data() {return{
files: {
name:"",
type:""},
headerImage:null,
picValue:null,
upImgUrl,
}
},//组件方法 获取 流
asynconRead(file) {//console.log(file);//console.log(file.file);
this.files.name = file.file.name; //获取文件名
this.files.type = file.file.type; //获取类型
this.picValue = file.file; //文件流
this.imgPreview(this.picValue);
},//处理图片
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 = newFileReader();//将图片2将转成 base64 格式
reader.readAsDataURL(file);//读取成功后的回调
reader.onloadend =function () {//console.log(this.result);
let result = this.result;
let img= newImage();
img.src=result;//判断图片是否大于500K,是就直接上传，反之压缩图片
if (this.result.length <= 500 * 1024) {
self.headerImage= this.result;
self.postImg();
}else{
img.οnlοad=function () {
let data=press(img, Orientation);
self.headerImage=data;
self.postImg();
};
}
};
}
},//压缩图片
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);
tCanvas.width= tCanvas.height = canvas.width = canvas.height = 0;returnndata;
},//旋转图片
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;
}
},//将base64转换为文件
dataURLtoFile(dataurl) {var arr = dataurl.split(","),
bstr= atob(arr[1]),
n=bstr.length,
u8arr= newUint8Array(n);while (n--) {
u8arr[n]=bstr.charCodeAt(n);
}return new File([u8arr], this.files.name, {
type:this.files.type
});
},//这里写接口
asyncpostImg() {
let file= this.dataURLtoFile(this.headerImage);
let formData= newwindow.FormData();
formData.append("file", file);
toast_loding(this, "图片上传中···");try{
let res= await util.ajax.post(this.upImgUrl, formData, {
headers: {"Content-Type": "multipart/form-data"}
});
}catch(e) {
console.log(e);
}
}
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