Re: GSDisplayServer

[Adam Fedor]

Fred Kiefer wrote:

> Hi Adam,
>
> I like that new interface, it makes things much more explicit. There is 
> still one method I am missing:
> - (NSRect) boundsForScreen: (int) screen;


I wanted to add that also, but forgot. I'll do that.


> What is still a bit unclear to me is the relationship between a context 
> and a display server. A graphics context for plotting does not know 
> about a display, but one drawing to a window should. And may the same 
> context be used for different display server, e.g in the case that a 
> window move to a different screen. Or are all screens managed by the 
> same display server?


A display graphic context (i.e. one that plots to the screen) knows how 
to plot to a screen given certain information. It gets this information 
through the [GSDisplayServer -windowdevice:] method. -windowdevice 
should call something like [NSGraphicsContext -setgcdrawable::::], 
although since this is done in the backend we are more free to define 
another interface or add more commands to set the proper information in 
the context.

contexts have separate gstates, each one holding separate windowdevice 
information, so it's conceivable that one context works on more than one 
display - although the Xgps backend, at least, is not structured to 
handle this.

One display, on X-Windows handles all screens. I think there is 
flexibility in the definition so that this may or may not be the case on 
other servers.

> PS: Did you have a look at that abstract non PostScript context and 
> gsgstate classes I did send you. I think we should introduce them to 
> GNUstep at the same time we add the display server.

Yes, it's nice - I had not realized how much of it was device 
independant.  I'm currently trying to simplify the NSGraphicsContext 
interface also, but I will integrate this in.




--
Adam Fedor, Digital Optics Corp.      | I'm glad I hate spinach, because
http://www.doc.com                    | if I didn't, I'd eat it, and you
                                      | know how I hate the stuff.