1、问题：在html5中利用canvas对上传图片压缩的时候，ios手机竖着拍照时，图片会旋转90°，其他情况正常。
2、解决方法：获取拍照角度，对Ios竖着拍的照片进行角度处理
3、利用exif.js获取到照片的拍摄信息，这里主要用到Orientation，这个属性
Orientation 旋转角度
1 0°
3 180°
6 90°
8 270°
旋转方向都为顺时针
下面介绍图片的压缩和对ios拍照问题的解决案例
先要引入exif.js文件和jquery.js文件
<script src="http://i.gtimg.cn/qzone/biz/gdt/lib/jquery/jquery-2.1.4.js?max_age=31536000"></script>
<script type="text/javascript" src='js/exif.js?v=b5d2a25070'></script>4、html
<input type="file" id="upLoad" name="image">
<!-- 显示上传之后的图片 -->
<div id='previewImg'>
<img id='viewImg'/>
</div>5、js
$('#upLoad').on('change',function(){
$('#loding').css('display','block');
var filePath = $(this).val(),//获取到input的value，里面是文件的路径
fileFormat = filePath.substring(filePath.lastIndexOf(".")).toLowerCase(),// src = '',//转成可以在本地预览的blob格式
imgBase64 = '',//存储图片的imgBase64
fileObj = document.getElementById('upLoad').files[0]; //上传文件的对象,要这样写才行，用jquery写法获取不到对象
uploadAddress = globalConfig.pre_api_url + '/wxwall_api/msg/pa_upload_img.php',data = null;
// 检查是否是图片
if( !fileFormat.match(/.png|.jpg|.jpeg/) ) {
error_prompt_alert('上传错误,文件格式必须为：png/jpg/jpeg');
$('#loding').css('display','none');
return;
}
// 对图片进行压缩
compress(fileObj,function(imgBase64){
imgBase64 = imgBase64;
// 对图片压缩成功之后，在定义上传参数，和请求；放在compress（）外面的话，则先执行request（）请求，此时imgBase64还未赋值赋值
// 定义上传的参数
data = {
'imgBase64':imgBase64,'openid':openid
};
// 发送上传图片的请求
request(uploadAddress,data,function(res){
console.log(res.msg);
$('#loding').css('display','none');
remote_pa_img_path = res.data.remote_pa_img_path;
$('#viewImg').attr('src',imgBase64); //显示预览图片
$('#imgBox').addClass('imgBox2');
},'none');
});
});
});
// 不对图片进行压缩，直接转成base64
function directTurnIntoBase64(fileObj,callback){
var r = new FileReader();
// 转成base64
r.onload = function(){
//变成字符串
imgBase64 = r.result;
console.log(imgBase64);
callback(imgBase64);
}
r.readAsDataURL(fileObj); //转成Base64格式
}
// 对图片进行压缩
function compress(fileObj,callback) {
if ( typeof (FileReader) === 'undefined') {
console.log("当前浏览器内核不支持base64图标压缩");
//调用上传方式不压缩
directTurnIntoBase64(fileObj,callback);
} else {
try {
var Orientation=null,reader = new FileReader();
// reader.readAsDataURL(fileObj);
//获取图片Orientation参数
EXIF.getData(fileObj,function() {
Orientation = EXIF.getTag(this,'Orientation');
});
reader.onload = function (e) {
var image = $('<img/>');
image.attr('src',e.target.result);
image.load(function(){
var data='',canvas = document.createElement('canvas'),context = canvas.getContext('2d'),imageWidth = this.width,imageHeight = this.height;
//压缩图片
if(imageWidth > 1000 || imageHeight > 1000) {
//等比例压缩，不失真，不裁剪
if( imageWidth > imageHeight){
imageWidth = 1000;
imageHeight = imageWidth*imageHeight/this.width;
}else{
imageHeight = 1000;
imageWidth = imageHeight*imageWidth/this.height;
}
}
//旋转到正常角度,位置偏移
var angle = 0;
var x =0,y=0,w=imageWidth,h=imageHeight; //canvas画布
// 定义画布的大小
canvas.width = imageWidth;
canvas.height = imageHeight;
context.drawImage(this,x,y,imageWidth,imageHeight);
/*
Orientation:
3:ios手机底部在左边，拍出来的横图是倒置的，需要旋转180度
6:ios手机底部朝下，拍出来的照片是头在右边，需要逆时针旋转90度
*/
switch(Orientation){
case 3:
rotateImg(this,'half',canvas);//转两次
break;
case 6:
rotateImg(this,'left',canvas);
break;
case 8:
rotateImg(this,'right',canvas);
break;
default:
break;
}
