[RESOLVED] TextBox.GetLastVisibleLineIndex-Method not available

[.paul.]

here's an extensions module with 2 functions that extend the textbox class:

Module extensions
 
    Private Declare Function SendMessage Lib "user32" _
            Alias "SendMessageA" (ByVal hwnd As Integer, _
            ByVal wMsg As Integer, ByVal wParam As Integer, _
            ByVal lParam As Integer) As Integer
 
    Private Const EM_GETFIRSTVISIBLELINE As Integer = &HCE
 
    <System.Runtime.CompilerServices.Extension()> _
    Public Function GetFirstVisibleLineIndex(ByVal instance As TextBox) As Integer
        Return SendMessage(instance.Handle.ToInt32, EM_GETFIRSTVISIBLELINE, 0, 0)
    End Function
 
    <System.Runtime.CompilerServices.Extension()> _
    Public Function GetLastVisibleLineIndex(ByVal instance As TextBox) As Integer
        Dim height As Integer = CInt(instance.CreateGraphics().MeasureString("0123456789", instance.Font, instance.Width).Height)
        Dim bottomLineIndex As Integer = ((instance.ClientSize.Height \ height) + SendMessage(instance.Handle.ToInt32, EM_GETFIRSTVISIBLELINE, 0, 0)) - 1
        Return If(bottomLineIndex <= instance.Lines.GetUpperBound(0), bottomLineIndex, instance.Lines.GetUpperBound(0))
    End Function
 
End Module

to use the functions, add the module to your project, then:

MsgBox(TextBox1.GetFirstVisibleLineIndex)
MsgBox(TextBox1.GetLastVisibleLineIndex)