本文实例为大家分享了Vue2.0实现调用摄像头进行拍照功能的具体代码，以及图片上传功能引用exif.js，供大家参考，具体内容如下
可以在github 上下载demo链接
vue组件代码
<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, \'Orientation\');
});
// 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 == \'right\') {
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(\'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,\'left\',canvas);
break;
case 8://需要逆时针（向右）90度旋转
this.rotateImg(img,\'right\',canvas);
break;
case 3://需要180度旋转
this.rotateImg(img,\'right\',canvas);//转两次
this.rotateImg(img,\'right\',canvas);
break;
}
}
//进行最小压缩
let ndata = canvas.toDataURL(\'image/jpeg\', 0.1);
console.log(\'压缩前：\' + initSize);
console.log(\'压缩后：\' + ndata.length);
console.log(\'压缩率：\' + ~~(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>
引用的exif.js代码
(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));
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
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