bug#56691: outline-minor-mode displays navigation arrow buttons as emojis

[Lars Ingebrigtsen]

Po Lu <luangruo@yahoo.com> writes:

> Only if the font is already opened, and it's a fairly slow operation
> that involves a roundtrip to the X server outside of Cairo.  One of the
> Java X servers also supports color fonts, but they seem to be
> implemented as an overlay, because if I draw some color glyphs to a
> window and then use XGetImage, those glyphs do not show up in the
> resulting image, even though they do show up on display.

Hm, interesting...

>> Or alternatively -- query the font whether it has colour glyphs, but I
>> don't know whether that's easy, either.  Anybody know?
>
> I think FC_COLOR gets you halfway there, but it says nothing about Emoji
> specifically.

Thanks.  If it doesn't have FC_COLOR, then it definitely isn't an Emoji
font, so I suspect we'll be able to weed out most of the false
positives.  So it might be useful as a test in there somewhere.

> There is no equivalent on Haiku or NS AFAICT, and on MS Windows we
> simply don't support color fonts.

FC_COLOR isn't defined on NS?