【发布时间】:2020-09-15 14:52:13
【问题描述】:
我正在按照下面的线程来创建多行组合框。我目前正在使用 Visual Studio 2019,该线程来自 2013 年。
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,完全按照说明进行操作,它显示“未定义类型‘记录’。”我一直在寻找有关“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),但到目前为止没有一个对我有帮助。
我的声誉目前
(添加标签 visual-studio-2019 和 .net-4.7.2 以防 VS 或 .NET 版本是问题)
【问题讨论】:
-
该问题的答案中有大量链接,而您还没有告诉我们您使用的是哪个链接。您似乎应该自己创建了
Record类。它显然不是标准的 .NET 类型,那么您认为它应该来自哪里? -
@jmcilhinney 很抱歉我粘贴了错误的链接。这是正确的:stackoverflow.com/questions/15514698/…
标签: vb.net winforms combobox visual-studio-2019 .net-4.7.2