小猿圈web前端讲师为了大家更好的学习前端知识决定每天分享一个web前端案例，希望对你与学习前端的你有所帮助，今天分享的是移动端Vue+Vant的Uploader实现上传、压缩、旋转图片等功能的详细介绍。

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);

}

}

以上就是小猿圈web前端讲师给大家分享的移动端Vue+Vant的Uploader实现上传、压缩、旋转图片等功能的详细介绍，希望对你有所帮助web前端自学②群：738735873，想要了解更多内容的小伙伴可以到小猿圈官网进行学习，里面有最新最全面的课程内容等你来学习，而且小猿圈上所有的视频都是免费的学习的。