From 6f99afe23399d6aae735955432440b39a614a533 Mon Sep 17 00:00:00 2001
From: UttamAstrin <nishantup2005@gmail.com>
Date: Thu, 21 May 2026 13:06:05 +0530
Subject: [PATCH] Highlight same-net traces on hover

---
 lib/components/SchematicViewer.tsx            |   7 +
 lib/hooks/useHighlightSameNetTracesOnHover.ts | 169 ++++++++++++++++++
 2 files changed, 176 insertions(+)
 create mode 100644 lib/hooks/useHighlightSameNetTracesOnHover.ts

diff --git a/lib/components/SchematicViewer.tsx b/lib/components/SchematicViewer.tsx
index ab4fd20..3857e06 100644
--- a/lib/components/SchematicViewer.tsx
+++ b/lib/components/SchematicViewer.tsx
@@ -5,6 +5,7 @@ import {
 import { su } from "@tscircuit/soup-util"
 import { useChangeSchematicComponentLocationsInSvg } from "lib/hooks/useChangeSchematicComponentLocationsInSvg"
 import { useChangeSchematicTracesForMovedComponents } from "lib/hooks/useChangeSchematicTracesForMovedComponents"
+import { useHighlightSameNetTracesOnHover } from "lib/hooks/useHighlightSameNetTracesOnHover"
 import { useSchematicGroupsOverlay } from "lib/hooks/useSchematicGroupsOverlay"
 import { enableDebug } from "lib/utils/debug"
 import { useCallback, useEffect, useMemo, useRef, useState } from "react"
@@ -345,6 +346,12 @@ export const SchematicViewer = ({
     editEvents: editEventsWithUnappliedEditEvents,
   })
 
