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vue2.0でカメラを呼び出す手順を詳しく解説

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リリース: 2018-05-15 10:34:10
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今回はvue2.0でカメラを呼び出す手順を詳しく説明します。vue2.0を使用してカメラを呼び出す際の注意点は何ですか?実際の事例を見てみましょう。

github でデモのリンクをダウンロードできます

vue コンポーネント コード

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<template>

 <p>

  <p style="padding:20px;">

   <p class="show">

    <p class="picture" :style="&#39;backgroundImage:url(&#39;+headerImage+&#39;)&#39;"></p>

   </p>

   <p style="margin-top:20px;">

    <input type="file" id="upload" accept="image/jpg" @change="upload">

    <label for="upload"></label>

   </p>

  </p>

 </p>

</template>

<script>

import {Exif} from &#39;./exif.js&#39;

export default {

 data () {

  return {

   headerImage:&#39;&#39;,picValue:&#39;&#39;

  }

 },

 mounted () {

 },

 methods: {

  upload (e) {

   let files = e.target.files || e.dataTransfer.files;

   if (!files.length) return;

   this.picValue = files[0];

   this.imgPreview(this.picValue);

   console.log(this.picValue)

  },

  imgPreview (file) {

   let self = this;

   let Orientation;

   //去获取拍照时的信息,解决拍出来的照片旋转问题

    Exif.getData(file, function(){

      Orientation = Exif.getTag(this, &#39;Orientation&#39;);

    });

   // 看支持不支持FileReader

   if (!file || !window.FileReader) return;

   if (/^image/.test(file.type)) {

     // 创建一个reader

     let reader = new FileReader();

     // 将图片2将转成 base64 格式

     reader.readAsDataURL(file);

     // 读取成功后的回调

     reader.onloadend = function () {

      let result = this.result;

      let img = new Image();

      img.src = result;

      //判断图片是否大于100K,是就直接上传,反之压缩图片

      if (this.result.length <= (100 * 1024)) {

       self.headerImage = this.result;

       self.postImg();

      }else {

       img.onload = function () {

        let data = self.compress(img,Orientation);

        self.headerImage = data;

        self.postImg();

       }

      }

     }

    }

   },

   postImg () {

    //这里写接口

   },

   rotateImg (img, direction,canvas) {

    //最小与最大旋转方向,图片旋转4次后回到原方向

    const min_step = 0;

    const max_step = 3;

    if (img == null)return;

    //img的高度和宽度不能在img元素隐藏后获取,否则会出错

    let height = img.height;

    let width = img.width;

    let step = 2;

    if (step == null) {

      step = min_step;

    }

    if (direction == &#39;right&#39;) {

      step++;

      //旋转到原位置,即超过最大值

      step > max_step && (step = min_step);

    } else {

      step--;

      step < min_step && (step = max_step);

    }

    //旋转角度以弧度值为参数

    let degree = step * 90 * Math.PI / 180;

    let ctx = canvas.getContext(&#39;2d&#39;);

    switch (step) {

     case 0:

       canvas.width = width;

       canvas.height = height;

       ctx.drawImage(img, 0, 0);

       break;

     case 1:

       canvas.width = height;

       canvas.height = width;

       ctx.rotate(degree);

       ctx.drawImage(img, 0, -height);

       break;

     case 2:

       canvas.width = width;

       canvas.height = height;

       ctx.rotate(degree);

       ctx.drawImage(img, -width, -height);

       break;

     case 3:

       canvas.width = height;

       canvas.height = width;

       ctx.rotate(degree);

       ctx.drawImage(img, -width, 0);

       break;

    }

  },

  compress(img,Orientation) {

   let canvas = document.createElement("canvas");

   let ctx = canvas.getContext(&#39;2d&#39;);

    //瓦片canvas

   let tCanvas = document.createElement("canvas");

   let tctx = tCanvas.getContext("2d");

   let initSize = img.src.length;

   let width = img.width;

   let height = img.height;

