Question

我正在下面的线程中创建多行组合框。我目前正在使用Visual Studio 2019，该线程来自2013。

Any way for a combo box with 2 values per line?

我复制的代码：

    Public Class MultiLineComboBox : Inherits ComboBox
   Public Sub New()
      ' Call the base class.
      MyBase.New()

      ' Typing a value into this combobox won't make sense, so make it impossible.
      Me.DropDownStyle = ComboBoxStyle.DropDownList

      ' Set the height of each item to be twice its normal value
      ' (because we have two lines instead of one).
      Me.ItemHeight *= 2
   End Sub

   Protected Overrides Sub OnDrawItem(e As DrawItemEventArgs)
      ' Call the base class.
      MyBase.OnDrawItem(e)

      ' Fill the background.
      e.DrawBackground()

      ' Extract the Record object corresponding to the combobox item to be drawn.
      If (e.Index >= 0) Then
         Dim record As Record = DirectCast(Me.Items(e.Index), Record)

         ' Format the item's caption string.
         Dim caption As String = String.Format("ID: {0}{1}Name: {2}", record.UniqueID.ToString(), Environment.NewLine, record.Name)

         ' And then draw that string, left-aligned and vertically centered.
         TextRenderer.DrawText(e.Graphics, caption, e.Font, e.Bounds, e.ForeColor, TextFormatFlags.Left Or TextFormatFlags.VerticalCenter)
      End If

      ' Finally, draw the focus rectangle.
      e.DrawFocusRectangle()
   End Sub
End Class

我创建了一个名为MultiLineComboBox的类，严格按照说明进行操作，并说“未定义类型'Record'”。我一直在搜索“记录”或DirectCast类型的答案（例如https://docs.microsoft.com/en-us/dotnet/visual-basic/language-reference/operators/directcast-operator），但到目前为止，它们都没有帮助我。

我的声誉当前为<50，因此我也无法在该主题的答案上发表评论。大家可以帮我吗？

（在出现VS或.NET版本的情况下添加了标签visual-studio-2019和.net-4.7.2）

Answer 1

阅读整个答案。 Record类在此处声明；您也需要它，并且您想要更改代码以匹配组合框的字段。

在自定义类vb.net中未定义“记录”类型

1 个答案: