fix(pie): tangential rotation with startAngle #15980

[Ovilia]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Fix pie label rotation when startAngle is set to values like 0.

Fixed issues

• Issue with piechart label using startAngle and label.rotate = 'tangential' and label.position='inside' #15980

Details

Before: What was the problem?

In some cases, the text rotation is up-side-down and hard to read.

After: How is it fixed in this PR?

All text is rotated upwards for better reading.

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

• test/pie-label-rotate.html

The run button changes startAngle and data to test it works in all situations.

Others

Merging options

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

Other information

[echarts-bot]

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[echarts-bot]

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