Re: [matplotlib-devel] RFC: double click support in matplotlib

[Benjamin R. <ben...@ou...>]

On Saturday, October 22, 2011, Daniel Hyams <dh...@gm...> wrote:
> matplotlib doesn't support double clicks, and I was wondering if that
> was a design decision, or something that had been relegated to the "to
> do" box for someday. Hoping that it was still in the "todo" box, I
> think I can put most of it in without too much trouble, and supply you
> with a patch.
>
> The changes would be:
>  1) an extra flag MouseEvent, so that in a button_press_event
> handler, you can can tell if the press was a result of a double click
> or not, and
>  2) code in the backends to catch and set the double click flag properly
>
> I looked through the backends, and it was clear what to do in order to
> support double clicks for all but backend_macosx.py.  I might be able
> to deduce what to do there, but will likely need some support from
> someone in order to get that one done.
>
> To support the double clicks, I would rather not create a new event
> like 'button_doubleclick_event', for backwards compatibility.  I
> believe that if we just stick with 'button_press_event' and set an
> extra flag within the MouseEvent, any existing mpl code will still
> work properly, because the normal sequence of events on a double click
> are; DOWN, UP, DBLCLICK, UP.  In current versions of matplotlib, the
> DBLCLICK event is treated as a DOWN, and the strategy of just adding a
> extra flag in MouseEvent would mean that existing mpl code would still
> see the double click event as a DOWN.
>
> Anyway, I want to "throw a feeler" out there, and ask if the patch
> would be accepted were I to go ahead and do it. I didn't want to spend
> the time working on it if a decision had already been made a while
> back to not ever support double clicks.
>

My vote would be yes, but I think i would want it as a separate event.
 Consider some of the widgets like lasso and the zoom bbox.  If one were to
attach a button_press_event for the purpose of detecting double clicks, I
would imagine that there may exist conflicts (or those widget codes would
have to be adjusted to exclusively respond only to single clicks).  Would
existing widgets also fire even if a double-click occured?

My 2 cents,
Ben Rootl