Canvas MVC

["John Stowers" <john stowers gmail com>]

Hey Guys,

Just a quick update on my progress. Because I am still travelling, and have sporadic net access, I have been spending most of my time hacking on the canvas mvc branch. At the moment It is quite close to be finished, architecture wise. There are still a number of feature regressions however. Basically the goal here is to remove the dependency on goocanvas such that conduit can be run headless (previously the dataproviders derived from GoocanvasItem which was architecturally ugly)

The new architecture is basically
Model -> View
Conduit -> ConduitCanvasItem
DataProvider -> DataProviderCanvasItem
Converter -> ConnectorCanvasItem

All communication from the model to the view elements is via gobject signals. All of the canvas code will now live in 
Canvas.py. The big remaining bits are

* What do we want to do with converters in future? What things should I design for re the Connectors which represent a converter
* What should the model for the Canvas look like, At the moment its just a list of Conduits
* In the new branch pending dataproviders are just represented as a ConduitCanvasItem whose model is None. 

Its probably about 20 hours away from being complete but I think it is a step in the correct direction

John