PDFSharp / How to set zoom level on an existing document

I have an existing document on which I set some p开发者_运维知识库roperties. I would like to set the Zoom level but don't know how. Anybody knows if and how I can set the zoom level on an existing document with PDFSharp.

This is the existing (VB) code:

Dim doc = PdfReader.Open(New MemoryStream(bytesContent))

doc.ViewerPreferences.CenterWindow = True
doc.ViewerPreferences.FitWindow = True
doc.ViewerPreferences.HideToolbar = False
doc.PageLayout = PdfPageLayout.SinglePage

Thank you

My answer can be found in the other forum where you also asked that question:

http://forum.pdfsharp.net/viewtopic.php?p=4449#p4449