PDF for UWP makes it very easy to create documents, mainly because the object model mimics the well-known .NET Graphics model. However, not all methods available in the Graphics class are available in PDF for UWP. Plus, you may have existing code that draws to a Graphics object and that you do not want to rewrite even if most methods are very similar.

In these cases, you can reuse your existing .NET code by sending the drawing commands to a Metafile, then rendering the Metafile into PDF for UWP using the C1PdfDocument.DrawImage command. This method allows you to expose any graphics you create as images or as PDF documents.

For example, suppose you have an application that generates documents using the PrintDocument pattern of drawing each page into a Graphics object. You could then use the same methods to create a collection of metafiles, one per page, and then convert the list into a PDF document using the following code:

' Get the document as a list of Metafiles, one per page.
Dim pages As ArrayList = GetMetafiles()

' Loop through the pages and create a PDF document.
_c1pdf.Clear()
Dim i As Integer
for i = 0 i <= pages.Count

    ' Get ith page.
    Dim page As Metafile = CType(Metafile.FromFile(pages[i]), Metafile)
    If Not (page Is Nothing) Then

        ' Calculate the page size.
        Dim sz As SizeF = page.PhysicalDimension
        sz.Width = Math.Round(sz.Width * 72.0F / 2540.0F, 2)
        sz.Height = Math.Round(sz.Height * 72.0F / 2540.0F, 2)

        ' Add a page and set the size.
        If i > 0 Then
            _c1pdf.NewPage()
        End If
        _c1pdf.PageSize = sz

        ' Draw the page into the PDF document.
        _c1pdf.DrawImage(page, _c1pdf.PageRectangle())
    End If
Next

// Get the document as a list of Metafiles, one per page.
ArrayList pages = GetMetafiles();

// Loop through the pages and create a PDF document.
_c1pdf.Clear();
for (int i = 0; i < pages.Count; i++)
{

    // Get ith page.
    Metafile page = (Metafile)Metafile.FromFile(pages[i]);
    if (page == null)
    {
        continue;
    }

    // Calculate the page size.
    SizeF sz = page.PhysicalDimension;
    sz.Width  = (float)Math.Round(sz.Width  * 72f / 2540f, 2);
    sz.Height = (float)Math.Round(sz.Height * 72f / 2540f, 2);

    // Add a page and set the size.
    if (i > 0) _c1pdf.NewPage();
    _c1pdf.PageSize = sz;

    // Draw the page into the PDF document.
    _c1pdf.DrawImage(page, _c1pdf.PageRectangle());
}

Save the document using the Save method as explained in the quick start topic, Step 3 of 4: Saving the document.

The code gets each metafile on the list, calculates its size in points (each page could have a different size), then draws the metafile into the page. The metafiles could be generated by a reporting engine, drawing or charting program, or any application that can create metafile images.