Method to get data from canvas elements charts

[marius-dr]

Right now there is no way to get data from a chart created with the canvas elements (not the Canvas app) from our automation tools. And from what we can tell there is no way for a screen reader to get the data from those charts.
What we would propose is to have a something like a hidden element with the values from the charts that a screen reader could access and that we could also access from the automation framework.

We're open for any other suggestions on how to make the chart data accessible.

cc @LeeDr

[myasonik]

I agree with the premise that making charts more screen reader friendly will also make them easier to test but I want to divest this issue from accessibility and leave it focused on testing.

There are other tickets in Kibana tracking the accessibility of charts (#11842 is a good broad issue) so I'm going to divest this one from accessibility.

I'm leaving it open in case testing folks want it for their own tracking but feel free to close if it's not needed.

[markov00]

We have added a debugState flag, currently under the alpha tag, in charts to provide the internal representation of the data, lines, areas, bars, axis and legend of the chart: elastic/elastic-charts#834
We are using this to replace the existing functional tests that use to get the SVG elements heights, compare them with the axis element height to get the original data back.
We can extend to cover the accessibility providing the data not only as part of our status element attribute, but in a HTML table inside the chart element if preferred.

[timroes]

Since we're planning to switch using elastic-charts, I'll close this issue in favor of a11y (elastic/elastic-charts#300) and automated testing (#70176) issues related to elastic-charts.