BUG(?): Player doesn't play if displaying twice

[hai-schrodinger]

Hi there,

Please try above. If display once, the player will play and the slider value keeps changing. If displaying twice and clicking the play button, the slider value only changes once.

[afonit]

Putting your code here so others can reproduce more quickly - I can confirm the behavior you are seeing.

from ipywidgets import IntSlider, Play
from traitlets import link

player = Play()
slider = IntSlider(max=10, min=0, step=1)
link((player, 'value'), (slider, 'value'))
slider

the behavior also occurs when using observe (not sure if that does the exact same thing as the link you used)

from ipywidgets import IntSlider, Play, HBox
from traitlets import link

player = Play(interval=500)
slider = IntSlider(max=100, min=0, step=1)
# link((player, 'value'), (slider, 'value'))

def on_value_change(change):
    slider.value = change['new']
    # print(change['new'])
    

player.observe(on_value_change, names='value')

# uncomment the below line to see the working model
# HBox([slider, player])

# uncomment the below line to see that when you hit play it only increments once for each time play is clicked
# HBox([slider, player, player])

[asaboor-gh]

I encountered same issue. Also, if you delete a display of Play widget and display again, it does not play again.

[asaboor-gh]

I have created another version of Play widget based on anywidget with the comprehensive help of Microsoft Copilot.
It lets you play/pause as usual but also enables you to pick an arbitrary frame using a slider. The issue of a not playing duplicate display or on re-displaying is apparently solved in this case.

Here is Python and ESM source code for this widget.

from ipywidgets import interact
from ipyslides.utils import AnimationSlider

widget = AnimationSlider(interval=20, nframes=20, continuous_update=False) 

@interact(w=widget)
def animate(w):
    print('w^2 = ', w**2)

widget

20250324-1530-36.2471137.mp4