vb.net - VB.net 级联组合框从 Access 连接到数据集 - 更改单位和小数到分数

Question

我有一个相当复杂的 ComboBox 场景，并且作为编程新手，我正在努力寻找最好的方法。

我有一个带有 DataTable 的 DataSet，该 DataTable 有几个数字列的数据。数字数据由以美国标准单位给出的距离组成。我目前有我的 ComboBoxes 设置和工作，但我需要以两种方式扩展我目前拥有的内容。

1. 我需要能够将显示的数据列中的小数转换为分数，有没有办法做到这一点并维护数据绑定？在这种情况下，它是数据源的显示成员......

2. 我需要能够以不同的单位集显示我的下拉选项......我已经编写了单位转换类来帮助解决这个问题，但我不知道我是否也能以某种方式做到这一点并维护数据绑定? 我也想转换显示成员上的单位......

   Private Sub ComboBox1_SelectedIndexChanged(sender As System.Object, e As         System.EventArgs) Handles ComboBox1.SelectionChangeCommitted
    Select Case ComboBox1.SelectedItem
       Case "Tire1"
           With ComboBox2
               .DataSource = Tire1BindingSource
               .ValueMember = "OD"
               .DisplayMember = "OD"
           End With
       Case "Tire2"
           With ComboBox2
               .DataSource = Tire2BindingSource
               .ValueMember = "OD"
               .DisplayMember = "OD"
           End With
       Case "Tire3"
           With ComboBox2
               .DataSource = Tire3BindingSource
               .ValueMember = "OD"
               .DisplayMember = "OD"
           End With
       Case "HubCap"
           ComboBox3.DataSource = Nothing
           With ComboBox2
               .DataSource = HubcapBindingSource
               .ValueMember = "ID"
               .DisplayMember = "ID"
           End With
     End Select
   End Sub
   
   Private Sub ComboBox2_SelectedIndexChanged(sender As System.Object, e As      System.EventArgs) Handles ComboBox2.SelectionChangeCommitted
   Select Case ComboBox1.SelectedItem
       Case "Tire1"
           With ComboBox3
               .DataSource = Tire1BindingSource
               .ValueMember = "ID"
               .DisplayMember = "Weight"
           End With
       Case "Tire2"
           With ComboBox3
               .DataSource = Tire2BindingSource
               .ValueMember = "ID"
               .DisplayMember = "Weight"
           End With
       Case "Tire3"
           With ComboBox3
               .DataSource = Tire3BindingSource
               .ValueMember = "ID"
               .DisplayMember = "Weight"
           End With
       Case "HubCap"
           ComboBox3.DataSource = Nothing
           With ComboBox2
               .DataSource = HubCapBindingSource
               .ValueMember = "ID"
               .DisplayMember = "ID"
           End With
   End Select
   

在处理显示分数和单位等问题时，使用组合框的最佳方法是什么...

Answer 1

是的，您可以在不影响 DataBindings 的情况下绘制分数。您必须设置 DrawMode 属性和句柄DrawItem和MeasureItem事件。有关更多信息，请阅读此MSDN 文章；