Always show hover line on charts (#2830)

* Turn on always

* changeset

* More complete default config

Author: tsck

.changeset/cold-planes-listen.md

@@ -0,0 +1,5 @@
+---
+'@lg-charts/core': patch
+---
+
+Renders a vertical line on hover regardless of whether a ChartTooltip is rendered

charts/core/src/Chart/config/getDefaultChartOptions.ts

@@ -95,4 +95,14 @@ export const getDefaultChartOptions = (
       },
     },
   },
+
+  // Adds vertical dashed line on hover, even when no tooltip is shown
+  tooltip: {
+    axisPointer: {
+      z: 0, // Prevents dashed emphasis line from being rendered on top of mark lines and labels
+    },
+    show: true,
+    trigger: 'axis',
+    formatter: () => '',
+  },
 });

charts/core/src/ChartTooltip/ChartTooltip.tsx

@@ -32,11 +32,6 @@ export function ChartTooltip({
       {
         tooltip: {
           id,
-          axisPointer: {
-            z: 0, // Prevents dashed emphasis line from being rendered on top of mark lines and labels
-          },
-          show: true,
-          trigger: 'axis',
           // Still adding background color to prevent peak of color at corners
           backgroundColor:
             color[theme].background[Variant.InversePrimary][
@@ -79,7 +74,12 @@ export function ChartTooltip({
         {
           tooltip: {
             id,
-            show: false,
+            axisPointer: {
+              z: 0, // Prevents dashed emphasis line from being rendered on top of mark lines and labels
+            },
+            show: true,
+            trigger: 'axis',
+            formatter: () => '',
           },
         },
         ['tooltip'],