Noto Sans Symbols: U+1F1EB loses its cross bar in 15px on Linux about noto HOT 11 OPEN

Attachment added.

+werner

Confirmed with pango-view.  FreeType autohinter fail.

Currently FreeType hints the U+1F100..1F1FF Enclosed Alphanumeric Supplement 
(and the non-supplement one) with Latin, whereas fonts typically have smaller 
letter shapes for these.  I think they need to be separated and treated 
differently.

Or maybe the fact that an entire stem is being lost is a bug on its own that 
can be fixed.

Note that the stem appears again in smaller and larger sizes. Something happens 
at 15px.

This is certainly an autohinter bug.  It gets confused by the lack of bluezones 
and existence of the dotted box around the glyph.  The part of code that is 
misfiring looks wrong to me.  This branch:

diff --git a/src/autofit/aflatin.c b/src/autofit/aflatin.c
index a1f2b33..1de6c10 100644
--- a/src/autofit/aflatin.c
+++ b/src/autofit/aflatin.c
@@ -2603,7 +2603,7 @@
         edge->flags  |= AF_EDGE_DONE;
         edge2->flags |= AF_EDGE_DONE;

-        if ( edge > edges && edge->pos < edge[-1].pos )
+        if ( 0 && edge > edges && edge->pos < edge[-1].pos )
         {
 #ifdef FT_DEBUG_LEVEL_TRACE
           FT_TRACE5(( "  BOUND: edge %d (pos=%.2f) moved to %.2f\n",

Werner, any chance you can take a look at this?

I'm on vacation right now so it will take some time until I can work on this.  
However, I guess that the `BOUND' action misses an additional constraint – 
I've contacted David Turner whether he can remember a typical usecase for it so 
that I can implement something sensible...

This works for me using pango-view, so perhaps it has been fixed?  Behdad can 
you confirm?

Still reproduces for me:

pango-view --font='Noto Sans Symbols 15px' 
--text=`~/hb/test/shaping/hb-unicode-encode 1f1eb`

Note the "15px".  Or you can use 15 with --dpi=72.

I also didn't see any fix for this going in.

Oh, left of the 'px'.  Yes, not fixed.

... and David told me that he no longer knows what he was coding :-(

I hope to finally start a FreeType font rendering database project soon, 
collecting renderings of fonts.  This should help play with modified settings 
and rules in the auto-hinter.

Yeah, if we have such a database, making the change the autohinter is trivial.

Want to talk about it?

Yes :-)  If you have thoughts on this, please share them on the freetype-devel 
mailing list!  I'm a complete noob with setting test suites, so any guidance 
would be a great help.