ComboBox.DropDownOpened 事件

  • 参考

定义

命名空间:
System.Windows.Controls
程序集:
PresentationFramework.dll

当打开组合框的下拉列表时发生。

public:
 event EventHandler ^ DropDownOpened;
public event EventHandler DropDownOpened;
member this.DropDownOpened : EventHandler 
Public Custom Event DropDownOpened As EventHandler

事件类型

EventHandler

示例

以下示例演示如何分配事件处理程序并处理 DropDownOpened 和 DropDownClosed 事件。

<ComboBox Name="cb" StaysOpenOnEdit="true" IsEditable="true" DropDownOpened="OnDropDownOpened" 
        DropDownClosed="OnDropDownClosed">

void OnDropDownOpened(object sender, EventArgs e)
{
    if (cb.IsDropDownOpen == true)
    {
        cb.Text = "Combo box opened";
    }
}

void OnDropDownClosed(object sender, EventArgs e)
{
    if (cb.IsDropDownOpen == false)
    {
        cb.Text = "Combo box closed";
    }
}

Private Sub OnDropDownOpened(ByVal Sender As Object, ByVal e As EventArgs)

    If (cb.IsDropDownOpen = True) Then
        cb.Text = "Combo box opened"
    End If

End Sub

Private Sub OnDropDownClosed(ByVal Sender As Object, ByVal e As EventArgs)

    If (cb.IsDropDownOpen = False) Then
        cb.Text = "Combo box closed"
    End If

End Sub

适用于