On release slider event?

I would like to have access to a on_mouse_release event for a IntSlider, while still having continuous_update=True.

I am slicing through a 3D data cube with ipyvolume and using a slider to control the z coordinate of the slice. Updating the slice and its colors every single step of the way slows down the performance quite a lot.

I would like to do something similar to what Paraview does, where while I interact with the slider, I am only moving an outline (in red on my figure) of the slice, and once I relase the slider, then update the position of the real slice and its colors. Moving the outline is very cheap.

Hence I still need to have the slider move the outline (update_outline()) in continuous_update but then trigger another function (update_slice()) once I relase the mouse button.

I tried playing around with linking a first slider in continuous_update=True to a second slider in continuous_update=False which would then trigger the update_slice(), but linking the values means that the second slider still considers every step to be a value change and triggers update_slice() every time.

I would basically need to have something like

sl = IntSlider(min=0, max=nz-1, continuous_update=True)
sl.observe(update_outline, names="value")
sl.on_mouse_release(update_slice, names="value")

I found in the documentation that you can send more than just the value to the observer function. Apparently, setting names and type to All should capture all events, and maybe there is something I could use in there, but I have not been successful in trying to use this. When I tried

sl = IntSlider(min=0, max=nz-1, continuous_update=True)
sl.observe(update_outline, names="All", type="All")

nothing happens, the function update_outline is never called (I had a print statement also in that function which never prints).

I tried to look around the documentation and the web for an example of using names="All", type="All" but found nothing.

Any help is very much appreciated!

[davidbrochart]

I can look into implementing a “debounce” pattern. While talking with @martinRenou, it could be useful to have it on both sides:

• in the front-end, because it is where “time is real”, reducing communications with the kernel.
• in the back-end, where “time is not real” because communications may arrive through a slow network, reducing potentially heavy computations.

[betolink]

related to this, somebody mentioned the continuous_update parameter and in my case it waits to send the events until the user stops dragging the slider but it sends all the changes! not just the last one, is there a way to prevent this or that’s the expected behaviour?

EDIT: nevermind, I just need to access the new value but still the whole chain of old values is sent to the kernel and resulted in a lot of traffic so I had to increase NotebookApp.iopub_data_rate_limit. It would be a good idea to implement what you guys already started talking about or even better have a “mute” property so some events are not sent as a whole if there is heavy interaction in the front end.