[haiku-appserver] Re: drawing thread

  • From: "Rudolf" <drivers.be-hold@xxxxxxxxxxxx>
  • To: haiku-appserver@xxxxxxxxxxxxx
  • Date: Thu, 21 Oct 2004 15:48:27 +0200 CEST


I get the feeling Axel is thinking about that 'other' doublebuffering 
feature we shortly mentioned just now.
Confusing, this stuff :)


> Adi Oanca <adioanca@xxxxxxxxxxxxx> wrote:
> > > Locking, semaphores. Only one thread draws in the graphicsRAM at 
> > > a 
> > > time.
> >     OK. Perfect! That would be Poller Thread if DW agrees.
> Not really, there can still be any number of threads - they just have 
> to be serialized when accessing the same buffer.
> Anyway, you could also use double buffering by only having one copy 
> of 
> the whole screen around in main memory - I don't know if it makes 
> more 
> sense to have different bitmaps for every layer, because that would 
> make transparent stuff a lot harder to do.
> When you have a setup like this, all threads could even 
> simultaneously 
> access the main memory, since they will all only access their 
> clipping 
> region (with potential speed restrictions as well, just like video 
> memory, but less drastic). Only if there are more than one thread 
> accessing the same region (which can only happen because of 
> transparency), they would have to be serialized.
> Of course, having more than one thread drawing off-screen would be 
> great for systems with more than one CPU.
> Bye,
>    Axel.

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