fix(linear-gradient): avoid the infinite value in linearMap util.

[plainheart]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Fix a bug that the chart cannot be rendered for Infinite value, fix #7293, #14534, #14601.

Fixed issues

• y轴类型为log时，启用visualMap出现异常 #7293
• TypeError Failed to execute 'createLinearGradient' on 'CanvasRenderingContext2D': The provided double value is non-finite. #14534
• y轴类型为log时，启用visualMap,serice配置areaStyle: {}出现如下异常： Failed to execute 'createLinearGradient' on 'CanvasRenderingContext2D': The provided double value is non-finite. #14601

Details

Before: What was the problem?

The chart cannot be rendered since the error below,

Failed to execute 'createLinearGradient' on 'CanvasRenderingContext2D': The provided double value is non-finite

After: How is it fixed in this PR?

Usage

Are there any API changes?

• The API has been changed.

Related test cases or examples to use the new APIs

Please refer to test/linear-gradient.html.

Others

Merging options

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

Other information

Related PR in zrender: ecomfe/zrender#748

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[pissang]

@plainheart I think linearMap(Infinity, domain, range) has Infinity result is reasonable.

We can clamp it if we want to limit it in the range: linearMap(Infinity, domain, range, true). Or validate it before using it as coord of gradient. In this case, validation seems better.

[plainheart]

@pissang For the case in #14534, it seems to differ from the case in #14601, some changes may need to be applied to zrender.

When all values of the line series are null, the width and height of the computed bounding rectangle of area polygon will both be infinite, which makes the gradient color can't be drawn.

[pissang]

@plainheart Sorry for the late reply. I agree use Infinity width and height in bounding rect is a bad idea when there is data in the polygon. It should all be 0.

[echarts-bot]

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