VB.NET ComBox高度自定义设置

分析进步

1，可以看出 AddHandler list.DrawItem，sun******  这里是转换过来的，其实这里是一个事件过程

2，可以优化到第二个版本，代码易读性更强比较容易看。

最开始的版本

    Public Shared Sub Bind(ByVal list As Windows.Forms.ComboBox, ByVal itemHeight As Integer)
        list.DropDownStyle = ComboBoxStyle.DropDownList
        list.ItemHeight = itemHeight
        list.DrawMode = DrawMode.OwnerDrawFixed

        AddHandler list.DrawItem, Sub(sender As Object, e As DrawItemEventArgs)
                                      If e.Index < 0 Then
                                          Return
                                      End If
                                      e.DrawBackground()
                                      e.DrawFocusRectangle()
                                      e.Graphics.DrawString(list.Items(e.Index).ToString(), e.Font, New SolidBrush(e.ForeColor), e.Bounds.X, e.Bounds.Y + 3)
                                  End Sub
    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        Bind(ComboBox1, 20)
    End Sub
End Class

优化后的版本

  ''' <summary>
    '''1，窗体加载的时候绑定ChangeComBoxHeight
    ''' </summary>
    ''' <param name="sender"></param>
    ''' <param name="e"></param>
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        ChangeComBoxHeight(ComboBox1, 20)
    End Sub

    ''' <summary>
    ''' 2，修改COMBOX的属性
    ''' </summary>
    ''' <param name="csComboBox"></param>
    ''' <param name="itemHeight"></param>
    Private Sub ChangeComBoxHeight(ByVal csComboBox As Windows.Forms.ComboBox, ByVal itemHeight As Integer)
        '设置DropDownStyle属性
        csComboBox.DropDownStyle = ComboBoxStyle.DropDownList
        '设置高度
        csComboBox.ItemHeight = itemHeight
        '设置DrawMode
        csComboBox.DrawMode = DrawMode.OwnerDrawFixed
        AddHandler csComboBox.DrawItem, AddressOf ComboBox_DrawItemold
    End Sub

    ''' <summary>
    ''' 执行DrawItemold事件
    ''' </summary>
    ''' <param name="sender"></param>
    ''' <param name="e"></param>
    Private Sub ComboBox_DrawItemold(sender As Object, e As DrawItemEventArgs)
        If e.Index < 0 Then
            Return
        End If
        e.DrawBackground()
        e.DrawFocusRectangle()
        e.Graphics.DrawString(sender.Items(e.Index).ToString(), e.Font, New SolidBrush(e.ForeColor), e.Bounds.X, e.Bounds.Y + 3)
    End Sub