Re: MacOSX compatibility : detachDrawingThread:toTarget:withObject:

[Adam Fedor]

Pierre-Yves Rivaille wrote:

> On Sun, 19 Aug 2001, Adam Fedor wrote:
>
> I think (I will check as soon as I get back to my MOSX cube) that
> multithread drawing is implemented through multiple context.


I didn't originally think that would work, but I guess it is possible.


>   [NSGraphicsContext setCurrentContext: 
>              [NSGraphicsContext graphicsContextWithWindow: window]];


This implies that you can only draw into a window with the same context 
which the window has been created with (i.e. you can't draw into a 
window with two different contexts).

> So the problem is does GNUstep backend (xgps/xdps) support multiple
> contexts ? According to the NEWS file in dgs, it seems that the support is
> not so good when using xdps + dgs.


dgs does not, but the backends themsleves do (I'd recomment xgps). It 
hasn't been tested at all though.


> The first problem I found when using xgps with the previous chunk of code,
> is in [NSWindow gstate] which gives back a value which is related to the
> main thread context and causes a crash when called by a thread using its
> own GraphicsContext.


Well the previous code indicates that this is the correct behaviour 
(well perhaps it shouldn't crash...). Although we could extend this by 
adding a window method -gstateWithContext:

There may be other issues but I can't really think of any now.


Adam Fedor, Digital Optics            | Fudd's law of opposition: Push
fedor@doc.com  http://www.doc.com     | something hard enough, and it
fedor@gnu.org  http://www.gnustep.org | will fall over.