// context.rotate(angle);
// 画图
// context.drawImage(this,imageHeight);
data = canvas.toDataURL('image/jpeg'); //转成bae64编码
callback(data);
});
};
reader.readAsDataURL(fileObj);
} catch(e) {
console.log("压缩失败!");
//调用直接上传方式 不压缩
directTurnIntoBase64(fileObj,callback);
}
}
}
//对图片旋转处理 added by lzk
function rotateImg(img,direction,canvas) {
//alert(img);
//最小与最大旋转方向，图片旋转4次后回到原方向
var min_step = 0;
var max_step = 4;
//var img = document.getElementById(pid);
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
var height = img.height;
var width = img.width;
//var step = img.getAttribute('step');
var 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 if(direction == 'half'){
} else{
step--;
step < min_step && (step = max_step);
}
//img.setAttribute('step',step);
/*var canvas = document.getElementById('pic_' + pid);
if (canvas == null) {
img.style.display = 'none';
canvas = document.createElement('canvas');
canvas.setAttribute('id','pic_' + pid);
img.parentNode.appendChild(canvas);
} */
//旋转角度以弧度值为参数
var degree = step * 90 * Math.PI / 180;
var ctx = canvas.getContext('2d');
switch (step) {
case 0:
canvas.width = width;
canvas.height = height;
ctx.drawImage(img,0);
break;
case 1:
canvas.width = height;
canvas.height = width;
ctx.rotate(degree);
ctx.drawImage(img,-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,0);
break;
}
} 6、exif.js代码如下：
(function() {
var debug = false;
var root = this;
var EXIF = function(obj) {
if (obj instanceof EXIF) return obj;
if (!(this instanceof EXIF)) return new EXIF(obj);
this.EXIFwrapped = obj;
};
if (typeof exports !== 'undefined') {
if (typeof module !== 'undefined' && module.exports) {
exports = module.exports = EXIF;
}
exports.EXIF = EXIF;
} else {
root.EXIF = EXIF;
}
var ExifTags = EXIF.Tags = {
// version tags
0x9000 : "ExifVersion",// EXIF version
0xA000 : "FlashpixVersion",// Flashpix format version
// colorspace tags
0xA001 : "ColorSpace",// Color space information tag
// image configuration
0xA002 : "PixelXDimension",// Valid width of meaningful image
0xA003 : "PixelYDimension",// Valid height of meaningful image
0x9101 : "ComponentsConfiguration",// Information about channels
0x9102 : "CompressedBitsPerPixel",// Compressed bits per pixel
// user information
0x927C : "MakerNote",// Any desired information written by the manufacturer
0x9286 : "UserComment",// Comments by user
// related file
0xA004 : "RelatedSoundFile",// Name of related sound file
// date and time
0x9003 : "DateTimeOriginal",// Date and time when the original image was generated
0x9004 : "DateTimeDigitized",// Date and time when the image was stored digitally
0x9290 : "SubsecTime",// Fractions of seconds for DateTime
0x9291 : "SubsecTimeOriginal",// Fractions of seconds for DateTimeOriginal
0x9292 : "SubsecTimeDigitized",// Fractions of seconds for DateTimeDigitized
// picture-taking conditions
0x829A : "ExposureTime",// Exposure time (in seconds)
0x829D : "FNumber",// F number
0x8822 : "ExposureProgram",// Exposure program
0x8824 : "SpectralSensitivity",// Spectral sensitivity
0x8827 : "ISOSpeedRatings",// ISO speed rating
0x8828 : "OECF",// Optoelectric conversion factor
0x9201 : "ShutterSpeedValue",// Shutter speed
0x9202 : "ApertureValue",// Lens aperture
