tool activate()

[Boudewijn Rempt]

On Sun, 20 Mar 2005, Casper Boemann wrote:

> Hi
>
> I was trying to make activate and deactivate functions of KisTool, but then I
> realised that the concrete subclasses KisToolPaint and KisToolNonPaint both
> has an activate() slot. Don't know if it does what I need, which is to
> provide me a place to do some toolspecific initialisation each time the tool
> is started. More specifically in my transform code I need to draw handles on
> screen as soon as the tool is activated. And the handles need to go away (and
> the transform committed) when the tool deactives (ie another tool is
> selected)
>
> Can someone enlighten me as what I should do to provide a deactivate, and
> should it also be a slot, and why aren't activate directly made in KisTool
>

Okay... The reason there is no deactivate is that until now tools were
supposed to finish their job on mouse-up. This already broke down somewhat
with the primitive crop tool I implemented some time ago, but with your
work, this model breaks down completely.

What we need, therefore, is to add a deactive() that is called whenever
another tool is activated for a certain pointer. Keep in mind that we
can easily have any number of tools active at the same moment: one for
the mouse, one for the stylus, one for the eraser, one for another Wacom
stylus, etc. You cannot simply assume that there is only one tool active
at a given time.

(I know that we don't have finished the gui to represent this complication
to the user, though -- but we cannot go back on this. There will always
be a set of active tools, each associated with a certain pointing device.)

A temporary solution would be to follow the crop tool lead: have
two buttons, one to activate the handles, and another to commit the
changes. Not ideal, but a possibility. If you want to go all the way
and implement a pointer-specific activation and deactivation routine,
by all means, go ahead. It'll be better in the long run, even if it's more
work right now. The place to call the current-tool::deactivate is just
before the new-tool::activate in KisView, I guess.

Maybe Adrian Page (who did the work to support mouse, stylus and eraser
initially) has an opinion on this topic, too.

Boudewijn