miniprogram/wwwroot/skin/app/default/static/js/exif.js

(function() {

  var debug = false;

  var root = this;

  var EXIF = function(obj) {
      if (obj instanceof EXIF) return obj;
      if (!(this instanceof EXIF)) return new EXIF(obj);
      this.EXIFwrapped = obj;
  };

  if (typeof exports !== 'undefined') {
      if (typeof module !== 'undefined' && module.exports) {
          exports = module.exports = EXIF;
      }
      exports.EXIF = EXIF;
  } else {
      root.EXIF = EXIF;
  }

  var ExifTags = EXIF.Tags = {

      // version tags
      0x9000 : "ExifVersion",             // EXIF version
      0xA000 : "FlashpixVersion",         // Flashpix format version

      // colorspace tags
      0xA001 : "ColorSpace",              // Color space information tag

      // image configuration
      0xA002 : "PixelXDimension",         // Valid width of meaningful image
      0xA003 : "PixelYDimension",         // Valid height of meaningful image
      0x9101 : "ComponentsConfiguration", // Information about channels
      0x9102 : "CompressedBitsPerPixel",  // Compressed bits per pixel

      // user information
      0x927C : "MakerNote",               // Any desired information written by the manufacturer
      0x9286 : "UserComment",             // Comments by user

      // related file
      0xA004 : "RelatedSoundFile",        // Name of related sound file

      // date and time
      0x9003 : "DateTimeOriginal",        // Date and time when the original image was generated
      0x9004 : "DateTimeDigitized",       // Date and time when the image was stored digitally
      0x9290 : "SubsecTime",              // Fractions of seconds for DateTime
      0x9291 : "SubsecTimeOriginal",      // Fractions of seconds for DateTimeOriginal
      0x9292 : "SubsecTimeDigitized",     // Fractions of seconds for DateTimeDigitized

      // picture-taking conditions
      0x829A : "ExposureTime",            // Exposure time (in seconds)
      0x829D : "FNumber",                 // F number
      0x8822 : "ExposureProgram",         // Exposure program
      0x8824 : "SpectralSensitivity",     // Spectral sensitivity
      0x8827 : "ISOSpeedRatings",         // ISO speed rating
      0x8828 : "OECF",                    // Optoelectric conversion factor
      0x9201 : "ShutterSpeedValue",       // Shutter speed
      0x9202 : "ApertureValue",           // Lens aperture
      0x9203 : "BrightnessValue",         // Value of brightness
      0x9204 : "ExposureBias",            // Exposure bias
      0x9205 : "MaxApertureValue",        // Smallest F number of lens
      0x9206 : "SubjectDistance",         // Distance to subject in meters
      0x9207 : "MeteringMode",            // Metering mode
      0x9208 : "LightSource",             // Kind of light source
      0x9209 : "Flash",                   // Flash status
      0x9214 : "SubjectArea",             // Location and area of main subject
      0x920A : "FocalLength",             // Focal length of the lens in mm
      0xA20B : "FlashEnergy",             // Strobe energy in BCPS
      0xA20C : "SpatialFrequencyResponse",    //
      0xA20E : "FocalPlaneXResolution",   // Number of pixels in width direction per FocalPlaneResolutionUnit
      0xA20F : "FocalPlaneYResolution",   // Number of pixels in height direction per FocalPlaneResolutionUnit
      0xA210 : "FocalPlaneResolutionUnit",    // Unit for measuring FocalPlaneXResolution and FocalPlaneYResolution
      0xA214 : "SubjectLocation",         // Location of subject in image
      0xA215 : "ExposureIndex",           // Exposure index selected on camera
      0xA217 : "SensingMethod",           // Image sensor type
      0xA300 : "FileSource",              // Image source (3 == DSC)
      0xA301 : "SceneType",               // Scene type (1 == directly photographed)
      0xA302 : "CFAPattern",              // Color filter array geometric pattern
      0xA401 : "CustomRendered",          // Special processing
      0xA402 : "ExposureMode",            // Exposure mode
      0xA403 : "WhiteBalance",            // 1 = auto white balance, 2 = manual
      0xA404 : "DigitalZoomRation",       // Digital zoom ratio
      0xA405 : "FocalLengthIn35mmFilm",   // Equivalent foacl length assuming 35mm film camera (in mm)
      0xA406 : "SceneCaptureType",        // Type of scene
      0xA407 : "GainControl",             // Degree of overall image gain adjustment
      0xA408 : "Contrast",                // Direction of contrast processing applied by camera
      0xA409 : "Saturation",              // Direction of saturation processing applied by camera
      0xA40A : "Sharpness",               // Direction of sharpness processing applied by camera
      0xA40B : "DeviceSettingDescription",    //
      0xA40C : "SubjectDistanceRange",    // Distance to subject

