🔍 Duplicate Code Detected: Niivue Initialization Config and Tuple-Mapping Coordinate Functions

[github-actions]

Analysis of recent commits — triggered by @thewtex

Assignee: @copilot

Summary

Two significant duplication patterns were found in the codebase during semantic code analysis:

1. Near-identical Niivue initialization functions in examples/convert/main.ts
2. Structurally identical tuple-mapping functions in fidnii/src/utils/coordinates.ts

---

Pattern 1: Duplicated Niivue Initialization

Details

• Severity: Medium
• Occurrences: 2
• Locations:
  • examples/convert/main.ts (lines 261–274) — initNiivue()
  • examples/convert/main.ts (lines 300–314) — initMinimapNiivue()

Code Sample

// initNiivue (lines 261–274)
function initNiivue(): void {
  if (nv) return
  nv = new Niivue({
    show3Dcrosshair: false,
    crosshairWidth: 0,
    backColor: [0.384, 0.365, 0.353, 1],
    isOrientCube: false,
    isOrientationTextVisible: false,
    clipPlaneHotKey: "",
  })
  nv.attachToCanvas(canvas)
  nv.addColormap("fast", FAST_COLORMAP)
}

// initMinimapNiivue (lines 300–314)
function initMinimapNiivue(): void {
  if (minimapNv) return
  minimapNv = new Niivue({
    show3Dcrosshair: false,
    crosshairWidth: 0,
    backColor: [0.384, 0.365, 0.353, 1],
    isOrientCube: false,
    isOrientationTextVisible: false,
    clipPlaneHotKey: "",
  })
  minimapNv.attachToCanvas(minimapCanvas)
  minimapNv.addColormap("fast", FAST_COLORMAP)
  minimapNv.addColormap("roi", buildRoiColormap())  // only difference
}

The constructor options object (6 fields) and the first addColormap call are identical across both functions. Only the variable name, canvas reference, and the extra ROI colormap differ.

Refactoring Recommendation

Extract shared Niivue construction into a factory helper:

const SHARED_NV_OPTIONS = {
  show3Dcrosshair: false,
  crosshairWidth: 0,
  backColor: [0.384, 0.365, 0.353, 1] as [number, number, number, number],
  isOrientCube: false,
  isOrientationTextVisible: false,
  clipPlaneHotKey: "",
} as const

function createNiivue(
  canvasEl: HTMLCanvasElement,
  extraColormaps?: Array<{ name: string; colormap: unknown }>,
): Niivue {
  const instance = new Niivue(SHARED_NV_OPTIONS)
  instance.attachToCanvas(canvasEl)
  instance.addColormap("fast", FAST_COLORMAP)
  for (const { name, colormap } of extraColormaps ?? []) {
    instance.addColormap(name, colormap)
  }
  return instance
}

---

Pattern 2: Structurally Identical Tuple-Mapping Coordinate Functions

Details

• Severity: Low
• Occurrences: 3 (plus one existing clampPixelCoord of related shape)
• Locations:
  • fidnii/src/utils/coordinates.ts (lines 233–241) — roundPixelCoord
  • fidnii/src/utils/coordinates.ts (lines 249–257) — floorPixelCoord
  • fidnii/src/utils/coordinates.ts (lines 265–273) — ceilPixelCoord

Code Sample

export function roundPixelCoord(pixelCoord: [number, number, number]): [number, number, number] {
  return [Math.round(pixelCoord[0]), Math.round(pixelCoord[1]), Math.round(pixelCoord[2])]
}
export function floorPixelCoord(pixelCoord: [number, number, number]): [number, number, number] {
  return [Math.floor(pixelCoord[0]), Math.floor(pixelCoord[1]), Math.floor(pixelCoord[2])]
}
export function ceilPixelCoord(pixelCoord: [number, number, number]): [number, number, number] {
  return [Math.ceil(pixelCoord[0]), Math.ceil(pixelCoord[1]), Math.ceil(pixelCoord[2])]
}

All three apply a Math rounding function element-wise to a 3-element tuple. The only variation is which Math.* method is used.

Refactoring Recommendation

Introduce a private mapPixelCoord helper and keep the public named exports (for clarity and stable API):

function mapPixelCoord(
  pixelCoord: [number, number, number],
  fn: (v: number) => number,
): [number, number, number] {
  return [fn(pixelCoord[0]), fn(pixelCoord[1]), fn(pixelCoord[2])]
}

export const roundPixelCoord = (c: [number, number, number]) => mapPixelCoord(c, Math.round)
export const floorPixelCoord = (c: [number, number, number]) => mapPixelCoord(c, Math.floor)
export const ceilPixelCoord  = (c: [number, number, number]) => mapPixelCoord(c, Math.ceil)

Note: Refactoring the public API is optional — the named exports can remain function declarations for clarity. The key change is centralising the triple-element application logic.

---

Impact Analysis

Pattern	Maintainability	Bug Risk	Code Bloat
Niivue init	If the Niivue options need to change (e.g. new flag), both functions must be updated in sync	Inconsistent NV configs could cause subtle visual differences between main and minimap views	~12 duplicate lines
Pixel coord	Low — Math methods are stable	Very low	~15 duplicate lines across 3 functions

---

Implementation Checklist

• Review the initNiivue/initMinimapNiivue findings in examples/convert/main.ts
• Extract shared Niivue options constant and/or factory function
• Consider extracting a mapPixelCoord helper in fidnii/src/utils/coordinates.ts
• Verify the refactored example still builds and behaves correctly (bun run build)
• Run bun run check to ensure Biome is satisfied

---

Analysis Metadata

• Analyzed Files: fidnii/src/**/*.ts, examples/convert/main.ts, examples/getting-started/main.ts
• Detection Method: Serena semantic code analysis + symbol body inspection
• Analysis Date: 2026-03-25

Generated by Duplicate Code Detector

To install this agentic workflow, run

gh aw add github/gh-aw/.github/workflows/duplicate-code-detector.md@33cd6c7f1fee588654ef19def2e6a4174be66197