0x9203 : "BrightnessValue",// Value of brightness
0x9204 : "ExposureBias",// Exposure bias
0x9205 : "MaxApertureValue",// Smallest F number of lens
0x9206 : "SubjectDistance",// Distance to subject in meters
0x9207 : "MeteringMode",// Metering mode
0x9208 : "LightSource",// Kind of light source
0x9209 : "Flash",// Flash status
0x9214 : "SubjectArea",// Location and area of main subject
0x920A : "FocalLength",// Focal length of the lens in mm
0xA20B : "FlashEnergy",// Strobe energy in BCPS
0xA20C : "SpatialFrequencyResponse",//
0xA20E : "FocalPlaneXResolution",// Number of pixels in width direction per FocalPlaneResolutionUnit
0xA20F : "FocalPlaneYResolution",// Number of pixels in height direction per FocalPlaneResolutionUnit
0xA210 : "FocalPlaneResolutionUnit",// Unit for measuring FocalPlaneXResolution and FocalPlaneYResolution
0xA214 : "SubjectLocation",// Location of subject in image
0xA215 : "ExposureIndex",// Exposure index selected on camera
0xA217 : "SensingMethod",// Image sensor type
0xA300 : "FileSource",// Image source (3 == DSC)
0xA301 : "SceneType",// Scene type (1 == directly photographed)
0xA302 : "CFAPattern",// Color filter array geometric pattern
0xA401 : "CustomRendered",// Special processing
0xA402 : "ExposureMode",// Exposure mode
0xA403 : "WhiteBalance",// 1 = auto white balance,2 = manual
0xA404 : "DigitalZoomRation",// Digital zoom ratio
0xA405 : "FocalLengthIn35mmFilm",// Equivalent foacl length assuming 35mm film camera (in mm)
0xA406 : "SceneCaptureType",// Type of scene
0xA407 : "GainControl",// Degree of overall image gain adjustment
0xA408 : "Contrast",// Direction of contrast processing applied by camera
0xA409 : "Saturation",// Direction of saturation processing applied by camera
0xA40A : "Sharpness",// Direction of sharpness processing applied by camera
0xA40B : "DeviceSettingDescription",//
0xA40C : "SubjectDistanceRange",// Distance to subject
// other tags
0xA005 : "InteroperabilityIFDPointer",0xA420 : "ImageUniqueID" // Identifier assigned uniquely to each image
};
var TiffTags = EXIF.TiffTags = {
0x0100 : "ImageWidth",0x0101 : "ImageHeight",0x8769 : "ExifIFDPointer",0x8825 : "GPSInfoIFDPointer",0xA005 : "InteroperabilityIFDPointer",0x0102 : "BitsPerSample",0x0103 : "Compression",0x0106 : "PhotometricInterpretation",0x0112 : "Orientation",0x0115 : "SamplesPerPixel",0x011C : "PlanarConfiguration",0x0212 : "YCbCrSubSampling",0x0213 : "YCbCrPositioning",0x011A : "XResolution",0x011B : "YResolution",0x0128 : "ResolutionUnit",0x0111 : "StripOffsets",0x0116 : "RowsPerStrip",0x0117 : "StripByteCounts",0x0201 : "JPEGInterchangeFormat",0x0202 : "JPEGInterchangeFormatLength",0x012D : "TransferFunction",0x013E : "WhitePoint",0x013F : "PrimaryChromaticities",0x0211 : "YCbCrCoefficients",0x0214 : "ReferenceBlackWhite",0x0132 : "DateTime",0x010E : "ImageDescription",0x010F : "Make",0x0110 : "Model",0x0131 : "Software",0x013B : "Artist",0x8298 : "Copyright"
};
var GPSTags = EXIF.GPSTags = {
