feat(polar): hide series bar when no data

[Ovilia]

What problem does this feature solve?

For bar series in polar, it will display a circle when data value is 0. This may be strange to users if they don't know this is data 0.

Current

Expected

We should provide an optionmake it default that the developer can choose to display nothing when data is 0.

What does the proposed API look like?

No extra option.

[foolzhang]

can we hava a try ? 😁

[Ovilia]

@foolzhang Sure! You're more than welcomed to make a pull request about this.

The bar series in the polar system was introduced in #11393.

I think we should not add the shape (or remove the previous shape) if the option is set to be true and the startAngle and the endAngle is the same. @pissang Is this the correct way?
Related code is https://github.com/apache/incubator-echarts/pull/11393/files#diff-9f3e66cf4f6fab7ab14223075cd4df3bR339-R341.

And do we need to remove bars in the cartesian coordinate system also? The result would be not having borders any more for zero bars. I don't think this is necessary, but just out of the uniformity.

[pissang]

The main concern from me is that there will be no differences between '-' and 0 data if this option is enabled.

[Ovilia]

'-' means no data, but when there is data as 0, and the user wants to hide the circle (maybe he doesn't care about whether it will cause confusion with '-'), we should provide a way to do so.

[Ovilia]

@foolzhang You can set the fill and stroke to be 'none' when the startAngle and endAngle are the same, and set the shape to be silent: true to avoid using emphasis style when the user hovers on it.
This is also required for bars without roundCap and bar series under the cartesian coordinate system.
Please comment here if you need some extra help.

[foolzhang]

you mean is No extra option and data 0 should hide series bar ，is right?
currently roundCap is only available for polar . how about like this
in BarView.js

polar:function(...){
   // ...
   var ShapeClass = (!isRadial && (roundCap && layout.startAngle!=layout.endAngle)) ? Sausage : graphic.Sector;
  // ...
}

i think this easy to satisfy your request

@Ovilia

[Ovilia]

No extra option and data 0 should hide series bar

Yes.

We still need to add the shape, only that the fill and stroke are set to be transparent. Otherwise, it may cause error when data update since there was no previous shape.

[foolzhang]

@Ovilia pr

[Ovilia]

Merged in #11557. Thanks @foolzhang !