From 35864b4de79f2864dd7dfd1b765bff8246ef68ef Mon Sep 17 00:00:00 2001
From: Achraf Jalleli <150543929+JalleliAchraf@users.noreply.github.com>
Date: Wed, 25 Feb 2026 16:42:37 +0100
Subject: [PATCH] 1186 target line static (#1162)

* graph: render historical dashed targets as static overlay

* movement improved

* formatting

* more performance optimizations

* formatting
---
 electron/src/components/graph/BigGraph.tsx    |  15 +-
 .../components/graph/TargetDashOverlay.tsx    | 411 ++++++++++++++++++
 electron/src/components/graph/createChart.ts  | 153 +------
 3 files changed, 424 insertions(+), 155 deletions(-)
 create mode 100644 electron/src/components/graph/TargetDashOverlay.tsx

diff --git a/electron/src/components/graph/BigGraph.tsx b/electron/src/components/graph/BigGraph.tsx
index 8a8796ff..803b4bc8 100644
--- a/electron/src/components/graph/BigGraph.tsx
+++ b/electron/src/components/graph/BigGraph.tsx
@@ -20,6 +20,7 @@ import { TouchButton } from "../touch/TouchButton";
 import { seriesToUPlotData } from "@/lib/timeseries";
 import { ControlCard } from "@/control/ControlCard";
 import { getAllTimeSeries } from "./createChart";
+import { TargetDashOverlay } from "./TargetDashOverlay";
 
 // Collects lines connected to visible series for rendering
 const getVisibleLines = (data: any, visibleSeries: boolean[]) => {
@@ -595,10 +596,18 @@ export function BigGraph({
 
