input type=“file”方式上传
在项目中，这里用到了input type="file"方式上传图片
在项目测试中发现，使用苹果手机点击input标签直接调用相机功能上传照片（从相册选择图片上传则正常），却发现后台接收到的图片被翻转了90度，而在安卓机测试却不会，最终解决的方法是：使用npm库的exif-js插件。
解决步骤如下：
step1安装插件：
cnpm install exif-js --save
step2在当前组件引用插件：
import Vue from "vue";
import EXIF from "exif-js";
Vue.use(EXIF); //全局申明
step3 获取change事件传递过来的图片（例如：this.$refs.foreheadCir.files[0]）
var Orientation = null;
if (file) {
if (navigator.userAgent.match(/Android/i)) {
console.log("正在上传,请稍后...");
var rFilter = /^(image\/jpeg|image\/png)$/i; // 检查图片格式
if (!rFilter.test(file.type)) {
//showMyTips("请选择jpeg、png格式的图片", false);
return;
}
console.log("2222"+Orientation);
if (/^image/.test(file.type)) {
// 创建一个reader
var reader = new FileReader();
// 将图片将转成 base64 格式
reader.readAsDataURL(file);
// 读取成功后的回调
reader.onloadend = function (e) {
/*var obj={};
obj["src"]=this.result;
self.upPhoto(index,obj["src"],areaId);//传给后台*/
var base64S = null;
var img = new Image,
width = 2048, //image resize
quality = 0.8, //image quality
canvas = document.createElement("canvas"),
drawer = canvas.getContext("2d");
img.src = this.result;
img.onload = function() {
canvas.width = width;
canvas.height = width * (img.height / img.width);
drawer.drawImage(img, 0, 0, canvas.width, canvas.height);
base64S = canvas.toDataURL("image/jpeg", quality);
console.log(img.src);
self.upPhoto(index,base64S,areaId);
}
}
}
}else{
console.log("正在上传,请稍后...");
var rFilter = /^(image\/jpeg|image\/png)$/i; // 检查图片格式
if (!rFilter.test(file.type)) {
//showMyTips("请选择jpeg、png格式的图片", false);
return;
}
// var URL = URL || webkitURL;
//获取照片方向角属性，用户旋转控制
EXIF.getData(file, function() {
// alert(EXIF.pretty(this));
EXIF.getAllTags(this);
//alert(EXIF.getTag(this, 'Orientation'));
Orientation = EXIF.getTag(this, 'Orientation');
//return;
});
var oReader = new FileReader();
oReader.onload = function(e) {
//var blob = URL.createObjectURL(file);
//_compress(blob, file, basePath);
var image = new Image();
image.src = e.target.result;
image.onload = function() {
var expectWidth = this.naturalWidth;
var expectHeight = this.naturalHeight;
/* if (this.naturalWidth > this.naturalHeight && this.naturalWidth > 800) {
expectWidth = 800;
expectHeight = expectWidth * this.naturalHeight / this.naturalWidth;
} else if (this.naturalHeight > this.naturalWidth && this.naturalHeight > 1200) {
expectHeight = 1200;
expectWidth = expectHeight * this.naturalWidth / this.naturalHeight;
}*/
var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
canvas.width = expectWidth;
canvas.height = expectHeight;
ctx.drawImage(this, 0, 0, expectWidth, expectHeight);
var base64 = null;
//修复ios
if (navigator.userAgent.match(/iphone/i)) {
console.log('iphone');
// alert("苹果");
//alert(expectWidth + ',' + expectHeight);
//如果方向角不为1，都需要进行旋转 added by lzk
if(Orientation != "" && Orientation != 1){
// alert('旋转处理');
switch(Orientation){
case 6://需要顺时针（向左）90度旋转
// alert('需要顺时针（向左）90度旋转');
self.rotateImg(this,'left',canvas);
break;
case 8://需要逆时针（向右）90度旋转
// alert('需要顺时针（向右）90度旋转');
self.rotateImg(this,'right',canvas);
break;
case 3://需要180度旋转
// alert('需要180度旋转');
/*self.rotateImg(this,'right',canvas);//转两次
self.rotateImg(this,'right',canvas);*/
self.rotateImg(this,'turntwo',canvas);
break;
}
}
/*var mpImg = new MegaPixImage(image);
mpImg.render(canvas, {
maxWidth: 800,
maxHeight: 1200,
quality: 0.8,
orientation: 8
});*/
base64 = canvas.toDataURL("image/jpeg", 0.8);
}/*else if (navigator.userAgent.match(/Android/i)) {// 修复android
// var encoder = new JPEGEncoder();
// base64 = encoder.encode(ctx.getImageData(0, 0, expectWidth, expectHeight), 80);
alert("安卓");
base64 = ctx.getImageData(0, 0, expectWidth, expectHeight);
}*/else{
//alert(Orientation);
// alert("其它");
if(Orientation != "" && Orientation != 1){
//alert('旋转处理');
switch(Orientation){
case 6://需要顺时针（向左）90度旋转
// alert('需要顺时针（向左）90度旋转');
self.rotateImg(this,'left',canvas);
break;
case 8://需要逆时针（向右）90度旋转
// alert('需要顺时针（向右）90度旋转');
self.rotateImg(this,'right',canvas);
break;
case 3://需要180度旋转
// alert('需要180度旋转');
/*self.rotateImg(this,'right',canvas);//转两次
self.rotateImg(this,'right',canvas);*/
self.rotateImg(this,'turntwo',canvas);
break;
}
}
base64 = canvas.toDataURL("image/jpeg", 0.8);
}
self.upPhoto(index,base64,areaId);//传给后台
// $("#myImage").attr("src", base64);
};
};
oReader.readAsDataURL(file);
}
}
step4通过画布，对图片进行旋转处理：
rotateImg:function(img, direction,canvas) {
console.log("拉拉");
//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 = 3;
//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 {
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, 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;
}
},
stpe5最后将生成的图片转换为base64格式，通过ajax请求发送給后端。