Function getOrientation

static/cropper/2.3.4/cropper.js:320–393

(arrayBuffer)

  }

  function getOrientation(arrayBuffer) {
    var dataView = new DataView(arrayBuffer);
    var length = dataView.byteLength;
    var orientation;
    var exifIDCode;
    var tiffOffset;
    var firstIFDOffset;
    var littleEndian;
    var endianness;
    var app1Start;
    var ifdStart;
    var offset;
    var i;

    // Only handle JPEG image (start by 0xFFD8)
    if (dataView.getUint8(0) === 0xFF && dataView.getUint8(1) === 0xD8) {
      offset = 2;

      while (offset < length) {
        if (dataView.getUint8(offset) === 0xFF && dataView.getUint8(offset + 1) === 0xE1) {
          app1Start = offset;
          break;
        }

        offset++;
      }
    }

    if (app1Start) {
      exifIDCode = app1Start + 4;
      tiffOffset = app1Start + 10;

      if (getStringFromCharCode(dataView, exifIDCode, 4) === 'Exif') {
        endianness = dataView.getUint16(tiffOffset);
        littleEndian = endianness === 0x4949;

        if (littleEndian || endianness === 0x4D4D /* bigEndian */) {
          if (dataView.getUint16(tiffOffset + 2, littleEndian) === 0x002A) {
            firstIFDOffset = dataView.getUint32(tiffOffset + 4, littleEndian);

            if (firstIFDOffset >= 0x00000008) {
              ifdStart = tiffOffset + firstIFDOffset;
            }
          }
        }
      }
    }

    if (ifdStart) {
      length = dataView.getUint16(ifdStart, littleEndian);

      for (i = 0; i < length; i++) {
        offset = ifdStart + i * 12 + 2;

        if (dataView.getUint16(offset, littleEndian) === 0x0112 /* Orientation */) {

          // 8 is the offset of the current tag's value
          offset += 8;