var migraDocument = new Document();
//Add the bar chart
WriteDocument(migraDocument);

//Render the MigraDoc document
DocumentRenderer documentRenderer = new DocumentRenderer(migraDocument);
documentRenderer.PrepareDocument();

//Use PdfSharp to draw with XGraphics
PdfDocument pdfDocument = new PdfDocument();
int pageCount = documentRenderer.FormattedDocument.PageCount;

for (int pageNumber = 1; pageNumber <= pageCount; pageNumber++) // Note that page numbers start with 1.
{
   PdfPage pdfPage = pdfDocument.AddPage();
   XGraphics xGraphics = XGraphics.FromPdfPage(pdfPage);

   //draw some random lines to see it works
   XPen pen = new XPen(XColors.DarkGreen, 6);
   XPoint[] points = new XPoint[] { new XPoint(20, 100), new XPoint(60, 120), new XPoint(90, 20), new XPoint(170, 90), new XPoint(230, 40) };
   xGraphics.DrawLines(pen, points);

   documentRenderer.RenderPage(xGraphics, pageNumber);
}

pdfDocument.Save("output.pdf");