Re: Opal/CoreGraphics (was Re: UIKit?)

[Nicolas Roard]

On Sat, Jan 2, 2010 at 11:45 PM, Riccardo Mottola <multix@ngi.it> wrote:
> Hi,
>>
>> There are a few ways we could use Opal in GNUstep. The possibility I am
>> currently exploring (planning to put in a branch in svn) is modifying -gui
>> to use CoreGraphics directly. This would entail making Opal a dependency of
>> -gui, eliminating the Display PostScript api between -gui and -back. -back
>> would be reduced to the xlib and Win32 window server code. At the cost of
>> not having a choice of graphics backend, this could make the code in -gui
>> clearer, improve performance, and make possible a CoreAnimation
>> implementation and porting a larger set of OS X applications.
>
> I despise that choice, having a hard dependency on cairo is bad, as much as
> Fred likes that. I have yet to see those backens match xlib in flexibility
> and speed of several operations.
> We must consider that workstations are not our only target. Increasing so in
> the future. Depending on something like libart or cairo for a small netbook
> or a handheld is too much of a burden. Portability is also a major concern,
> since cairo isn't that portable at all. (Just to cite, it doesn't support
> the not-so-ancient mac 10.3.x).

Frankly, at one point we need to move on... Cairo is here to stay,
will keep improving (best of all, without us having to work on it, and
considering the low man power we have...), is available on most (all?)
platforms we target, and implement (nearly?) all we need for -back.
Xlib isn't implementing all we need -- just enough of it that for most
apps it's ok, but advanced gui operations won't be available with
it...
On top of that, Cairo has the potential to add proper hw acceleration,
and if we only had Cairo, -back could be quite simpler.

Don't tell me that Cairo is too much of a burden for a netbook --
that's what I'm using... and hw acceleration would make that even more
of an obvious choice (would be much better to use a hw-accelerated
cairo than xlib on an underpowered machine). OSX support for Cairo
would also be irrelevant if in effect we base -back on Opal...

I agree that Handheld is maybe the only thing where xlib would still
really make a difference, but even though, with modern CPUs
(snapdragon..) things are becoming more and more fuzzy in terms of
what a smartphone can/cannot do compared to a PC... (and they too are
now sporting hw-accelerated graphics chips).

Anyway, just throwing my 2 cents in the discussion. Cairo might not be
perfect, but it sounds much better to target it (via Opal) than using
xlib, even if some xlib ops may be faster -- Cairo will improve, not
xlib.

> I like Felipes idea of doing things at the low level, on the other hand I
> can understand that if it is available in Cairo, why not use it?
>
> Riccardo
>
>
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-- 
Nicolas Roard
"I love deadlines. I like the whooshing sound
they make as they fly by." -- Douglas Adams