TYP: Make glyph indices distinct from character codes #30143
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Note, fixing this would require updating 20 images (for very minimal changes), which I originally rolled into #29816, but it could be moved here. |
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Since #29816 is now just the FreeType change, I've moved the kerning correction here. |
Also, check some expected conditions at parse time instead of somewhere during use of the data.
Previously, these were both typed as `int`, which means you could mix and match them erroneously. While the character code can't be made a distinct type (because it's used for `chr`/`ord`), typing glyph indices as a distinct type means these can't be fully swapped. Unfortunately, you can still go back to the base type, so glyph indices still work as character codes. But this is still sufficient to catch errors such as the wrong call to `FT2Font.get_kerning` in `_mathtext.py`.
The `FontInfo.num` value returned by `TruetypeFonts._get_info` is a character code, but `FT2Font.get_kerning` takes *glyph indices*, meaning that kerning was likely off in most cases.
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PR summary
Previously, these were both typed as
int, which means you could mix and match them erroneously. While the character code can't be made a distinct type (because it's used forchr/ord), typing glyph indices as a distinct type means these can't be fully swapped.Unfortunately, you can still go back to the base type, so glyph indices still work as character codes. But this is still sufficient to catch errors such as the wrong call to
FT2Font.get_kerningin_mathtext.py.This depends on #30134.
PR checklist