We're basing our system on FreeBSD and there seems to be a DirectFB port,
however I don't know how complete it is. For our purpose, as long as it
runs on BSD, it's OK.

Johannes Lundberg
BRILLIANTSERVICE CO., LTD. <http://www.brilliantservice.co.jp>


On Fri, Apr 26, 2013 at 6:46 PM, Ivan Vučica <[email protected]> wrote:

> I think David refers to the need to cache as much drawables into
> OpenGL/OpenGL ES textures as possible and then composite them on screen
> using OpenGL/OpenGL ES. Putting pixels and updating them using 2D drawing
> commands ("put a rectangle here", "copy this rectangle into this
> rectangle") stops paying off at some point. For example, if you have a lot
> of alpha blending, or UI that animates without changing its own content, it
> probably makes little sense to do compositing in software.
>
> I'm not too familiar with DirectFB; does it expose a way to create an
> OpenGL context?
>
> Regards,
>
> Ivan Vučica
> via phone
>
> On 26. 4. 2013., at 11:32, "Lundberg, Johannes" <
> [email protected]> wrote:
>
> Do you mean that if rendering is offloaded to the CPU the performance
> gained from moving from X to DirectFB is not that big?
>
> For our head mount display all events will be generated from things like
> gestures and voice control so we don't really need X for input events.
>
> Johannes Lundberg
> BRILLIANTSERVICE CO., LTD. <http://www.brilliantservice.co.jp>
>
>
> On Fri, Apr 26, 2013 at 5:53 PM, Ivan Vučica <[email protected]> wrote:
>
>> On 26. 4. 2013., at 09:13, David Chisnall <[email protected]> wrote:
>>
>> > On 26 Apr 2013, at 07:41, "Lundberg, Johannes" <
>> [email protected]> wrote:
>> >
>> >> While we're discussing lower level graphics API I would like to ask
>> one more thing.
>> >>
>> >> What would it take to run GNUstep on DirectFB instead of X? Is this
>> possible at this time?
>> >
>> > Someone did create a DirectFB back end, but it was never pushed
>> upstream.  I'm not sure it's such an interesting target anymore, because
>> with GLES hardware becoming ubiquitous it's more important to be able to
>> offload rendering to the GPU (for power efficiency, and also to do
>> compositing of complex UIs at a reasonable speed).
>> >
>> > Note that there are three parts to a back end:
>> >
>> > - The rendering part, which is responsible for managing graphics
>> contexts and putting pixels on the screen (or not - it would be nice to
>> have a stub back end for headless applications that wanted to use AppKit
>> things for PDF rendering and so on)
>> >
>> > - The input handling part, which is responsible for mapping host system
>> input events to NSEvents for the correct target.
>> >
>> > - The host environment integration, which includes things like exposing
>> the same fonts as other applications and ensuring that copy-and-paste /
>> drag-and-drop work with non-GNUstep applications.
>> >
>> > These are not entirely separated in the back end.  It would be nice for
>> Ivan's GSoC project to disentangle them a bit more so that each nominal
>> back end is formed by cleanly composing classes for each of these things.
>>  For example, DirectFB will want to supply its own event handling, but will
>> reuse the font management via FreeType and will reuse the drawing from
>> Cairo / Opal, but will provide its own graphics context setup code.
>> >
>> > David
>> >
>> > -- Sent from my Cray X1
>> >
>>
>> I'll take a look and try to integrate some of that into the proposal. :-)
>>
>> Regards,
>>
>> Ivan Vučica
>> via phone
>>
>
>
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