Set a wildcard fallback for fonts

[osnard]

I have set up a webservice that converts HTML into PDF. Recently, I faced this error:

ERROR 1 --- [html2pdf] [nio-8080-exec-6] c.h.m.services.html2pdf.MainController   : Error creating PDF
com.openhtmltopdf.pdfboxout.fontstore.FontNotFoundException: No font for the following specification has been found: Font specification: families: [Lato] size: 267.0 weight: normal style: normal variant: normal
       at com.openhtmltopdf.pdfboxout.PdfBoxFastOutputDevice.setFont(PdfBoxFastOutputDevice.java:388) ~[openhtmltopdf-pdfbox-1.1.31.jar!/:na]
       at com.openhtmltopdf.render.AbstractOutputDevice.drawText(AbstractOutputDevice.java:75) ~[openhtmltopdf-core-1.1.31.jar!/:na]
       at com.openhtmltopdf.render.InlineText.paint(InlineText.java:171) ~[openhtmltopdf-core-1.1.31.jar!/:na]
       at com.openhtmltopdf.render.InlineLayoutBox.paintInline(InlineLayoutBox.java:287) ~[openhtmltopdf-core-1.1.31.jar!/:na]
       at com.openhtmltopdf.render.displaylist.DisplayListPainter.paintInlineContent(DisplayListPainter.java:135) ~[openhtmltopdf-core-1.1.31.jar!/:na]
       at com.openhtmltopdf.render.displaylist.DisplayListPainter.paint(DisplayListPainter.java:262) ~[openhtmltopdf-core-1.1.31.jar!/:na]
       at com.openhtmltopdf.pdfboxout.PdfBoxRenderer.paintPageFast(PdfBoxRenderer.java:883) ~[openhtmltopdf-pdfbox-1.1.31.jar!/:na]
       at com.openhtmltopdf.pdfboxout.PdfBoxRenderer.writePDFFast(PdfBoxRenderer.java:596) ~[openhtmltopdf-pdfbox-1.1.31.jar!/:na]
       at com.openhtmltopdf.pdfboxout.PdfBoxRenderer.createPdfFast(PdfBoxRenderer.java:496) ~[openhtmltopdf-pdfbox-1.1.31.jar!/:na]
       at com.openhtmltopdf.pdfboxout.PdfBoxRenderer.createPDF(PdfBoxRenderer.java:427) ~[openhtmltopdf-pdfbox-1.1.31.jar!/:na]
       at com.openhtmltopdf.pdfboxout.PdfRendererBuilder.run(PdfRendererBuilder.java:44) ~[openhtmltopdf-pdfbox-1.1.31.jar!/:na]

It looks like the HTML/CSS has set a font styling to "Lato". My webservice does not ship this font.

Is there a way to avoid this error and have OpenHTML2PDF fall back to some standard (like sans-serif) in such cases?

Unfortunately, I didn't find a good way to do that. E. g. It seems one can not set a custom FontResolver using the PdfRendererBuilder.

Any help is much appreciated!

[zacharysiegel]

Are you specifying normal CSS fallbacks?

[osnard]

Unfortunately, I am not in control over the HTML that is provided to the service. It is user generated content. So, no, I can not grantee that a CSS fallback is set in the CSS.

I was wondering if there is a way to stop the library code from breaking in such a case? A graceful degradation to "serif" similar to what a browser would do?

[osnard]

Actually, I was wondering if the issue here was not just the font, but more the combination with the very odd size of 267.0 (without any units). I can not tell where this value is even coming from. It is not part of the HTML/CSS provided to the library code.

[zacharysiegel]

Actually, I was wondering if the issue here was not just the font, but more the combination with the very odd size of 267.0 (without any units). I can not tell where this value is even coming from. It is not part of the HTML/CSS provided to the library code.

Does this mean that your server is, indeed, providing the Lato font to the system?

[zacharysiegel]

The library does handle a default serif fallback. It seems to me from looking through the code briefly that the Lato font is indeed being loaded, but is malformed–at least with respect to the assumptions made by the library.

[osnard]

Thanks for the research! Could you maybe point me to the code in question?

I am more and more convinced, it is not about the font itself (as you pointed out, there should be a fallback), but about other parts of the "font specification" like weight or variant. On the other hand: The error message shows a value of normal for each of them, so that looks unlikely.

The size of 267.0 seems to be very odd to me. I can not figure out why it is set this way. The source HTML/CSS does not contain anything like this. Maybe the number exceeds some value (255?) the library is limited to?

[zacharysiegel]

Thanks for the research! Could you maybe point me to the code in question?

See:

• com.openhtmltopdf.pdfboxout.fontstore.BuiltinFontStore
• com.openhtmltopdf.pdfboxout.fontstore.AbstractFontStore

For the Java2D renderer:

• com.openhtmltopdf.java2d.Java2DFontResolver#init

IDK anything about why the font size might be set like that.

Are you using PDF A/UA conformance mode? Perhaps this might be related: (from com.openhtmltopdf.pdfboxout.PdfBoxFontResolver#PdfBoxFontResolver)

[osnard]

Are you using PDF A/UA conformance mode?

I do, indeed! Thanks! I'll check.