How to set a OCG layer to be off by default when opening a PDF?

[Ryan]

Question:

I have a PDF file, that contains layers. One of the layers is set to display by default, but I want to modify the PDF so that the layer is off by default.

Answer:

Given the layer name is in the variable layer_to_turn_off, then the following code will do this.

using (PDFDoc doc = new PDFDoc(filepath))
{
    doc.InitSecurityHandler();
    Config config = doc.GetOCGConfig();
    Obj ocgs = doc.GetOCGs();
    if (ocgs == null) return;
    int ocg_sz = ocgs.Size();
    for(int i = 0; i < ocg_sz; ++i)

    {
        Obj ocg = ocgs.GetAt(i);
        Group group = new Group(ocg);
        string ocg_name = group.GetName();
        Console.WriteLine(ocg_name);
        if (ocg_name == layer_to_turn_off) group.SetInitialState(config, false);
    }
    doc.Save(outfilepath, SDFDoc.SaveOptions.e_linearized);
}