Brush change based on tablet pressure

[Bart Coppens]

Currently, we only support a single hardcoded brush modification by pressure: 
brush size. It would be interesting to change this into something a bit more 
configurable; an artist might want not only to change shape, but also want 
brush opacity to be dependent on how hard he presses on the tablet. The GIMP 
already does this, so there's always the reason of 'compatibility' ;-)

Now my question is where we should add this (if at all for 1.5)? Should each 
paintop have a seperate configuration dialog, like Boudewijn suggested on 
IRC? Or should it be the brush itself that carries such a setting?

I think it might be nice for the user to have (not now, in the future) a kind 
of dialog like the dialog on how KMail and other KDE applications let you add 
a configurable list of 'filter actions'. Each paintop (or not, maybe a 
generic list suffices?) could have a list of "actions", like for example 
"scale", "opacity", "color darkness". Then the user could have a dialog that 
lets him add as much 'rules/actions' as he wants (with More/Fewer/Clear 
buttons, like KMail). For each such a rule, he then can select from 2 
dropdown lists: tablet input, and paintop action. So, he might connect 
"pressure" to "opacity" and "scale", and at the same time connect "rotation" 
to "darkness". The problem here might be that configurability might mean a 
(slight?) performance loss...

Any comments on this?

Bart Coppens