Add option to preventDefault on scroll event

[ianhi]

closes: #222

Following the way resizeable was added I added capture_scroll to the canvas object with a default of False. If set to true then the entire notebook will not scroll when a user scrolls the mouse over a canvas. This allows the enduser to implement things such as custom scroll to zoom methods.

[tacaswell]

This seems sensible and correct to me

[dzanaga]

@martinRenou regarding #240 I tried the new feature. After installing the latest from master, I tried to set fig.canvas.capture_scroll to either True or False but it doesn't work for me. Still getting the page scrolling when trying to scroll on the canvas.

Maybe I am not using it properly... I am using it like this:

self.fig, self.axs = plt.subplots(1, 2, **figure_options)
self.fig.canvas.capture_scroll = True

[martinRenou]

Could it be an installation issue? Are you using JupyterLab or Jupyter Notebook?

[dzanaga]

I am using JupyterLab. If that's the way it should be used, could indeed be an installation issue...I am gonna try to do a fresh install of the miniconda environment when I have time and see if it's fixed there. Thanks

[martinRenou]

Be sure to run jupyter labextension install js locally (from the ipympl root directory).

[dzanaga]

That's it, it works now. Thanks for helping out and for the great work!

[martinRenou]

Nice. We should make a release with this fix.

[ianhi]

Also the readme currently says jupyter labextension link ./js and this should probably instead say install see https://gitter.im/jupyterlab/jupyterlab?at=5ee6abf324a3382d5d68b2ae

[martinRenou]

@ianhi If we do that, the cd js && npm run watch will not be relevant anymore so we might want to remove it.

[ianhi]

@martinRenou instructions updated in #243

Nice. We should make a release with this fix.

👍 yes please

[martinRenou]

@ianhi Release done on PyPi. It should come soon on conda-forge as well.