@chestnutlabs/gcode-preview-vue

Thin Vue 3 integration for the Chestnut Labs G-code viewer: parse .gcode / .gcode.3mf off the main thread, render an interactive Three.js toolpath (layers, scrub, per-file build plates, honest live progress), and never block your UI. This package is glue only — the engine lives in @chestnutlabs/gcode-parser, @chestnutlabs/gcode-renderer-three, and @chestnutlabs/toolpath-core (design: DD-007).

npm install @chestnutlabs/gcode-preview-vue three
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(three is a peerDependency of the renderer, supported range ^0.178.0 — npm ≥ 7 installs it automatically; pnpm/yarn users add it explicitly. See the support policy.)

Two adoption levels, one implementation (the component is a shell over the composable):

Ready-to-use component

<script setup lang="ts">
import { GcodePreview } from '@chestnutlabs/gcode-preview-vue';
import { shallowRef } from 'vue';

const file = shallowRef<File | null>(null);
</script>

<template>
  <input type="file" accept=".gcode,.3mf" @change="file = ($event.target as HTMLInputElement).files?.[0] ?? null" />
  <div style="height: 70vh">
    <GcodePreview :source="file" @ready="(s) => console.log(`${s.segments} segments`)" />
  </div>
</template>
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That is a complete viewer. The full surface is ~24 optional props with sensible defaults — the frequently reached-for ones:

Emits (13): ready, camera-change, parse-error, parse-cancelled, parse-progress, stage, build-complete, quality-fallback, machine-geometry-mismatch, machine-geometry-discovered, progress-presentation-changed, disclosure, error. The underlying handle is exposed for template refs (ref.preview); its controls reach the imperative surface — getRenderStats() (render diagnostics), pickSegment(ndcX, ndcY, threshold?) (source-mapping / picking), isColorModeAvailable(mode), and capture(opts?) (image Blob, also handle.capture). The handle state carries capability-aware UI data (availableColorModes, hasRetractions, hasColorChanges).

Headless composable (build your own controls)

import { useGcodePreview } from '@chestnutlabs/gcode-preview-vue';

const preview = useGcodePreview();          // in setup(); auto-disposes with the scope
// bind: <canvas :ref="(el) => (preview.canvasRef.value = el as HTMLCanvasElement)" />
await preview.parse(bytes);                 // worker parse + progressive preview
preview.controls.setLayerRange(0, 42);      // scrub / colors / quality / bed / frame ...
preview.observeProgress(obs);               // DD-006 live progress (tick ~1 Hz for staleness)
preview.state;                              // shallow read-only reactive summaries
preview.raw.session; preview.raw.renderer();// escape hatches (non-reactive)
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The composable owns the sharp edges: dispose-on-unmount/HMR, SSR-import safety, canvas resize (ResizeObserver + fallback), and a strict reactivity boundary (toolpath buffers are never proxied).

Workers: default and custom (both first-class)

Default (zero setup): the batteries worker — all supported slicer/firmware dialect adapters plus .gcode.3mf container support — is created automatically via the bundler-native new Worker(new URL(...)) pattern. Vite resolves this out of the box (this path is exercised by the repo's Vite demo and consumer fixture).

Custom (smaller builds / custom adapters / strict CSP / other bundlers):

useGcodePreview({
  createWorker: () => new Worker(new URL('@chestnutlabs/gcode-parser/dist/worker-slim.js', import.meta.url), { type: 'module' })
});
// or your own worker built with createWorkerHandler(...) — see the parser package docs
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Linked-workspace development note: Vite consumers using file: links should add every @chestnutlabs/* package the worker pulls in to optimizeDeps.exclude (installed tarballs/registry packages need no configuration).

Model viewing (Prepare side)

The /model subpath ships a <ModelViewer> — the Prepare-side counterpart to <GcodePreview>. Where <GcodePreview> draws the toolpath (how a print runs), <ModelViewer> draws the source model (an .stl / .3mf mesh) — the object before slicing.

<script setup lang="ts">
import { ModelViewer } from '@chestnutlabs/gcode-preview-vue/model';

const source = { kind: '3mf' as const, bytes };
</script>

<template>
  <div style="height: 70vh">
    <ModelViewer :source="source" @ready="(info) => console.log(info.objectCount, info.materials)" />
  </div>
</template>
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@ready carries the honest material-colour tier: info.materials is 'known' / 'approximated' when the file declared colours the render used, and 'unavailable' when it declared none (a neutral default, never faked). The kebab props (:view, :background, :render-scope, …), matching emits, and the useModelViewer composable mirror the toolpath component. See docs/manual/adapters.md "Two viewers: Preview and Prepare" for the cross-adapter tour, and tools/example-vue/model.html for a runnable minimal page.

Examples

tools/example-vue in the repository is a Vite app with two tiers, both driving this published package (no raw renderer or parser imports):

• minimal.html — the smallest real integration: <GcodePreview :source> plus a fixture picker and a layer slider. One short component to copy when getting started.
• showcase.html — the full declarative surface: capability-gated color modes (a mode greys out with a plain-language reason when the file can't support it), declarative :hidden-feature-roles, camera, and getRenderStats()/pickSegment() diagnostics through the component ref's handle (viewer.preview.controls), whose state mirror is directly reactive in Vue.

Run it with npm install --prefix tools/example-vue && npm run dev --prefix tools/example-vue (port 5203).

Capability honesty

Everything the engine reports as inferred/approximated/unavailable stays that way at this layer: feature coloring refuses rather than fabricates, live progress shows a band instead of a fake-precise marker, and decimation is disclosed via the disclosure emit — surface it.

Support

.gcode (Marlin/Klipper/RepRap-flavor; PrusaSlicer, Orca/Bambu, Cura annotations), .gcode.3mf (sliced-plate export; multi-plate via parse-options.plate), per-file build plates, multi-tool/AMS color, object exclusion, arcs. See the repository's docs/compatibility/dialects-and-containers.md for the evidence-dated matrix and docs/reference/progress-signal-contract.md for the live-progress contract.