0x0000 : "GPSVersionID",0x0001 : "GPSLatitudeRef",0x0002 : "GPSLatitude",0x0003 : "GPSLongitudeRef",0x0004 : "GPSLongitude",0x0005 : "GPSAltitudeRef",0x0006 : "GPSAltitude",0x0007 : "GPSTimeStamp",0x0008 : "GPSSatellites",0x0009 : "GPSStatus",0x000A : "GPSMeasureMode",0x000B : "GPSDOP",0x000C : "GPSSpeedRef",0x000D : "GPSSpeed",0x000E : "GPSTrackRef",0x000F : "GPSTrack",0x0010 : "GPSImgDirectionRef",0x0011 : "GPSImgDirection",0x0012 : "GPSMapDatum",0x0013 : "GPSDestLatitudeRef",0x0014 : "GPSDestLatitude",0x0015 : "GPSDestLongitudeRef",0x0016 : "GPSDestLongitude",0x0017 : "GPSDestBearingRef",0x0018 : "GPSDestBearing",0x0019 : "GPSDestDistanceRef",0x001A : "GPSDestDistance",0x001B : "GPSProcessingMethod",0x001C : "GPSAreaInformation",0x001D : "GPSDateStamp",0x001E : "GPSDifferential"
};
// EXIF 2.3 Spec
var IFD1Tags = EXIF.IFD1Tags = {
0x0100: "ImageWidth",0x0101: "ImageHeight",0x0102: "BitsPerSample",0x0103: "Compression",0x0106: "PhotometricInterpretation",0x0111: "StripOffsets",0x0112: "Orientation",0x0115: "SamplesPerPixel",0x0116: "RowsPerStrip",0x0117: "StripByteCounts",0x011A: "XResolution",0x011B: "YResolution",0x011C: "PlanarConfiguration",0x0128: "ResolutionUnit",0x0201: "JpegIFOffset",// When image format is JPEG,this value show offset to JPEG data stored.(aka "ThumbnailOffset" or "JPEGInterchangeFormat")
0x0202: "JpegIFByteCount",this value shows data size of JPEG image (aka "ThumbnailLength" or "JPEGInterchangeFormatLength")
0x0211: "YCbCrCoefficients",0x0212: "YCbCrSubSampling",0x0213: "YCbCrPositioning",0x0214: "ReferenceBlackWhite"
};
var StringValues = EXIF.StringValues = {
ExposureProgram : {
0 : "Not defined",1 : "Manual",2 : "Normal program",3 : "Aperture priority",4 : "Shutter priority",5 : "Creative program",6 : "Action program",7 : "Portrait mode",8 : "Landscape mode"
},MeteringMode : {
0 : "Unknown",1 : "Average",2 : "CenterWeightedAverage",3 : "Spot",4 : "MultiSpot",5 : "Pattern",6 : "Partial",255 : "Other"
},LightSource : {
0 : "Unknown",1 : "Daylight",2 : "Fluorescent",3 : "Tungsten (incandescent light)",4 : "Flash",9 : "Fine weather",10 : "Cloudy weather",11 : "Shade",12 : "Daylight fluorescent (D 5700 - 7100K)",13 : "Day white fluorescent (N 4600 - 5400K)",14 : "Cool white fluorescent (W 3900 - 4500K)",15 : "White fluorescent (WW 3200 - 3700K)",17 : "Standard light A",18 : "Standard light B",19 : "Standard light C",20 : "D55",21 : "D65",22 : "D75",23 : "D50",24 : "ISO studio tungsten",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,return light detected",0x0010 : "Flash did not fire,0x0018 : "Flash did not fire,auto mode",0x0019 : "Flash fired,0x001D : "Flash fired,auto mode,0x001F : "Flash fired,0x0020 : "No flash function",0x0041 : "Flash fired,red-eye reduction mode",0x0045 : "Flash fired,red-eye reduction mode,0x0047 : "Flash fired,0x0049 : "Flash fired,0x004D : "Flash fired,0x004F : "Flash fired,0x0059 : "Flash fired,0x005D : "Flash fired,return light not detected,0x005F : "Flash fired,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",SubjectDistanceRange : {
0 : "Unknown",1 : "Macro",2 : "Close view",3 : "Distant view"
},FileSource : {
3 : "DSC"
},Components : {
0 : "",1 : "Y",2 : "Cb",3 : "Cr",4 : "R",5 : "G",6 : "B"
}
};
function addEvent(element,event,handler) {
if (element.addEventListener) {
element.addEventListener(event,handler,false);
} else if (element.attachEvent) {
element.attachEvent("on" + event,handler);
}
}
