wpf richtextbox check if caret is in the last line or count how many lines it has

I am trying to find out in a richtext box whether the caret 开发者_JAVA技巧is position in the last line. Is this possible?

NOTE: At the end I also added: or count how many lines it has, this is because in the miscrosoft forum there is an example for detecting in which line the caret is.

thanks

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Please verify the msdn link

http://social.msdn.microsoft.com/Forums/en/wpf/thread/667b5d2a-84c3-4bc0-a6c0-33f9933db07f

If you really wanted to know the line number of the caret, you could do something like the following (probably needs some tweaking):

TextPointer caretLineStart = rtb.CaretPosition.GetLineStartPosition(0);
TextPointer p = rtb.Document.ContentStart.GetLineStartPosition(0);
int caretLineNumber = 1;

while (true)
{
    if (caretLineStart.CompareTo(p) < 0)
    {
        break;
    }

    int result;
    p = p.GetLineStartPosition(1, out result);

    if (result == 0)
    {
        break;
    }

    caretLineNumber++;
}

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The code to get the number of lines:

Int32 CountDisplayedLines(RichTextBox rtb)
{
    Int32 result = -1;

    rtb.CaretPosition = rtb.Document.ContentStart;

    while (rtb.CaretPosition.GetLineStartPosition(++result) != null)
    {
    }

    return result;
}

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I have found a solution. Maybe there is a simpler way, if so please let me know

    private void OnHasRtbReachedEnd(System.Windows.Controls.RichTextBox rtb)
    {
        TextPointer pointer1 = rtb.CaretPosition;
        int iCurrentLine = GetLineNumber(rtb);
        rtb.CaretPosition = rtb.Document.ContentEnd;
        int iLastLine = GetLineNumber(rtb);

        if (iCurrentLine == iLastLine)
        {
            if (!_bIsRtbMovingUpDown)
                MoveToNextDataGridRow();
            _bIsRtbMovingUpDown= false;
        }
        else
        {
            _bIsRtbMovingUpDown= true;
        }
        rtb.CaretPosition = pointer1;
    }

//This code comes from //http://social.msdn.microsoft.com/Forums/en/wpf/thread/667b5d2a-84c3-4bc0-a6c0-33f9933db07f

    private int GetLineNumber(System.Windows.Controls.RichTextBox rtb)
    {
        TextPointer caretLineStart = rtb.CaretPosition.GetLineStartPosition(0);
        TextPointer p = rtb.Document.ContentStart.GetLineStartPosition(0);
        int caretLineNumber = 1;

        while (true)
        {
            if (caretLineStart.CompareTo(p) < 0)
            {
                break;
            }

            int result;
            p = p.GetLineStartPosition(1, out result);

            if (result == 0)
            {
                break;
            }

            caretLineNumber++;
        }
        return caretLineNumber;

    }

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I tried the code and is not giving correct results always. One smart way to do it is this

    int previousCursorPosition;
    private void RichTarget_KeyDown_1(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Up || e.Key == Key.Down)
        {
            Xceed.Wpf.Toolkit.RichTextBox rich = (Xceed.Wpf.Toolkit.RichTextBox)sender;
            previousCursorPosition = rich.CaretPosition.GetOffsetToPosition(rich.CaretPosition.DocumentStart);
        }
    }
    private void RichTextBox_KeyUp_1(object sender, KeyEventArgs e)
    {

            if (e.Key == Key.Up)
            {
                Xceed.Wpf.Toolkit.RichTextBox rich = (Xceed.Wpf.Toolkit.RichTextBox)sender;

                if (previousCursorPosition == rich.CaretPosition.GetOffsetToPosition(rich.CaretPosition.DocumentStart))
                {
                     //do your staff

                }

            }
            else if (e.Key == Key.Down)
            {
                Xceed.Wpf.Toolkit.RichTextBox rich = (Xceed.Wpf.Toolkit.RichTextBox)sender;
                if (previousCursorPosition == rich.CaretPosition.GetOffsetToPosition(rich.CaretPosition.DocumentStart))
                {
                    //do your staff
                }
            }


    }