      // other tags
      0xA005 : "InteroperabilityIFDPointer",
      0xA420 : "ImageUniqueID"            // Identifier assigned uniquely to each image
  };

  var TiffTags = EXIF.TiffTags = {
      0x0100 : "ImageWidth",
      0x0101 : "ImageHeight",
      0x8769 : "ExifIFDPointer",
      0x8825 : "GPSInfoIFDPointer",
      0xA005 : "InteroperabilityIFDPointer",
      0x0102 : "BitsPerSample",
      0x0103 : "Compression",
      0x0106 : "PhotometricInterpretation",
      0x0112 : "Orientation",
      0x0115 : "SamplesPerPixel",
      0x011C : "PlanarConfiguration",
      0x0212 : "YCbCrSubSampling",
      0x0213 : "YCbCrPositioning",
      0x011A : "XResolution",
      0x011B : "YResolution",
      0x0128 : "ResolutionUnit",
      0x0111 : "StripOffsets",
      0x0116 : "RowsPerStrip",
      0x0117 : "StripByteCounts",
      0x0201 : "JPEGInterchangeFormat",
      0x0202 : "JPEGInterchangeFormatLength",
      0x012D : "TransferFunction",
      0x013E : "WhitePoint",
      0x013F : "PrimaryChromaticities",
      0x0211 : "YCbCrCoefficients",
      0x0214 : "ReferenceBlackWhite",
      0x0132 : "DateTime",
      0x010E : "ImageDescription",
      0x010F : "Make",
      0x0110 : "Model",
      0x0131 : "Software",
      0x013B : "Artist",
      0x8298 : "Copyright"
  };

  var GPSTags = EXIF.GPSTags = {
      0x0000 : "GPSVersionID",
      0x0001 : "GPSLatitudeRef",
      0x0002 : "GPSLatitude",
      0x0003 : "GPSLongitudeRef",
      0x0004 : "GPSLongitude",
      0x0005 : "GPSAltitudeRef",
      0x0006 : "GPSAltitude",
      0x0007 : "GPSTimeStamp",
      0x0008 : "GPSSatellites",
      0x0009 : "GPSStatus",
      0x000A : "GPSMeasureMode",
      0x000B : "GPSDOP",
      0x000C : "GPSSpeedRef",
      0x000D : "GPSSpeed",
      0x000E : "GPSTrackRef",
      0x000F : "GPSTrack",
      0x0010 : "GPSImgDirectionRef",
      0x0011 : "GPSImgDirection",
      0x0012 : "GPSMapDatum",
      0x0013 : "GPSDestLatitudeRef",
      0x0014 : "GPSDestLatitude",
      0x0015 : "GPSDestLongitudeRef",
      0x0016 : "GPSDestLongitude",
      0x0017 : "GPSDestBearingRef",
      0x0018 : "GPSDestBearing",
      0x0019 : "GPSDestDistanceRef",
      0x001A : "GPSDestDistance",
      0x001B : "GPSProcessingMethod",
      0x001C : "GPSAreaInformation",
      0x001D : "GPSDateStamp",
      0x001E : "GPSDifferential"
  };

   // EXIF 2.3 Spec
  var IFD1Tags = EXIF.IFD1Tags = {
      0x0100: "ImageWidth",
      0x0101: "ImageHeight",
      0x0102: "BitsPerSample",
      0x0103: "Compression",
      0x0106: "PhotometricInterpretation",
      0x0111: "StripOffsets",
      0x0112: "Orientation",
      0x0115: "SamplesPerPixel",
      0x0116: "RowsPerStrip",
      0x0117: "StripByteCounts",
      0x011A: "XResolution",
      0x011B: "YResolution",
      0x011C: "PlanarConfiguration",
      0x0128: "ResolutionUnit",
      0x0201: "JpegIFOffset",    // When image format is JPEG, this value show offset to JPEG data stored.(aka "ThumbnailOffset" or "JPEGInterchangeFormat")
      0x0202: "JpegIFByteCount", // When image format is JPEG, this value shows data size of JPEG image (aka "ThumbnailLength" or "JPEGInterchangeFormatLength")
      0x0211: "YCbCrCoefficients",
      0x0212: "YCbCrSubSampling",
      0x0213: "YCbCrPositioning",
      0x0214: "ReferenceBlackWhite"
  };

