internal void RegisterLayer(IPdfOCG layer)
{
PdfWriter.CheckPdfIsoConformance(this, PdfIsoKeys.PDFISOKEY_LAYER, null);
if (layer is PdfLayer) {
PdfLayer la = (PdfLayer)layer;
if (la.Title == null) {
if (!documentOCG.ContainsKey(layer)) {
documentOCG[layer] = null;
documentOCGorder.Add(layer);
}
}
else {
documentOCGorder.Add(layer);
}
}
else
throw new ArgumentException(MessageLocalization.GetComposedMessage("only.pdflayer.is.accepted"));
}