Re: cario and shmget problems

[Eric Wasylishen]

Hi Fred,
I had the same plan as you - Opal will use the existing back/x11 code
for window buffers/event handling, so if there are bugs to fix /
performance improvements to make in back/x11, they will benefit Opal
as well.

Eric

On Fri, Jul 9, 2010 at 3:37 PM, Fred Kiefer <address@hidden> wrote:
> Am 09.07.2010 12:10, schrieb David Chisnall:
>> In fact, the use of shared memory with the Cairo back end is
>> currently completely wrong - it may work, but it's a design that will
>> give absolutely the worst possible performance possible from Cairo,
>> because we're implicitly telling Cairo not to use hardware
>> acceleration for drawing and then telling the X server to perform a
>> redundant copy if it wants to do hardware acceleration.  This is
>> something that Opal will fix by not trying to make Cairo look like
>> libart, so I'm not sure if it's worth bothering chasing a short-term
>> fix.
>
> David,
>
> could you please elaborate a bit more how the way Eric is implementing
> Opal will be different in the way it handles window memory? Up to now I
> had expected that Opal would leave all the window (and event) management
> to the existing code and only provide a slightly different way to
> package up the drawing code. The current code structure isn't actually
> modelled after libart, it is based on the PostScript drawing structure
> GNUstep inherited from OpenStep.
>
> As far as I remember the usage of XWindowBuffer via the
> XGCairoXImageSurface was added to allow the usage of 32 bits to have
> transparency handling even when the graphic card didn't support it
> (Which was the normal case at that time). This may be obsolete now for
> most modern graphic cards, but if there is an easy way to change this,
> doing so in back wont be any harden than doing it just in Opal.
>
> Or am I completely missing something here?
> Fred
>
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