[Fontconfig] Re: [Cairo] Text API proposal

[Keith Packard]

Around 12 o'clock on Aug 12, Owen Taylor wrote:

>  - What *is* the printer resolution? This information isn't always
>    available.

Yup, and so we'll have some kind of default and a way for applications to
provide that (or users to configure it, I dunno).  I dont' know what
alternative we have; lacking a PDF-compatible printer, we're going to have 
to render things in software.

>  - Rendering at printer resolution is often a waste because printers
>    usually can't do their full color or grayscale range at full
>    resolution.

True enough; as I said, this is just a 'first cut' which can be refined in 
the future.

>  - Mondo huge is *huge* (At a modest resolution of 600dpi, 
>    a 8.5x11 page is 128 megs. Not counting temporary group buffers
>    that might need to be created.)

Which is why a better implementation would use some kind of metafile 
format, avoiding bitmaps where possible and then generating those in 
stripes.

> One note is that any metafile entirely implemented inside Cairo 
> should be limited in usage for printing.

Unless we could adopt some existing metafile format (like PDF 1.4), we 
will have to be very careful to make sure the existence of the metafile 
format is well hidden from the outside world.

> Compare the two attached images; the second demonstrates why you
> want to be able to take device metrics into account when doing final
> positioning of glyphs.

Having a device resolution (even if incorrect) will at least make things 
look equally bad everywhere, instead of using glyphs rendered at one size 
set at spacing for a difference size.

We're mostly counting on scary printer resolution to keep these effects to 
a minimum.

-keith