feat: nameFormatter and headerFormatter added

[jiawulin001]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

New APIs tooltip.nameFormatter and tooltip.headerFormatter that allow user to change name and header respectively in tooltip are added.

Fixed issues

• fix [Question][Feature] How do you specify date format in tooltip? #16703

Details

Before: What was the problem?

"New formatter" like tooltip.valueFormatter is requested to change the name and header in tooltip. With these formatters users can change only the series name or the header (x-axis value), without changing the other default parts of the tooltip.

Users cannot change the format of date and have to display the exact time despite they don't need it.

After: How is it fixed in this PR?

New APIs tooltip.nameFormatter and tooltip.headerFormatter are added. They allow user to change name and header respectively in tooltip without changing other default part.

After setting tooltip to:

tooltip: {
    trigger: 'axis',
    headerFormatter: header => `${new Date(header).toDateString()}`,
    nameFormatter: name => `Score`,
    valueFormatter: value => `${value}/10`
  }

We have

User can change name and header as wish without having to write the whole thing from scratch with tooltip.formatter.

Misc

• The API has been changed (apache/echarts-doc#xxx).
• This PR depends on ZRender changes (ecomfe/zrender#xxx).

Related test cases or examples to use the new APIs

N.A.

Others

Merging options

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

Other information

[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.

Document changes are required in this PR. Please also make a PR to apache/echarts-doc for document changes and update the issue id in the PR description. When the doc PR is merged, the maintainers will remove the PR: awaiting doc label.

[Airkro]

headerFormatter is really useful. Is it possible to land this feature sooner? Milestone 5.4 is too far.

There is a replacement: #16703 (comment)

[DavidMarquezF]

Any plans on merging this? nameFormatter would be really useful

[Ovilia]

This feature looks great! Please also provide a test case using npm mktest xxx.

[Ovilia]

Missing ;