The framework-neutral preview controller for the Chestnut Labs G-code Preview stack
(design: DD-007). This is the single engine under the Vue, React, Svelte, and Web Component
(@chestnutlabs/gcode-preview-element) adapters — parse
session + renderer + progress mapper glued into one lifecycle with an immutable-snapshot state
model (getState() returns a new identity per mutation; onStateChange notifies), which every
framework's reactivity can bridge cheaply.
import { createPreviewController } from '@chestnutlabs/gcode-preview-core';
const preview = createPreviewController();
preview.bindCanvas(canvas); // resize-observed
await preview.parse(bytes); // worker parse + progressive build
preview.controls.setLayerRange(0, 42); // scrub / quality / colors / bed / frame ...
preview.observeProgress(obs); // DD-006 live progress
preview.onStateChange(cb); // snapshots: summaries only, never toolpath buffers
preview.dispose();
parse() hands a Uint8Array or ArrayBuffer to the parse worker without copying it, so the
buffer you passed is empty afterwards. To parse the same file again (for example a different plate
via parse(bytes, { plate: 1 })), keep your own copy and pass bytes.slice() each time. Passing
the already-transferred bytes fails with E_POST_FAILED, and the preview keeps working.
Building an adapter for another framework? The portable behavioral suite is exported from
@chestnutlabs/gcode-preview-core/testing — runBehavioralSuite(...) is the same parity
contract the Vue, React, Svelte, and Web Component adapters pass in CI, and it is the anti-drift
firewall for any new integration.
Part of Chestnut Labs G-code Preview · MIT