Alexshwing外观
文件转换
Base64字符串转Blob
javascript
function dataURL2Blob(dataurl) {
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 Blob([u8arr], {type: mime})
}Base64字符串转file
javascript
function dataURL2File(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})
}图片url 转 Base64
js
/**
* 将给定 url 的图片转换为 base64 字符串
* @param {String} url 图片 url
* @return {String} base64 字符串
*/
async url2Base64(url) {
return new Promise((resolve, reject) => {
let canvas = document.createElement('canvas')
const ctx = canvas.getContext('2d')
let img = new Image()
img.src = url
img.onload = function () {
canvas.height = img.height
canvas.width = img.width
ctx.fillStyle = '#fff'
ctx.fillRect(0, 0, img.width, img.height)
ctx.drawImage(img, 0, 0)
const dataURL = canvas.toDataURL('image/jpeg', 1)
resolve(dataURL)
canvas = null
img = null
}
img.onerror = function () {
reject(new Error('Could not load image at ' + imageUrl))
}
})
},