DateTimePicker.DropDown 事件

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

來源:

DateTimePicker.cs

發生於下拉式月曆顯示時。

public:
 event EventHandler ^ DropDown;

public event EventHandler? DropDown;

member this.DropDown : EventHandler 

Public Custom Event DropDown As EventHandler 

事件類型

EventHandler

範例

下列程式碼範例示範如何使用 和 MaxDateTime 欄位來處理 DropDownDateTimePicker 和 MinDateTime 的事件。 若要執行此範例，請將下列程式碼貼到包含 DateTimePicker 具名 DateTimePicker1 的表單中。

// When the calendar drops down, display a MessageBox indicating 
// that DateTimePicker will not accept dates before MinDateTime or 
// after MaxDateTime. Use a StringBuilder object to build the string
// for efficiency.
void DateTimePicker1_DropDown( Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
   System::Text::StringBuilder^ messageBuilder = gcnew System::Text::StringBuilder;
   messageBuilder->Append( "Choose a date after: " );
   messageBuilder->Append( DateTimePicker::MinDateTime.ToShortDateString() );
   messageBuilder->Append( " and a date before: " );
   messageBuilder->Append( DateTimePicker::MaxDateTime.ToShortDateString() );
   MessageBox::Show( messageBuilder->ToString() );
}

// When the calendar drops down, display a MessageBox indicating 
// that DateTimePicker will not accept dates before MinDateTime or 
// after MaxDateTime. Use a StringBuilder object to build the string
// for efficiency.
private void DateTimePicker1_DropDown(object sender, 
    System.EventArgs e)
{

    System.Text.StringBuilder messageBuilder = 
        new System.Text.StringBuilder();
    messageBuilder.Append("Choose a date after: ");
    messageBuilder.Append
        (DateTimePicker.MinDateTime.ToShortDateString());
    messageBuilder.Append(" and a date before: ");
    messageBuilder.Append
        (DateTimePicker.MaxDateTime.ToShortDateString());
    MessageBox.Show(messageBuilder.ToString());
}

' When the calendar drops down, display a MessageBox indicating 
' that DateTimePicker will not accept dates before MinDateTime or 
' after MaxDateTime. Use a StringBuilder object to build the string
' for efficiency.
Private Sub DateTimePicker1_DropDown(ByVal sender As Object, _
    ByVal e As EventArgs) Handles DateTimePicker1.DropDown

    Dim messageBuilder As New System.Text.StringBuilder
    messageBuilder.Append("Choose a date after: ")
    messageBuilder.Append(DateTimePicker.MinDateTime.ToShortDateString)
    messageBuilder.Append(" and a date before: ")
    messageBuilder.Append(DateTimePicker.MaxDateTime.ToShortDateString)
    MessageBox.Show(messageBuilder.ToString())
End Sub

備註

如需處理事件的詳細資訊，請參閱 處理和引發事件。

另請參閱

• OnDropDown(EventArgs)