The Tooltip event is sent to check if a visual element underneath the pointer is able to display a tooltip. This is an Editor-only event.
Tooltips are usually set using the tooltip
property. You can also respond to the Tooltip event to set tooltips.
You can handle the Tooltip event in two ways:
TooltipEvent
. This adds a tooltip to a visual element that doesn’t have one set. This can also override the tooltip set to a visual element.ExecuteDefaultAction
method.If you set the callback or implement a custom visual element to declare tooltips, don’t set the value for the tooltip
property via code or UXML.
When you set a tooltip
property, the visual element under the mouse cursor automatically registers a callback to handle the TooltipEvent
. This callback also stops further propagation of the event.
If you register a custom callback to handle the TooltipEvent
, you must stop the propagation of the event, or the tooltip can be overridden later in the propagation phase.
The base class for Tooltip events is the EventBase class.
Event | Description | Trickles down | Bubbles up | Cancellable |
---|---|---|---|---|
TooltipEvent | Sent just before Unity displays a tooltip. | Yes | Yes | Yes |
rect
: Rectangle of the hovered visual element in the panel coordinate system.
tooltip
: The tooltip
property is a text string to display inside the tooltip box during the tooltip
event. The following callback event sets the tooltip property during the event:
evt.tooltip = "Tooltip set by parent!";
The TooltipEvent
is sent just before the Unity Editor displays a tooltip. The handler should set the TooltipEvent.tooltip
string and the TooltipEvent.rect
.
target
: The visual element under the mouse.
The following examples display the behavior of the ToolTipEvent
.
To view an example:
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;
public class SampleWindow : EditorWindow
{
[MenuItem("Window/UI Toolkit/SampleWindow")]
public static void ShowExample()
{
SampleWindow wnd = GetWindow<SampleWindow>();
wnd.titleContent = new GUIContent("SampleWindow");
}
public void CreateGUI()
{
VisualElement label = new Label("Hello World! This is a UI Toolkit Label.");
rootVisualElement.Add(label);
label.tooltip = "And this is a tooltip";
// If you comment out the registration of the callback, the tooltip that displays for the label is "And this is a tooltip".
// If you keep the registration of the callback, the tooltip that displays for the label (and any other child of rootVisualElement)
// is "Tooltip set by parent!".
rootVisualElement.RegisterCallback<TooltipEvent>(evt =>
{
evt.tooltip = "Tooltip set by parent!";
evt.rect = (evt.target as VisualElement).worldBound;
evt.StopPropagation();
}, TrickleDown.TrickleDown); // Pass the TrickleDown.TrickleDown parameter to intercept the event before it reaches the label.
}
}
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;
public class SampleWindow : EditorWindow
{
[MenuItem("Window/UI Toolkit/SampleWindow")]
public static void ShowExample()
{
SampleWindow wnd = GetWindow<SampleWindow>();
wnd.titleContent = new GUIContent("SampleWindow");
}
private void CreateGUI()
{
CustomLabel custom1 = new CustomLabel("custom 1");
rootVisualElement.Add(custom1);
CustomLabel custom2 = new CustomLabel("custom 2");
rootVisualElement.Add(custom2);
}
}
public class CustomLabel : Label
{
private static int m_InstanceCounter = 0;
private int m_CurrentCounter;
public CustomLabel(string labelText) : base(labelText)
{
m_CurrentCounter = m_InstanceCounter++;
}
protected override void ExecuteDefaultAction(EventBase evt)
{
// Other events need to be handled as usual.
base.ExecuteDefaultAction(evt);
if (evt.eventTypeId == TooltipEvent.TypeId())
{
TooltipEvent e = (TooltipEvent)evt;
// Apply an offset to the tooltip position.
var tooltipRect = new Rect(worldBound);
tooltipRect.x += 10;
tooltipRect.y += 10;
e.rect = tooltipRect;
// Set a custom/dynamic tooltip.
e.tooltip = $"This is instance # {m_CurrentCounter + 1} of my CustomLabel";
// Stop propagation avoids other instances of handling of the event that may override the values set here.
e.StopPropagation();
}
}
}