Select Range of Text in WPF RichTextBox (FlowDocument) Programmatically

Public Function GoToPoint(ByVal start As TextPointer, ByVal x As Integer) As TextPointer    Dim out As TextPointer = start    Dim i As Integer = 0    Do While i < x        If out.GetPointerContext(LogicalDirection.Backward) = TextPointerContext.Text Or _             out.GetPointerContext(LogicalDirection.Backward) = TextPointerContext.None Then            i += 1        End If        If out.GetPositionAtOffset(1, LogicalDirection.Forward) Is Nothing Then            Return out        Else            out = out.GetPositionAtOffset(1, LogicalDirection.Forward)        End If    Loop    Return outEnd Function

Try this, this should return a text pointer for the given char offset. (Sorry its in VB, but thats what I am working in...)

Try that :

var textRange = MyRichTextBox.Selection;var start = MyRichTextBox.Document.ContentStart;var startPos = start.GetPositionAtOffset(3);var endPos = start.GetPositionAtOffset(8);textRange.Select(startPos, endPos);textRange.ApplyPropertyValue(TextElement.ForegroundProperty, new SolidColorBrush(Colors.Blue));textRange.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Bold);

I tried using the solution posted by KratzVB but found that it was ignoring newlines. If you want to count \r and \n symbols then this code should work:

private static TextPointer GetPoint(TextPointer start, int x){        var ret = start;        var i = 0;        while (ret != null)        {            string stringSoFar = new TextRange(ret, ret.GetPositionAtOffset(i, LogicalDirection.Forward)).Text;            if (stringSoFar.Length == x)                    break;            i++;            if (ret.GetPositionAtOffset(i, LogicalDirection.Forward) == null)                return ret.GetPositionAtOffset(i-1, LogicalDirection.Forward)        }        ret=ret.GetPositionAtOffset(i, LogicalDirection.Forward);        return ret;}