实现 base64图片的压缩？

[JslinSir]

原理

通过 cavas的方式 把图片进行压缩

/**
 * 压缩base64 图片
 * @param {*} quality  压缩系数0-1之间
 */
export const compressBase64Img = ({quality=0.6,base64Img}) => {
    return new Promise((revose,reject)=>{
        const newImage = new Image()
        newImage.src = base64Img
        newImage.setAttribute("crossOrigin", 'Anonymous')
        newImage.onload = function () {
            const canvas = document.createElement('canvas')
            const ctx = canvas.getContext("2d")
            canvas.width = this.width
            canvas.height = this.height
            ctx.clearRect(0, 0, canvas.width, canvas.height)
            ctx.drawImage(this, 0, 0, canvas.width, canvas.height)
            const newBase64 = canvas.toDataURL("image/jpeg", quality)
            revose(newBase64) 
        }
        newImage.onerror = function () {
            reject('图片加载出错')
        }

    })
  
 
}