function imageHasData(img) {
return !!(img.exifdata);
}
function base64ToArrayBuffer(base64,contentType) {
contentType = contentType || base64.match(/^data\:([^\;]+)\;base64,/mi)[1] || ''; // e.g. 'data:image/jpeg;base64,...' => 'image/jpeg'
base64 = base64.replace(/^data\:([^\;]+)\;base64,/gmi,'');
var binary = atob(base64);
var len = binary.length;
var buffer = new ArrayBuffer(len);
var view = new Uint8Array(buffer);
for (var i = 0; i < len; i++) {
view[i] = binary.charCodeAt(i);
}
return buffer;
}
function objectURLToBlob(url,callback) {
var http = new XMLHttpRequest();
http.open("GET",url,true);
http.responseType = "blob";
http.onload = function(e) {
if (this.status == 200 || this.status === 0) {
callback(this.response);
}
};
http.send();
}
function getImageData(img,callback) {
function handleBinaryFile(binFile) {
var data = findEXIFinJPEG(binFile);
img.exifdata = data || {};
var iptcdata = findIPTCinJPEG(binFile);
img.iptcdata = iptcdata || {};
if (EXIF.isXmpEnabled) {
var xmpdata= findXMPinJPEG(binFile);
img.xmpdata = xmpdata || {};
}
if (callback) {
callback.call(img);
}
}
if (img.src) {
if (/^data\:/i.test(img.src)) { // Data URI
var arrayBuffer = base64ToArrayBuffer(img.src);
handleBinaryFile(arrayBuffer);
} else if (/^blob\:/i.test(img.src)) { // Object URL
var fileReader = new FileReader();
fileReader.onload = function(e) {
handleBinaryFile(e.target.result);
};
objectURLToBlob(img.src,function (blob) {
fileReader.readAsArrayBuffer(blob);
});
} else {
var http = new XMLHttpRequest();
http.onload = function() {
if (this.status == 200 || this.status === 0) {
handleBinaryFile(http.response);
} else {
throw "Could not load image";
}
http = null;
};
http.open("GET",img.src,true);
http.responseType = "arraybuffer";
http.send(null);
}
} else if (self.FileReader && (img instanceof self.Blob || img instanceof self.File)) {
var fileReader = new FileReader();
fileReader.onload = function(e) {
if (debug) console.log("Got file of length " + e.target.result.byteLength);
handleBinaryFile(e.target.result);
};
fileReader.readAsArrayBuffer(img);
}
}
function findEXIFinJPEG(file) {
var dataView = new DataView(file);
if (debug) console.log("Got file of length " + file.byteLength);
if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
if (debug) console.log("Not a valid JPEG");
return false; // not a valid jpeg
}
var offset = 2,length = file.byteLength,marker;
while (offset < length) {
if (dataView.getUint8(offset) != 0xFF) {
if (debug) console.log("Not a valid marker at offset " + offset + ",found: " + dataView.getUint8(offset));
return false; // not a valid marker,something is wrong
}
marker = dataView.getUint8(offset + 1);
if (debug) console.log(marker);
// we could implement handling for other markers here,// but we're only looking for 0xFFE1 for EXIF data
if (marker == 225) {
if (debug) console.log("Found 0xFFE1 marker");
return readEXIFData(dataView,offset + 4,dataView.getUint16(offset + 2) - 2);
// offset += 2 + file.getShortAt(offset+2,true);
} else {
offset += 2 + dataView.getUint16(offset+2);
}
}
}
function findIPTCinJPEG(file) {
var dataView = new DataView(file);
if (debug) console.log("Got file of length " + file.byteLength);
if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