  var StringValues = EXIF.StringValues = {
      ExposureProgram : {
          0 : "Not defined",
          1 : "Manual",
          2 : "Normal program",
          3 : "Aperture priority",
          4 : "Shutter priority",
          5 : "Creative program",
          6 : "Action program",
          7 : "Portrait mode",
          8 : "Landscape mode"
      },
      MeteringMode : {
          0 : "Unknown",
          1 : "Average",
          2 : "CenterWeightedAverage",
          3 : "Spot",
          4 : "MultiSpot",
          5 : "Pattern",
          6 : "Partial",
          255 : "Other"
      },
      LightSource : {
          0 : "Unknown",
          1 : "Daylight",
          2 : "Fluorescent",
          3 : "Tungsten (incandescent light)",
          4 : "Flash",
          9 : "Fine weather",
          10 : "Cloudy weather",
          11 : "Shade",
          12 : "Daylight fluorescent (D 5700 - 7100K)",
          13 : "Day white fluorescent (N 4600 - 5400K)",
          14 : "Cool white fluorescent (W 3900 - 4500K)",
          15 : "White fluorescent (WW 3200 - 3700K)",
          17 : "Standard light A",
          18 : "Standard light B",
          19 : "Standard light C",
          20 : "D55",
          21 : "D65",
          22 : "D75",
          23 : "D50",
          24 : "ISO studio tungsten",
          255 : "Other"
      },
      Flash : {
          0x0000 : "Flash did not fire",
          0x0001 : "Flash fired",
          0x0005 : "Strobe return light not detected",
          0x0007 : "Strobe return light detected",
          0x0009 : "Flash fired, compulsory flash mode",
          0x000D : "Flash fired, compulsory flash mode, return light not detected",
          0x000F : "Flash fired, compulsory flash mode, return light detected",
          0x0010 : "Flash did not fire, compulsory flash mode",
          0x0018 : "Flash did not fire, auto mode",
          0x0019 : "Flash fired, auto mode",
          0x001D : "Flash fired, auto mode, return light not detected",
          0x001F : "Flash fired, auto mode, return light detected",
          0x0020 : "No flash function",
          0x0041 : "Flash fired, red-eye reduction mode",
          0x0045 : "Flash fired, red-eye reduction mode, return light not detected",
          0x0047 : "Flash fired, red-eye reduction mode, return light detected",
          0x0049 : "Flash fired, compulsory flash mode, red-eye reduction mode",
          0x004D : "Flash fired, compulsory flash mode, red-eye reduction mode, return light not detected",
          0x004F : "Flash fired, compulsory flash mode, red-eye reduction mode, return light detected",
          0x0059 : "Flash fired, auto mode, red-eye reduction mode",
          0x005D : "Flash fired, auto mode, return light not detected, red-eye reduction mode",
          0x005F : "Flash fired, auto mode, return light detected, red-eye reduction mode"
      },
      SensingMethod : {
          1 : "Not defined",
          2 : "One-chip color area sensor",
          3 : "Two-chip color area sensor",
          4 : "Three-chip color area sensor",
          5 : "Color sequential area sensor",
          7 : "Trilinear sensor",
          8 : "Color sequential linear sensor"
      },
      SceneCaptureType : {
          0 : "Standard",
          1 : "Landscape",
          2 : "Portrait",
          3 : "Night scene"
      },
      SceneType : {
          1 : "Directly photographed"
      },
      CustomRendered : {
          0 : "Normal process",
          1 : "Custom process"
      },
      WhiteBalance : {
          0 : "Auto white balance",
          1 : "Manual white balance"
      },
      GainControl : {
          0 : "None",
          1 : "Low gain up",
          2 : "High gain up",
          3 : "Low gain down",
          4 : "High gain down"
      },
      Contrast : {
          0 : "Normal",
          1 : "Soft",
          2 : "Hard"
      },
      Saturation : {
          0 : "Normal",
          1 : "Low saturation",
          2 : "High saturation"
      },
      Sharpness : {
          0 : "Normal",
          1 : "Soft",
          2 : "Hard"
      },
      SubjectDistanceRange : {
          0 : "Unknown",
          1 : "Macro",
          2 : "Close view",
          3 : "Distant view"
      },
      FileSource : {
          3 : "DSC"
      },

      Components : {
          0 : "",
          1 : "Y",
          2 : "Cb",
          3 : "Cr",
          4 : "R",
          5 : "G",
          6 : "B"
      }
  };

  function addEvent(element, event, handler) {
      if (element.addEventListener) {
          element.addEventListener(event, handler, false);
      } else if (element.attachEvent) {
          element.attachEvent("on" + event, handler);
      }
  }

  function imageHasData(img) {
      return !!(img.exifdata);
  }


  function base64ToArrayBuffer(base64, contentType) {
      contentType = contentType || base64.match(/^data\:([^\;]+)\;base64,/mi)[1] || ''; // e.g. 'data:image/jpeg;base64,...' => 'image/jpeg'
      base64 = base64.replace(/^data\:([^\;]+)\;base64,/gmi, '');
      var binary = atob(base64);
      var len = binary.length;
      var buffer = new ArrayBuffer(len);
      var view = new Uint8Array(buffer);
      for (var i = 0; i < len; i++) {
          view[i] = binary.charCodeAt(i);
      }
      return buffer;
  }

