PDFSharp WPF 1.32 private fonts will not work with Azure Blob storage

Question

I have some code that adds text using a private font to a PDF file using PDFSharp. This works successfully if the font is located on the local file system but does not work when I provide it with a url to a font stored on a Azure blog storage. I also tried using a google font on their CDN, which also didn't work. Is there some problem with loading fonts from a web url?

The sample code is below. Note that I have solved the CORS issue on Azure blob storage so it isn't that.

private readonly XPdfFontOptions _fontOptions = 
    new XPdfFontOptions(PdfFontEncoding.Unicode, PdfFontEmbedding.Always);
private static readonly XPrivateFontCollection PrivateFontCollection =
    XPrivateFontCollection.Global;

[Test]
public async Task Test01RawPdfSharp()
{
    //SETUP 
    var account = "labelapptest";
    var fs = new FileStore(account);
    var fontUrl =
        "http://labelapptest.blob.core.windows.net/designernospamcom/justyna sokolowska - erazm-regular.otf";
    var pdfUrl =
        "https://labelapptest.blob.core.windows.net/label-highrez-blank/blank-label00001.pdf";
    var fontFamily = "Erazm Regular";
    var localFontPath = Path.Combine(TestFileHelpers.GetTestDataFileDirectory(@"\TestFonts"),
        "Justyna Sokolowska - Erazm-Regular.otf");

    //ATTEMPT
    var sFontFamilyname = "./#" + fontFamily;
    var uri = new Uri(fontUrl);
    PrivateFontCollection.Add(uri, sFontFamilyname);

    var readDirStatus = await fs.GetDirHandleAsync(FileStorageTypes.LabelHighRezBlank);
    using (var readStream = new MemoryStream())
    {
        await readDirStatus.Result.ReadFileAsync(readStream, pdfUrl);
        readStream.Seek(0, SeekOrigin.Begin);
        var document = PdfReader.Open(readStream);
        var gfx = XGraphics.FromPdfPage(document.Pages[0]);

        var font = new XFont(fontFamily, new XUnit(12, XGraphicsUnit.Point), XFontStyle.Regular, _fontOptions);
        var brush = new XSolidBrush(XColor.FromKnownColor(XKnownColor.Red));
        gfx.DrawString("Hello world", font, brush, 10, 10);
    }
    //VERIFY
}    

In the example above if I use the fontUrl in the uri for adding the font then the code fails at the line where the XFont is created (6th from bottom). If on the other hand I use the localFontPath then it works.

The error is: Cannot get a matching glyph typeface for font 'Erazm Regular' at line at PdfSharp.Drawing.XFont.Initialize() in XFont.cs: line 234.

NOTE : I have downloaded and edited the 1.32 PDFSharp code to replace the Debugger.Break statement with an exception at this point. The NuGet version has a Debugger.Break which causes a hang in released code - see my SO question about that issue.

UPDATE

In the end I swapped to PDFsharp WPF 1.50 beta as its font handling is much better and I wasn't getting anywhere with the problem of loading a font via a http link. Seems to be working really well.

Answer 1

The call to PrivateFontCollection.Add(uri, sFontFamilyname) just passes the URI to new System.Windows.Media.FontFamily(baseUri, familyName) . I don't know whether Media.FontFamily can handle URIs for Azure storage.

We use the PrivateFontCollection with fonts from resources - and loading fonts from resources is the only sample given in the help for FontFamily Constructor (Uri, String) . That's the type of URI that is known to work with PDFsharp.

The syntax for FontFamily Constructor (Uri, String) is somewhat cryptic and the smallest error will lead to "not found".