Q: I have one question about PDF overlay added by PDFSDK.NET (http://
www.pdftron.com/pdfnet/). Actually, I tried to use the SDK to add a
logo image as a new layer on a multiple pages PDF. However, when I
paged down to the page on which a logo image layer was overlaid, I
found the logo image was not on the page. And then
I page up and page down again, the image appeared again. It looks like
the page was not refresh
such that the image was not shown.
A: How do you add image to PDF? Are you using the approach from
AddImage or ElemebtBuilder sample projects (http://www.pdftron.com/
pdfnet/samplecode.html#AddImage) or are you creating actual new layers
(a.k.a. OCG-s) similar to PDFLayers sample?
Also based on your description it seems that you are adding image
stamp as part of a PDF viewing application. In this case you need to:
1) lock the document before adding the stamp (pdfview.GetDoc().Lock
2) read or modify the document (i.e. add the stamp).
3) unlock lock the document (pdfview.GetDoc().Unlock())
4) Refresh the view using pdfview.Update() or pdfview.UpdateRect
(rect) if you would like to refresh only a subset of a page.