Click events

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 elements 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.

独特的属性

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.

事件列表

ClickEvent

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); 
}

示例

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.

要查看示例运行效果，请执行以下操作：

1. Create a new C# script called ClickEventExampleWindow.
2. 将该示例代码复制到 C# 脚本。
3. Under Window > UI Toolkit > Click Event Example, open the newly created Editor window.

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));
  }
}