Web Browser Processing Pipelines

These processing pipeline execution functions can be used from within a web browser. Processing pipeline TypeScript interfaces internally use the runPipeline function, documented below.

The processing pipeline functions generated with itk-wasm bindgen return a Promise that resolves an object. The object there functions return includes a a webWorker property with the WebWorker used for computation. They also optionally accept a web worker from a previous execution as a webWorker property on their last argument. A per-package default web worker is reused throughout the session if no option is set. Alternatively, a web worker can be manually created with createWebWorker and passed. Or, if null is passed, the worker will be created internally. If the worker is created explicitly, either through createWebWorker or passing null, it must terminate()’d manually once it is no longer needed to avoid resource leaks. Passing the value false for webWorker will run the computation in the current thread.

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runPipeline

runPipeline(webWorker: Worker | null | boolean,
  pipelinePath: string | URL,
  args: string[],
  outputs: PipelineOutput[] | null,
  inputs: PipelineInput[] | null
  pipelineBaseUrl: string | URL = 'pipelinesUrl',
  pipelineWorkerUrl?: string | URL | null,
  ):
  Promise<{
    returnValue: number,
    stdout: string,
    stderr: string,
    outputs: PipelineOutput[],
    webWorker: Worker,
  }>

Run an itk-wasm Emscripten module in a web browser.

webWorker

Re-use a WebWorker generated by a previous call to runPipeline. Usually, null is passed here instead, which will result in generation of a new WebWorker. If false is passed, the pipeline will be instead executed in the current context.

pipelinePath

Pipeline module path, without .js or .wasm extensions. Can be the basename of the pipeline or a full URL to the pipeline.

args

A JavaScript Array of strings to pass to the execution of the main function, i.e. arguments that would be passed on the command line to a native executable.

outputs

A JavaScript Array of desired PipelineOutput’s that provide an interface type and an optional path when required by an interface type.

• type is one of the InterfaceTypes.

• path is the optional file path on the filesystem to write after execution has completed.

inputs

A JavaScript Array of PipelineInput’s or null that provide an interface type, an optional path when required by an interface type, and the input data.

• type is one of the InterfaceTypes.

• data contains the corresponding data for the interface type.

• path is the optional file path on the filesystem to read after execution has completed.

pipelineBaseUrl

When pipelinePath is a basename, this is the base URL for the pipeline module.

pipelineWorkerUrl

Optional path or URL to the itk-wasm pipeline worker script. Fetched from JsDelivr by default. Set to null to use a version vendored by bundlers by Vite or WebPack.

Result

Promise resolving a JavaScript object with the properties:

• returnValue: Integer return code from the pipeline.

• stdout: Text sent to stdout

• stderr: Text sent to stderr

• outputs: An Array of PipelineOutput’s with the data property populated.

• webWorker: WebWorker used for computation. Pass to another runPipeline call for re-use or call terminate() to clean up used resources.