you define the behaviors 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
. However, when defining UI elements and styles, in addition to C#, you can visually define UI controls in UI Builder or write in an XML-like text file (called UXML) directly. For more information, see Simple UI Toolkit workflow.

Immediate versus retained mode

With IMGUI, you describe the UI tree when the UI is repainted within the OnGUI() function. You must call this function when an event enters the UI or when you repaint the UI. There is no persistent information pertaining the UI tree between different events. Whereas, you create visual elementsA 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
with UI Toolkit in a tree structure called Visual TreeAn object graph, made of lightweight nodes, that holds all the elements in a window or panel. It defines every UI you build with the UI Toolkit.
See in Glossary
. Information in the Visual Trees is retained persistently.

Constant versus state changes

IMGUI is based around the OnGUI() function that runs at least once every frame. You define the look and the behaviors of the UI for every possible frame. The body of OnGUI() might contain many conditions and different states.

UI Toolkit operates in an event-driven system. You define the look of the UI in its default state and define the behaviors of the UI in response to events. Any changes you make in UI Toolkit cause persistent changes to the state of your UI.

For example, the declaration of a button in IMGUI looks like the following:

if (GUILayout.Button("Click me!"))
    //Code runs here in frames where the user clicks the button.

    //Code makes changes to the UI for frames where the user has just clicked the button.
    //Code specifies what happens in all other frames.

The example above looks like the following in UI Toolkit:

UIDocument document = GetComponent<UIDocument>();

//Create button.
Button button = new Button();
button.text = "Click me!";

//Set up event handler.
button.RegisterCallback<ClickEvent>((ClickEvent evt) =>
    //Code runs here after button receives ClickEvent.

//Add button to UI.

For a completed example on how to create a custom Editor window with UI Toolkit, see Simple UI Toolkit workflow.

IMGUI support

Use the IMGUIContainer to place IMGUI code inside of a VisualElement. Everything you can do inside of OnGUI() is supported.

You can arrange multiple IMGUIContainers and lay them out by mixing GUILayout and UI Toolkit layouts. Note that it’s not possible to add VisualElement instances inside of an IMGUIContainer.

IMGUIContainer example
IMGUIContainer example

From IMGUI to UI Toolkit conversion

The following table lists the equivalent functions between IMGUI and UI Toolkit:

Action IMGUI UI Toolkit
Create an Editor Window EditorWindow.OnGUI() EditorWindow.CreateGUI()
Create a Property DrawerA Unity feature that allows you to customize the look of certain controls in the Inspector window by using attributes on your scripts, or by controlling how a specific Serializable class should look More info
See in Glossary
or a Property Attribute
PropertyDrawer.OnGUI() PropertyDrawer.CreatePropertyGUI()
Create a custom Editor for the InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
See in Glossary
Editor.OnInspectorGUI() Editor.CreateInspectorGUI()

The following table lists the equivalent methods, classes, attributes between IMGUI and UI Toolkit:

