feat: improve default tooltip

Author: woothu

src/generateChartComponent.js

@@ -49,7 +49,26 @@ export default function generateChartComponent (name, type) {
           return {
             tooltips: {
               enabled: false,
-              custom: customTooltips
+              custom: customTooltips,
+              intersect: true,
+              mode: 'index',
+              position: 'nearest',
+              callbacks: {
+                labelColor (tooltipItem, chart) {
+                  function getValue (prop) {
+                    return typeof prop === 'object' ? prop[tooltipItem.index] : prop
+                  }
+                  const dataset = chart.data.datasets[tooltipItem.datasetIndex]
+                  //tooltipLabelColor is coreUI custom prop used only here
+                  const backgroundColor = getValue(
+                    dataset.tooltipLabelColor ||
+                    dataset.pointHoverBackgroundColor ||
+                    dataset.borderColor ||
+                    dataset.backgroundColor
+                  )
+                  return { backgroundColor }
+                }
+              }
             }
           }
         }