if (debug) console.log("Not a valid JPEG");
return false; // not a valid jpeg
}
var offset = 2,length = file.byteLength;
var isFieldSegmentStart = function(dataView,offset){
return (
dataView.getUint8(offset) === 0x38 &&
dataView.getUint8(offset+1) === 0x42 &&
dataView.getUint8(offset+2) === 0x49 &&
dataView.getUint8(offset+3) === 0x4D &&
dataView.getUint8(offset+4) === 0x04 &&
dataView.getUint8(offset+5) === 0x04
);
};
while (offset < length) {
if ( isFieldSegmentStart(dataView,offset )){
// Get the length of the name header (which is padded to an even number of bytes)
var nameHeaderLength = dataView.getUint8(offset+7);
if(nameHeaderLength % 2 !== 0) nameHeaderLength += 1;
// Check for pre photoshop 6 format
if(nameHeaderLength === 0) {
// Always 4
nameHeaderLength = 4;
}
var startOffset = offset + 8 + nameHeaderLength;
var sectionLength = dataView.getUint16(offset + 6 + nameHeaderLength);
return readIPTCData(file,startOffset,sectionLength);
break;
}
// Not the marker,continue searching
offset++;
}
}
var IptcFieldMap = {
0x78 : 'caption',0x6E : 'credit',0x19 : 'keywords',0x37 : 'dateCreated',0x50 : 'byline',0x55 : 'bylineTitle',0x7A : 'captionWriter',0x69 : 'headline',0x74 : 'copyright',0x0F : 'category'
};
function readIPTCData(file,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,bigEnd);
}
return tags;
}
function readTagValue(file,bigEnd) {
var type = file.getUint16(entryOffset+2,numValues = file.getUint32(entryOffset+4,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,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,second is denominator
if (numValues == 1) {
return file.getInt32(valueOffset,!bigEnd) / file.getInt32(valueOffset+4,!bigEnd);
} else {
vals = [];
for (n=0;n<numValues;n++) {
vals[n] = file.getInt32(valueOffset + 8*n,!bigEnd) / file.getInt32(valueOffset+4 + 8*n,!bigEnd);
}
return vals;
}
}
}
/**
* Given an IFD (Image File Directory) start offset
* returns an offset to next IFD or 0 if it's the last IFD.
*/
function getNextIFDOffset(dataView,bigEnd){
//the first 2bytes means the number of directory entries contains in this IFD
var entries = dataView.getUint16(dirStart,!bigEnd);
// After last directory entry,there is a 4bytes of data,// it means an offset to next IFD.
// If its value is '0x00000000',it means this is the last IFD and there is no linked IFD.
return dataView.getUint32(dirStart + 2 + entries * 12,!bigEnd); // each entry is 12 bytes long
}
function readThumbnailImage(dataView,firstIFDOffset,bigEnd){
// get the IFD1 offset
var IFD1OffsetPointer = getNextIFDOffset(dataView,tiffStart+firstIFDOffset,bigEnd);
if (!IFD1OffsetPointer) {
// console.log('******** IFD1Offset is empty,image thumb not found ********');
return {};
}
else if (IFD1OffsetPointer > dataView.byteLength) { // this should not happen
// console.log('******** IFD1Offset is outside the bounds of the DataView ********');
return {};
}
// console.log('******* thumbnail IFD offset (IFD1) is: %s',IFD1OffsetPointer);
var thumbTags = readTags(dataView,tiffStart + IFD1OffsetPointer,IFD1Tags,bigEnd)
// EXIF 2.3 specification for JPEG format thumbnail
// If the value of Compression(0x0103) Tag in IFD1 is '6',thumbnail image format is JPEG.