  function objectURLToBlob(url, callback) {
      var http = new XMLHttpRequest();
      http.open("GET", url, true);
      http.responseType = "blob";
      http.onload = function(e) {
          if (this.status == 200 || this.status === 0) {
              callback(this.response);
          }
      };
      http.send();
  }

  function getImageData(img, callback) {
      function handleBinaryFile(binFile) {
          var data = findEXIFinJPEG(binFile);
          img.exifdata = data || {};
          var iptcdata = findIPTCinJPEG(binFile);
          img.iptcdata = iptcdata || {};
          if (EXIF.isXmpEnabled) {
             var xmpdata= findXMPinJPEG(binFile);
             img.xmpdata = xmpdata || {};               
          }
          if (callback) {
              callback.call(img);
          }
      }

      if (img.src) {
          if (/^data\:/i.test(img.src)) { // Data URI
              var arrayBuffer = base64ToArrayBuffer(img.src);
              handleBinaryFile(arrayBuffer);

          } else if (/^blob\:/i.test(img.src)) { // Object URL
              var fileReader = new FileReader();
              fileReader.onload = function(e) {
                  handleBinaryFile(e.target.result);
              };
              objectURLToBlob(img.src, function (blob) {
                  fileReader.readAsArrayBuffer(blob);
              });
          } else {
              var http = new XMLHttpRequest();
              http.onload = function() {
                  if (this.status == 200 || this.status === 0) {
                      handleBinaryFile(http.response);
                  } else {
                      throw "Could not load image";
                  }
                  http = null;
              };
              http.open("GET", img.src, true);
              http.responseType = "arraybuffer";
              http.send(null);
          }
      } else if (self.FileReader && (img instanceof self.Blob || img instanceof self.File)) {
          var fileReader = new FileReader();
          fileReader.onload = function(e) {
              if (debug) console.log("Got file of length " + e.target.result.byteLength);
              handleBinaryFile(e.target.result);
          };

          fileReader.readAsArrayBuffer(img);
      }
  }

  function findEXIFinJPEG(file) {
      var dataView = new DataView(file);

      if (debug) console.log("Got file of length " + file.byteLength);
      if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
          if (debug) console.log("Not a valid JPEG");
          return false; // not a valid jpeg
      }

      var offset = 2,
          length = file.byteLength,
          marker;

      while (offset < length) {
          if (dataView.getUint8(offset) != 0xFF) {
              if (debug) console.log("Not a valid marker at offset " + offset + ", found: " + dataView.getUint8(offset));
              return false; // not a valid marker, something is wrong
          }

          marker = dataView.getUint8(offset + 1);
          if (debug) console.log(marker);

          // we could implement handling for other markers here,
          // but we're only looking for 0xFFE1 for EXIF data

          if (marker == 225) {
              if (debug) console.log("Found 0xFFE1 marker");

              return readEXIFData(dataView, offset + 4, dataView.getUint16(offset + 2) - 2);

              // offset += 2 + file.getShortAt(offset+2, true);

          } else {
              offset += 2 + dataView.getUint16(offset+2);
          }

      }

  }

  function findIPTCinJPEG(file) {
      var dataView = new DataView(file);

      if (debug) console.log("Got file of length " + file.byteLength);
      if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
          if (debug) console.log("Not a valid JPEG");
          return false; // not a valid jpeg
      }

      var offset = 2,
          length = file.byteLength;


      var isFieldSegmentStart = function(dataView, offset){
          return (
              dataView.getUint8(offset) === 0x38 &&
              dataView.getUint8(offset+1) === 0x42 &&
              dataView.getUint8(offset+2) === 0x49 &&
              dataView.getUint8(offset+3) === 0x4D &&
              dataView.getUint8(offset+4) === 0x04 &&
              dataView.getUint8(offset+5) === 0x04
          );
      };

      while (offset < length) {

          if ( isFieldSegmentStart(dataView, offset )){

              // Get the length of the name header (which is padded to an even number of bytes)
              var nameHeaderLength = dataView.getUint8(offset+7);
              if(nameHeaderLength % 2 !== 0) nameHeaderLength += 1;
              // Check for pre photoshop 6 format
              if(nameHeaderLength === 0) {
                  // Always 4
                  nameHeaderLength = 4;
              }

              var startOffset = offset + 8 + nameHeaderLength;
              var sectionLength = dataView.getUint16(offset + 6 + nameHeaderLength);

              return readIPTCData(file, startOffset, sectionLength);

              break;

          }


          // Not the marker, continue searching
          offset++;

