Create the functionality save to svg

[ThomAub]

In order to save the chart render one can use web browser opened and click on save pngor save svg.
in the Altair documentation they use selenium to bypass the manual part and save directly.
It would be nice to have this feature also. see here for altair documentation

A selenium crate seems to exist and thus the same technic could be used : selenium-rs

[davidB]

• this features could be moved as part of in procyon crate (higher level), or showata
• https://crates.io/crates/fantoccini should also be evaluated as an alternative to selenium
• every webdriver will use lot of dependencies

[ThomAub]

• I agree.
• I will look into it !
• Yes we will make sure this is not the default behaviour but imho it's still a nice feature to have.

[ThomAub]

Just to keep track : https://github.com/jakevdp/altair_savechart

[ChristianBeilschmidt]

@ThomAub did you try out selenium and maybe have an example of how to do it?
Is it performance-wise a good idea to render the plots this way?

[ThomAub]

Hello @ChristianBeilschmidt ,

Thanks for your interest ! Unfortunately I didn't put much effort into the selenium option. As you pointed out it's not a great idea performance-wise but it's currently the only solution I found. If I find some times in the coming days to do a complete example I will update this issue.

[ThomAub]

Hello,
I have made good progress on this issue. I can use fantoccini and geckodriver, still need to implement it for to automatically save the current chart to an svg or png file. I still need to polish the API of this render_and_save function and will publish it to procyon. The procyon crate will be a high level wrapper arround the vega_lite_3 and vega_lite_4 crate thus it will be more appropriate to publish it there.

[ChristianBeilschmidt]

That sounds great 👍. I guess it makes sense to put it into a common crate rather than to duplicate functionality. I'm looking forward to using it.

So you basically use a headless Firefox for rendering the charts and returning the SVG? Is there a way to keep the browser instance open? I'm not quite sure what the performance penalties are for starting the process over again.

[ThomAub]

So you basically use a headless Firefox for rendering the charts and returning the SVG?

Yes that's exactly it.

Is there a way to keep the browser instance open?

Yes it's possible this mean that you want to save multiple charts ?

[ChristianBeilschmidt]

Is there a way to keep the browser instance open?

Yes it's possible this mean that you want to save multiple charts?

Yeah, I plan to investigate it for a server process. For histograms, it is good to transfer it to a client browser and have an interactive plot but for scatter plots with lots of points you not necessarily want to transfer all data to the client.

[ChristianBeilschmidt]

Did you manage to make some progress on this issue or maybe push your current state to a public branch?

[ThomAub]

Hello,
Yes i managed to have something even if it's a bit ugly .. I will ask for review of another contributor and push it to a public branch in the following days.