createFilterWorker options

How the worker runs filters, and which browsers use it, is in the image filters guide.

import {
  canRunInWorker,
  createFilterWorker,
  runFilterPipeline,
} from "fabricjs-document-engine/filters";

createFilterWorker options

function createFilterWorker(options?: FilterWorkerOptions): FilterWorker

Runs Fabric image filters in a Web Worker, with progress, cancel and newest-run-wins.

Name	Type	Default	Description
createWorker	() => Worker	the shipped worker	Makes a worker, for bundlers that need their own worker setup.
worker	boolean	true	`false` runs filters in steps on the main thread instead.
poolSize	number	1	Workers to run at once.
bandRows	number	64	Rows per step for pixel filters.
engine	DocumentEngine	none	Records each finished run as one undo step and drops runs that finish after another document opened.

FilterWorker

Name	Type	Default	Description
apply*	(image: FabricImage, filters?: ImageFilter[], options?: ApplyFilterOptions): Promise<boolean>	—	Applies filters to an image. Resolves `true` when it changed, `false` when a newer run replaced it. Rejects with the signal's reason when aborted.
mode*	"worker" \| "main-thread"	—	`worker` or `main-thread`.
terminate*	(): void	—	Stops the workers. Runs still going resolve `false`.

Name	Type	Default	Description
signal	AbortSignal	none	Cancels the run; the image is left as it was.
onProgress	(done: number) => void	none	Called with the share done, from 0 to 1.

The pipeline

runFilterPipeline is what the worker runs. It also works on the main thread with any ImageData, for your own tools.

function runFilterPipeline(filters: readonly PipelineFilter[], state: PipelineState, options?: PipelineOptions): Promise<ImageData | undefined>

Runs filters on ImageData in steps, with progress and cancel.

function canRunInWorker(filters: ReadonlyArray<{
  type?: unknown;
  subFilters?: unknown[];
}>): boolean

True when every filter, inside Composed ones too, can run in a worker.

Name	Type	Default	Description
bandRows	number	64	Rows per step for pixel filters.
onProgress	(done: number) => void	none	Called after each step with the share done.
isCancelled	() => boolean	none	Checked after each step; `true` stops the run.
pause	() => Promise<void>	none	Lets other work run between steps.

PIXEL_FILTERS and WORKER_FILTERS list the filter types run in bands of rows, and every type a worker can run. Any other filter makes apply use Fabric's applyFilters, whatever the createFilterWorker options say.

Filters API