[haiku-appserver] Re: invalidation again

Hi Stephan,

Stephan Assmus wrote:
> Hi,
> 
> I was trying to make BView::Invalidate() work. I'm giving up, because I 
> don't understand the code.

        If you spend some time on it, you will. Same happen to me when I came
to work on app_server. :-) But I can understand you as the code is more
complex now.

> I have an idea what the problem is, but I 
> have no idea where to fix it. The triggering of update requests works 
> for moving windows arround. So I thought it must be simple to make 
> BView::Invalidate() work.

        It is simple. If it doesn't work, that's another problem...
GetRootLayer()->GoRedraw(cl, reg) should've worked in this case.

> However, there is no one central mechanism, 
> while it should be the same thing.

        There is a central mechanism:
RootLayer::GoInvalidate()
RootLayer::GoRedraw()
        from a tread != RootLayer's one
RootLayer::invalidate_layer()
RootLayer::redraw_layer()
        from inside RootLayer's thread.

> Instead, there is horrible 
> commenting, bad naming of member variables and functions. A ton of 
> similar functions that seem to be ment for the same thing. Refactoring 
> is desperately needed.

        Yes, I agree.

> A little commenting about the *structure* of the 
> code and the interacting parts would help too.

        When I'll have time I'll make a diagram about how region rebuilding
and region invalidation works.
        You'll see that's it's pretty simple to grab by someone with your
experience.

[ The main idea is that all region rebuilding and canvas cleaning is done from
one thread only: RootLayer's one. If you want to understand how that works
start with RootLayer::invalidate_layer() and go down until you hit Painter
:-) ]

> Adi, if you find some time, it would be really nice if you could make 
> BView::Invalidate() work. I would do it, but I'm just clueless.

        OK, I will see what's wrong during this weekend.

> Since this is an open source project, we all benefit from people 
> digging in and trying to help. So code should be written with that in 
> mind.

        We don't even have an alpha going, this is still early stage
development, specifications are not complete and thus code is not that
clear until a certain point in time when a cleaning is required.
Clipping code still has some things left to be done, like BView origin
support(not that big of a deal), dragging transparent surfaces, etc.
        I have started a big cleanup in window management code (RooLayer,
WinBorder, Workspace, ServerWindow partially) and I'm almost finished,
but I have not yet reached the clipping and update code.


bye,
Adi.

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