All files / packages/core/src/utilities createUint8SharedArray.ts

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import global from '../global';
import { getShouldUseSharedArrayBuffer } from '../init';
 
/**
 * A helper function that creates a new Float32Array that utilized a shared
 * array buffer. This allows the array to be updated  simultaneously in
 * workers or the main thread. Depending on the system (the CPU, the OS, the Browser)
 * it can take a while until the change is propagated to all contexts.
 *
 * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/SharedArrayBuffer|MDN: SharedArrayBuffer}
 * @remarks
 * We use SharedArrayBuffers in our ImageCache class. It's what allows us to
 * stream data to build a volume. It's important to note that SharedArrayBuffer
 * does not work out of the box for all web browsers. In some, it is disabled
 * behind a flag; in others, it has been removed entirely.
 *
 * @example
 * Creating an array for a Volume with known dimensions:
 * ```
 * const dimensions = [512, 512, 25];
 * const scalarData = createUint8SharedArray(dimensions[0] * dimensions[1] * dimensions[2]);
 * ```
 *
 * @param length - frame size * number of frames
 * @returns a Uint8Array with an underlying SharedArrayBuffer
 * @public
 */
function createUint8SharedArray(length: number): Uint8Array {
  Iif (!getShouldUseSharedArrayBuffer()) {
    throw new Error(
      'Your page is NOT cross-origin isolated, see https://developer.mozilla.org/en-US/docs/Web/API/crossOriginIsolated'
    );
  }
  Iif (window.SharedArrayBuffer === undefined) {
    throw new Error(
      'SharedArrayBuffer is NOT supported in your browser see https://developer.chrome.com/blog/enabling-shared-array-buffer/'
    );
  }
 
  const sharedArrayBuffer = new SharedArrayBuffer(length);
 
  return new Uint8Array(sharedArrayBuffer);
}
 
export default createUint8SharedArray;