[RESOLVED] Goto Line In TextBox

[BenJones]

hi I am trying to use the API sendmessage to goto a line in my textbox but I get this error.

A call to PInvoke function 'MyBasic!MyBasic.frmmain::SendMessage' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

    Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long,
    ByVal wParam As Long, ByVal LParam As Integer) As Long

    Private Sub GotoLine(ByVal tb As TextBox, ByVal Line As Integer)
        Dim Ret As Integer = SendMessage(tb.Handle, EM_LINEINDEX, Line - 1, 0)
        tb.SelectionStart = Ret
    End Sub

GotoLine(txtCode, 5)

[Chris001]

Your declaration of SendMessage is wrong.

http://www.pinvoke.net/default.aspx/user32.sendmessage

[dbasnett]

Without the API

    Private Sub GotoLine(ByVal tb As TextBox, ByVal Line As Integer)
        Dim idx As Integer = 0
        For x As Integer = 0 To Line - 1
            For Each c As Char In tb.Lines(x)
                idx += 1
            Next
            idx += Environment.NewLine.Length
        Next
        tb.SelectionStart = idx
        tb.SelectionLength = 0
        tb.Select()
    End Sub

assumes that Line is based on a zero index, the first line is at index 0.

[BenJones]

Thanks to both working now.

[.paul.]

there's a simpler method than both of the previously mentioned methods:

Public Class Form1

    Private Sub NumericUpDown1_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NumericUpDown1.ValueChanged
        TextBox1.SelectionStart = TextBox1.GetFirstCharIndexFromLine(CInt(NumericUpDown1.Value))
        TextBox1.Focus()
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        NumericUpDown1.Minimum = 0
        NumericUpDown1.Maximum = 9
        'TextBox1 contains 10 lines of text
        NumericUpDown1.Value = 0
    End Sub

End Class

[dbasnett]

there's a simpler method than both of the previously mentioned methods:

Public Class Form1

    Private Sub NumericUpDown1_ValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles NumericUpDown1.ValueChanged
        TextBox1.SelectionStart = TextBox1.GetFirstCharIndexFromLine(CInt(NumericUpDown1.Value))
        TextBox1.Focus()
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        NumericUpDown1.Minimum = 0
        NumericUpDown1.Maximum = 9
        'TextBox1 contains 10 lines of text
        NumericUpDown1.Value = 0
    End Sub

End Class

Applauding GetFirstCharIndexFromLine!