Add a new PDF Layer in Android

To add a PDF layer or OCG (optional content group) to a new document.

PDFDoc doc = new PDFDoc();
ElementBuilder builder = new ElementBuilder(); // ElementBuilder is used to build new Element objects
ElementWriter writer = new ElementWriter(); // ElementWriter is used to write Elements to the page

// Create a layer
Group image_layer = Group.create(doc, "Image Layer");
Config cfg = Config.create(doc, true);
cfg.setName("Default");

// Add the new OCG to the list of layers that should appear in PDF viewer GUI.
Obj layer_order_array = doc.createIndirectArray();
cfg.setOrder(layer_order_array);
layer_order_array.pushBack(image_layer.getSDFObj());

// Start a new page
Page page = doc.pageCreate();
writer.begin(page); // Begin writing to the page

// Add new content to the page and associate it with one of the layers.
Image img = Image.create(doc.getSDFDoc(), imagename);
img.GetSDFObj().Put("OC", image_layer.GetSDFObj());
writer.writePlacedElement(builder.createImage(img, 300, 600, 200, -150));
writer.end();    // save changes to the current page
doc.pagePushBack(page);

PDF layers (OCG)
Full sample code which demonstrates how to create, extract, render PDF layers.