Set a limit of lines in a richtextbox

Good Day,

I am setting my richtextbox lines to a maximum number of 2 by determining the location of my cursor.

Code:

---

    Private line As Integer

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Code:

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      Private Sub RichTextBox1_SelectionChanged(sender As Object, e As EventArgs) Handles RichTextBox1.SelectionChanged
        Dim index As Integer = RichTextBox1.SelectionStart
        line = RichTextBox1.GetLineFromCharIndex(index)
        End Sub

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And trapping my user not to enter anymore text on keypress

Code:

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    Private Sub RichTextBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles RichTextBox1.KeyPress
        If Char.IsLetterOrDigit(e.KeyChar) = True Then
            If line = 2 Then
                e.Handled = True
            End If
        End If
        If e.KeyChar = Convert.ToChar(13) Then
            If line = 2 Then
                e.Handled = True
            End If
        End If
    End Sub

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My problem is when the user type a word or a text that is on the edge , that basically does not fit on the line, it will be moved on the nextline.

My question is how can i prevent the user to enter a text that will cause the word to moved on the nextline, that is when the cursor is on the last line of the richtextbox.

And the wordwrap must be valued as true.

Thanks.

You should set the MaxLength property equal to the amount of characters allowed per line times the desired amount of maximum lines(in this case 2).

In order to do this, I would suggest using a monospaced font such as Consolas or Courier. Then once you've determined the font, you can get the width of a single character by using Graphics.MeasureString. Once you've the width of a single character, divide the width of the RichTextBox by the width of the single character to get the amount of characters allowed per line. Finally you multiply that amount by your desired maximum lines(2).

Here is an example, I would suggest using the SizeChanged event of the RichTextBox so that you get an accurate amount each time the size of the RichTextBox changes:

Code:

---

Private Sub MyRichTextBox_SizeChanged(ByVal sender As Object, ByVal e As EventArgs) Handles MyRichTextBox.SizeChanged
    'Get the width of a single character
    Dim charWidth As Integer
    Using g As Graphics = MyRichTextBox.CreateGraphics()
        charWidth = g.MeasureString("A", MyRichTextBox.Font).Width
    End Using

    'Get the maximum amount of characters per line
    Dim maxLineChar As Integer = MyRichTextBox.Width \ charWidth

    'Set the MaxLength equal to the maxLineChar * maximum amount of lines
    MyRichTextBox.MaxLength = maxLineChar * 2
End Sub

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If you do not want to use a monospace font, which I agree, is a great solution. Then keep track of the keystrokes and when the line jumps to 3, do a backtrace and delete the last key pressed.

Try this:

Code:

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Public Class Form1

    Private maxLines As Integer = 5

    Private Sub RichTextBox1_KeyPress(ByVal sender As Object, ByVal e As KeyPressEventArgs) Handles RichTextBox1.KeyPress
        Dim lines As New List(Of String)(RichTextBox1.Lines)
        Dim caretPosition As Integer = RichTextBox1.SelectionStart
        RichTextBox1.Lines = lines.Take(maxLines).ToArray
        RichTextBox1.SelectionStart = If(caretPosition > RichTextBox1.Text.Length, RichTextBox1.Text.Length, caretPosition)
    End Sub

End Class

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Hi,

Thank you for all of your reply..

All the code are working fine, but if the user does not press the enter key and just continue to input a text and the user just put an space on the edge of the RTB the cursor must be on the next line.

Thanks.