IMGUI IMGUI namespaces UI Toolkit
AddCursorRect() EditorGUIUtility Set, or set a visual element’s cursor texture in the UI Builder or USS. For more detailed interactivity, use C# events.
AreaScope GUILayout Scopes are generally not needed in UI Toolkit. See BeginArea().
BeginArea() GUILayout To define the area itself, create a visual element and set style.position to Position.Absolute. To create children for the area, create child visual elements under it.
BeginBuildTargetSelectionGrouping() EditorGUILayout No equivalent.
BeginChangeCheck() EditorGUI Register callbacks on each element in the change check range. If using a PropertyField as a stand-in for a serialized field in a custom Inspector, use PropertyField.RegisterCallback<SerializedPropertyChangeEvent>() or PropertyField.RegisterValueChangeCallback(). In all other cases, use VisualElement.RegisterCallback<ChangeEvent<T>>() or VisualElement.RegisterValueChangedCallback<T>().
BeginDisabledGroup() EditorGUI VisualElement.SetEnabled(false)
BeginFoldoutHeaderGroup() EditorGUI, EditorGUILayout See Foldout().
BeginGroup() GUI See BeginArea().
BeginHorizontal() EditorGUILayout, GUILayout See BeginArea().
BeginProperty() EditorGUI If you use BeginProperty()/EndProperty() to bind a simple control to a serialized property, you can do that in UI Toolkit by calling BindProperty(), by setting bindingPath, or by setting the binding-path UXML attribute. If you use BeginProperty()/EndProperty() to make a single property out of complex custom UI, that is not supported well in UI Toolkit.
BeginScrollView() EditorGUILayout, GUI, GUILayout UnityEngine.UIElements.ScrollView
BeginToggleGroup() EditorGUILayout No equivalent.
BeginVertical() EditorGUILayout, GUILayout See BeginArea().
BoundsField() EditorGUI, EditorGUILayout BoundsField
BoundsIntField() EditorGUI, EditorGUILayout BoundsIntField
Box() GUI, GUILayout Box
BringWindowToBack() GUI See Window().
BringWindowToFront() GUI See Window().
Button() GUI, GUILayout Button
CanCacheInspectorGUI() EditorGUI Not needed in retained mode.
ChangeCheckScope EditorGUI Scopes are generally not needed in UI Toolkit. See BeginChangeCheck().
ColorField() EditorGUI, EditorGUILayout ColorField
CommandEvent() EditorGUIUtility Generally not needed in retained mode. Use C# callbacks to handle events.
CurveField() EditorGUI, EditorGUILayout CurveField
DelayedDoubleField() EditorGUI, EditorGUILayout DoubleField with isDelayed set to true.
DelayedFloatField() EditorGUI, EditorGUILayout FloatField with isDelayed set to true.
DelayedIntField() EditorGUI, EditorGUILayout IntegerField with isDelayed set to true.
DelayedTextField() EditorGUI, EditorGUILayout TextField with isDelayed set to true.
DisabledScope EditorGUI Scopes are generally not needed in UI Toolkit. See BeginDisabledGroup().
DoubleField() EditorGUI, EditorGUILayout DoubleField
DragWindow() GUI See Window().
DrawPreviewTexture() EditorGUI No equivalent.
DrawRect() EditorGUI Use VisualElement. Set style.position to Absolute. Set and style.left to define the position. Set style.width and style.height to define the size. Set style.backgroundColor to set the color.
DrawTexture() GUI Image. Set tintColor in place of color. There is no equivalent for a false alphaBlend. There are no equivalents for borderWidth, borderWidths, borderRadius, or borderRadiuses.
DrawTextureAlpha() EditorGUI No equivalent.
DrawTextureWithTexCoords() GUI Image. Set uv in place of texCoords. There is no equivalent for a false alphaBlend.
DropdownButton() EditorGUI, EditorGUILayout No exact equivalent. Use fully-fledged DropdownFields instead of just a DropdownButton().
DropShadowLabel() EditorGUI Label with shadow values set in style.textShadow.
EditorToolbar() EditorGUILayout Create a Toolbar with one ToolbarButton for each tool. For each ToolbarButton, register a callback when clicked to call either ToolManager.SetActiveTool() or ToolManager.RestorePreviousTool() to make that button activate the tool or deactivate it, respectively.
EndArea() GUILayout See BeginArea().
EndBuildTargetSelectionGrouping() EditorGUILayout See BeginBuildTargetSelectionGrouping().
EndChangeCheck() EditorGUI See BeginChangeCheck().
EndDisabledGroup() EditorGUI See BeginDisabledGroup().
EndFoldoutHeaderGroup() EditorGUI, EditorGUILayout See Foldout().
EndGroup() GUI See BeginArea().
EndHorizontal() EditorGUILayout, GUILayout See BeginArea().
EndProperty() EditorGUI See BeginProperty().
EndScrollView() EditorGUILayout, GUI, GUILayout See BeginScrollView().
EndToggleGroup() EditorGUILayout See BeginToggleGroup().
EndVertical() EditorGUILayout, GUILayout See BeginArea().
EnumFlagsField() EditorGUI, EditorGUILayout EnumFlagsField