         <div className="flex-1 overflow-hidden rounded-b-3xl pt-4">
           <div
-            ref={containerRef}
-            className={`h-full w-full overflow-hidden transition-opacity duration-100`}
+            className={`relative h-full w-full overflow-hidden transition-opacity duration-100`}
             style={{ backgroundColor: colors.background }}
-          />
+          >
+            <div ref={containerRef} className="h-full w-full overflow-hidden" />
+            <TargetDashOverlay
+              uplotRef={uplotRef}
+              newData={newData}
+              config={enhancedConfig}
+              selectedTimeWindow={selectedTimeWindow}
+              isLiveMode={isLiveMode}
+            />
+          </div>
         </div>
       </div>
     </div>
diff --git a/electron/src/components/graph/TargetDashOverlay.tsx b/electron/src/components/graph/TargetDashOverlay.tsx
new file mode 100644
index 00000000..6639b276
--- /dev/null
+++ b/electron/src/components/graph/TargetDashOverlay.tsx
@@ -0,0 +1,411 @@
+import React, { useEffect, useMemo, useState, useId } from "react";
+import uPlot from "uplot";
+import { BigGraphProps, GraphConfig } from "./types";
+import { getAllTimeSeries } from "./createChart";
+
+type OverlayLine = {
+  key: string;
+  color: string;
+  width: number;
+  dash: number[];
+  d: string;
+};
+
+type ClipRect = {
+  x: number;
+  y: number;
+  width: number;
+  height: number;
+};
+
+function findFirstGe(arr: number[], value: number): number {
+  let lo = 0;
+  let hi = arr.length - 1;
+  let ans = arr.length;
+
+  while (lo <= hi) {
+    const mid = (lo + hi) >> 1;
+    if (arr[mid] >= value) {
+      ans = mid;
+      hi = mid - 1;
+    } else {
+      lo = mid + 1;
+    }
+  }
+
+  return ans;
+}
+
+function findLastLe(arr: number[], value: number): number {
+  let lo = 0;
+  let hi = arr.length - 1;
+  let ans = -1;
+
+  while (lo <= hi) {
+    const mid = (lo + hi) >> 1;
+    if (arr[mid] <= value) {
+      ans = mid;
+      lo = mid + 1;
+    } else {
+      hi = mid - 1;
+    }
+  }
+
+  return ans;
+}
+
+function buildSteppedPath(
+  u: uPlot,
+  xData: number[],
+  yData: Array<number | null>,
+): string {
+  const xMin = u.scales.x?.min;
+  const xMax = u.scales.x?.max;
+
+  if (xData.length < 2 || xMin === undefined || xMax === undefined) {
+    return "";
+  }
+
+  const firstVisibleIdx = Math.max(0, findFirstGe(xData, xMin) - 1);
+  const lastVisibleIdx = Math.min(
+    xData.length - 1,
+    findLastLe(xData, xMax) + 1,
+  );
+
+  if (lastVisibleIdx < firstVisibleIdx) {
+    return "";
+  }
+
+  const parts: string[] = [];
+  let started = false;
+  let prevX = 0;
+  let prevY = 0;
+
+  for (let i = firstVisibleIdx; i <= lastVisibleIdx; i++) {
+    const value = yData[i];
+    if (value === null || value === undefined) continue;
+
+    const x = u.valToPos(xData[i], "x", true);
+    const y = u.valToPos(value, "y", true);
+
+    if (!started) {
+      parts.push(`M ${x} ${y}`);
+      started = true;
+      prevX = x;
+      prevY = y;
+      continue;
+    }
+
+    if (x !== prevX) {
+      parts.push(`L ${x} ${prevY}`);
+    }
+    if (y !== prevY) {
+      parts.push(`L ${x} ${y}`);
+    }
+
+    prevX = x;
+    prevY = y;
+  }
+
+  return parts.join(" ");
+}
+
+function buildFlatLatestValuePath(
+  u: uPlot,
+  yData: Array<number | null>,
+): string {
+  let latestValue: number | null = null;
+
+  for (let i = yData.length - 1; i >= 0; i--) {
+    const value = yData[i];
+    if (value !== null && value !== undefined) {
+      latestValue = value;
+      break;
+    }
+  }
+
+  if (latestValue === null) {
+    return "";
+  }
+
+  const y = u.valToPos(latestValue, "y", true);
+  const left = u.bbox.left;
+  const right = u.bbox.left + u.bbox.width;
+
+  return `M ${left} ${y} L ${right} ${y}`;
+}
+
+function getHistoricalDashTargets(
+  data: BigGraphProps["newData"],
+  config: GraphConfig,
+): Array<{
+  dataIndex: number;
+  dash: number[];
+  color: string;
+  width: number;
+}> {
+  const allOriginalSeries = getAllTimeSeries(data);
+  const firstConfigLineDataIndex = 1 + allOriginalSeries.length;
+  let visibleLineIndex = 0;
+
+  const targets: Array<{
+    dataIndex: number;
+    dash: number[];
+    color: string;
+    width: number;
+  }> = [];
+
+  config.lines?.forEach((line) => {
+    if (line.show === false) return;
+
+    const dash = line.dash ?? (line.type === "threshold" ? [5, 5] : undefined);
+    const isHistoricalDashedTarget = !!line.targetSeries && !!dash?.length;
+
+    if (isHistoricalDashedTarget) {
+      targets.push({
+        dataIndex: firstConfigLineDataIndex + visibleLineIndex,
+        dash: dash!,
+        color: line.color,
+        width: line.width ?? 1,
+      });
+    }
+
+    visibleLineIndex++;
+  });
+
+  return targets;
+}
+
+function areDashArraysEqual(a: number[], b: number[]): boolean {
+  if (a.length !== b.length) return false;
+  for (let i = 0; i < a.length; i++) {
+    if (a[i] !== b[i]) return false;
+  }
+  return true;
+}
+
+function areOverlayLinesEqual(a: OverlayLine[], b: OverlayLine[]): boolean {
+  if (a.length !== b.length) return false;
+  for (let i = 0; i < a.length; i++) {
+    if (
+      a[i].key !== b[i].key ||
+      a[i].color !== b[i].color ||
+      a[i].width !== b[i].width ||
+      a[i].d !== b[i].d ||
+      !areDashArraysEqual(a[i].dash, b[i].dash)
+    ) {
+      return false;
+    }
+  }
+  return true;
+}
+
+function isSameClipRect(a: ClipRect | null, b: ClipRect): boolean {
+  return (
+    !!a &&
+    a.x === b.x &&
+    a.y === b.y &&
+    a.width === b.width &&
+    a.height === b.height
+  );
+}
+
+export function TargetDashOverlay({
+  uplotRef,
+  newData,
+  config,
+  selectedTimeWindow,
+  isLiveMode,
+}: {
+  uplotRef: React.RefObject<uPlot | null>;
