kc3-lang/freetype

2017-02-13T09:34:17

[autofit] Prevent overlapping blue zones. Problem reported as https://github.com/google/fonts/issues/632 The font in question (Nunito) has values 705 and 713 for the reference and overshoot values, respectively, of the first blue zone. Blue zone 2, however, has value 710 for both the reference and overshoot. At 12ppem, reference and overshoot of blue zone 0 becomes 8px, while blue zone 2 becomes 9px. A peculiarity of this font is that the tops of isolated vertical stems like `N' have a slight overshoot also. The auto-hinter tries to find the nearest blue zone using the *original* coordinates. For vertical stems, this is value 713. For normal horizontal tops like in character `E', this is value 710. Since value 713 is mapped to 8px but value 710 to 9px, `N' and similar characters are one pixel higher than `E', which looks very bad. This commit sanitizes blue zones to avoid such a behaviour. * src/autofit/aflatin.c (af_latin_sort_blue): New function. (af_latin_metrics_init_blues): Sort blue values and remove overlaps.