npm install vue-signature 

import vueSignature from "vue-signature"
Vue.use(vueSignature)

<template>
	<div id="app">
		<vueSignature ref="signature" :sigOption="option" :w="'800px'" :h="'400px'"></vueSignature> 
		<vueSignature ref="signature1" :sigOption="option"></vueSignature> 
		<button @click="save">Save</button>
		<button @click="clear">Clear</button>
		<button @click="undo">Undo</button>
		<button @click="addWaterMark">addWaterMark</button>
	</div>
</template>

<script>
export default {
	name: "app",
	data() {
		return {
			option:{
				penColor:"rgb(0, 0, 0)",
				backgroundColor:"rgb(255,255,255)"
			}
		};
	},
	methods:{
		save(){
			var _this = this;
			var png = _this.$refs.signature.save()
			var jpeg = _this.$refs.signature.save('image/jpeg')
			var svg = _this.$refs.signature.save('image/svg+xml');
			console.log(png);
			console.log(jpeg)
			console.log(svg)
		},
		clear(){
			var _this = this;
			_this.$refs.signature.clear();
		},
		undo(){
			var _this = this;
			_this.$refs.signature.undo();
		},
		addWaterMark(){
			var _this = this;
			_this.$refs.signature.addWaterMark({
				text:"mark text",          // watermark text, > default ''
				font:"20px Arial",         // mark font, > default '20px sans-serif'
				style:'all',               // fillText and strokeText,  'all'/'stroke'/'fill', > default 'fill		
				fillStyle:"red",           // fillcolor, > default '#333' 
				strokeStyle:"blue",	   // strokecolor, > default '#333'	
				x:100,                     // fill positionX, > default 20
				y:200,                     // fill positionY, > default 20				
				sx:100,                    // stroke positionX, > default 40
				sy:200                     // stroke positionY, > default 40
			});
		},
		fromDataURL(url){
			var _this = this;
			_this.$refs.signature.fromDataURL("data:image/png;base64,iVBORw0K...");
		}
	}
};
</script>