      }

  }
  var IptcFieldMap = {
      0x78 : 'caption',
      0x6E : 'credit',
      0x19 : 'keywords',
      0x37 : 'dateCreated',
      0x50 : 'byline',
      0x55 : 'bylineTitle',
      0x7A : 'captionWriter',
      0x69 : 'headline',
      0x74 : 'copyright',
      0x0F : 'category'
  };
  function readIPTCData(file, startOffset, sectionLength){
      var dataView = new DataView(file);
      var data = {};
      var fieldValue, fieldName, dataSize, segmentType, segmentSize;
      var segmentStartPos = startOffset;
      while(segmentStartPos < startOffset+sectionLength) {
          if(dataView.getUint8(segmentStartPos) === 0x1C && dataView.getUint8(segmentStartPos+1) === 0x02){
              segmentType = dataView.getUint8(segmentStartPos+2);
              if(segmentType in IptcFieldMap) {
                  dataSize = dataView.getInt16(segmentStartPos+3);
                  segmentSize = dataSize + 5;
                  fieldName = IptcFieldMap[segmentType];
                  fieldValue = getStringFromDB(dataView, segmentStartPos+5, dataSize);
                  // Check if we already stored a value with this name
                  if(data.hasOwnProperty(fieldName)) {
                      // Value already stored with this name, create multivalue field
                      if(data[fieldName] instanceof Array) {
                          data[fieldName].push(fieldValue);
                      }
                      else {
                          data[fieldName] = [data[fieldName], fieldValue];
                      }
                  }
                  else {
                      data[fieldName] = fieldValue;
                  }
              }

          }
          segmentStartPos++;
      }
      return data;
  }



  function readTags(file, tiffStart, dirStart, strings, bigEnd) {
      var entries = file.getUint16(dirStart, !bigEnd),
          tags = {},
          entryOffset, tag,
          i;

      for (i=0;i<entries;i++) {
          entryOffset = dirStart + i*12 + 2;
          tag = strings[file.getUint16(entryOffset, !bigEnd)];
          if (!tag && debug) console.log("Unknown tag: " + file.getUint16(entryOffset, !bigEnd));
          tags[tag] = readTagValue(file, entryOffset, tiffStart, dirStart, bigEnd);
      }
      return tags;
  }


  function readTagValue(file, entryOffset, tiffStart, dirStart, bigEnd) {
      var type = file.getUint16(entryOffset+2, !bigEnd),
          numValues = file.getUint32(entryOffset+4, !bigEnd),
          valueOffset = file.getUint32(entryOffset+8, !bigEnd) + tiffStart,
          offset,
          vals, val, n,
          numerator, denominator;

      switch (type) {
          case 1: // byte, 8-bit unsigned int
          case 7: // undefined, 8-bit byte, value depending on field
              if (numValues == 1) {
                  return file.getUint8(entryOffset + 8, !bigEnd);
              } else {
                  offset = numValues > 4 ? valueOffset : (entryOffset + 8);
                  vals = [];
                  for (n=0;n<numValues;n++) {
                      vals[n] = file.getUint8(offset + n);
                  }
                  return vals;
              }

          case 2: // ascii, 8-bit byte
              offset = numValues > 4 ? valueOffset : (entryOffset + 8);
              return getStringFromDB(file, offset, numValues-1);

          case 3: // short, 16 bit int
              if (numValues == 1) {
                  return file.getUint16(entryOffset + 8, !bigEnd);
              } else {
                  offset = numValues > 2 ? valueOffset : (entryOffset + 8);
                  vals = [];
                  for (n=0;n<numValues;n++) {
                      vals[n] = file.getUint16(offset + 2*n, !bigEnd);
                  }
                  return vals;
              }

          case 4: // long, 32 bit int
              if (numValues == 1) {
                  return file.getUint32(entryOffset + 8, !bigEnd);
              } else {
                  vals = [];
                  for (n=0;n<numValues;n++) {
                      vals[n] = file.getUint32(valueOffset + 4*n, !bigEnd);
                  }
                  return vals;
              }

          case 5:    // rational = two long values, first is numerator, second is denominator
              if (numValues == 1) {
                  numerator = file.getUint32(valueOffset, !bigEnd);
                  denominator = file.getUint32(valueOffset+4, !bigEnd);
                  val = new Number(numerator / denominator);
                  val.numerator = numerator;
                  val.denominator = denominator;
                  return val;
              } else {
                  vals = [];
                  for (n=0;n<numValues;n++) {
                      numerator = file.getUint32(valueOffset + 8*n, !bigEnd);
                      denominator = file.getUint32(valueOffset+4 + 8*n, !bigEnd);
                      vals[n] = new Number(numerator / denominator);
                      vals[n].numerator = numerator;
                      vals[n].denominator = denominator;
                  }
                  return vals;
              }

