用于Font Combo Box的ComboBox DrawItem事件处理 - WinForms，VB.NET

Question

我正在创建一个组合框，它在列表中显示字体，每个字体项都以自己的字体样式显示。组合框加载没有错误，但显示的列表只有一种字体。我设置了DrawMode = OwnerDrawVariable和IntegralHeight = false，但仍然没有结果。您可以在这里看到的DrawItem代码来自MSDN网站，根据我的要求进行了一些更改。这是我的代码：

表单加载时会调用

1. BindCOmboboxes()。

   Private Sub w_BindComboBoxes()   (StyleControl is a User Control containing the combobox)
   
       'Set Properties
   
       Dim tFont As Font = Nothing
   
       StyleControl.TS1Font.DrawMode = DrawMode.OwnerDrawVariable
   
       For Each fntfam As FontFamily In FontFamily.Families
           If fntfam.IsStyleAvailable(FontStyle.Regular) Then
               tFont = New Font(fntfam, 12, FontStyle.Regular)
               StyleControl.TS1Font.Items.Add(tFont.Name & ",Regular")               
           End If
   
           If fntfam.IsStyleAvailable(FontStyle.Italic) Then
               tFont = New Font(fntfam, 12, FontStyle.Italic)
               StyleControl.TS1Font.Items.Add(tFont.Name & ",Italic")
           End If
   
           If fntfam.IsStyleAvailable(FontStyle.Bold) Then
               tFont = New Font(fntfam, 12, FontStyle.Bold)
               StyleControl.TS1Font.Items.Add(tFont.Name & ",Bold")
           End If
       Next
   
   End Sub
   

2. DrawItem TS1Font组合框的功能

   Private Sub FontComboBoxDrawItems(sender As Object, e As DrawItemEventArgs)
   
       Dim size As Integer = 12
       Dim myFont As System.Drawing.Font
       Dim family As FontFamily = new FontFamily("Arial", 12)   <-- to avoid crash
       Dim fntStyle As FontStyle = FontStyle.Regular   <-- To avoid crash
       Dim animalColor As System.Drawing.Color = Color.Black
   
       Dim str As String = DirectCast(sender, ComboBox).Items(e.Index).ToString.Trim
       Dim brk() As String = str.Split(",")
       For Each fam As FontFamily In FontFamily.Families
           If fam.Name = brk(0) Then family = fam
       Next
       Select Case brk(1)
           Case "Regular"
               fntStyle = FontStyle.Regular
           Case "Bold"
               fntStyle = FontStyle.Bold
           Case "Italic"
               fntStyle = FontStyle.Italic
       End Select
   
       ' Draw the background of the item.
       e.DrawBackground()
   
       ' Draw each string in the array, using a different size, color, 
       ' and font for each item.
   
       myFont = New Font(family, size, fntStyle)
       e.Graphics.DrawString(DirectCast(sender, ComboBox).Items(e.Index).ToString, myFont, System.Drawing.Brushes.Black, 
           New PointF(e.Bounds.X, e.Bounds.Y))
   
   
       ' Draw the focus rectangle if the mouse hovers over an item.
       e.DrawFocusRectangle()
   
   End Sub
   

在DrawItem函数中进行调试时，语句e.Graphics.DrawString =中的值显示正确的字体系列，样式和大小值。那么为什么不以这种方式绘制物品呢？

结果：