获取文本框当前光标所在的行和列

<System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)> _
Public Structure HWND__

    '''int
    Public unused As Integer
End Structure

Partial Public Class TextBoxHelper

    Const EM_LINEFROMCHAR As Integer = &HC9
    Const EM_LINEINDEX As Integer = &HBB
    Const EM_GETLINE As Integer = &HC4
    Const EM_GETSEL As Integer = &HB0



    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Ansi, EntryPoint:="SendMessageW")> _
   Public Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal msg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As Integer
    End Function


    ''' <summary>
    ''' 获取指定文本框当前光标所在的行和列
    ''' </summary>
    ''' <param name="texthwnd"></param>
    ''' <param name="iLineX">列</param>
    ''' <param name="iLineY">行</param>
    ''' <remarks></remarks>
    Public Sub GetCaretPos(ByVal texthwnd As System.IntPtr, ByRef iLineX As Long, ByRef iLineY As Long)

        Dim l, l1, l2 As Integer
        l = SendMessage(texthwnd, EM_LINEINDEX, -1, 0)

        iLineY = SendMessage(texthwnd, EM_LINEFROMCHAR, l, 0)
        iLineY += 1

        iLineX = SendMessage(texthwnd, EM_GETSEL, 0, 0)
        iLineX = CInt(iLineX / 2 ^ 16) - l + 1

    End Sub

End Class

测试调用：

  Private Sub RichTextBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles RichTextBox1.MouseDown
        Dim h As New TextBoxHelper
        Dim l, c As Long
        h.GetCaretPos(Me.RichTextBox1.Handle, c, l)
        Me.Label1.Text = String.Format("L:{0};C{1}", l, c)
    End Sub