Write page content to PDF in Xamarin

To write page content to a new document.

PDFDoc doc = new PDFDoc();

// ElementBuilder is used to build new Element objects
ElementBuilder builder = new ElementBuilder(); 

// ElementWriter is used to write Elements to the page
ElementWriter writer = new ElementWriter(); 

// Start a new page
Page page = doc.PageCreate();

// Begin writing to this page
writer.Begin(page);  

// Create an Image that can be reused multiple times in the document or multiple on the same page.
MappedFile img_file = new MappedFile(imagename);
FilterReader img_data = new FilterReader(img_file);
Image img = Image.Create(doc, img_data, 400, 600, 8, ColorSpace.CreateDeviceRGB(), Image.InputFilter.e_jpeg);
Element element = builder.CreateImage(img, new Matrix2D(200, -145, 20, 300, 200, 150));
writer.WritePlacedElement(element);

// Use the same image (just change its matrix)
GState gstate = element.GetGState();
gstate.SetTransform(200, 0, 0, 300, 50, 450);
writer.WritePlacedElement(element);

// Use the same image (just change its matrix)
writer.WritePlacedElement(builder.CreateImage(img, 300, 600, 200, -150));

// save changes to the current page
writer.End();  

// Add the new page to the document sequence
doc.PagePushBack(page);

Build, Write, Embed Elements in PDF Pages
Full code sample which illustrates how to use PDFNet page writing API, how to embed fonts and images and how to copy graphical elements from one page to another.

New page content can be added to an existing page or a blank new page using ElementBuilder and ElementWriter. ElementBuilder is used to instantiate one or more Elements that can be written to one or more pages using ElementWriter:

Note that once the Element is instantiated using ElementBuilder, you have full control over its properties and graphics state.

Page content can also come from existing pages. For example, you can use ElementReader to read paths, text, and images from existing pages and copy them to the current page. Note that, along the way, you can fully modify an Element's properties or its graphics state. This is how to perform page content editing. For example, the following copies all Elements from an existing page and changes text color to blue:

PDFDoc doc = new PDFDoc(filename);
ElementWriter writer = new ElementWriter();
ElementReader reader = new ElementReader();

reader.Begin(doc.PageBegin().Current());

Page new_page = doc.PageCreate(new Rect(0, 0, 612, 794));
doc.PagePushBack(new_page);

writer.Begin(new_page);

Element element;
while ((element = reader.Next()) != null)
{
  switch (element.GetType())
  {
    case Element.Type.e_text:
    {
      // Set all text to blue color.
      GState gs = element.GetGState();
      gs.SetFillColorSpace(ColorSpace.CreateDeviceRGB());
      gs.SetFillColor(new ColorPt(0, 0, 1));
      writer.WriteElement(element);
      break;
    }
    default:
      writer.WriteElement(element);
      break;
  }
}

writer.End();
reader.End();

PDF Editor (Programmatic)
Full code sample which strips all images from the page and changes text color to blue.