Control.OnControlRemoved(ControlEventArgs) 方法

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

Source:

Control.cs

引发 ControlRemoved 事件。

C#

protected virtual void OnControlRemoved(System.Windows.Forms.ControlEventArgs e);

参数

e

ControlEventArgs

包含事件数据的 ControlEventArgs。

示例

下面的代码示例使用 ControlRemoved 从窗体中删除控件，并在 中 MessageBox显示已删除的控件的名称。

C#

// This example demonstrates the use of the ControlAdded and
// ControlRemoved events. This example assumes that two Button controls
// are added to the form and connected to the addControl_Click and
// removeControl_Click event-handler methods.
private void Form1_Load(object sender, System.EventArgs e)
{
    // Connect the ControlRemoved and ControlAdded event handlers
    // to the event-handler methods.
    // ControlRemoved and ControlAdded are not available at design time.
    this.ControlRemoved += new System.Windows.Forms.ControlEventHandler(this.Control_Removed);
    this.ControlAdded += new System.Windows.Forms.ControlEventHandler(this.Control_Added);
}

private void Control_Added(object sender, System.Windows.Forms.ControlEventArgs e)
{
    MessageBox.Show("The control named " + e.Control.Name + " has been added to the form.");
}

private void Control_Removed(object sender, System.Windows.Forms.ControlEventArgs e)
{
    MessageBox.Show("The control named " + e.Control.Name + " has been removed from the form.");
}

// Click event handler for a Button control. Adds a TextBox to the form.
private void addControl_Click(object sender, System.EventArgs e)
{
    // Create a new TextBox control and add it to the form.
    TextBox textBox1 = new TextBox();
    textBox1.Size = new Size(100,10);
    textBox1.Location = new Point(10,10);
    // Name the control in order to remove it later. The name must be specified
    // if a control is added at run time.
    textBox1.Name = "textBox1";

    // Add the control to the form's control collection.
    this.Controls.Add(textBox1);
}

// Click event handler for a Button control.
// Removes the previously added TextBox from the form.
private void removeControl_Click(object sender, System.EventArgs e)
{
    // Loop through all controls in the form's control collection.
    foreach (Control tempCtrl in this.Controls)
    {
        // Determine whether the control is textBox1,
        // and if it is, remove it.
        if (tempCtrl.Name == "textBox1")
        {
            this.Controls.Remove(tempCtrl);
        }
    }
}

注解

从控件中删除子控件时调用。

引发事件时，将通过委托调用事件处理程序。 有关详细信息，请参阅 处理和引发事件。

OnControlRemoved 方法还允许派生类对事件进行处理而不必附加委托。 这是在派生类中处理事件的首选技术。

继承者说明

在派生类中重写 OnControlRemoved(ControlEventArgs) 时，一定要调用基类的 OnControlRemoved(ControlEventArgs) 方法，以便已注册的委托对事件进行接收。

适用于

另请参阅

• ControlRemoved