使用html2canvas进行div截图时，存在svg和img的解决办法
写在前面：
1.网上html2canvas资料少，即使你复制拿来用了，也发现各种问题是不是？
2.它的官网也没有好的demo，不好解决我们的问题。
3.我自己研究了两天，自创绝招，搞定了它。
以下不废话：
vue使用html2canvas截图时，存在svg或者img时截图时空白，或者不全
当然再导入canvas，通过img转canvas去替换原来的子节点，再使用html2canvas导出图片。对于组件层级不多的页面是可用的。
javascript
const changeToCanvas = async (element) => {
const imgElems = element.querySelectorAll('img')
let svgelems = [...imgElems]
svgelems.forEach((node) => {
let parentNode = node.parentNode
let canvas = document.createElement('canvas')
canvas.style.zIndex = 999
//处理img转换canvas
if (node.tagName == 'IMG') {
canvas.width = node.width
canvas.height = node.height
canvas.getContext('2d').drawImage(node, 0, 0)
parentNode.removeChild(node)
let index = parentNode.firstChild
if (index != null) {
parentNode.insertBefore(canvas, index)
} else {
parentNode.appendChild(canvas)
}
}
})
}但是如果你组件层级多时，你会发现这种办法不是很好用，容易出现各种意想不到的问题。
如果你的原元素是svg，那么思路是，遍历div内的svg,把svg转图片，遍历图片转canvas再用html2canvas截图，如果你这么做了成功了，图片没有缺失。那么恭喜你，因为大多数都会存在各种问题。
解决办法如下
第一步，svg或者img先转base64
这里我推荐两个网站，可以将你的svg或img转base64
javascript
https://www.chahuo.com/svg2css.html#google_vignette
https://www.bejson.com/image/imgzoom/#google_vignette第二步，将转换后的base64设置为新元素的content属性：
如下，用新的div的css的content属性代替原来的svg或者img。这样就不需要canvas，只用html2canvas就能实现截图下载。
javascript
::v-deep(.vxe-icon-square-minus) {
pointer-events: none;
&::before {
content: url('data:image/svg+xml;base64,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');
background-repeat: no-repeat;
background-position: center;
width: 1em;
height: 1em;
display: inline-block;
}
}
::v-deep(.vxe-icon-square-plus) {
pointer-events: none;
&::before {
content: url('data:image/svg+xml;base64,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');
background-repeat: no-repeat;
background-position: center;
width: 1em;
height: 1em;
display: inline-block;
}
}
::v-deep(.icon_cri_1) {
&::before {
content: url('data:image/png;base64,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');
background-repeat: no-repeat;
background-position: center;
width: 1em;
height: 1em;
margin-right: 5px;
margin-top: 3px;
display: inline-block;
}
}
::v-deep(.icon_cri) {
&::before {
content: url('data:image/png;base64,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');
background-repeat: no-repeat;
background-position: center;
width: 1em;
height: 1em;
margin-right: 5px;
display: inline-block;
margin-top: 3px;
}
}第三步，实现div的截图下载
一：html2canvas npm
javascript
npm install html2canvas@1.4.1 二：引入
javascript
import html2canvas from 'html2canvas'三：实现
javascript
// 生成图片
const creatImg = async () => {
try {
const setup = {
useCORS: true, // 使用跨域
backgroundColor: null,
allowTaint: true,
logging: true, // 打印日志来检查是否有加载问题
background: '#ffffff', // 一定要添加背景颜色，否则出来的图片，背景全部都是透明的
async: true, // 是否异步解析和呈现元素
scale: 2, // 处理模糊问题
// dpi: 1000 // 处理模糊问题
scrollY: 0, // html2canvas默认绘制视图内的页面，需要把scrollY，scrollX设置为0
scrollX: 0,
ignoreElements: (element) => {//过滤不需要截图的元素
return element.className === 'vxe-tree--btn-wrapper'
}
}
const $image = divImage.value.childNodes[0].childNodes[1]
await html2canvas($image, setup).then((canvasimg) => {
const link = canvasimg.toDataURL('image/png')
const fileName = 'CRI_History_Image_' + getDate()
exportPicture(link, fileName)
})
} catch (e) {
console.log(e)
}
}
// 导出图片
const exportPicture = (link, name) => {
try {
const file = document.createElement('a')
file.style.display = 'none'
file.download = decodeURI(name)
let blob = dataURLtoBlob(link)
let url = URL.createObjectURL(blob)
file.href = url
document.body.appendChild(file)
file.click()
document.body.removeChild(file)
} catch (e) {
console.log(e)
}
}
const dataURLtoBlob = (dataurl) => {
var arr = dataurl.split(',')
var mime = arr[0].match(/:(.*?);/)[1]
var bstr = atob(arr[1])
var n = bstr.length
var u8arr = new Uint8Array(n)
while (n--) {
u8arr[n] = bstr.charCodeAt(n)
}
return new Blob([u8arr], { type: mime })
}