代码如下
upload组件的 afterRead 方法:
const afterRead = async file => {
file.status = "uploading";
file.message = "上传中...";
const { data } = await upLoaderImg(file.file); //使用上传的方法。file.file
if (data) {
file.status = "done";
// fileList.value.push(data);
} else {
file.status = "failed";
file.message = "上传失败";
}
};
共用文件中的方法如下:
export const upLoaderImg = async (file) => {
let _file = file;
const maxSize = 200;
// 先压缩 再上传
if (file.size / 1024 > maxSize) {
const img = await readImg(file);
const base64Data = compress(img);
_file = dataURLtoFile(base64Data, file.name);
}
// file为 你读取成功的回调文件信息
// new 一个FormData格式的参数
let params = new FormData();
params.append("file", _file);
const config = {
headers: {
token: getToken()
}
};
return new Promise((resolve, reject) => {
axios
.post(`${baseURL}/upload`, params, config)
.then(res => {
if (res && res.data && res.status === 200) {
//如果为真 resolve出去
if (res.data.data) {
resolve(res.data);
} else {
showFailToast(res.data.message);
resolve(res.data);
}
} else {
//否则 showFailToast 提示
showFailToast("请求失败");
resolve({});
}
})
.catch(err => {
console.log("err", err);
showFailToast("请求失败");
resolve({});
});
});
};
const compress = img => {
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) {
ratio = Math.sqrt(ratio);
width /= ratio;
height /= ratio;
} else {
ratio = 1;
}
let canvas = document.createElement("canvas"),
ctx = canvas.getContext("2d");
let tCanvas = document.createElement("canvas"),
tctx = tCanvas.getContext("2d");
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) {
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);
}
//进行最小压缩
let ndata = canvas.toDataURL("image/jpeg", 0.1);
console.log("压缩前:" + initSize);
console.log("压缩后:" + ndata.length);
// console.log(
// "压缩率:" + ~~((100 * (initSize - ndata.length)) / initSize) + "%"
// );
tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0;
return ndata;
};
// File文件转为base64
const readImg = file => {
return new Promise((resolve, reject) => {
const reader = new FileReader();
reader.onload = e => {
// 创建一个Image对象
const img = new Image();
img.src = e.target.result;
img.onload = () => {
// 获取图片宽度和高度
console.log(`图片宽度: ${img.width}, 图片高度: ${img.height}`);
// return img;
resolve(img);
};
};
// 以DataURL的形式读取文件内容
reader.readAsDataURL(file);
});
};
//将base64转换为文件
const dataURLtoFile = (dataurl, filename) => {
var arr = dataurl.split(","),
mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]),
n = bstr.length,
u8arr = new Uint8Array(n);
while (n--) {
u8arr[n] = bstr.charCodeAt(n);
}
return new File([u8arr], filename, { type: mime });
};
标签:const,img,h5,width,vant4,let,file,vue3,height
From: https://www.cnblogs.com/ZerlinM/p/18167925