Added property outerArcLength to Sunburst

[jon-a-nygaard]

Description

Added the property outerArcLength to use as an alternative filter instead of innerArcLength.
In the case of points where innerR is 0, the innerArcLength will also be 0, which may cause unwanted behaviour.
It can be seen in our current Sunburst demo that the data label in the top node is filtered away, even though there is enough space for the data label.

The sample highcharts/demo/sunburst is modified to use outerArcLength on level 1, but it is depedent upon the changes in #7680 for level.levelIsConstant to work properly.

Note: I removed innerArcFraction and perimeter, because I found that innerArcLength could be expressed as radians * values.innerR.

Example(s)

• https://utils.highcharts.local/samples/#view/highcharts/demo/sunburst

Related issue(s)

• Sunburst chart - When zoomed in the intermediate level ,series label of zoomed in parent is not visible ,only series labels of its children are shown #7597

[oysteinmoseng]

Probably good, just wondering if we should avoid the magic number 6.28? Assuming this is 2*PI, could we just store that in a variable since we are using that anyway? Or at least add a comment on how this works

[jon-a-nygaard]

Thanks @oysteinmoseng! I agree that we should avoid magic numbers.

[jon-a-nygaard]

Closed by accident