          case 9: // slong, 32 bit signed int
              if (numValues == 1) {
                  return file.getInt32(entryOffset + 8, !bigEnd);
              } else {
                  vals = [];
                  for (n=0;n<numValues;n++) {
                      vals[n] = file.getInt32(valueOffset + 4*n, !bigEnd);
                  }
                  return vals;
              }

          case 10: // signed rational, two slongs, first is numerator, second is denominator
              if (numValues == 1) {
                  return file.getInt32(valueOffset, !bigEnd) / file.getInt32(valueOffset+4, !bigEnd);
              } else {
                  vals = [];
                  for (n=0;n<numValues;n++) {
                      vals[n] = file.getInt32(valueOffset + 8*n, !bigEnd) / file.getInt32(valueOffset+4 + 8*n, !bigEnd);
                  }
                  return vals;
              }
      }
  }

  /**
  * Given an IFD (Image File Directory) start offset
  * returns an offset to next IFD or 0 if it's the last IFD.
  */
  function getNextIFDOffset(dataView, dirStart, bigEnd){
      //the first 2bytes means the number of directory entries contains in this IFD
      var entries = dataView.getUint16(dirStart, !bigEnd);

      // After last directory entry, there is a 4bytes of data,
      // it means an offset to next IFD.
      // If its value is '0x00000000', it means this is the last IFD and there is no linked IFD.

      return dataView.getUint32(dirStart + 2 + entries * 12, !bigEnd); // each entry is 12 bytes long
  }

  function readThumbnailImage(dataView, tiffStart, firstIFDOffset, bigEnd){
      // get the IFD1 offset
      var IFD1OffsetPointer = getNextIFDOffset(dataView, tiffStart+firstIFDOffset, bigEnd);

      if (!IFD1OffsetPointer) {
          // console.log('******** IFD1Offset is empty, image thumb not found ********');
          return {};
      }
      else if (IFD1OffsetPointer > dataView.byteLength) { // this should not happen
          // console.log('******** IFD1Offset is outside the bounds of the DataView ********');
          return {};
      }
      // console.log('*******  thumbnail IFD offset (IFD1) is: %s', IFD1OffsetPointer);

      var thumbTags = readTags(dataView, tiffStart, tiffStart + IFD1OffsetPointer, IFD1Tags, bigEnd)

      // EXIF 2.3 specification for JPEG format thumbnail

      // If the value of Compression(0x0103) Tag in IFD1 is '6', thumbnail image format is JPEG.
      // Most of Exif image uses JPEG format for thumbnail. In that case, you can get offset of thumbnail
      // by JpegIFOffset(0x0201) Tag in IFD1, size of thumbnail by JpegIFByteCount(0x0202) Tag.
      // Data format is ordinary JPEG format, starts from 0xFFD8 and ends by 0xFFD9. It seems that
      // JPEG format and 160x120pixels of size are recommended thumbnail format for Exif2.1 or later.

      if (thumbTags['Compression']) {
          // console.log('Thumbnail image found!');

          switch (thumbTags['Compression']) {
              case 6:
                  // console.log('Thumbnail image format is JPEG');
                  if (thumbTags.JpegIFOffset && thumbTags.JpegIFByteCount) {
                  // extract the thumbnail
                      var tOffset = tiffStart + thumbTags.JpegIFOffset;
                      var tLength = thumbTags.JpegIFByteCount;
                      thumbTags['blob'] = new Blob([new Uint8Array(dataView.buffer, tOffset, tLength)], {
                          type: 'image/jpeg'
                      });
                  }
              break;

          case 1:
              console.log("Thumbnail image format is TIFF, which is not implemented.");
              break;
          default:
              console.log("Unknown thumbnail image format '%s'", thumbTags['Compression']);
          }
      }
      else if (thumbTags['PhotometricInterpretation'] == 2) {
          console.log("Thumbnail image format is RGB, which is not implemented.");
      }
      return thumbTags;
  }

  function getStringFromDB(buffer, start, length) {
      var outstr = "";
      for (n = start; n < start+length; n++) {
          outstr += String.fromCharCode(buffer.getUint8(n));
      }
      return outstr;
  }

  function readEXIFData(file, start) {
      if (getStringFromDB(file, start, 4) != "Exif") {
          if (debug) console.log("Not valid EXIF data! " + getStringFromDB(file, start, 4));
          return false;
      }

      var bigEnd,
          tags, tag,
          exifData, gpsData,
          tiffOffset = start + 6;

