[ttx] cmap format 13 not merged correctly

Cf. https://twitter.com/fr_brennan/status/1560057391684763649 Related commit https://github.com/MFEK/Mienai.ttf/commit/e1d99216b75274deaa58cea0ae610d07446c4f39

I fixed it by temporarily overwriting the _IsInSameRun function:

class cmap_format_13(cmap_format_12_or_13):

    _format_step = 0

    def __init__(self, format=13):
        cmap_format_12_or_13.__init__(self, format)

    def _computeGIDs(self, startingGlyph, numberOfGlyphs):
        return [startingGlyph] * numberOfGlyphs

    def _IsInSameRun(self, glyphID, lastGlyphID, charCode, lastCharCode):
        return (glyphID == lastGlyphID)

I don’t know if this is the right fix in general, or just for Mienai. Please advise.

Thanks @kenlunde for his help.

[anthrotype]

feel free to propose a PR to support that – but which doesn’t break backward compat

[behdad]

If you want format13 to cover everything you need to list everything in ttx. That’s inconvenient, I know.

That is, you need to have all one million different entries in your ttx file.