+  useHighlightSameNetTracesOnHover({
+    svgDivRef,
+    circuitJson,
+    circuitJsonKey,
+  })
+
   // Add group overlays when enabled
   useSchematicGroupsOverlay({
     svgDivRef,
diff --git a/lib/hooks/useHighlightSameNetTracesOnHover.ts b/lib/hooks/useHighlightSameNetTracesOnHover.ts
new file mode 100644
index 0000000..5920cb9
--- /dev/null
+++ b/lib/hooks/useHighlightSameNetTracesOnHover.ts
@@ -0,0 +1,169 @@
+import { useEffect, useMemo } from "react"
+import type { CircuitJson } from "circuit-json"
+
+const HOVER_TRACE_COLOR = "#60a5fa"
+
+type CircuitElement = CircuitJson[number] & Record<string, any>
+
+const getTraceNetKey = (
+  sourceTrace: CircuitElement | undefined,
+  sourceTraceId: string | undefined,
+) => {
+  if (!sourceTrace) return sourceTraceId
+
+  if (sourceTrace.subcircuit_connectivity_map_key) {
+    return `connectivity:${sourceTrace.subcircuit_connectivity_map_key}`
+  }
+
+  if (sourceTrace.connected_source_net_ids?.length) {
+    return `nets:${[...sourceTrace.connected_source_net_ids].sort().join(",")}`
+  }
+
+  if (sourceTrace.connected_source_port_ids?.length) {
+    return `ports:${[...sourceTrace.connected_source_port_ids].sort().join(",")}`
+  }
+
+  return sourceTraceId
+}
+
+const getVisibleTracePaths = (
+  svg: HTMLDivElement,
+  schematicTraceIds: Set<string>,
+) => {
+  const tracePaths: SVGPathElement[] = []
+
+  for (const path of Array.from(
+    svg.querySelectorAll<SVGPathElement>(
+      '[data-circuit-json-type="schematic_trace"] path',
+    ),
+  )) {
+    if (path.getAttribute("class")?.includes("invisible")) continue
+
+    const traceGroup = path.closest("[data-schematic-trace-id]")
+    const schematicTraceId = traceGroup?.getAttribute("data-schematic-trace-id")
+    if (schematicTraceId && schematicTraceIds.has(schematicTraceId)) {
+      tracePaths.push(path)
+    }
+  }
+
+  return tracePaths
+}
+
+/**
+ * Highlights every rendered schematic trace that belongs to the same source net
+ * as the trace currently under the pointer.
+ */
+export const useHighlightSameNetTracesOnHover = ({
+  svgDivRef,
+  circuitJson,
+  circuitJsonKey,
+}: {
+  svgDivRef: React.RefObject<HTMLDivElement | null>
+  circuitJson: CircuitJson
+  circuitJsonKey: string
+}) => {
+  const schematicTraceIdsByNetKey = useMemo(() => {
+    const sourceTracesById = new Map<string, CircuitElement>()
+    const traceIdsByNetKey = new Map<string, Set<string>>()
+
+    for (const element of circuitJson as CircuitElement[]) {
+      if (element.type === "source_trace") {
+        sourceTracesById.set(element.source_trace_id, element)
+      }
+    }
+
+    for (const element of circuitJson as CircuitElement[]) {
+      if (element.type !== "schematic_trace") continue
+
+      const sourceTraceId = element.source_trace_id as string | undefined
+      const netKey = getTraceNetKey(
+        sourceTraceId ? sourceTracesById.get(sourceTraceId) : undefined,
+        sourceTraceId,
+      )
+      if (!netKey || !element.schematic_trace_id) continue
+
+      if (!traceIdsByNetKey.has(netKey)) {
+        traceIdsByNetKey.set(netKey, new Set())
+      }
+      traceIdsByNetKey.get(netKey)!.add(element.schematic_trace_id)
+    }
+
+    return traceIdsByNetKey
+  }, [circuitJson, circuitJsonKey])
+
+  const netKeyBySchematicTraceId = useMemo(() => {
+    const netKeyByTraceId = new Map<string, string>()
+    for (const [netKey, traceIds] of schematicTraceIdsByNetKey) {
+      for (const traceId of traceIds) {
+        netKeyByTraceId.set(traceId, netKey)
+      }
+    }
+    return netKeyByTraceId
+  }, [schematicTraceIdsByNetKey])
+
+  useEffect(() => {
+    const svg = svgDivRef.current
+    if (!svg) return
+
+    const highlightedPaths = new Map<SVGPathElement, string | null>()
+
+    const clearHighlight = () => {
+      for (const [path, originalStroke] of highlightedPaths) {
+        if (originalStroke === null) {
+          path.removeAttribute("stroke")
+        } else {
+          path.setAttribute("stroke", originalStroke)
+        }
+      }
+      highlightedPaths.clear()
+    }
+
+    const highlightTrace = (schematicTraceId: string) => {
+      const netKey = netKeyBySchematicTraceId.get(schematicTraceId)
+      const schematicTraceIds = netKey
+        ? schematicTraceIdsByNetKey.get(netKey)
+        : undefined
+      if (!schematicTraceIds) return
+
+      clearHighlight()
+
+      for (const path of getVisibleTracePaths(svg, schematicTraceIds)) {
+        highlightedPaths.set(path, path.getAttribute("stroke"))
+        path.setAttribute("stroke", HOVER_TRACE_COLOR)
+      }
+    }
+
+    const getTraceGroupFromTarget = (target: EventTarget | null) => {
+      if (!(target instanceof Element)) return null
+      return target.closest("[data-schematic-trace-id]")
+    }
+
+    const handlePointerOver = (event: PointerEvent) => {
+      const traceGroup = getTraceGroupFromTarget(event.target)
+      const schematicTraceId = traceGroup?.getAttribute(
+        "data-schematic-trace-id",
+      )
+      if (schematicTraceId) {
+        highlightTrace(schematicTraceId)
+      }
+    }
+
+    const handlePointerOut = (event: PointerEvent) => {
+      const traceGroup = getTraceGroupFromTarget(event.target)
+      const relatedTraceGroup = getTraceGroupFromTarget(event.relatedTarget)
+      if (traceGroup && traceGroup === relatedTraceGroup) return
+      clearHighlight()
+    }
+
+    svg.addEventListener("pointerover", handlePointerOver)
+    svg.addEventListener("pointerout", handlePointerOut)
+    svg.addEventListener("pointerleave", clearHighlight)
+
+    return () => {
+      clearHighlight()
+      svg.removeEventListener("pointerover", handlePointerOver)
+      svg.removeEventListener("pointerout", handlePointerOut)
+      svg.removeEventListener("pointerleave", clearHighlight)
+    }
+  }, [svgDivRef, schematicTraceIdsByNetKey, netKeyBySchematicTraceId])
+}