[Bug] RadialGradient backgroundColor can't render by svg

[zhiqingchen]

Version

5.4.0

Link to Minimal Reproduction

https://echarts.apache.org/examples/zh/editor.html?c=bubble-gradient

Steps to Reproduce

1. add RadialGradient background

option = {
  backgroundColor: new echarts.graphic.RadialGradient(0.3, 0.3, 0.8, [
    {
      offset: 0,
      color: '#f7f8fa'
    },
    {
      offset: 1,
      color: '#cdd0d5'
    }
  ]),
}

2. use svg render
3. result

Current Behavior

Expected Behavior

Environment

- OS:macOS Monterey
- Browser:Chrome 96.0.4664.55
- Framework:no

Any additional comments?

No response

[plainheart]

SVG renderer only supports setting a color string as the background now. This feature is in progress and may be supported in future releases. See also the svg-background branch.

[koliharesh]

Hello Sir/Madam, I would like to contribute in your project to solve this issue.