loaders.gl/dist/es6/common/loader-utils/get-image-size.js

Framework-independent loaders for 3D graphics formats

function _slicedToArray(arr, i) { return _arrayWithHoles(arr) || _iterableToArrayLimit(arr, i) || _nonIterableRest(); }

function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance"); }

function _iterableToArrayLimit(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }

function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }

// Attributions
// * Based on binary-gltf-utils under MIT license: Copyright (c) 2016-17 Karl Cheng
const mimeTypeMap = new Map([['image/png', getPngSize], ['image/jpeg', getJpegSize], ['image/gif', getGifSize], ['image/bmp', getBmpSize]]);
const ERR_INVALID_TYPE = `Invalid MIME type. Supported MIME types are: ${Array.from(mimeTypeMap.keys()).join(', ')}`;
/**
 * Sniffs the contents of a file to attempt to deduce the image type and extract image size.
 * Supported image types are PNG, JPEG, GIF and BMP.
 *
 * @param {Buffer} contents
 * @param {string} [mimeType]
 */

export function getImageSize(contents, mimeType) {
  // Looking for only a specific MIME type.
  if (mimeType) {
    const handler = mimeTypeMap.get(mimeType);

    if (!handler) {
      throw new Error(ERR_INVALID_TYPE);
    }

    const result = handler(contents);

    if (!result) {
      throw new Error(`invalid image data for type: ${mimeType}`);
    }

    return result;
  } // Loop through each file type and see if they work.


  for (const _ref of mimeTypeMap.entries()) {
    var _ref2 = _slicedToArray(_ref, 2);

    const supportedMimeType = _ref2[0];
    const handler = _ref2[1];
    const result = handler(contents);

    if (result) {
      result.mimeType = supportedMimeType;
      return result;
    }
  } // Seems not :(


  throw new Error(ERR_INVALID_TYPE);
}
/**
 * Extract size from a binary PNG file
 * @param {Buffer} contents
 */

function getPngSize(contents) {
  // Check file contains the first 4 bytes of the PNG signature.
  if (contents.readUInt32BE(0) !== 0x89504e47) {
    return null;
  }

  return {
    width: contents.readUInt32BE(16),
    height: contents.readUInt32BE(20)
  };
}
/**
 * Extract size from a binary GIF file
 * @param {Buffer} contents
 * TODO: GIF is not this simple
 */


function getGifSize(contents) {
  // Check first 4 bytes of the GIF signature ("GIF8").
  if (contents.readUInt32BE(0) !== 0x47494638) {
    return null;
  } // GIF is little endian.


  return {
    width: contents.readUInt16LE(6),
    height: contents.readUInt16LE(8)
  };
}
/**
 * @param {Buffer} contents
 * TODO: BMP is not this simple
 */


function getBmpSize(contents) {
  // Check magic number is valid (first 2 characters should be "BM").
  if (contents.readUInt16BE(0) !== 0x424d) {
    return null;
  } // BMP is little endian.


  return {
    width: contents.readUInt32LE(18),
    height: contents.readUInt32LE(22)
  };
}
/**
 * Extract size from a binary JPEG file
 * @param {Buffer} contents
 */


function getJpegSize(contents) {
  // Check file contains the JPEG "start of image" (SOI) marker.
  if (contents.readUInt16BE(0) !== 0xffd8) {
    return null;
  }

  const _getJpegMarkers = getJpegMarkers(),
        tableMarkers = _getJpegMarkers.tableMarkers,
        sofMarkers = _getJpegMarkers.sofMarkers; // Exclude the two byte SOI marker.


  let i = 2;

  while (i < contents.length) {
    const marker = contents.readUInt16BE(i); // The frame that contains the width and height of the JPEG image.

    if (sofMarkers.has(marker)) {
      return {
        height: contents.readUInt16BE(i + 5),
        // Number of lines
        width: contents.readUInt16BE(i + 7) // Number of pixels per line

      };
    } // Miscellaneous tables/data preceding the frame header.


    if (!tableMarkers.has(marker)) {
      return null;
    } // Length includes size of length parameter but not the two byte header.


    i += 2;
    i += contents.readUInt16BE(i);
  }

  return null;
}

function getJpegMarkers() {
  // Tables/misc header markers.
  // DQT, DHT, DAC, DRI, COM, APP_n
  const tableMarkers = new Set([0xffdb, 0xffc4, 0xffcc, 0xffdd, 0xfffe]);

  for (let i = 0xffe0; i < 0xfff0; ++i) {
    tableMarkers.add(i);
  } // SOF markers and DHP marker.
  // These markers are after tables/misc data.


  const sofMarkers = new Set([0xffc0, 0xffc1, 0xffc2, 0xffc3, 0xffc5, 0xffc6, 0xffc7, 0xffc9, 0xffca, 0xffcb, 0xffcd, 0xffce, 0xffcf, 0xffde]);
  return {
    tableMarkers,
    sofMarkers
  };
}
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