Winforms RichTextBox: How can I determine how many lines of text are visible?

Question

I have a Winforms app containing a RichTextBox.

How can I determine how many lines of text are displayed, currently visible?

Reason: I want to scroll th

Answer 1

To display the number of lines that a RichTextBox is capable of displaying, even if there is no text there currently, try:

Dim s As SizeF = TextRenderer.MeasureText("A", rtb.Font, rtb.Size, TextFormatFlags.WordBreak)
Dim letterHeight As Integer = CInt(s.Height)
Dim displayableLines As Integer = rtb.Height / letterHeight

This uses the height of a test letter 'A' in the current font to find the line height in pixels.