+  newData: BigGraphProps["newData"];
+  config: GraphConfig;
+  selectedTimeWindow: number | "all";
+  isLiveMode: boolean;
+}) {
+  const targetMeta = useMemo(
+    () => getHistoricalDashTargets(newData, config),
+    [newData, config],
+  );
+  const clipPathId = useId().replace(/:/g, "");
+
+  const [lines, setLines] = useState<OverlayLine[]>([]);
+  const [clipRect, setClipRect] = useState<ClipRect | null>(null);
+
+  useEffect(() => {
+    if (targetMeta.length === 0) {
+      setLines([]);
+      setClipRect(null);
+    }
+  }, [targetMeta]);
+
+  useEffect(() => {
+    let rafId: number | null = null;
+    let bootstrapRafId: number | null = null;
+    let recalcScheduled = false;
+    let hooksAttached = false;
+    const removeHookFns: Array<() => void> = [];
+    let resizeObserver: ResizeObserver | null = null;
+
+    const recalc = () => {
+      recalcScheduled = false;
+      const u = uplotRef.current;
+      if (!u || targetMeta.length === 0) {
+        return;
+      }
+
+      const xData = u.data[0] as number[] | undefined;
+      if (!xData || xData.length < 2) {
+        return;
+      }
+
+      const nextLines = targetMeta
+        .map((meta, index) => {
+          const yData = u.data[meta.dataIndex] as
+            | Array<number | null>
+            | undefined;
+          if (!yData || yData.length < 2) return null;
+
+          const useFlatShortWindowPath =
+            isLiveMode &&
+            selectedTimeWindow !== "all" &&
+            selectedTimeWindow <= 60_000;
+
+          const d = useFlatShortWindowPath
+            ? buildFlatLatestValuePath(u, yData)
+            : buildSteppedPath(u, xData, yData);
+          if (!d) return null;
+
+          return {
+            key: `${meta.dataIndex}-${index}`,
+            color: meta.color,
+            width: meta.width,
+            dash: meta.dash,
+            d,
+          } as OverlayLine;
+        })
+        .filter((line): line is OverlayLine => !!line);
+
+      if (nextLines.length > 0) {
+        setLines((prev) =>
+          areOverlayLinesEqual(prev, nextLines) ? prev : nextLines,
+        );
+        const nextClipRect: ClipRect = {
+          x: u.bbox.left,
+          y: u.bbox.top,
+          width: u.bbox.width,
+          height: u.bbox.height,
+        };
+        setClipRect((prev) =>
+          isSameClipRect(prev, nextClipRect) ? prev : nextClipRect,
+        );
+      }
+    };
+
+    const scheduleRecalc = () => {
+      if (recalcScheduled) return;
+      recalcScheduled = true;
+      rafId = window.requestAnimationFrame(recalc);
+    };
+
+    scheduleRecalc();
+
+    if (targetMeta.length === 0) {
+      return;
+    }
+
+    const addHook = (u: any, hookName: string, fn: () => void) => {
+      const hooks = u.hooks?.[hookName];
+      if (!Array.isArray(hooks)) return;
+      hooks.push(fn);
+      removeHookFns.push(() => {
+        const idx = hooks.indexOf(fn);
+        if (idx >= 0) hooks.splice(idx, 1);
+      });
+    };
+
+    const onWindowResize = () => scheduleRecalc();
+    window.addEventListener("resize", onWindowResize);
+
+    const attachHooks = (): boolean => {
+      if (hooksAttached) return true;
+      const u = uplotRef.current as any;
+      if (!u) return false;
+
+      addHook(u, "draw", scheduleRecalc);
+      addHook(u, "setScale", scheduleRecalc);
+      addHook(u, "setData", scheduleRecalc);
+
+      const rootElement = u.root as HTMLElement | undefined;
+      if (rootElement && typeof ResizeObserver !== "undefined") {
+        resizeObserver = new ResizeObserver(() => scheduleRecalc());
+        resizeObserver.observe(rootElement);
+      }
+
+      hooksAttached = true;
+      scheduleRecalc();
+      return true;
+    };
+
+    if (!attachHooks()) {
+      const tryAttach = () => {
+        if (attachHooks()) return;
+        bootstrapRafId = window.requestAnimationFrame(tryAttach);
+      };
+      bootstrapRafId = window.requestAnimationFrame(tryAttach);
+    }
+
+    return () => {
+      if (rafId !== null) {
+        window.cancelAnimationFrame(rafId);
+      }
+      if (bootstrapRafId !== null) {
+        window.cancelAnimationFrame(bootstrapRafId);
+      }
+      removeHookFns.forEach((fn) => fn());
+      window.removeEventListener("resize", onWindowResize);
+      resizeObserver?.disconnect();
+    };
+  }, [uplotRef, targetMeta, isLiveMode, selectedTimeWindow]);
+
+  if (lines.length === 0) {
+    return null;
+  }
+
+  return (
+    <svg
+      className="pointer-events-none absolute inset-0 h-full w-full"
+      aria-hidden
+    >
+      {clipRect && (
+        <defs>
+          <clipPath id={clipPathId}>
+            <rect
+              x={clipRect.x}
+              y={clipRect.y}
+              width={clipRect.width}
+              height={clipRect.height}
+            />
+          </clipPath>
+        </defs>
+      )}
+
+      <g clipPath={clipRect ? `url(#${clipPathId})` : undefined}>
+        {lines.map((line) => {
+          return (
+            <path
+              key={line.key}
+              d={line.d}
+              fill="none"
+              stroke={line.color}
+              strokeWidth={line.width}
+              strokeLinecap="butt"
+              strokeDasharray={line.dash.join(" ")}
+              strokeDashoffset={0}
+            />
+          );
+        })}
+      </g>
+    </svg>
+  );
+}
diff --git a/electron/src/components/graph/createChart.ts b/electron/src/components/graph/createChart.ts
index da400664..fdcbc87d 100644
--- a/electron/src/components/graph/createChart.ts
+++ b/electron/src/components/graph/createChart.ts
@@ -12,15 +12,6 @@ import {
 import { BigGraphProps, CreateChartParams } from "./types";
 import { normalizeDataSeries } from "./animation";
 
