@kibeo/loaders.gl-textures/dist/es5/lib/parsers/parse-npy.js

Framework-independent loaders for compressed and super compressed (basis) textures

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.parseNPY = parseNPY;

function systemIsLittleEndian() {
  var a = new Uint32Array([0x12345678]);
  var b = new Uint8Array(a.buffer, a.byteOffset, a.byteLength);
  return !(b[0] === 0x12);
}

var LITTLE_ENDIAN_OS = systemIsLittleEndian();
var DTYPES = {
  u1: Uint8Array,
  i1: Int8Array,
  u2: Uint16Array,
  i2: Int16Array,
  u4: Uint32Array,
  i4: Int32Array,
  f4: Float32Array,
  f8: Float64Array
};

function parseNPY(arrayBuffer, options) {
  if (!arrayBuffer) {
    return null;
  }

  var view = new DataView(arrayBuffer);

  var _parseHeader = parseHeader(view),
      header = _parseHeader.header,
      headerEndOffset = _parseHeader.headerEndOffset;

  var numpyType = header.descr;
  var ArrayType = DTYPES[numpyType.slice(1, 3)];

  if (!ArrayType) {
    console.warn("Decoding of npy dtype not implemented: ".concat(numpyType));
    return null;
  }

  var nArrayElements = header.shape.reduce(function (a, b) {
    return a * b;
  });
  var arrayByteLength = nArrayElements * ArrayType.BYTES_PER_ELEMENT;
  var data = new ArrayType(arrayBuffer.slice(headerEndOffset, headerEndOffset + arrayByteLength));

  if (numpyType[0] === '>' && LITTLE_ENDIAN_OS || numpyType[0] === '<' && !LITTLE_ENDIAN_OS) {
    console.warn('Data is wrong endianness, byte swapping not yet implemented.');
  }

  return {
    data: data,
    header: header
  };
}

function parseHeader(view) {
  var majorVersion = view.getUint8(6);
  var offset = 8;
  var headerLength;

  if (majorVersion >= 2) {
    headerLength = view.getUint32(8, true);
    offset += 4;
  } else {
    headerLength = view.getUint16(8, true);
    offset += 2;
  }

  var encoding = majorVersion <= 2 ? 'latin1' : 'utf-8';
  var decoder = new TextDecoder(encoding);
  var headerArray = new Uint8Array(view.buffer, offset, headerLength);
  var headerText = decoder.decode(headerArray);
  offset += headerLength;
  var header = JSON.parse(headerText.replace(/'/g, '"').replace('False', 'false').replace('(', '[').replace(/,*\),*/g, ']'));
  return {
    header: header,
    headerEndOffset: offset
  };
}
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