xref: /external/chromium_org/chrome/common/extensions/docs/examples/extensions/imageinfo/imageinfo/exif.js

/*
 * Javascript EXIF Reader 0.1.2
 * Copyright (c) 2008 Jacob Seidelin, cupboy@gmail.com, http://blog.nihilogic.dk/
 * MIT License [http://www.opensource.org/licenses/mit-license.php]
 */


var EXIF = {};

(function() {

var bDebug = false;

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
};

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"
}

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.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(oElement, strEvent, fncHandler)
{
  if (oElement.addEventListener) {
    oElement.addEventListener(strEvent, fncHandler, false);
  } else if (oElement.attachEvent) {
    oElement.attachEvent("on" + strEvent, fncHandler);
  }
}


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

function getImageData(oImg, fncCallback)
{
  BinaryAjax(
    oImg.src,
    function(oHTTP) {
      var oEXIF = findEXIFinJPEG(oHTTP.binaryResponse);
      oImg.exifdata = oEXIF || {};
      if (fncCallback) fncCallback();
    }
  )
}

function findEXIFinJPEG(oFile) {
  var aMarkers = [];

  if (oFile.getByteAt(0) != 0xFF || oFile.getByteAt(1) != 0xD8) {
    return false; // not a valid jpeg
  }

  var iOffset = 2;
  var iLength = oFile.getLength();
  while (iOffset < iLength) {
    if (oFile.getByteAt(iOffset) != 0xFF) {
      if (bDebug) console.log("Not a valid marker at offset " + iOffset + ", found: " + oFile.getByteAt(iOffset));
      return false; // not a valid marker, something is wrong
    }

    var iMarker = oFile.getByteAt(iOffset+1);

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

    if (iMarker == 22400) {
      if (bDebug) console.log("Found 0xFFE1 marker");
      return readEXIFData(oFile, iOffset + 4, oFile.getShortAt(iOffset+2, true)-2);
      iOffset += 2 + oFile.getShortAt(iOffset+2, true);

    } else if (iMarker == 225) {
      // 0xE1 = Application-specific 1 (for EXIF)
      if (bDebug) console.log("Found 0xFFE1 marker");
      return readEXIFData(oFile, iOffset + 4, oFile.getShortAt(iOffset+2, true)-2);

    } else {
      iOffset += 2 + oFile.getShortAt(iOffset+2, true);
    }

  }

}


function readTags(oFile, iTIFFStart, iDirStart, oStrings, bBigEnd)
{
  var iEntries = oFile.getShortAt(iDirStart, bBigEnd);
  var oTags = {};
  for (var i=0;i<iEntries;i++) {
    var iEntryOffset = iDirStart + i*12 + 2;
    var strTag = oStrings[oFile.getShortAt(iEntryOffset, bBigEnd)];
    if (!strTag && bDebug) console.log("Unknown tag: " + oFile.getShortAt(iEntryOffset, bBigEnd));
    oTags[strTag] = readTagValue(oFile, iEntryOffset, iTIFFStart, iDirStart, bBigEnd);
  }
  return oTags;
}


function readTagValue(oFile, iEntryOffset, iTIFFStart, iDirStart, bBigEnd)
{
  var iType = oFile.getShortAt(iEntryOffset+2, bBigEnd);
  var iNumValues = oFile.getLongAt(iEntryOffset+4, bBigEnd);
  var iValueOffset = oFile.getLongAt(iEntryOffset+8, bBigEnd) + iTIFFStart;

  switch (iType) {
    case 1: // byte, 8-bit unsigned int
    case 7: // undefined, 8-bit byte, value depending on field
      if (iNumValues == 1) {
        return oFile.getByteAt(iEntryOffset + 8, bBigEnd);
      } else {
        var iValOffset = iNumValues > 4 ? iValueOffset : (iEntryOffset + 8);
        var aVals = [];
        for (var n=0;n<iNumValues;n++) {
          aVals[n] = oFile.getByteAt(iValOffset + n);
        }
        return aVals;
      }
      break;

    case 2: // ascii, 8-bit byte
      var iStringOffset = iNumValues > 4 ? iValueOffset : (iEntryOffset + 8);
      return oFile.getStringAt(iStringOffset, iNumValues-1);
      break;

    case 3: // short, 16 bit int
      if (iNumValues == 1) {
        return oFile.getShortAt(iEntryOffset + 8, bBigEnd);
      } else {
        var iValOffset = iNumValues > 2 ? iValueOffset : (iEntryOffset + 8);
        var aVals = [];
        for (var n=0;n<iNumValues;n++) {
          aVals[n] = oFile.getShortAt(iValOffset + 2*n, bBigEnd);
        }
        return aVals;
      }
      break;