// Most of Exif image uses JPEG format for thumbnail. In that case,you can get offset of thumbnail
// by JpegIFOffset(0x0201) Tag in IFD1,size of thumbnail by JpegIFByteCount(0x0202) Tag.
// Data format is ordinary JPEG format,starts from 0xFFD8 and ends by 0xFFD9. It seems that
// JPEG format and 160x120pixels of size are recommended thumbnail format for Exif2.1 or later.
if (thumbTags['Compression']) {
// console.log('Thumbnail image found!');
switch (thumbTags['Compression']) {
case 6:
// console.log('Thumbnail image format is JPEG');
if (thumbTags.JpegIFOffset && thumbTags.JpegIFByteCount) {
// extract the thumbnail
var tOffset = tiffStart + thumbTags.JpegIFOffset;
var tLength = thumbTags.JpegIFByteCount;
thumbTags['blob'] = new Blob([new Uint8Array(dataView.buffer,tOffset,tLength)],{
type: 'image/jpeg'
});
}
break;
case 1:
console.log("Thumbnail image format is TIFF,which is not implemented.");
break;
default:
console.log("Unknown thumbnail image format '%s'",thumbTags['Compression']);
}
}
else if (thumbTags['PhotometricInterpretation'] == 2) {
console.log("Thumbnail image format is RGB,which is not implemented.");
}
return thumbTags;
}
function getStringFromDB(buffer,start,length) {
var outstr = "";
for (n = start; n < start+length; n++) {
outstr += String.fromCharCode(buffer.getUint8(n));
}
return outstr;
}
function readEXIFData(file,start) {
if (getStringFromDB(file,4) != "Exif") {
if (debug) console.log("Not valid EXIF data! " + getStringFromDB(file,4));
return false;
}
var bigEnd,tags,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 + 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 + tags.GPSInfoIFDPointer,GPSTags,bigEnd);
for (tag in gpsData) {
switch (tag) {
case "GPSVersionID" :
gpsData[tag] = gpsData[tag][0] +
"." + gpsData[tag][1] +
"." + gpsData[tag][2] +
"." + gpsData[tag][3];
break;
}
tags[tag] = gpsData[tag];
}
}
// extract thumbnail
tags['thumbnail'] = readThumbnailImage(file,bigEnd);
return tags;
}
function findXMPinJPEG(file) {
if (!('DOMParser' in self)) {
// console.warn('XML parsing not supported without DOMParser');
return;
}
var dataView = new DataView(file);
if (debug) console.log("Got file of length " + file.byteLength);
if ((dataView.getUint8(0) != 0xFF) || (dataView.getUint8(1) != 0xD8)) {
if (debug) console.log("Not a valid JPEG");
return false; // not a valid jpeg
}
var offset = 2,dom = new DOMParser();
while (offset < (length-4)) {
if (getStringFromDB(dataView,4) == "http") {
var startOffset = offset - 1;
var sectionLength = dataView.getUint16(offset - 2) - 1;
var xmpString = getStringFromDB(dataView,sectionLength)
var xmpEndIndex = xmpString.indexOf('xmpmeta>') + 8;
xmpString = xmpString.substring( xmpString.indexOf( '<x:xmpmeta' ),xmpEndIndex );
var indexOfXmp = xmpString.indexOf('x:xmpmeta') + 10
//Many custom written programs embed xmp/xml without any namespace. Following are some of them.
