How can I extract the Fonts used in a PDF file via PDFSharp?

Question

I am trying to extract the fonts used in a PDF document via PDFSharp (http://www.pdfsharp.net/).

Unfortunately I am not able to do so since I keep on getting strange results and I don't know how to interpret them. In the assembly I have seen classes like PdfFontTable etc, but they are all internal. When decompiling the PdfResources class again everything related to Fonts is internal.

I have tried to access the Resources to get the fonts as:

var reader = Reader.Open(stream, PdfDocumentOpenMode.InformationOnly);
foreach (var page in reader.Pages)
{
    var resources = page.Resources;
    var fonts = resources.Elements.GetValue("/Font");
}

But that gives me an incomprehensible response:

Is there a way to extract the list of fonts used just like I see them in Adobe Acrobat Reader?

Answer 1

There is no direct API way to query the fonts. But it is possible to query the internal document data structures. The following code works and returns a list with fonts.

List<string> fonts = new List<string>();
PdfDocument pdfDoc = PdfReader.Open("YourFileName.pdf");
foreach (PdfObject obj in pdfDoc.Internals.GetAllObjects())
{
    if ("dictionary" == obj.Internals.TypeID)
    {
        for (int i = 0; i < ((PdfDictionary)obj).Elements.Count; ++i)
        {
            if (((PdfDictionary)obj).Elements.ContainsKey("/BaseFont"))
            {
                PdfItem item = ((PdfDictionary)obj).Elements.GetValue("/BaseFont");
                string fontname = item.ToString();
                int idx = fontname.IndexOf('+');
                if (idx > 0)
                {
                    fontname = fontname.Substring(idx + 1).Trim();
                    if (!fonts.Contains(fontname))
                        fonts.Add(fontname);
                }
            }
        }
    }
}