How to use PDF Sharp objects in my Migradoc document - watermark

Question

I have an application that generates PDFs using the MigraDoc framework, however I have a requirement to add in a text driven watermark. I have found some examples of this being done using PDF Sharp here, however I just cant seem t be able to figure out how this will integrate with my Migradoc Document() object I am rendering.
I have the following code:
public byte[] render()
{
PdfDocument document = new PdfDocument();
CreateWaterMarks(document);
// *****************************
PdfDocumentRenderer renderer = new PdfDocumentRenderer(true);
renderer.Document = this.document;
renderer.RenderDocument();
byte[] pdfContents = null;
using (MemoryStream stream = new MemoryStream())
{
renderer.PdfDocument.Save(stream, true);
pdfContents = stream.ToArray();
}
return pdfContents;
}
This method is what is called to render the MigraDoc document and pass it out as a byte array. The second line of code in here calls the following method which is not doing what I am looking for:
void CreateWaterMarks(PdfDocument document)
{
PdfPage page = document.AddPage();
Document doc = this.document;
MigraDoc.Rendering.DocumentRenderer docRenderer = new DocumentRenderer(doc);
docRenderer.PrepareDocument();
XRect A4Rect = new XRect(0, 0, pageActiveWidth, pageActiveHeight);
int pageCount = docRenderer.FormattedDocument.PageCount;
for (int idx = 0; idx < pageCount; idx++)
{
XFont font = new XFont("Verdana", 13, XFontStyle.Bold);
XGraphics gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Prepend);
XSize size = gfx.MeasureString("Watermark", font);
gfx.TranslateTransform(pageActiveWidth / 2, pageActiveHeight / 2);
gfx.RotateTransform(-Math.Atan(pageActiveHeight / pageActiveWidth) * 180 / Math.PI);
gfx.TranslateTransform(-pageActiveWidth / 2, -pageActiveHeight / 2);
XStringFormat format = new XStringFormat();
format.Alignment = XStringAlignment.Near;
format.LineAlignment = XLineAlignment.Near;
XBrush brush = new XSolidBrush(XColor.FromArgb(128, 255, 0, 0));
gfx.DrawString("Watermark", font, brush, new XPoint((pageActiveWidth - size.Width) / 2, (pageActiveHeight - size.Height) / 2), format);
docRenderer.RenderPage(gfx, idx + 1);
}
}
I was hoping that this would magically make these PDFSharp watermarks appear but alas I get nothing!

Answer 1

I have this working using the following code:
public byte[] render()
{
PdfDocumentRenderer renderer = new PdfDocumentRenderer(true);
renderer.Document = this.document;
renderer.RenderDocument();
renderer.PrepareRenderPages();
CreateWatermarks(renderer);
byte[] pdfContents = null;
using (MemoryStream stream = new MemoryStream())
{
renderer.PdfDocument.Save(stream, true);
pdfContents = stream.ToArray();
}
return pdfContents;
}
private void CreateWatermarks(PdfDocumentRenderer renderer)
{
int pages = renderer.DocumentRenderer.FormattedDocument.PageCount;
for (int i = 0; i < pages; ++i)
{
var page = renderer.PdfDocument.Pages[i];
XFont font = new XFont("Verdana", 27, XFontStyle.Bold);
XGraphics gfx = XGraphics.FromPdfPage(page, XGraphicsPdfPageOptions.Prepend);
XSize size = gfx.MeasureString("Watermark", font);
gfx.TranslateTransform(pageActiveWidth / 2, pageActiveHeight / 2);
gfx.RotateTransform(-Math.Atan(pageActiveHeight / pageActiveWidth) * 180 / Math.PI);
gfx.TranslateTransform(-pageActiveWidth / 2, -pageActiveHeight / 2);
XStringFormat format = new XStringFormat();
format.Alignment = XStringAlignment.Near;
format.LineAlignment = XLineAlignment.Near;
XBrush brush = new XSolidBrush(XColor.FromArgb(128, 255, 0, 0));
gfx.DrawString("Watermark", font, brush, new XPoint((pageActiveWidth - size.Width) / 2, (pageActiveHeight - size.Height) / 2), format);
}
}