1. Determine the OCGs present and which ones are visible and non-visible

2. Remove the non-visible OCGs and their content from the document

3. Save the PDF which now has just the visible OCGs remaining

Based on the Library documentation, this seemed simple enough, but I am running into various problems.  The source PDF I am testing with has one page and two OCGS - a visible OCG containing English text and a non-visible OCG containing French text.  Based on the code snippet below, I expect that QuickPDF will tell me that the first OCG is visible and the second one non-visible:

Okay, so far, so good, QuickPDF does indeed indicate on visible and one non-visible OCG.

Next, I want to add a call to Remove the non-visible OCG and then save what should now be a PDF with just the single remaining visible, English text, OCG:

So, here is the problem - the new PDF does have just one remaining OCG but instead of only showing the English text from the original visible OCG, it shows both the English AND French text on top of each other!  

Can someone tell me why the French text is even still in the PDF and why it has been put into the remaining OCG?  How do I make sure that content from a removed OCG is removed from the PDF?

Thanks!

What you want to do is delete the OCG and its associated content streams, however, this can be fraught with danger as not all content streams are safe to delete (i.e. might mess up your document in unexpected ways), so it requires testing with your documents.

I will put together some sample code for you tomorrow. The function you use to delete content streams is DeleteContentStream but the trick is determining which content stream the OCG is assigned to (if you already know this then it's obviously easier and you can probably work it out yourself).

 

                int xPageCount = qp.PageCount();
                // Go through each page and encapsulate content streams
                for (int i = 1; i <= xPageCount; i++)
                {
                    result = qp.SelectPage(i);

                    int xContentStreamCount = qp.ContentStreamCount();
                    for (int x = 1; x <= xContentStreamCount; x++)
                    {
                        result = qp.SelectContentStream(x);
                        byte [] var = (byte[]) qp.GetContentStreamToVariant();
                        string contentString = Encoding.UTF8.GetString(var, 0, var.Length);
                    }
                }

 

The source doc has a single page with two OCGs:  the first, visible one contains English text; the second, non-visible one contains French text.

Unfortunately, even though the code above does find two content streams, it seems that the first stream has all the text, both English and French, while the second stream appears to be empty.

 

Thoughts?

As you can see, it should be possible to accomplish what you are trying to do but due to the fact that each OCG doesn't have its own content stream it becomes complicated.

Will Quick PDF be able to handle this now or will it require changes to the library?  Or do I need to look at handling this some other way?

Thanks!