Thanks Alexei for chiming in at https://github.com/googlei18n/fontmake/issues/492#issuecomment-448249543.
> The following seems to be different: hhea does not seem to be used in VF. > Compare and decide which one is correct. > > https://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/src/truetype/ttgxvar.c#n1365 > https://git.savannah.gnu.org/cgit/freetype/freetype2.git/tree/src/sfnt/sfobjs.c#n1670 The OpenType spec says nothing variation specific about hhea/typo/win metrics, except that hhea vmetrics don't seem to be supported by the `MVAR` in that only win and typo metrics have `MVAR` tags: - https://docs.microsoft.com/en-us/typography/opentype/spec/hhea#39hhea39-table-and-opentype-font-variations - https://docs.microsoft.com/en-us/typography/opentype/spec/mvar#value-tags - https://docs.microsoft.com/en-us/typography/opentype/spec/os2#stypoascender - https://docs.microsoft.com/en-us/typography/opentype/spec/os2#uswinascent Regarding ascender, descender and height calculation in sfobjs.c and ttgxvar.c: the math seems to be the same: - hhea: ascender 983, descender -217, line gap 0 -> total height 1200 fU - typo: ascender 739, descender -217, line gap 244 -> total height 1200 fU - win: ascender 983, descender 217, line gap 0 -> total height 1200 fU For static fonts, FT uses hhea metrics: `root->height = root->ascender - root->descender + face->horizontal.Line_Gap;` or `983 - (- 217) + 0 = 1200` For instances, it uses typo metrics: `root->height = root->ascender - root->descender + face->os2.sTypoLineGap;` or `739 - (-217) + 244 = 1200` Will look into this deeper later. _______________________________________________ Freetype-devel mailing list Freetype-devel@nongnu.org https://lists.nongnu.org/mailman/listinfo/freetype-devel