//Without these namespaces,XML is thought to be invalid by parsers
xmpString = xmpString.slice(0,indexOfXmp)
+ 'xmlns:Iptc4xmpCore="http://iptc.org/std/Iptc4xmpCore/1.0/xmlns/" '
+ 'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" '
+ 'xmlns:tiff="http://ns.adobe.com/tiff/1.0/" '
+ 'xmlns:plus="http://schemas.android.com/apk/lib/com.google.android.gms.plus" '
+ 'xmlns:ext="http://www.gettyimages.com/xsltExtension/1.0" '
+ 'xmlns:exif="http://ns.adobe.com/exif/1.0/" '
+ 'xmlns:stEvt="http://ns.adobe.com/xap/1.0/sType/ResourceEvent#" '
+ 'xmlns:stRef="http://ns.adobe.com/xap/1.0/sType/ResourceRef#" '
+ 'xmlns:crs="http://ns.adobe.com/camera-raw-settings/1.0/" '
+ 'xmlns:xapGImg="http://ns.adobe.com/xap/1.0/g/img/" '
+ 'xmlns:Iptc4xmpExt="http://iptc.org/std/Iptc4xmpExt/2008-02-29/" '
+ xmpString.slice(indexOfXmp)
var domDocument = dom.parseFromString( xmpString,'text/xml' );
return xml2Object(domDocument);
} else{
offset++;
}
}
}
function xml2json(xml) {
var json = {};
if (xml.nodeType == 1) { // element node
if (xml.attributes.length > 0) {
json['@attributes'] = {};
for (var j = 0; j < xml.attributes.length; j++) {
var attribute = xml.attributes.item(j);
json['@attributes'][attribute.nodeName] = attribute.nodeValue;
}
}
} else if (xml.nodeType == 3) { // text node
return xml.nodeValue;
}
// deal with children
if (xml.hasChildNodes()) {
for(var i = 0; i < xml.childNodes.length; i++) {
var child = xml.childNodes.item(i);
var nodeName = child.nodeName;
if (json[nodeName] == null) {
json[nodeName] = xml2json(child);
} else {
if (json[nodeName].push == null) {
var old = json[nodeName];
json[nodeName] = [];
json[nodeName].push(old);
}
json[nodeName].push(xml2json(child));
}
}
}
return json;
}
function xml2Object(xml) {
try {
var obj = {};
if (xml.children.length > 0) {
for (var i = 0; i < xml.children.length; i++) {
var item = xml.children.item(i);
var attributes = item.attributes;
for(var idx in attributes) {
var itemAtt = attributes[idx];
var dataKey = itemAtt.nodeName;
var dataValue = itemAtt.nodeValue;
if(dataKey !== undefined) {
obj[dataKey] = dataValue;
}
}
var nodeName = item.nodeName;
if (typeof (obj[nodeName]) == "undefined") {
obj[nodeName] = xml2json(item);
} else {
if (typeof (obj[nodeName].push) == "undefined") {
var old = obj[nodeName];
obj[nodeName] = [];
obj[nodeName].push(old);
}
obj[nodeName].push(xml2json(item));
}
}
} else {
obj = xml.textContent;
}
return obj;
} catch (e) {
console.log(e.message);
}
}
EXIF.enableXmp = function() {
EXIF.isXmpEnabled = true;
}
EXIF.disableXmp = function() {
EXIF.isXmpEnabled = false;
}
EXIF.getData = function(img,callback) {
if (((self.Image && img instanceof self.Image)
|| (self.HTMLImageElement && img instanceof self.HTMLImageElement))
&& !img.complete)
return false;
if (!imageHasData(img)) {
getImageData(img,callback);
} else {
if (callback) {
callback.call(img);
}
}
return true;
}
EXIF.getTag = function(img,tag) {
if (!imageHasData(img)) return;
return img.exifdata[tag];
}
EXIF.getIptcTag = function(img,tag) {
if (!imageHasData(img)) return;
return img.iptcdata[tag];
}
EXIF.getAllTags = function(img) {
if (!imageHasData(img)) return {};
var a,data = img.exifdata,tags = {};
for (a in data) {
if (data.hasOwnProperty(a)) {
tags[a] = data[a];
}
}
return tags;
}
EXIF.getAllIptcTags = function(img) {
if (!imageHasData(img)) return {};
var a,data = img.iptcdata,tags = {};
for (a in data) {
if (data.hasOwnProperty(a)) {
tags[a] = data[a];
}
}
return tags;
}
EXIF.pretty = function(img) {
if (!imageHasData(img)) return "";
var a,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));
js如何实现弹出form提交表单？（图文+视频）
js怎么获取复选框选中的值
js如何实现倒计时跳转页面
如何用js控制图片放大缩小