feat: add border style for legend item

[chengwb53]

One-line summary [问题简述]

When fill color is transparent with border for a bar series, the rectangle in the legend is transparent without border, so it's almost invisible.

So legend should add border width and border color of the series.

Version & Environment [版本及环境]

• ECharts version [ECharts 版本]:3.8
• Browser version [浏览器类型和版本]:chrome
• OS Version [操作系统类型和版本]:win10

Expected behaviour [期望结果]

Legend style have the same border style as series.

ECharts option [ECharts配置项]

option = {
    color: ['#3398DB'],
    tooltip : {
        trigger: 'axis',
        axisPointer : {            // 坐标轴指示器，坐标轴触发有效
            type : 'shadow'        // 默认为直线，可选为：'line' | 'shadow'
        }
    },
    legend: {
        data: ['直接访问', '间接访问']
    },
    grid: {
        left: '3%',
        right: '4%',
        bottom: '3%',
        containLabel: true
    },
    xAxis : [
        {
            type : 'category',
            data : ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'],
            axisTick: {
                alignWithLabel: true
            }
        }
    ],
    yAxis : [
        {
            type : 'value'
        }
    ],
    series : [
        {
            name:'间接访问',
            type:'bar',
            barWidth: '30%',
            data:[10, 52, 200, 334, 390, 330, 220],
            stack: ['直接访问'],
            itemStyle: {
                normal: {
                    borderWidth: 2,
                    color: 'blue',
                    borderColor: 'blue'
                }
            }
        },
        {
            name:'直接访问',
            type:'bar',
            barWidth: '30%',
            data:[10, 52, 200, 334, 390, 330, 220],
            itemStyle: {
                normal: {
                    borderColor: 'red',
                    borderWidth: 2,
                    color: 'rgba(0,0,0,0)'
                }
            },
            stack: ['直接访问']
        },
    ]
};

Other comments [其他信息]

[songxiulin2011]

Same problem here.

[100pah]

A itemStyle option should be added to legend option, similar to series.itemStyle. It should take borderColor, borderWidth, borderType from series by default, and can be overwritten by legend.itemStyle.