[cairo] scaled_font lifecycle issue

[Lawrence D'Oliveiro]

On Sun, 10 Apr 2016 11:27:31 +0930, Adrian Johnson wrote:

> On 10/04/16 09:08, Lawrence D'Oliveiro wrote:
>
>> A more general invalidate-cache-for-specified-font-face function
>> would be very useful. It would help with use of multiple-master-type
>> font technologies.  
> 
> I'm not sure how well this would work for PDF/PS/SVG as these backends
> hold on to the font_face of every font used until after all pages have
> been emitted before all the fonts are emitted.

I guess the only answer is to do what we already do now, and that is
have separate font_face objects, so that Cairo maintains a separate
cache for each. Just it would be nice if these could share underlying
font data somehow, instead of having to load multiple copies.