      // test for TIFF validity and endianness
      if (file.getUint16(tiffOffset) == 0x4949) {
          bigEnd = false;
      } else if (file.getUint16(tiffOffset) == 0x4D4D) {
          bigEnd = true;
      } else {
          if (debug) console.log("Not valid TIFF data! (no 0x4949 or 0x4D4D)");
          return false;
      }

      if (file.getUint16(tiffOffset+2, !bigEnd) != 0x002A) {
          if (debug) console.log("Not valid TIFF data! (no 0x002A)");
          return false;
      }

      var firstIFDOffset = file.getUint32(tiffOffset+4, !bigEnd);

      if (firstIFDOffset < 0x00000008) {
          if (debug) console.log("Not valid TIFF data! (First offset less than 8)", file.getUint32(tiffOffset+4, !bigEnd));
          return false;
      }

      tags = readTags(file, tiffOffset, tiffOffset + firstIFDOffset, TiffTags, bigEnd);

      if (tags.ExifIFDPointer) {
          exifData = readTags(file, tiffOffset, tiffOffset + tags.ExifIFDPointer, ExifTags, bigEnd);
          for (tag in exifData) {
              switch (tag) {
                  case "LightSource" :
                  case "Flash" :
                  case "MeteringMode" :
                  case "ExposureProgram" :
                  case "SensingMethod" :
                  case "SceneCaptureType" :
                  case "SceneType" :
                  case "CustomRendered" :
                  case "WhiteBalance" :
                  case "GainControl" :
                  case "Contrast" :
                  case "Saturation" :
                  case "Sharpness" :
                  case "SubjectDistanceRange" :
                  case "FileSource" :
                      exifData[tag] = StringValues[tag][exifData[tag]];
                      break;

                  case "ExifVersion" :
                  case "FlashpixVersion" :
                      exifData[tag] = String.fromCharCode(exifData[tag][0], exifData[tag][1], exifData[tag][2], exifData[tag][3]);
                      break;

                  case "ComponentsConfiguration" :
                      exifData[tag] =
                          StringValues.Components[exifData[tag][0]] +
                          StringValues.Components[exifData[tag][1]] +
                          StringValues.Components[exifData[tag][2]] +
                          StringValues.Components[exifData[tag][3]];
                      break;
              }
              tags[tag] = exifData[tag];
          }
      }

      if (tags.GPSInfoIFDPointer) {
          gpsData = readTags(file, tiffOffset, tiffOffset + tags.GPSInfoIFDPointer, GPSTags, bigEnd);
          for (tag in gpsData) {
              switch (tag) {
                  case "GPSVersionID" :
                      gpsData[tag] = gpsData[tag][0] +
                          "." + gpsData[tag][1] +
                          "." + gpsData[tag][2] +
                          "." + gpsData[tag][3];
                      break;
              }
              tags[tag] = gpsData[tag];
          }
      }

      // extract thumbnail
      tags['thumbnail'] = readThumbnailImage(file, tiffOffset, firstIFDOffset, bigEnd);

      return tags;
  }

 function findXMPinJPEG(file) {

      if (!('DOMParser' in self)) {
          // console.warn('XML parsing not supported without DOMParser');
          return;
      }
      var dataView = new DataView(file);

      if (debug) console.log("Got file of length " + file.byteLength);
      if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
         if (debug) console.log("Not a valid JPEG");
         return false; // not a valid jpeg
      }

      var offset = 2,
          length = file.byteLength,
          dom = new DOMParser();

      while (offset < (length-4)) {
          if (getStringFromDB(dataView, offset, 4) == "http") {
              var startOffset = offset - 1;
              var sectionLength = dataView.getUint16(offset - 2) - 1;
              var xmpString = getStringFromDB(dataView, startOffset, sectionLength)
              var xmpEndIndex = xmpString.indexOf('xmpmeta>') + 8;
              xmpString = xmpString.substring( xmpString.indexOf( '<x:xmpmeta' ), xmpEndIndex );

              var indexOfXmp = xmpString.indexOf('x:xmpmeta') + 10
              //Many custom written programs embed xmp/xml without any namespace. Following are some of them.
              //Without these namespaces, XML is thought to be invalid by parsers
              xmpString = xmpString.slice(0, indexOfXmp)
                          + 'xmlns:Iptc4xmpCore="http://iptc.org/std/Iptc4xmpCore/1.0/xmlns/" '
                          + 'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" '
                          + 'xmlns:tiff="http://ns.adobe.com/tiff/1.0/" '
                          + 'xmlns:plus="http://schemas.android.com/apk/lib/com.google.android.gms.plus" '
                          + 'xmlns:ext="http://www.gettyimages.com/xsltExtension/1.0" '
                          + 'xmlns:exif="http://ns.adobe.com/exif/1.0/" '
                          + 'xmlns:stEvt="http://ns.adobe.com/xap/1.0/sType/ResourceEvent#" '
                          + 'xmlns:stRef="http://ns.adobe.com/xap/1.0/sType/ResourceRef#" '
                          + 'xmlns:crs="http://ns.adobe.com/camera-raw-settings/1.0/" '
                          + 'xmlns:xapGImg="http://ns.adobe.com/xap/1.0/g/img/" '
                          + 'xmlns:Iptc4xmpExt="http://iptc.org/std/Iptc4xmpExt/2008-02-29/" '
                          + xmpString.slice(indexOfXmp)

