Use global element hidden status for Pie charts

[kurkle]

Fixes: #6746

[etimberg]

Is it a good idea to store something on the chart for this?

[kurkle]

Is it a good idea to store something on the chart for this?

Seemed like a good holder, but maybe not. I pushed an alternative solution to review.

[benmccann]

What's expected when you update the chart? Should it clear the hidden elements? E.g. you have a completely new dataset, I'm guessing you might not want to hide based on index of the previously clicked dataset

[kurkle]

What's expected when you update the chart? Should it clear the hidden elements? E.g. you have a completely new dataset, I'm guessing you might not want to hide based on index of the previously clicked dataset

As in the linked issue, when you hide an item and then add another dataset, the legend shows that the item is hidden, but its only hidden from the old dataset(s). When you click the legend again, the old datasets show that index and the new dataset hides that index. I don't think anyone expects that kind of behavior.

So this pr: the new dataset's item is also hidden = in sync with the legend.

This does not work with custom legend implementation though, because there is no api.

[benmccann]

It looks like DatasetController.getMinMax used hidden. You might have to override it in the doughnut / polarArea controllers? I'm also wondering if we still need hidden in core.element after this?

[kurkle]

It looks like DatasetController.getMinMax used hidden. You might have to override it in the doughnut / polarArea controllers? I'm also wondering if we still need hidden in core.element after this?

I went ahead and removed the hidden

[benmccann]

I'm very happy to have hidden removed!

Can we move toggleDataVisibility, getDataVisibility, and _hiddenIndices from core.controller.js to the doughnut and polarArea controllers? It seems quite specific to those charts, so I'm not sure I want to expose it globally when it will have no effect on the other chart types

Also, I wonder if there's a way we can share the legend settings between the doughnut and polarArea charts? (there's one extra if check in the doughnut onClick, so we'd have to make sure to use the doughnut version of the code so as not to accidentally lose that extra check)

[kurkle]

It would actually work for others too, it does not care what indices are used. So could as well be datasetIndex. Could remove the hidden from dataset too. How does that sound?

[benmccann]

Ok. I guess that would be fine

[kurkle]

It would actually work for others too, it does not care what indices are used. So could as well be datasetIndex. Could remove the hidden from dataset too. How does that sound?

Ok. I guess that would be fine

I'm not going to do that though.