protected override void AttachInterfaces(object nativeActiveXObject)
{
base.AttachInterfaces(nativeActiveXObject);
this.axIWebBrowser2 = (IWebBrowser2)nativeActiveXObject;
}

protected override void DetachInterfaces()
{
base.DetachInterfaces();
this.axIWebBrowser2 = null;
}

public void Zoom(int factor)
{

object pvaIn = factor;
try
{
this.axIWebBrowser2.ExecWB(OLECMDID.OLECMDID_OPTIC AL_ZOOM, OLECMDEXECOPT.OLECMDEXECOPT_DONTPROMPTUSER, ref pvaIn, IntPtr.Zero);
}
catch (Exception)
{
throw;
}
}

orjinal link : http://slingkid.blogsome.com/categor...ng/webbrowser/