Re: NSBackingStoreNonretained

[Adam Fedor]

Frederic De Jaeger wrote:

> In the current implementation, there are three problems: 
>    - there is no compression of expose events. 

I think there is, at least for Nonretained windows. In the backend, 
XGServerEvent (case Expose). But perhaps you are talking about a more 
extensive version of coalescing events than what is implemented. Or 
maybe it's not working correctly?

>    - when an expose event arrives, all the content of the window is
> refreshed instead of the necessary parts.  

All the expose rectangles are stored in window->exposedRects, so it 
should be simple to NSUnionRect these. The problem here is figuring out 
which views need to be redisplayed based on the rect. This can be done 
in the front end, but it seems odd to call a front end method from the 
backend (even though that's the way it is done now). Perhaps this could 
be cleaned up some - or we could define a new AppKit specific event to 
handle the expose in the front end.

>    - when the window is refreshed, it begins by repainting its content
> with the background color (which is already done by the Xserver (but
> it does it with the wrong color))

X windows allows you to set the default background, although currently 
it's setup to do XSetWindowBackgroundPixmap 
(XGServerWindow:_createBuffer), which perhaps is wrong.

Then we have the fact that the frontend doesn't know this. Maybe we 
should document that all backends need to paint exposed areas in the 
windows background color and take this out of the frontend.


--
Adam Fedor, Digital Optics Corp.      | I'm glad I hate spinach, because
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