[roger64]

Hi

I checked again. I reinstalled Calibre 7.1. (Archlinux) using the Calibre Linux custom install script and the terminal reported no problem during install.

I remember using Calibre subsetting during these last years. At least from 2021, it did save open-type variations after subsetting. But the size of the subset was bigger than today say roughly 15%.

About one or two years ago, the Calibre subsetting process was made more efficient, reducing the subset to about 5%. I noticed at that time during calibre install on my Linux distro a dependency problem with fonttools. So I reverted to the Calibre linux install script. Since that time however, the calibre subset does not save anymore the open-type variations.

Another install of Calibre reports the same error message as me and the same faulty results. I would like to know how to get rid of this message which appears when subsetting even when I perform a regular Calibre script install.

Patches

You say that patches are welcome. The current version of fonttools (the Archlinux package is python-fonttools 4.44.3-1) does indeed preserve open-type variations so there could be some benefit to use it.

Here is a test case to illustrate my point. I added enclosed in this zip a version obtained with the Sigil subset plugin which preserves the open-type variations. It uses exclusively the latest fonttools.

Note: for users of this forum, to see how open-type variations are preserved, just look for the display of the Date paragraph style which you'll find at the beginning of each chapter.