js获取图片数据流

// 由Image对象获取图片的Base64

// img: Image对象， width、height调用时传入具体像素值，控制大小 ,不传则默认图像大小

function getBase64Image (img, width, height) {

const canvas = document.createElement('canvas')

canvas.width = width || img.width

canvas.height = height || img.height

const ctx = canvas.getContext('2d')

ctx.drawImage(img, 0, 0, canvas.width, canvas.height)

const dataURL = canvas.toDataURL()

return dataURL

}

// 根据网络地址获取图片的Base64

function getBase64 (img) {

const image = new Image()

image.crossOrigin = ''

image.src = img

return new Promise((resolve, reject) => {

image.onload = function () {

const base64Data = getBase64Image(image)

resolve(base64Data)

}

})

}