ToolStripItem.OnMouseEnter(EventArgs) ToolStripItem.OnMouseEnter(EventArgs) ToolStripItem.OnMouseEnter(EventArgs) ToolStripItem.OnMouseEnter(EventArgs) Method

定义

引发 MouseEnter 事件。Raises the MouseEnter event.

protected:
 virtual void OnMouseEnter(EventArgs ^ e);
protected virtual void OnMouseEnter (EventArgs e);
abstract member OnMouseEnter : EventArgs -> unit
override this.OnMouseEnter : EventArgs -> unit
Protected Overridable Sub OnMouseEnter (e As EventArgs)

参数

e
EventArgs EventArgs EventArgs EventArgs

包含事件数据的 EventArgsAn EventArgs that contains the event data.

示例

下面的代码示例演示如何重写OnMouseEnter方法。The following code example demonstrates how to override the OnMouseEnter method. 此代码示例是为ToolStripItem类提供的更大示例的一部分。This code example is part of a larger example provided for the ToolStripItem class.

// This method defines the behavior of the MouseEnter event.
// It sets the state of the rolloverValue field to true and
// tells the control to repaint.
protected override void OnMouseEnter(EventArgs e)
{
    base.OnMouseEnter(e);

    this.rolloverValue = true;

    this.Invalidate();
}
' This method defines the behavior of the MouseEnter event.
' It sets the state of the rolloverValue field to true and
' tells the control to repaint.
Protected Overrides Sub OnMouseEnter(e As EventArgs)
   MyBase.OnMouseEnter(e)
   
   Me.rolloverValue = True
   
   Me.Invalidate()
 End Sub

注解

引发事件时,将通过委托调用事件处理程序。Raising an event invokes the event handler through a delegate. 有关详细信息, 请参阅处理和引发事件For more information, see Handling and Raising Events.

OnMouseEnter 方法还允许派生类对事件进行处理而不必附加委托。The OnMouseEnter method also allows derived classes to handle the event without attaching a delegate. 这是在派生类中处理事件的首选技术。This is the preferred technique for handling the event in a derived class.

继承者说明

在派生类中重写 OnMouseEnter(EventArgs) 时,一定要调用基类的 OnMouseEnter(EventArgs) 方法,以便已注册的委托对事件进行接收。When overriding OnMouseEnter(EventArgs) in a derived class, be sure to call the base class's OnMouseEnter(EventArgs) method so that registered delegates receive the event.

适用于