Capturing background clicks with coordinates

[joders]

*Issue number of the reported bug or feature request: #972

Changes
I added a default click event to scatter plots which is triggered whenever the click interactions on the mark is set to neither 'add', 'delete' nor 'select'. The mark now has a further handler registration function called .on_background_click_with_coordinates().

This implementation might not be ideal as it doesn't tie in with the present background click handling and also it doesn't have its own click interaction on the mark.

Testing performed
I only manually observed the events emitted by the mark to confirm that the desired information is present.

[joders]

This also fixes #653

[joders]

to test:

from bqplot import *

xs=LinearScale(min=0,max=1)
ys=LinearScale(min=0,max=1)
xa=Axis(scale=xs)
ya=Axis(scale=ys,orientation='vertical')
mark=Scatter(scales={'x':xs,'y':ys},interactions={'click':''})   #  <-- IMPORTANT
fig=Figure(marks=[mark],axes=[xa,ya])

def background_click_handler(mark, event):
    print(event['point'])
mark.on_background_click_with_coordinates(background_click_handler)

fig

[martinRenou]

Should we not enhance the current on_background_click with the coordinates instead of adding a new Python method?

[martinRenou]

Thanks for the PR anyway! This is super useful :)

[joders]

Should we not enhance the current on_background_click with the coordinates instead of adding a new Python method?

I did have a look at that but as far as I can remember there is no easy way to do that (or it's impossible). On the other hand the background_click_with_coordinates could also serve the ordinary background click function though from what I remember this might have performance implications.

Thanks for the PR anyway! This is super useful :)

Thanks :)

[jfraymond]

This is a very useful addition.
I spent hours looking the the documentation for this feature.
It would be perfect it it was available for all types of plots, not only scatter plots.

[maartenbreddels]

Hi joders,

thanks, I think this could be very useful, even apart from #1066 which listens to all mouse events / clicks. I think there are many cases where we'd like to capture clicks that are not on a mark. However, I don't think the place should be in a Mark since it does not make sense in the case of multiple marks, do you agree? I think the best place would be in Figure.ts, which is actually the originator of the events (ctrl-f for bg_clicked in that file).

Regards,

aarten

[joders]

Hello,
I currently don't understand the architecture well enough to answer this and forgot quite a few things in the last months. I thought you can have multiple axes in one direction (in which case outputting a single coordinate for that direction isn't enough). I would definitely agree if axes in one direction are always aligned. Maybe I'm confusing scales and axes. Also, I guess it would fulfill @jfraymond 's needs.
Cheers,
Jonathan

[Mathemmagician]

Hello from the future,

Was anything like this ever merged? Especially interested in getting mouse coordinates for the bq.Map

[maartenbreddels]

Hi, you could maybe take a look at glue-viz/bqplot-image-gl#57 instead

[Mathemmagician]

Not sure that would work since Map allows for various zoom ins. I think the approach above works for stationary widgets. Cool library though

[maartenbreddels]

Not sure

not sure either, try it out :)