filters and their config

[Casper Boemann]

Hi

In my quest for making the brightness/contrast filter I am once again battling 
the configurationwidgets, configuration and filters.

Lets get this right this time. What we want is:

- a config widget that can configure the filter
- a config class that stores the configuration of the filter.
- a filter class that does the work

This is more or less what we already do. The problem comes when we want to use 
them im practice.

We would want the configWidget to be designed in qtdesigner, but this is not 
possible if we subclass from KisFilterConfigWidget, so KisFilterConfigWidget 
needs to contain the actual qt designed widget.

We would want to use the filter without having a configWidget. So it must be 
the filter that creates the configuration.

The configWidget must somehow be able to fill it with values and the filter 
must be able to use those values for processing.

Ideally the filter and configWidget should have nothing in common except the 
config class. This is like the MVC pattern. So the 
KisFilter::createConfigurationWidget() must go. On the other hand is it quite 
nice to have the widget being able to create a correct widget without too 
much trouble


please comment and argue as I have not thought this all the way though

-- 
best regards / venlig hilsen
Casper Boemann