[ft-devel] Bengali support in FreeType ttfautohint

[Werner LEMBERG]

I've now extended both FreeType and ttfautohint to handle the Bengali
script.  To get good hinting results, it was necessary to implement
top-to-bottom hinting – up to now, FreeType only supported
bottom-to-top hinting, this is, starting with the lowest blue zone,
searching serifs and stems while going upwards.  As a side effect,
Devenagari script support was also changed to use top-to-bottom
hinting, which should improve rendering.

For testing, the `noto-hinted' github repository has been extended
with NotoSansBengali[*] and NotoSansDevanagari.

  https://rawgit.com/lemzwerg/noto-hinted/master/

Enjoy!


    Werner


[*] GDI hinting, as shown e.g. on this page

      
https://raw.githubusercontent.com/lemzwerg/noto-hinted/master/NotoSansBengali/NotoSansBengali-Regular-gGD-bn-win8.1_firefox_37.0.png

    gets clipped at the top.  This could be fine-tuned with
    ttfautohint options, but I think it would be better to adjust
    NotSansBengali's value of `usWinAscent' in the `OS/2' table – if
    you look at

      
https://raw.githubusercontent.com/lemzwerg/noto-hinted/master/NotoSansBengali/NotoSansBengali-Regular-manual-bn-win8.1_firefox_37.0.png

    you can see that even with manual hinting the top gets cut off
    also at 9px.  The same happens for NotoSansDevanagari, BTW.