From b0b2ba0157edfc6b0d66eec7d46eb3da007bdebf Mon Sep 17 00:00:00 2001
From: Dominik Prokop <dominik.prokop@grafana.com>
Date: Mon, 15 Mar 2021 18:08:43 +0100
Subject: [PATCH] TooltipContainer - use resize observer instead of
 getClientBoundingRect (#31937)

* TooltipContainer - use resize observer instead of getClientBoundingRect

* Well, let's screw Safari, shall we?

* Memoize resize observer

* Make ts happy happy happy
---
 packages/grafana-data/src/types/geometry.ts   |  7 ++++
 .../src/components/Chart/TooltipContainer.tsx | 39 +++++++++++++++++--
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/packages/grafana-data/src/types/geometry.ts b/packages/grafana-data/src/types/geometry.ts
index a4a4558af8e..9bb223e56fe 100644
--- a/packages/grafana-data/src/types/geometry.ts
+++ b/packages/grafana-data/src/types/geometry.ts
@@ -5,3 +5,10 @@ export interface CartesianCoords2D {
   x: number;
   y: number;
 }
+/**
+ * 2d object dimensions.
+ */
+export interface Dimensions2D {
+  width: number;
+  height: number;
+}
diff --git a/packages/grafana-ui/src/components/Chart/TooltipContainer.tsx b/packages/grafana-ui/src/components/Chart/TooltipContainer.tsx
index 3efedc5a846..6ba4d183b4e 100644
--- a/packages/grafana-ui/src/components/Chart/TooltipContainer.tsx
+++ b/packages/grafana-ui/src/components/Chart/TooltipContainer.tsx
@@ -1,9 +1,9 @@
-import React, { useState, useLayoutEffect, useRef, HTMLAttributes } from 'react';
+import React, { useState, useLayoutEffect, useRef, HTMLAttributes, useMemo } from 'react';
 import { stylesFactory } from '../../themes/stylesFactory';
 import { css, cx } from 'emotion';
 import { useTheme } from '../../themes/ThemeContext';
 import useWindowSize from 'react-use/lib/useWindowSize';
-import { GrafanaTheme } from '@grafana/data';
+import { Dimensions2D, GrafanaTheme } from '@grafana/data';
 
 interface TooltipContainerProps extends HTMLAttributes<HTMLDivElement> {
   position: { x: number; y: number };
@@ -20,18 +20,49 @@ export const TooltipContainer: React.FC<TooltipContainerProps> = ({
 }) => {
   const theme = useTheme();
   const tooltipRef = useRef<HTMLDivElement>(null);
+  const tooltipMeasurementRef = useRef<Dimensions2D>({ width: 0, height: 0 });
   const { width, height } = useWindowSize();
   const [placement, setPlacement] = useState({
     x: positionX + offsetX,
     y: positionY + offsetY,
   });
 
+  const resizeObserver = useMemo(
+    () =>
+      // TS has hard time playing games with @types/resize-observer-browser, hence the ignore
+      // @ts-ignore
+      new ResizeObserver((entries) => {
+        for (let entry of entries) {
+          const tW = Math.floor(entry.contentRect.width + 2 * 8); //  adding padding until Safari supports borderBoxSize
+          const tH = Math.floor(entry.contentRect.height + 2 * 8);
+
+          if (tooltipMeasurementRef.current.width !== tW || tooltipMeasurementRef.current.height !== tH) {
+            tooltipMeasurementRef.current = {
+              width: tW,
+              height: tH,
+            };
+          }
+        }
+      }),
+    []
+  );
+
+  useLayoutEffect(() => {
+    if (tooltipRef.current) {
+      resizeObserver.observe(tooltipRef.current);
+    }
+
+    return () => {
+      resizeObserver.disconnect();
+    };
+  }, [resizeObserver]);
+
   // Make sure tooltip does not overflow window
   useLayoutEffect(() => {
     let xO = 0,
       yO = 0;
     if (tooltipRef && tooltipRef.current) {
-      const measurement = tooltipRef.current.getBoundingClientRect();
+      const measurement = tooltipMeasurementRef.current;
       const xOverflow = width - (positionX + measurement.width);
       const yOverflow = height - (positionY + measurement.height);
       if (xOverflow < 0) {
@@ -47,7 +78,7 @@ export const TooltipContainer: React.FC<TooltipContainerProps> = ({
       x: positionX + offsetX - xO,
       y: positionY + offsetY - yO,
     });
-  }, [tooltipRef, width, height, positionX, offsetX, positionY, offsetY]);
+  }, [width, height, positionX, offsetX, positionY, offsetY]);
 
   const styles = getTooltipContainerStyles(theme);