移动端折线tooltip的symbol响应的区域非常小，能否扩大响应范围

[dagundejuzi]

What problem does this feature solve?

symbol点击事件用户体验优化。

What does the proposed API look like?

折线图symbol的点击区域能更大一点，类似于绑定'axis'时那样的，点击临近区域就能响应事件。

目前在移动端点击折线symbol，非常难以点到，可能点7、8下才能点出响应事件，如果symbol在图表边缘就更难点到。如果每次点击间隔5s以上，似乎准确率能高一点。
点击事件的绑定是这样的：
`
……
tooltip: {
show: true,
confine: true,
trigger: 'item',
triggerOn: 'click',
}

……

myChart.on('click',function (param) {
// 响应事件操作
});
`

[echarts-bot]

Hi! We've received your issue and please be patient to get responded. 🎉
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In the meanwhile, please make sure that you have posted enough image to demo your request. You may also check out the API and chart option to get the answer.

Have a nice day! 🍵

[plainheart]

#17102 应该能够解决此类问题。参见 智能指针吸附