A ClickEvent occurs when the user clicks the left mouse button (or the first button on a pointing device) over a VisualElement.
A click consists of a pointer down event followed by a pointer up event on the same VisualElement. The pointer is allowed to move between the two events, as long as the down and up events occur over the same VisualElement.
This event can be used to detect clicks on 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 that aren’t buttons. For example, the implementation of the Toggle
control uses the ClickEvent
to show or hide the check mark, and to change the control’s value.
The base class for ClickEvent
is PointerEventBase. For more information please also see the documentation on Pointer Events.
Event | Description | Trickles down | Bubbles up | Cancellable |
---|---|---|---|---|
ClickEvent | Occurs when the left mouse button is clicked. | ✔ | ✔ | ✔ |
The ClickEvent
has no unique properties, but inherits all properties from its base class. You can find a list of properties on the Pointer Events page.
Unity sends this event when the left mouse button is clicked over a visual element.
target
: The element underneath the mouse or pointing device when the click occurred.
The following example registers for a ClickEvent
on a visual element:
btnClose.RegisterCallback<ClickEvent, VisualElement>(Clicked, asset); // asset is the root visual element that will be closed
private void Clicked(ClickEvent evt, VisualElement root)
{
root.ShowVisualElement(false);
}
The following example shows how to react to the ClickEvent on a colored visual element. When an element is clicked, its color will change to a new, random color.
To see the example in action, do the following:
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;
public class ClickEventExampleWindow : EditorWindow
{
[MenuItem("Window/UI Toolkit/ClickEventExample")]
public static void ShowExample()
{
var wnd = GetWindow<ClickEventExampleWindow>();
wnd.titleContent = new GUIContent("Click Event Example");
}
public void CreateGUI()
{
// Create a few different colored boxes
for (int i = 0; i < 4; i++)
{
// Create VisualElement with random background color
var newBox = new VisualElement() { style = { flexGrow = 1, backgroundColor = GetRandomColor() } };
rootVisualElement.Add(newBox);
// Register a click event to the visual element to change the background color to a new color
newBox.RegisterCallback<ClickEvent>(OnBoxClicked);
}
}
private void OnBoxClicked(ClickEvent evt)
{
// Only perform this action at the target, not in a parent
if (evt.propagationPhase != PropagationPhase.AtTarget)
return;
// Assign a random new color
var targetBox = evt.target as VisualElement;
targetBox.style.backgroundColor = GetRandomColor();
}
private Color GetRandomColor()
{
return new Color(Random.Range(0, 1f), Random.Range(0, 1f), Random.Range(0, 1f));
}
}