Among the type services I offer at Delve Fonts is Quality Assurance Testing of font data. Recently as part of some tests for a client, I discovered a problem and a solution I’d like to share.
The problem: While viewing a document, Adobe Acrobat presents a notice “A number is out of Range”. In addition, while it wasn’t visible in the application (InDesign in this case) the spacing appeared to be extremely affected.
After a little testing, I tracked the problem down to an error in a font being used in the document. This is the part where fellow type designers should take notice: A single glyph had a negative width (not negative side bearings; that’s perfectly acceptable, of course) but a negative width. So be aware, negative widths will create a reproducible problem in PDFs, even if they don’t present themselves in the layout app.
Well, I wrote a little ditty about it all, in Python that is. It’s a macro for use in FontLab and you can get it for free. It is free to use and redistribute (just keep the by-line intact). Alone, it can be run on one or all open fonts and provides a simple report in the output window. I imagine it would be most useful folded into your own QA batch processing routine instead of yet another stand-alone script to run. Refer to your FontLab Studio 5 manual for installation instructions.