FAQ

Does fonttools change the font metrics?

By default, fontTools/TTX recalculates the bounding boxes of the glyphs in the glyf table, as well as other related data other tables such as vhea values. If you want to disable this re-calculation when running TTX, you can pass the -b command line option, as explained in the help message ttx -h. Similarly, from within a Python script, you can pass the argument recalcBBoxes=False to the TTFont constructor.