我要评论面向百度开发
html
<van-uploader :after-read="onread" accept="image/*">
<img src="./icon_input_add.png" />
</van-uploader>
js
data() {
return {
files: {
name: "",
type: ""
},
headerimage: null,
picvalue: null,
upimgurl,
}
},
// 组件方法 获取 流
async onread(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 = 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 () {
// console.log(this.result);
let result = this.result;
let img = new image();
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.onload = function () {
let data = self.compress(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;
return ndata;
},
// 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 = new uint8array(n);
while (n--) {
u8arr[n] = bstr.charcodeat(n);
}
return new file([u8arr], this.files.name, {
type: this.files.type
});
},
//这里写接口
async postimg() {
let file = this.dataurltofile(this.headerimage);
let formdata = new window.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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