-type CustomDashedTargetLine = {
-  dataIndex: number;
-  dash: number[];
-  color: string;
-  width: number;
-};
-
-const DASH_FLOW_PX_PER_SEC = 180;
-
 export function createChart({
   containerRef,
   uplotRef,
@@ -161,8 +152,6 @@ export function createChart({
 
   // Build series configuration for ALL series (but control visibility)
   const seriesConfig: uPlot.Series[] = [{ label: "Time" }];
-  const customDashedTargetLines: CustomDashedTargetLine[] = [];
-  const dashFlowStartTime = performance.now();
 
   // Add ALL data series with visibility control
   const defaultColors = ["#3b82f6", "#ef4444", "#10b981", "#f59e0b", "#8b5cf6"];
@@ -188,35 +177,21 @@ export function createChart({
   });
 
   // Add config lines
-  let visibleLineIndex = 0;
-  const firstConfigLineDataIndex = 1 + allOriginalSeries.length;
   config.lines?.forEach((line) => {
     if (line.show !== false) {
       const dash =
         line.dash ?? (line.type === "threshold" ? [5, 5] : undefined);
-      const lineDataIndex = firstConfigLineDataIndex + visibleLineIndex;
       const isHistoricalDashedTarget = !!line.targetSeries && !!dash?.length;
 
-      if (isHistoricalDashedTarget) {
-        customDashedTargetLines.push({
-          dataIndex: lineDataIndex,
-          dash: dash!,
-          color: line.color,
-          width: line.width ?? 1,
-        });
-      }
-
       seriesConfig.push({
         label: line.label,
-        // Historical dashed targets are rendered manually in draw hook to
-        // avoid dash shimmer while the live x-axis slides.
+        // Historical dashed targets are rendered in an SVG overlay.
         stroke: isHistoricalDashedTarget ? "rgba(0,0,0,0)" : line.color,
         width: line.width ?? 1,
         dash: isHistoricalDashedTarget ? undefined : dash,
         show: true,
         points: { show: false },
       });
-      visibleLineIndex++;
     }
   });
 
