fix:node self pointed -add cubicBezierCurve

[HCLacids]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Fix the rendering of the edge that the target and the source is the same.

Fixed issues

Details

Before: What was the problem?

When the node has the self-loop-edge, it will render only one point in the previous condition that the algorithm only adapt to the quadratic bezierCurve.

After: How is it fixed in this PR?

Now the rendering method contians the cubic bezierCurve to paint the self-loop-edge.

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

NA.

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.

[susiwen8]

Please do not commit any change in dist folder. Also could you show us what problem does this PR fix?

[pissang]

@HCLacids Please don't delete the distribution files

[pissang]

Can you describe the change in more detail and add the result screenshot.

[100pah]

I have made a "draggable" test case to cover scenarios as much as possible.

Functional defects summary

1. In some of the angle the direction of the self-loop edge is not expected.

2. When scaling the graph, the label fly to wrong place.

3. The rotate of the the arrows are not correct.

---

A PR-fix: HCLacids#1 to fix this PR

This PR-fix fixed the issue 1 above, and add test cases.

Before that PR-fix: https://echarts-try.surge.sh/graph-self-loop-old/graph-self-loop.html
After that PR-fix: https://echarts-try.surge.sh/graph-self-loop/graph-self-loop.html

---

About curveness

At present, the curveness can be controlled by two ways:
(A) autoCurveness: true
(B) lineStyle.curveness.
lineStyle.curveness can be set on the whole series:

series: {
    type: 'graph',
    lineStyle: {
        curveness: 0.5
    }
}

or on some certain edges:

series: {
    type: 'graph',
    edges: [{
        source: 1,
        target: 4,
        lineStyle: {
            curveness: 0.7
        }
    }, {
        source: 1
        target: 4
    }]
}

When lineStyle.curveness is set to some edge, autoCurveness will not be accepted to that edge. Basically it's implemented by code like this:

const curveness = zrUtil.retrieve3(
    edge.getModel<GraphEdgeItemOption>().get(['lineStyle', 'curveness']),
    -getCurvenessForEdge(edge, seriesModel, index, true),
    0
);

• focus: 'adjacency'

emphasis: {
    focus: 'adjacency'
},

But I think we do not need to support autoCurveness in self-loop edges if the we accept the layout in this PR-fix.

---

@HCLacids Could the PR-fix be approved ?

Any issue can be discussed.

[History-1024]

So how do you use it？

[zl2fxy]

When will it be updated?