Re: [matplotlib-devel] wrote a selection bar widget (attached)

[Egor Z. <ez...@gm...>]

John Hunter wrote:
> On Wed, Nov 26, 2008 at 10:41 AM, Drain, Theodore R
> <the...@jp...> wrote:
>
>  
>> I'm pretty sure this is exactly what's happening.  This is also 
>> annoying when you're trying to use a zoom rectangle and want to start 
>> at some point in the plot and drag it to the boundary.  We've been 
>> planning on putting some time in to fix this this but just haven't 
>> been able to make the time yet.
>>
>> I think one possible solution is that anytime the mouse moves outside 
>> the axes, it should get one last event that is at the boundary which 
>> would require tracking which axes the last event was sent in.  We 
>> haven't tried to see how hard that is to implement thought...
>>     
>
> probably fairly easy using a class level attr in the MouseEvent.
> Another possibility would be to add support for figure_enter_event,
> figure_leave_event, axes_enter_event, axes_leave_event.  The user code
> would have to separately process the axes_leave_event but this might
> be the cleanest solution.  I am happy to add support for these ...
>   

John,

in my code, I implemented tests like:

       if self.valmin is not None:
           if val < self.valmin:
               val = self.valmin

which makes limit handling better than that of the Slider class this was 
based on:

       if self.slidermin is not None:
           if val<=self.slidermin.val: return


Theodore nailed what is happening. At the moment, tests like the one I 
used cannot be implemented because event.xdata returns None when outside 
the boundaries. This cannot be compared with ax.get_xlim().

Maybe a value should be returned even when outside. the event.inaxes 
should be enough to know if the mouse pointer is inside or outside.

Although that would probably break a few things that at the moment 
depend on event.xdata being None when outside!