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Select specified line in RichTextBox

This is a snippet utilizing Win32 API to select (scroll to) a specified line in a RichTextBox given the line number

Submitted By: PsychoCoder

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Views: 3,261

Language: VB.NET

Last Modified: October 23, 2008

Instructions: Provide the line number and RichTextBox

Snippet

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Const EM_SETSEL = &HB1
Private Const EM_GETLINECOUNT = &HBA
Private Const EM_LINEINDEX = &HBB
Private Sub SelectLine(ByRef lineNum As Long, ByRef rtb As System.Windows.Forms.RichTextBox)
Dim _start As Long
Dim _end As Long
Dim numLines As Long
With rtb
'Get the line count in the RichTextBox
numLines = SendMessage(.handle, EM_GETLINECOUNT, 0, 0&)
'Make sure the line number provided isnt greater
'than the number of lines in the box, if
'so then exit
If lineNum > numLines - 1 Then Exit Sub
'Get the beginning of the line
_start = SendMessage(.handle, EM_LINEINDEX, lineNum, 0&)
'Get the end of the line
_end = SendMessage(.handle, EM_LINEINDEX, lineNum + 1, 0&)
'Set focus to the control
.Focus()
'Highlight the desired row
Call SendMessage(.handle, EM_SETSEL, _start, _end)
End With
End Sub

Copy & Paste

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
  (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long

Private Const EM_SETSEL = &HB1
Private Const EM_GETLINECOUNT = &HBA
Private Const EM_LINEINDEX = &HBB

Private Sub SelectLine(ByRef lineNum As Long, ByRef rtb As System.Windows.Forms.RichTextBox)
    Dim _start As Long
    Dim _end As Long
    Dim numLines As Long

With rtb
        'Get the line count in the RichTextBox
        numLines = SendMessage(.handle, EM_GETLINECOUNT, 0, 0&)

'Make sure the line number provided isnt greater
        'than the number of lines in the box, if
        'so then exit
        If lineNum > numLines - 1 Then Exit Sub

'Get the beginning of the line
        _start = SendMessage(.handle, EM_LINEINDEX, lineNum, 0&)

'Get the end of the line
        _end = SendMessage(.handle, EM_LINEINDEX, lineNum + 1, 0&)

'Set focus to the control
        .Focus()

'Highlight the desired row
        Call SendMessage(.handle, EM_SETSEL, _start, _end)
    End With
End Sub