@@ -346,119 +321,6 @@ export function createChart({
             }
           },
         ],
-        draw: [
-          (u) => {
-            if (customDashedTargetLines.length === 0) return;
-            const xData = u.data[0] as number[] | undefined;
-            if (!xData || xData.length < 2) return;
-
-            const xMin = u.scales.x?.min;
-            const xMax = u.scales.x?.max;
-            if (xMin === undefined || xMax === undefined) return;
-
-            const ctx = u.ctx;
-            const left = u.bbox.left;
-            const top = u.bbox.top;
-            const snap = (v: number) => Math.round(v) + 0.5;
-            const findFirstGe = (arr: number[], value: number): number => {
-              let lo = 0;
-              let hi = arr.length - 1;
-              let ans = arr.length;
-              while (lo <= hi) {
-                const mid = (lo + hi) >> 1;
-                if (arr[mid] >= value) {
-                  ans = mid;
-                  hi = mid - 1;
-                } else {
-                  lo = mid + 1;
-                }
-              }
-              return ans;
-            };
-            const findLastLe = (arr: number[], value: number): number => {
-              let lo = 0;
-              let hi = arr.length - 1;
-              let ans = -1;
-              while (lo <= hi) {
-                const mid = (lo + hi) >> 1;
-                if (arr[mid] <= value) {
-                  ans = mid;
-                  lo = mid + 1;
-                } else {
-                  hi = mid - 1;
-                }
-              }
-              return ans;
-            };
-            const firstVisibleIdx = Math.max(0, findFirstGe(xData, xMin) - 1);
-            const lastVisibleIdx = Math.min(
-              xData.length - 1,
-              findLastLe(xData, xMax) + 1,
-            );
-            if (lastVisibleIdx < firstVisibleIdx) return;
-
-            ctx.save();
-            ctx.beginPath();
-            ctx.rect(left, top, u.bbox.width, u.bbox.height);
-            ctx.clip();
-            ctx.lineCap = "butt";
-
-            customDashedTargetLines.forEach(
-              ({ dataIndex, dash, color, width }) => {
-                const yData = u.data[dataIndex] as
-                  | Array<number | null>
-                  | undefined;
-                if (!yData || yData.length < 2) return;
-
-                const dashPeriod = dash.reduce((acc, curr) => acc + curr, 0);
-                ctx.setLineDash(dash);
-                const elapsedMs = performance.now() - dashFlowStartTime;
-                const dashTravelPx = (elapsedMs * DASH_FLOW_PX_PER_SEC) / 1000;
-                ctx.lineDashOffset =
-                  dashPeriod > 0 ? -(dashTravelPx % dashPeriod) : 0;
-                ctx.strokeStyle = color;
-                ctx.lineWidth = width;
-                ctx.beginPath();
-
-                let started = false;
-                let prevX = 0;
-                let prevY = 0;
-
-                for (let i = firstVisibleIdx; i <= lastVisibleIdx; i++) {
-                  const value = yData[i];
-                  if (value === null || value === undefined) continue;
-
-                  const x = snap(u.valToPos(xData[i], "x", true));
-                  const y = snap(u.valToPos(value, "y", true));
-
-                  if (!started) {
-                    ctx.moveTo(x, y);
-                    started = true;
-                    prevX = x;
-                    prevY = y;
-                    continue;
-                  }
-
-                  if (x !== prevX) {
-                    ctx.lineTo(x, prevY);
-                  }
-                  if (y !== prevY) {
-                    ctx.lineTo(x, y);
-                  }
-
-                  prevX = x;
-                  prevY = y;
-                }
-
-                if (started) {
-                  ctx.stroke();
-                }
-              },
-            );
-
-            ctx.restore();
-          },
-        ],
       },
       scales: {
         x: {
@@ -660,25 +522,12 @@ export function createChart({
 
   const cleanup = attachEventHandlers(containerRef.current, handlers);
 
-  let dashFlowAnimationFrame: number | null = null;
-  if (customDashedTargetLines.length > 0) {
-    const animateDashFlow = () => {
-      if (!uplotRef.current) return;
-      uplotRef.current.redraw();
-      dashFlowAnimationFrame = requestAnimationFrame(animateDashFlow);
-    };
-    dashFlowAnimationFrame = requestAnimationFrame(animateDashFlow);
-  }
-
   animationRefs.lastRenderedData.current = {
     timestamps: [...timestamps],
     values: [...primaryValues],
   };
 
   return () => {
-    if (dashFlowAnimationFrame !== null) {
-      cancelAnimationFrame(dashFlowAnimationFrame);
-    }
     cleanup();
   };
 }