    case 4: // long, 32 bit int
      if (iNumValues == 1) {
        return oFile.getLongAt(iEntryOffset + 8, bBigEnd);
      } else {
        var aVals = [];
        for (var n=0;n<iNumValues;n++) {
          aVals[n] = oFile.getLongAt(iValueOffset + 4*n, bBigEnd);
        }
        return aVals;
      }
      break;
    case 5:	// rational = two long values, first is numerator, second is denominator
      if (iNumValues == 1) {
        return oFile.getLongAt(iValueOffset, bBigEnd) / oFile.getLongAt(iValueOffset+4, bBigEnd);
      } else {
        var aVals = [];
        for (var n=0;n<iNumValues;n++) {
          aVals[n] = oFile.getLongAt(iValueOffset + 8*n, bBigEnd) / oFile.getLongAt(iValueOffset+4 + 8*n, bBigEnd);
        }
        return aVals;
      }
      break;
    case 9: // slong, 32 bit signed int
      if (iNumValues == 1) {
        return oFile.getSLongAt(iEntryOffset + 8, bBigEnd);
      } else {
        var aVals = [];
        for (var n=0;n<iNumValues;n++) {
          aVals[n] = oFile.getSLongAt(iValueOffset + 4*n, bBigEnd);
        }
        return aVals;
      }
      break;
    case 10: // signed rational, two slongs, first is numerator, second is denominator
      if (iNumValues == 1) {
        return oFile.getSLongAt(iValueOffset, bBigEnd) / oFile.getSLongAt(iValueOffset+4, bBigEnd);
      } else {
        var aVals = [];
        for (var n=0;n<iNumValues;n++) {
          aVals[n] = oFile.getSLongAt(iValueOffset + 8*n, bBigEnd) / oFile.getSLongAt(iValueOffset+4 + 8*n, bBigEnd);
        }
        return aVals;
      }
      break;
  }
}


function readEXIFData(oFile, iStart, iLength)
{
  if (oFile.getStringAt(iStart, 4) != "Exif") {
    if (bDebug) console.log("Not valid EXIF data! " + oFile.getStringAt(iStart, 4));
    return false;
  }

  var bBigEnd;

  var iTIFFOffset = iStart + 6;

  // test for TIFF validity and endianness
  if (oFile.getShortAt(iTIFFOffset) == 0x4949) {
    bBigEnd = false;
  } else if (oFile.getShortAt(iTIFFOffset) == 0x4D4D) {
    bBigEnd = true;
  } else {
    if (bDebug) console.log("Not valid TIFF data! (no 0x4949 or 0x4D4D)");
    return false;
  }

  if (oFile.getShortAt(iTIFFOffset+2, bBigEnd) != 0x002A) {
    if (bDebug) console.log("Not valid TIFF data! (no 0x002A)");
    return false;
  }

  if (oFile.getLongAt(iTIFFOffset+4, bBigEnd) != 0x00000008) {
    if (bDebug) console.log("Not valid TIFF data! (First offset not 8)", oFile.getShortAt(iTIFFOffset+4, bBigEnd));
    return false;
  }

  var oTags = readTags(oFile, iTIFFOffset, iTIFFOffset+8, EXIF.TiffTags, bBigEnd);

  if (oTags.ExifIFDPointer) {
    var oEXIFTags = readTags(oFile, iTIFFOffset, iTIFFOffset + oTags.ExifIFDPointer, EXIF.Tags, bBigEnd);
    for (var strTag in oEXIFTags) {
      switch (strTag) {
        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" :
          oEXIFTags[strTag] = EXIF.StringValues[strTag][oEXIFTags[strTag]];
          break;

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

        case "ComponentsConfiguration" :
          oEXIFTags[strTag] =
            EXIF.StringValues.Components[oEXIFTags[strTag][0]]
            + EXIF.StringValues.Components[oEXIFTags[strTag][1]]
            + EXIF.StringValues.Components[oEXIFTags[strTag][2]]
            + EXIF.StringValues.Components[oEXIFTags[strTag][3]];
          break;
      }
      oTags[strTag] = oEXIFTags[strTag];
    }
  }

  if (oTags.GPSInfoIFDPointer) {
    var oGPSTags = readTags(oFile, iTIFFOffset, iTIFFOffset + oTags.GPSInfoIFDPointer, EXIF.GPSTags, bBigEnd);
    for (var strTag in oGPSTags) {
      switch (strTag) {
        case "GPSVersionID" :
          oGPSTags[strTag] = oGPSTags[strTag][0]
            + "." + oGPSTags[strTag][1]
            + "." + oGPSTags[strTag][2]
            + "." + oGPSTags[strTag][3];
          break;
      }
      oTags[strTag] = oGPSTags[strTag];
    }
  }

  return oTags;
}


EXIF.getData = function(oImg, fncCallback)
{
  if (!oImg.complete) return false;
  if (!imageHasData(oImg)) {
    getImageData(oImg, fncCallback);
  } else {
    if (fncCallback) fncCallback();
  }
  return true;
}

EXIF.getTag = function(oImg, strTag)
{
  if (!imageHasData(oImg)) return;
  return oImg.exifdata[strTag];
}

EXIF.pretty = function(oImg)
{
  if (!imageHasData(oImg)) return "";
  var oData = oImg.exifdata;
  var strPretty = "";
  for (var a in oData) {
    if (oData.hasOwnProperty(a)) {
      if (typeof oData[a] == "object") {
        strPretty += a + " : [" + oData[a].length + " values]\r\n";
      } else {
        strPretty += a + " : " + oData[a] + "\r\n";
      }
    }
  }
  return strPretty;
}

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

function loadAllImages()
{
  var aImages = document.getElementsByTagName("img");
  for (var i=0;i<aImages.length;i++) {
    if (aImages[i].getAttribute("exif") == "true") {
      if (!aImages[i].complete) {
        addEvent(aImages[i], "load",
          function() {
            EXIF.getData(this);
          }
        );
      } else {
        EXIF.getData(aImages[i]);
      }
    }
  }
}

addEvent(window, "load", loadAllImages);

})();