Re: Font rendering question - Apple Color Emoji.ttc

[Andrew Murray]

After failing to figure out run a debug build of FreeType and get the output, I 
started just investigating with print statements.

I found that the error is coming from 
https://gitlab.freedesktop.org/freetype/freetype/-/blob/master/src/sfnt/ttsbit.c?ref_type=heads#L1555
 - the ‘graphicType’ tag that is unsupported is ‘flip’. This makes sense for 
'woman in a manual wheelchair facing right’.

The successful character on the other hand, 'woman in a manual wheelchair’, is 
has the graphic type ‘png ‘.

So this is indeed a feature that FreeType doesn’t support. I gather from your 
response that this is not at all a priority. Should I create an issue this over 
at https://gitlab.freedesktop.org/freetype/freetype, or should I just leave it 
be? Alternatively, if I felt inspired, and somehow figured this out, would it 
be worthwhile for me to create a merge request?

Thanks for your time.

> On 9 Jun 2024, at 2:23 AM, Werner LEMBERG <wl@gnu.org> wrote:
> 
> 
> Hello Andrew,
> 
> 
> sorry for the late reply.
> 
>> Over at Python Pillow, a user has tried to render an emoji with
>> macOS’ Apple Color Emoji.ttc -
> 
> I don't have this font.  I only have the ancient `Apple Color
> Emoji.ttf` version 8.0d7e1 from 2012...  Without having that font I
> can only do an educated guess.
> 
>> https://github.com/python-pillow/Pillow/issues/7854#issuecomment-2128088090
> 
> Looking at this report it seems that somehow the image should be
> mirrored horizontally – I guess this is the problem with FreeType.
> 
> Please remember that color emoji rendering support within FreeType is
> *very* limited and only partially implemented – it is *not* intended
> as a general solution but rather as a last resort for people who won't
> do the color bitmap blitting by themselves.
> 
> Rendering support of Emojis is a border case, since FreeType is
> decidedly *not* a graphics library.
> 
>> [some C code omitted]
> 
> You can get much more information if you do a debug build of FreeType,
> then setting the environment variable
> 
>  FT2_DEBUG=any:7
> 
> and redirect the stderr output of your demo program to a file.
> 
>> I’ve attached images that, as far as I can see, show that both
>> indexes are present in the font.
> 
> You haven't attached images, AFAICS.
> 
> 
>    Werner