From c52217c1ce9c9a138e28af3bbcc26e5b5bd02196 Mon Sep 17 00:00:00 2001
From: Petar Petrov <MindFreeze@users.noreply.github.com>
Date: Tue, 18 Feb 2025 08:57:07 +0200
Subject: [PATCH] Make part of the chart rendering async for large datasets
 (#24260)

---
 src/components/chart/ha-chart-base.ts | 41 ++++++++++++++++++++++-----
 1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/src/components/chart/ha-chart-base.ts b/src/components/chart/ha-chart-base.ts
index 78902bc018..deb89d24d2 100644
--- a/src/components/chart/ha-chart-base.ts
+++ b/src/components/chart/ha-chart-base.ts
@@ -6,7 +6,6 @@ import type { DataZoomComponentOption } from "echarts/components";
 import type { EChartsType } from "echarts/core";
 import type {
   ECElementEvent,
-  SetOptionOpts,
   XAXisOption,
   YAXisOption,
 } from "echarts/types/dist/shared";
@@ -25,6 +24,7 @@ import type { HomeAssistant } from "../../types";
 import { isMac } from "../../util/is_mac";
 import "../ha-icon-button";
 import { formatTimeLabel } from "./axis-label";
+import { ensureArray } from "../../common/array/ensure-array";
 
 export const MIN_TIME_BETWEEN_UPDATES = 60 * 5 * 1000;
 
@@ -68,12 +68,16 @@ export class HaChartBase extends LitElement {
 
   private _listeners: (() => void)[] = [];
 
+  private _originalZrFlush?: () => void;
+
   public disconnectedCallback() {
     super.disconnectedCallback();
     while (this._listeners.length) {
       this._listeners.pop()!();
     }
     this.chart?.dispose();
+    this.chart = undefined;
+    this._originalZrFlush = undefined;
   }
 
   public connectedCallback() {
@@ -86,7 +90,7 @@ export class HaChartBase extends LitElement {
       listenMediaQuery("(prefers-reduced-motion)", (matches) => {
         if (this._reducedMotion !== matches) {
           this._reducedMotion = matches;
-          this.chart?.setOption({ animation: !this._reducedMotion });
+          this._setChartOptions({ animation: !this._reducedMotion });
         }
       })
     );
@@ -96,7 +100,7 @@ export class HaChartBase extends LitElement {
       if ((isMac && ev.key === "Meta") || (!isMac && ev.key === "Control")) {
         this._modifierPressed = true;
         if (!this.options?.dataZoom) {
-          this.chart?.setOption({ dataZoom: this._getDataZoomConfig() });
+          this._setChartOptions({ dataZoom: this._getDataZoomConfig() });
         }
       }
     };
@@ -105,7 +109,7 @@ export class HaChartBase extends LitElement {
       if ((isMac && ev.key === "Meta") || (!isMac && ev.key === "Control")) {
         this._modifierPressed = false;
         if (!this.options?.dataZoom) {
-          this.chart?.setOption({ dataZoom: this._getDataZoomConfig() });
+          this._setChartOptions({ dataZoom: this._getDataZoomConfig() });
         }
       }
     };
@@ -131,10 +135,8 @@ export class HaChartBase extends LitElement {
       return;
     }
     let chartOptions: ECOption = {};
-    const chartUpdateParams: SetOptionOpts = { lazyUpdate: true };
     if (changedProps.has("data")) {
       chartOptions.series = this.data;
-      chartUpdateParams.replaceMerge = ["series"];
     }
     if (changedProps.has("options")) {
       chartOptions = { ...chartOptions, ...this._createOptions() };
@@ -142,7 +144,7 @@ export class HaChartBase extends LitElement {
       chartOptions.dataZoom = this._getDataZoomConfig();
     }
     if (Object.keys(chartOptions).length > 0) {
-      this.chart.setOption(chartOptions, chartUpdateParams);
+      this._setChartOptions(chartOptions);
     }
   }
 
@@ -509,6 +511,31 @@ export class HaChartBase extends LitElement {
     return Math.max(this.clientWidth / 2, 200);
   }
 
+  private _setChartOptions(options: ECOption) {
+    if (!this.chart) {
+      return;
+    }
+    if (!this._originalZrFlush) {
+      const dataSize = ensureArray(this.data).reduce(
+        (acc, series) => acc + (series.data as any[]).length,
+        0
+      );
+      if (dataSize > 10000) {
+        // for large datasets zr.flush takes 30-40% of the render time
+        // so we delay it a bit to avoid blocking the main thread
+        const zr = this.chart.getZr();
+        this._originalZrFlush = zr.flush.bind(zr);
+        zr.flush = () => {
+          setTimeout(() => {
+            this._originalZrFlush?.();
+          }, 10);
+        };
+      }
+    }
+    const replaceMerge = options.series ? ["series"] : [];
+    this.chart.setOption(options, { replaceMerge });
+  }
+
   private _handleZoomReset() {
     this.chart?.dispatchAction({ type: "dataZoom", start: 0, end: 100 });
   }