feat(graph): graph support multiple edges, for #6811

[wf123537200]

the type=graph support multiple edges between two nodes

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

the type=graph support multiple edges between two nodes

Fixed issues

#6811

Details

Before: What was the problem?

After: How is it fixed in this PR?

Usage

Are there any API changes?

• The API has been changed.

series > autoCurveness

// if number will set curveness list max length with params
// if function will use the return array as the curveness list 
autoCurveness: 'number | function() {}'

Related test cases or examples to use the new APIs

graph-mulitple-edges.html

Others

Merging options

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

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.

[wf123537200]

Chinese comments removed~~

[ohadleshno]

Great feature 👍

[stolenfather]

Hey , I really need this pr when will it be merged?

[travis1111]

Someone please review this :-) we also need this

[bionexit]

Hey , I really need this pr when will it be merged?

This is also my urgent need pr...

[wf123537200]

@100pah Thanks for your suggestions and code review, this is a great help!
I rebuild the code as suggested.
Please help me see if it is appropriate to review the current implementation.

Thanks!

[100pah]

@wf123537200
Sorry my review is too late.
There are several places could be enhanced.
The others look good to me.

[wf123537200]

@100pah 3q for the review and the suggest, i fixed it.

[echarts-bot]

Congratulations! Your PR has been merged. Thanks for your contribution! 👍

[100pah]

@wf123537200 Thanks for your great work!

[plainheart]

👍 Documentation about this new feature is waiting to be added.

[plainheart]

Though this PR has been merged, there may be some parts could be optimized.

[wf123537200]

@plainheart 3q for fix this

[wf123537200]

👍 Documentation about this new feature is waiting to be added.

i will add to documentation ASAP.

[ryancui92]

I found that in some cases, toggle legend will make multiple lines into single one.(overlapping)

Check it out in this demo: https://gallery.echartsjs.com/editor.html?c=xNQsu5DekH&v=2

Then I figured that edgeArray is undefined after selecting legend, maybe caused by incorrect node.dataIndex.

See here: https://github.com/wf123537200/incubator-echarts/blob/fd25c1a49d72cc32930c9a0836698d1a125b3298/src/chart/helper/multipleGraphEdgeHelper.js#L75

I changed two lines, and it worked.

// var source = [n1.id, n1.dataIndex].join('.');
var source = n1.id;
// var target = [n2.id, n2.dataIndex].join('.');
var target = n2.id;

I am wondering why dataIndex is needed in generating edgeKey here?