openlayers / ol-vite Goto Github PK

// compute an array of colors for every possible byte value
const colors = [];
for (let i = 0 ; i < 256 ; i++) {
  colors[i] = [i, 256 - i, i, 255];
}

const rasterSource = new RasterSource({
  sources: [rawLayer],
  operationType: 'pixel',
  operation: (pixels) => {
    const pixel = pixels[0];
    return colors[pixel[2]]; // apply the color from the look up table
  },
});

const __minion__ = (function createMinion(operation) {
  let workerHasImageData = true;
  try {
    new ImageData(10, 10);
  } catch (_) {
    workerHasImageData = false;
  }
  function newWorkerImageData(data, width, height) {
    if (workerHasImageData) {
      return new ImageData(data, width, height);
    } else {
      return { data, width, height };
    }
  }
  return function(data) {
    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] = newWorkerImageData(
          new Uint8ClampedArray(buffers[b]),
          width,
          height
        );
      }
      const output2 = operation(images, meta).data;
      return output2.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;
  };
})((pixels) => {
    const pixel = pixels[0];
    return colors[pixel[2]];
  });self.addEventListener("message", function(event) {  const buffer = __minion__(event.data);  self.postMessage({buffer: buffer, meta: event.data.meta}, [buffer]);});