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• Raster.js

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package.source.Raster.js Maven / Gradle / Ivy

/**
 * @module ol/source/Raster
 */
import Disposable from '../Disposable.js';
import Event from '../events/Event.js';
import EventType from '../events/EventType.js';
import ImageCanvas from '../ImageCanvas.js';
import ImageLayer from '../layer/Image.js';
import ImageSource from './Image.js';
import Source from './Source.js';
import TileLayer from '../layer/Tile.js';
import TileQueue from '../TileQueue.js';
import TileSource from './Tile.js';
import {createCanvasContext2D} from '../dom.js';
import {create as createTransform} from '../transform.js';
import {equals, getCenter, getHeight, getWidth} from '../extent.js';
import {getUid} from '../util.js';

/**
 * @typedef {Object} MinionData
 * @property {Array} buffers Array of buffers.
 * @property {Object} meta Operation metadata.
 * @property {boolean} imageOps The operation is an image operation.
 * @property {number} width The width of the image.
 * @property {number} height The height of the image.
 */

/* istanbul ignore next */
/**
 * Create a function for running operations.  This function is serialized for
 * use in a worker.
 * @param {function(Array, Object):*} operation The operation.
 * @return {function(MinionData):ArrayBuffer} A function that takes an object with
 * buffers, meta, imageOps, width, and height properties and returns an array
 * buffer.
 */
function createMinion(operation) {
  return function (data) {
    // bracket notation for minification support
    const buffers = data['buffers'];
    const meta = data['meta'];
    const imageOps = data['imageOps'];
    const width = data['width'];
    const height = data['height'];

    const numBuffers = buffers.length;
    const numBytes = buffers[0].byteLength;

    if (imageOps) {
      const images = new Array(numBuffers);
      for (let b = 0; b < numBuffers; ++b) {
        images[b] = new ImageData(
          new Uint8ClampedArray(buffers[b]),
          width,
          height,
        );
      }
      const output = operation(images, meta).data;
      return output.buffer;
    }

    const output = new Uint8ClampedArray(numBytes);
    const arrays = new Array(numBuffers);
    const pixels = new Array(numBuffers);
    for (let b = 0; b < numBuffers; ++b) {
      arrays[b] = new Uint8ClampedArray(buffers[b]);
      pixels[b] = [0, 0, 0, 0];
    }
    for (let i = 0; i < numBytes; i += 4) {
      for (let j = 0; j < numBuffers; ++j) {
        const array = arrays[j];
        pixels[j][0] = array[i];
        pixels[j][1] = array[i + 1];
        pixels[j][2] = array[i + 2];
        pixels[j][3] = array[i + 3];
      }
      const pixel = operation(pixels, meta);
      output[i] = pixel[0];
      output[i + 1] = pixel[1];
      output[i + 2] = pixel[2];
      output[i + 3] = pixel[3];
    }
    return output.buffer;
  };
}

/**
 * Create a worker for running operations.
 * @param {ProcessorOptions} config Processor options.
 * @param {function(MessageEvent): void} onMessage Called with a message event.
 * @return {Worker} The worker.
 */
function createWorker(config, onMessage) {
  const lib = Object.keys(config.lib || {}).map(function (name) {
    return 'const ' + name + ' = ' + config.lib[name].toString() + ';';
  });

  const lines = lib.concat([
    'const __minion__ = (' + createMinion.toString() + ')(',
    config.operation.toString(),
    ');',
    'self.addEventListener("message", function(event) {',
    '  const buffer = __minion__(event.data);',
    '  self.postMessage({buffer: buffer, meta: event.data.meta}, [buffer]);',
    '});',
  ]);

  const worker = new Worker(
    typeof Blob === 'undefined'
      ? 'data:text/javascript;base64,' +
        Buffer.from(lines.join('\n'), 'binary').toString('base64')
      : URL.createObjectURL(new Blob(lines, {type: 'text/javascript'})),
  );
  worker.addEventListener('message', onMessage);
  return worker;
}

/**
 * @typedef {Object} FauxMessageEvent
 * @property {Object} data Message data.
 */

/**
 * Create a faux worker for running operations.
 * @param {ProcessorOptions} config Configuration.
 * @param {function(FauxMessageEvent): void} onMessage Called with a message event.
 * @return {Object} The faux worker.
 */
function createFauxWorker(config, onMessage) {
  const minion = createMinion(config.operation);
  let terminated = false;
  return {
    postMessage: function (data) {
      setTimeout(function () {
        if (terminated) {
          return;
        }
        onMessage({data: {buffer: minion(data), meta: data['meta']}});
      }, 0);
    },
    terminate: function () {
      terminated = true;
    },
  };
}

/**
 * @typedef {function(Error, ImageData, (Object|Array