vue中添加文字或图片水印

'use strict'
 
var watermark = (className,str,type) => {
	let dom = document.getElementsByClassName(className)
	let canvas = document.createElement('canvas')
	let cxt = canvas.getContext('2d')
	let div = document.createElement('div')
	
	let imgScale = 0.6
	canvas.width = 200
	if(type == 'text'){
	  cxt.font = '16px Microsoft JhengHei'
	  cxt.fillStyle = 'rgba(200, 200, 200, 0.3)'
	  cxt.textAlign = 'left'
	  cxt.textBaseline = 'Middle'
	  cxt.fillText(str, 10, 50)
	  cxt.clearRect(0, 0, canvas.width, canvas.height);
	   div.style.background = 'url(' + canvas.toDataURL('image/png') + ') left top repeat'
	   drawImage(div,dom)  
	}else{
		//创建新的图片对象
		let img = new Image();
		//指定图片的URL
		img.src = str;
		//浏览器加载图片完毕后再绘制图片
		img.onload = function() {
			//cxt.drawImage(img,0,0);
			cxt.rotate(-20 * Math.PI / 180)
			let whScale = img.width / img.height
			cxt.clearRect(0, 0, canvas.width, canvas.height);
			 cxt.drawImage(img, //规定要使用的图像、画布或视频。
							0, 0, //开始剪切的 x 坐标位置。
							img.width, img.height,  //被剪切图像的高度。
							0, 50,//在画布上放置图像的 x 、y坐标位置。
							img.width * imgScale, img.height * imgScale  //要使用的图像的宽度、高度
							)
			div.style.opacity = 0.3
			div.style.background = 'url(' + canvas.toDataURL('image/png') + ') left top repeat'
			drawImage(div,dom) 
		}
	}
}
var drawImage = function (div,dom) {
	div.style.pointerEvents = 'none'
	  div.className = 'weterbox' //样式名
	  div.style.top = 0
	  div.style.left = 0
	  div.style.position = 'absolute'
	  div.style.zIndex = '100000'
	  div.style.width = '100%'
	  div.style.height = '100%'
	//console.log(dom) 
	if( dom.length > 0){
		for(let i = 0; i< dom.length;i++){
			let child = dom[i].getElementsByClassName('weterbox')
			if(child.length > 0){
				dom[i].removeChild(child[0])
			}
			dom[i].appendChild(div.cloneNode(true))
		//	console.log(i,dom[i])
		}
	}
}
 
export default watermark

watermark('需要添加水印的div元素的className','水印图片路径')
 

watermark('需要添加水印的div元素的className','水印文字'，'text')

.viewWeb{
		position: relative;
	}