feat: Introducing "mixed" valued Pie Chart

[kirgrim]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Adding "mixed" type of the pie chart that will allow generate roses of variable radius + variable arc lengths

Fixed issues

N/A

Details

Before: What was the problem?

Previously you could either specify "area" or "radius" for the roseType which reduced the number of possible dimensions of quantitative data to apply

After: How does it behave after the fixing?

Now you could specify "mixed" roseType for the pie chart and supply two elements to the array of values:

• first element is responsible for the radius
• second element is responsible for the arc length

Example of the newly supported roseType:

        const option = {
            title: {
                text: 'Rose Type Test',
                left: 'center'
            },
            tooltip: {
                trigger: 'item',
                formatter: function(params) {
                    if (Array.isArray(params.value) && params.value.length >= 2) {
                        return params.seriesName + '<br/>' +
                               params.name + ': Radius=' + params.value[0] + ', Angle=' + params.value[1] + ' (' + params.percent + '%)';
                    } else {
                        return params.seriesName + '<br/>' +
                               params.name + ': ' + params.value + ' (' + params.percent + '%)';
                    }
                }
            },
            series: [
                {
                    name: 'Rose Type',
                    type: 'pie',
                    radius: ['30%', '70%'],
                    center: ['50%', '50%'],
                    roseType: 'mixed',
                    data: [
                        { value: [10, 15], name: 'A' },
                        { value: [20, 25], name: 'B' },
                        { value: [30, 35], name: 'C' },
                        { value: [40, 45], name: 'D' },
                        { value: [50, 55], name: 'E' }
                    ],
                    label: {
                        show: true,
                        formatter: function(params) {
                            if (Array.isArray(params.value) && params.value.length >= 2) {
                                return params.name + ': R=' + params.value[0] + ', A=' + params.value[1];
                            } else {
                                return params.name + ': ' + params.value;
                            }
                        }
                    }
                }
            ]
        };

the full interactive example is added to:

test/pie-mixed-rose-type.html

Document Info

One of the following should be checked.

• [] This PR doesn't relate to document changes
• The document should be updated later
• The document changes have been made in apache/echarts-doc#xxx

Misc

ZRender Changes

• 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!
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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.