              var domDocument = dom.parseFromString( xmpString, 'text/xml' );
              return xml2Object(domDocument);
          } else{
           offset++;
          }
      }
  }

  function xml2json(xml) {
      var json = {};
    
      if (xml.nodeType == 1) { // element node
        if (xml.attributes.length > 0) {
          json['@attributes'] = {};
          for (var j = 0; j < xml.attributes.length; j++) {
            var attribute = xml.attributes.item(j);
            json['@attributes'][attribute.nodeName] = attribute.nodeValue;
          }
        }
      } else if (xml.nodeType == 3) { // text node
        return xml.nodeValue;
      }
    
      // deal with children
      if (xml.hasChildNodes()) {
        for(var i = 0; i < xml.childNodes.length; i++) {
          var child = xml.childNodes.item(i);
          var nodeName = child.nodeName;
          if (json[nodeName] == null) {
            json[nodeName] = xml2json(child);
          } else {
            if (json[nodeName].push == null) {
              var old = json[nodeName];
              json[nodeName] = [];
              json[nodeName].push(old);
            }
            json[nodeName].push(xml2json(child));
          }
        }
      }
      
      return json;
  }

  function xml2Object(xml) {
      try {
          var obj = {};
          if (xml.children.length > 0) {
            for (var i = 0; i < xml.children.length; i++) {
              var item = xml.children.item(i);
              var attributes = item.attributes;
              for(var idx in attributes) {
                  var itemAtt = attributes[idx];
                  var dataKey = itemAtt.nodeName;
                  var dataValue = itemAtt.nodeValue;

                  if(dataKey !== undefined) {
                      obj[dataKey] = dataValue;
                  }
              }
              var nodeName = item.nodeName;

              if (typeof (obj[nodeName]) == "undefined") {
                obj[nodeName] = xml2json(item);
              } else {
                if (typeof (obj[nodeName].push) == "undefined") {
                  var old = obj[nodeName];

                  obj[nodeName] = [];
                  obj[nodeName].push(old);
                }
                obj[nodeName].push(xml2json(item));
              }
            }
          } else {
            obj = xml.textContent;
          }
          return obj;
        } catch (e) {
            console.log(e.message);
        }
  }

  EXIF.enableXmp = function() {
      EXIF.isXmpEnabled = true;
  }

  EXIF.disableXmp = function() {
      EXIF.isXmpEnabled = false;
  }

  EXIF.getData = function(img, callback) {
      if (((self.Image && img instanceof self.Image)
          || (self.HTMLImageElement && img instanceof self.HTMLImageElement))
          && !img.complete)
          return false;

      if (!imageHasData(img)) {
          getImageData(img, callback);
      } else {
          if (callback) {
              callback.call(img);
          }
      }
      return true;
  }

  EXIF.getTag = function(img, tag) {
      if (!imageHasData(img)) return;
      return img.exifdata[tag];
  }
  
  EXIF.getIptcTag = function(img, tag) {
      if (!imageHasData(img)) return;
      return img.iptcdata[tag];
  }

  EXIF.getAllTags = function(img) {
      if (!imageHasData(img)) return {};
      var a,
          data = img.exifdata,
          tags = {};
      for (a in data) {
          if (data.hasOwnProperty(a)) {
              tags[a] = data[a];
          }
      }
      return tags;
  }
  
  EXIF.getAllIptcTags = function(img) {
      if (!imageHasData(img)) return {};
      var a,
          data = img.iptcdata,
          tags = {};
      for (a in data) {
          if (data.hasOwnProperty(a)) {
              tags[a] = data[a];
          }
      }
      return tags;
  }

  EXIF.pretty = function(img) {
      if (!imageHasData(img)) return "";
      var a,
          data = img.exifdata,
          strPretty = "";
      for (a in data) {
          if (data.hasOwnProperty(a)) {
              if (typeof data[a] == "object") {
                  if (data[a] instanceof Number) {
                      strPretty += a + " : " + data[a] + " [" + data[a].numerator + "/" + data[a].denominator + "]\r\n";
                  } else {
                      strPretty += a + " : [" + data[a].length + " values]\r\n";
                  }
              } else {
                  strPretty += a + " : " + data[a] + "\r\n";
              }
          }
      }
      return strPretty;
  }

  EXIF.readFromBinaryFile = function(file) {
      return findEXIFinJPEG(file);
  }

  if (typeof define === 'function' && define.amd) {
      define('exif-js', [], function() {
          return EXIF;
      });
  }
}.call(this));