@cleerlycode/cornerstone-wado-image-loader/src/webWorker/webWorker.js

Cornerstone ImageLoader for DICOM WADO-URI

// an object of task handlers
const taskHandlers = {};

// Flag to ensure web worker is only initialized once
let initialized = false;

// the configuration object passed in when the web worker manager is initialized
let config;

/**
 * Initialization function that loads additional web workers and initializes them
 * @param data
 */
function initialize (data) {
  // console.log('web worker initialize ', data.workerIndex);
  // prevent initialization from happening more than once
  if (initialized) {
    return;
  }

  // save the config data
  config = data.config;

  // load any additional web worker tasks
  if (data.config.webWorkerTaskPaths) {
    for (let i = 0; i < data.config.webWorkerTaskPaths.length; i++) {
      self.importScripts(data.config.webWorkerTaskPaths[i]);
    }
  }

  // initialize each task handler
  Object.keys(taskHandlers).forEach(function (key) {
    taskHandlers[key].initialize(config.taskConfiguration);
  });

  // tell main ui thread that we have completed initialization
  self.postMessage({
    taskType: 'initialize',
    status: 'success',
    result: {
    },
    workerIndex: data.workerIndex
  });

  initialized = true;
}

/**
 * Function exposed to web worker tasks to register themselves
 * @param taskHandler
 */
export function registerTaskHandler (taskHandler) {
  if (taskHandlers[taskHandler.taskType]) {
    console.log('attempt to register duplicate task handler "', taskHandler.taskType, '"');

    return false;
  }
  taskHandlers[taskHandler.taskType] = taskHandler;
  if (initialized) {
    taskHandler.initialize(config.taskConfiguration);
  }
}

/**
 * Function to load a new web worker task with updated configuration
 * @param data
 */
function loadWebWorkerTask (data) {
  config = data.config;
  self.importScripts(data.sourcePath);
}

/**
 * Web worker message handler - dispatches messages to the registered task handlers
 * @param msg
 */
self.onmessage = function (msg) {
  // console.log('web worker onmessage', msg.data);

  // handle initialize message
  if (msg.data.taskType === 'initialize') {
    initialize(msg.data);

    return;
  }

  // handle loadWebWorkerTask message
  if (msg.data.taskType === 'loadWebWorkerTask') {
    loadWebWorkerTask(msg.data);

    return;
  }

  // dispatch the message if there is a handler registered for it
  if (taskHandlers[msg.data.taskType]) {
    taskHandlers[msg.data.taskType].handler(msg.data, function (result, transferList) {
      self.postMessage({
        taskType: msg.data.taskType,
        status: 'success',
        result,
        workerIndex: msg.data.workerIndex
      }, transferList);
    });

    return;
  }

  // not task handler registered - send a failure message back to ui thread
  console.log('no task handler for ', msg.data.taskType);
  console.log(taskHandlers);
  self.postMessage({
    taskType: msg.data.taskType,
    status: 'failed - no task handler registered',
    workerIndex: msg.data.workerIndex
  });
};