   //如果图片大于四百万像素,计算压缩比并将大小压至400万以下

   let ratio;

   if ((ratio = width * height / 4000000) > 1) {

    console.log("大于400万像素")

    ratio = Math.sqrt(ratio);

    width /= ratio;

    height /= ratio;

   } else {

    ratio = 1;

   }

   canvas.width = width;

   canvas.height = height;

 //    铺底色

   ctx.fillStyle = "#fff";

   ctx.fillRect(0, 0, canvas.width, canvas.height);

   //如果图片像素大于100万则使用瓦片绘制

   let count;

   if ((count = width * height / 1000000) > 1) {

    console.log("超过100W像素");

    count = ~~(Math.sqrt(count) + 1); //计算要分成多少块瓦片

 //      计算每块瓦片的宽和高

    let nw = ~~(width / count);

    let nh = ~~(height / count);

    tCanvas.width = nw;

    tCanvas.height = nh;

    for (let i = 0; i < count; i++) {

     for (let j = 0; j < count; j++) {

      tctx.drawImage(img, i * nw * ratio, j * nh * ratio, nw * ratio, nh * ratio, 0, 0, nw, nh);

      ctx.drawImage(tCanvas, i * nw, j * nh, nw, nh);

     }

    }

   } else {

    ctx.drawImage(img, 0, 0, width, height);

   }

   //修复ios上传图片的时候 被旋转的问题

   if(Orientation != "" && Orientation != 1){

    switch(Orientation){

     case 6://需要顺时针(向左)90度旋转

       this.rotateImg(img,&#39;left&#39;,canvas);

       break;

     case 8://需要逆时针(向右)90度旋转

       this.rotateImg(img,&#39;right&#39;,canvas);

       break;

     case 3://需要180度旋转

       this.rotateImg(img,&#39;right&#39;,canvas);//转两次

       this.rotateImg(img,&#39;right&#39;,canvas);

       break;

    }

   }

   //进行最小压缩

   let ndata = canvas.toDataURL(&#39;image/jpeg&#39;, 0.1);

   console.log(&#39;压缩前:&#39; + initSize);

   console.log(&#39;压缩后:&#39; + ndata.length);

   console.log(&#39;压缩率:&#39; + ~~(100 * (initSize - ndata.length) / initSize) + "%");

   tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;

   return ndata;

  },

 }

}

</script>

<style>

*{

 margin: 0;

 padding: 0;

}

.show {

 width: 100px;

 height: 100px;

 overflow: hidden;

 position: relative;

 border-radius: 50%;

 border: 1px solid #d5d5d5;

}

.picture {

 width: 100%;

 height: 100%;

 overflow: hidden;

 background-position: center center;

 background-repeat: no-repeat;

 background-size: cover;

}

</style>

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引用された exif.js コード

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(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 !== &#39;undefined&#39;) {

    if (typeof module !== &#39;undefined&#39; && 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"

  };

  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] || &#39;&#39;; // e.g. &#39;data:image/jpeg;base64,...&#39; => &#39;image/jpeg&#39;

    base64 = base64.replace(/^data\:([^\;]+)\;base64,/gmi, &#39;&#39;);

    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);

      var iptcdata = findIPTCinJPEG(binFile);

      img.exifdata = data || {};

      img.iptcdata = iptcdata || {};

      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 (window.FileReader && (img instanceof window.Blob || img instanceof window.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&#39;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 : &#39;caption&#39;,

    0x6E : &#39;credit&#39;,

    0x19 : &#39;keywords&#39;,

    0x37 : &#39;dateCreated&#39;,

    0x50 : &#39;byline&#39;,

    0x55 : &#39;bylineTitle&#39;,

    0x7A : &#39;captionWriter&#39;,

    0x69 : &#39;headline&#39;,

    0x74 : &#39;copyright&#39;,

    0x0F : &#39;category&#39;

  };

  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;

        }

    }

  }

  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];

      }

    }

    return tags;

  }

  EXIF.getData = function(img, callback) {

    if ((img instanceof Image || img instanceof 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.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.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 === &#39;function&#39; && define.amd) {

    define(&#39;exif-js&#39;, [], function() {

      return EXIF;

    });

  }

}.call(this));

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