How many lines in a text ? for Geek Navigator

[Pautex]

Today Apple validate Geek Navigator first code source browser, inside first speed text scrolling but I connot find good way to compute number of lines in a webview.
A webview is used to show source code keeping active links only, text scroller need number of lines in view. Any idea ?
Implementation is with a linear function of text.lenght
JF

[Pautex]

i implement a mix between number of \n and lenght of text