[Bugfix] Chord chart zero value edge covers full circle in clockwise orientation

[rishyanthkondra]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

• Fix the rendering of chord edge when edge value is 0 in clockwise orientation

Fixed issues

N.A

Details

Before: What was the problem?

option = {
  series: [
    {
      type: 'chord',
      label: { show: false},
      data: [
        { name: 'A' },
        { name: 'B' },
        { name: 'C' },
        { name: 'D' }
      ],
      links: [
        { source: 'B', target: 'A', value: 100 },
        { source: 'C', target: 'B', value: 0 },
        { source: 'D', target: 'C', value:50 }
      ]
    }
  ]
};

with clockwise: false, its correct but without it, there is a shade on full circle

After: How does it behave after the fixing?

Document Info

One of the following should be checked.

• This PR doesn't relate to document changes
• The document should be updated later
• The document changes have been made in apache/echarts-doc#xxx

Misc

Security Checking

• This PR uses security-sensitive Web APIs.

ZRender Changes

• This PR depends on ZRender changes (ecomfe/zrender#xxx).

Related test cases or examples to use the new APIs

N.A.

Merging options

• Please squash the commits into a single one when merging.

Other information

N.A.

[echarts-bot]

Thanks for your contribution!
The community will review it ASAP. In the meanwhile, please checkout the coding standard and Wiki about How to make a pull request.

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[plainheart]

Thanks for your contribution! Could you add some test cases for this fix?