Vue2.0實現調用攝像頭進行拍照功能 exif.js實現圖片上傳功能

<template>
 <div>
 <div style="padding:20px;">
 <div class="show">
 <div class="picture" :style="'backgroundImage:url('+headerImage+')'"></div>
 </div>
 <div style="margin-top:20px;">
 <input type="file" id="upload" accept="image/jpg" @change="upload">
 <label for="upload"></label>
 </div>
 </div>
 </div>
</template>

<script>
import {Exif} from './exif.js'

export default {
 data () {
 return {
 headerImage:'',picValue:''
 }
 },
 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;
 //去獲取拍照時的信息，解決拍出來的照片旋轉問題
 Exif.getData(file, function(){
 Orientation = Exif.getTag(this, 'Orientation');
 });
 // 看支持不支持FileReader 
 if (!file || !window.FileReader) return;

 if (/^image/.test(file.type)) {
 // 創建一個reader
 let reader = new FileReader();
 // 將圖片2將轉成 base64 格式
 reader.readAsDataURL(file);
 // 讀取成功后的回調
 reader.onloadend = function () {
 let result = this.result;
 let img = new Image();
 img.src = result;
 //判斷圖片是否大于100K,是就直接上傳，反之壓縮圖片
 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 () {
 //這里寫接口
 },
 rotateImg (img, direction,canvas) {
 //最小與最大旋轉方向，圖片旋轉4次后回到原方向
 const min_step = 0;
 const max_step = 3;
 if (img == null)return;
 //img的高度和寬度不能在img元素隱藏后獲取，否則會出錯
 let height = img.height;
 let width = img.width;
 let step = 2;
 if (step == null) {
 step = min_step;
 }
 if (direction == 'right') {
 step++;
 //旋轉到原位置，即超過最大值
 step > max_step && (step = min_step);
 } else {
 step--;
 step < min_step && (step = max_step);
 }
 //旋轉角度以弧度值為參數
 let degree = step * 90 * Math.PI / 180;
 let ctx = canvas.getContext('2d');
 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('2d');
 //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;
 //如果圖片大于四百萬像素，計算壓縮比并將大小壓至400萬以下
 let ratio;
 if ((ratio = width * height / 4000000) > 1) {
 console.log("大于400萬像素")
 ratio = Math.sqrt(ratio);
 width /= ratio;
 height /= ratio;
 } else {
 ratio = 1;
 }
 canvas.width = width;
 canvas.height = height;
 // 鋪底色
 ctx.fillStyle = "#fff";
 ctx.fillRect(0, 0, canvas.width, canvas.height);
 //如果圖片像素大于100萬則使用瓦片繪制
 let count;
 if ((count = width * height / 1000000) > 1) {
 console.log("超過100W像素");
 count = ~~(Math.sqrt(count) + 1); //計算要分成多少塊瓦片
 // 計算每塊瓦片的寬和高
 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);
 }
 //修復ios上傳圖片的時候 被旋轉的問題
 if(Orientation != "" && Orientation != 1){
 switch(Orientation){
 case 6://需要順時針（向左）90度旋轉
 this.rotateImg(img,'left',canvas);
 break;
 case 8://需要逆時針（向右）90度旋轉
 this.rotateImg(img,'right',canvas);
 break;
 case 3://需要180度旋轉
 this.rotateImg(img,'right',canvas);//轉兩次
 this.rotateImg(img,'right',canvas);
 break;
 }
 }
 //進行最小壓縮
 let ndata = canvas.toDataURL('image/jpeg', 0.1);
 console.log('壓縮前：' + initSize);
 console.log('壓縮后：' + ndata.length);
 console.log('壓縮率：' + ~~(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>

(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"
 };

 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);
 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'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;
 }
 }
 }

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