EnumPopup() EditorGUI, EditorGUILayout EnumField
ExpandHeight() GUILayout No equivalent.
ExpandWidth() GUILayout No equivalent.
FlexibleSpace() GUILayout See Space().
FloatField() EditorGUI, EditorGUILayout FloatField
FocusControl() GUI VisualElement.Focus()
FocusTextInControl() EditorGUI TextField.Focus()
FocusWindow() GUI See Window().
Foldout() EditorGUI, EditorGUILayout Foldout
GetControlRect() EditorGUILayout Only needed to convert from EditorGUILayout to EditorGUI. Not needed in UI Toolkit.
GetNameOfFocusedControl() GUI VisualElement.focusController.focusedElement
GetPropertyHeight() EditorGUI PropertyField.layout.height
GradientField() EditorGUI, EditorGUILayout GradientField
GroupScope GUI Scopes are generally not needed in UI Toolkit. See BeginArea().
Height() GUILayout
HelpBox() EditorGUI, EditorGUILayout HelpBox
HorizontalScope EditorGUILayout, GUILayout Scopes are generally not needed in UI Toolkit. See BeginArea().
HorizontalScrollbar() GUI, GUILayout Scroller with direction set to Horizontal.
HorizontalSlider() GUI, GUILayout Slider with direction set to Horizontal
InspectorTitlebar() EditorGUI, EditorGUILayout No equivalent.
IntField() EditorGUI, EditorGUILayout IntegerField
IntPopup() EditorGUI, EditorGUILayout No equivalent.
IntSlider() EditorGUI, EditorGUILayout SliderInt
Label() GUI, GUILayout Label
LabelField() EditorGUI, EditorGUILayout TextField with isReadOnly set to true.
LayerField() EditorGUI, EditorGUILayout LayerField
LinkButton() EditorGUI, EditorGUILayout No equivalent.
Load() EditorGUIUtility If using C#, you can use this function as is and assign its return value to the property you want. If using USS, use function resource() with the same argument you would give to Load().
LongField() EditorGUI, EditorGUILayout LongField
MaskField() EditorGUI, EditorGUILayout MaskField
MaxHeight() GUILayout
MaxWidth() GUILayout
MinHeight() GUILayout
MinMaxSlider() EditorGUI, EditorGUILayout MinMaxSlider
MinWidth() GUILayout
ModalWindow() GUI See Window().
[NonReorderable] attribute Ensure that ListView.reorderable is false.
ObjectField() EditorGUI, EditorGUILayout ObjectField
PasswordField() EditorGUI, EditorGUILayout, GUI, GUILayout TextField with isPasswordField set to true
PixelsToPoints() EditorGUIUtility Valid for use with UI Toolkit.
PointsToPixels() EditorGUIUtility Valid for use with UI Toolkit.
Popup() EditorGUI, EditorGUILayout PopupField<T0>
ProgressBar() EditorGUI ProgressBar
PropertyField() EditorGUI, EditorGUILayout PropertyField
PropertyScope EditorGUI Scopes are generally not needed in UI Toolkit. See BeginProperty().
RectField() EditorGUI, EditorGUILayout RectField
RectIntField() EditorGUI, EditorGUILayout RectIntField
RepeatButton() GUI, GUILayout RepeatButton
ScrollTo() GUI ScrollView.ScrollTo() or ScrollView.scrollOffset
ScrollViewScope EditorGUILayout, GUI, GUILayout Scopes are generally not needed in UI Toolkit. See BeginScrollView().
SelectableLabel() EditorGUI, EditorGUILayout Label with isSelectable and focusable set to true.
SelectionGrid() GUI, GUILayout RadioButton
SetNextControlName() GUI
singleLineHeight EditorGUIUtility Use USS variable --unity-metrics-single_line-height.
Slider() EditorGUI, EditorGUILayout Slider
Space() EditorGUILayout, GUILayout Use flex properties to configure spacing between visual elements.
TagField() EditorGUI, EditorGUILayout TagField
TextArea() EditorGUI, EditorGUILayout, GUI, GUILayout TextField with multiline set to true, style.whiteSpace set to Normal, and ScrollView.verticalScrollerVisibility set to Auto.
TextField() EditorGUI, EditorGUILayout, GUI, GUILayout TextField with multiline set to true and style.whiteSpace set to NoWrap.
Toggle() EditorGUI, EditorGUILayout, GUI, GUILayout Toggle
ToggleGroupScope EditorGUILayout Scopes are generally not needed in UI Toolkit. See BeginToggleGroup().
ToggleLeft() EditorGUI, EditorGUILayout Toggle, but instead of setting label, set text.
Toolbar() GUI, GUILayout No equivalent.
UnfocusWindow() GUI See Window().
Vector2Field() EditorGUI, EditorGUILayout Vector2Field
Vector2IntField() EditorGUI, EditorGUILayout Vector2IntField
Vector3Field() EditorGUI, EditorGUILayout Vector3Field
Vector3IntField() EditorGUI, EditorGUILayout Vector3IntField
Vector4Field() EditorGUI, EditorGUILayout Vector4Field
VerticalScope EditorGUILayout, GUILayout Scopes are generally not needed in UI Toolkit. See BeginArea().
VerticalScrollbar() GUI, GUILayout Scroller with direction set to Vertical.
VerticalSlider() GUI, GUILayout Slider with direction set to Vertical.
Width() GUILayout
Window() GUI, GUILayout No equivalent.

Additional resources

Migrate from Unity UI (uGUI) to UI Toolkit
Unity UI