[Marble-devel] QGraphicsView Overlay for marble

Andrew Manson g.real.ate at gmail.com
Tue Mar 24 21:41:04 CET 2009

Hi all,

I guess you're all a little sick of my little emails every day by now, 
but i am making progress so thats good right? ;)

OK so the current update on the Marble Overlay stuff, i have been 
studying the code to try and find a nice way to let the PluginManager 
class "know" about the MarbleWidget. Unfortunately, from what i can see 
there is no nice or simple way to do this. The attachment is a diff that 
will take the naive way of doing it, simply passing a widget pointer 
down each constructor until it reaches the Plugin Manager.

Just for reference ( and in case you don't like looking at diffs ) the 
chain of constructors i was talking about is: MarbleWidget -> MarbleMap 
-> MarbleModel -> LayerManager -> PluginManager.

... this, as you all know, seems a bit unnecessary. Any alternative 
solution would need to alter the Architecture of marble in some way, the 
simplest way to do this i think might be to Change the PluginManager 
into a Singleton Class. This might even be able to maintain binary 
compatibility, which the diff attached clearly does not.

For PluginManager to become a singleton all we really need to do to 
alter the current code is to remove the loadPlugins() call from the 
constructor of PluginManager and have LayerManager get an/the instance 
of PluginManager and call loadPlugins on it. And of course actually 
making the PluginManager a singleton ;)

Anyone like to comment on this approach? Pros and Cons and stuff like 
that ;)

I will give this method a try on Thursday or Friday and keep you all 

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