基于JavaScript实现电子签名功能

npm install elesigncode

<div id="test" style="width: 60%;height: 500px;margin: auto;border: 1px solid #333">
</div>
<button id="undo">撤销</button>
<button id="clear">清除</button>
<button id="getJson">获取json</button>
<button id="downloadPng">获取透明图片</button>
<button id="downloadJpeg">获取不透明图片</button>

<script type="text/javascript" src="./release/lib/dzjm.min.js"></script>
<script>
    var ele = document.getElementById("test");
    var eleSign = new EleSign({
        ele: null
    });//实例化对象
    eleSign.init(); //初始化
    eleSign.moutedEle(ele) //将签名节点放入到传入的element节点中
 
    eleSign.setPen("default");//设置签名样式：default(默认样式),writing(毛笔样式)
 
    eleSign.setColor('#f00');//设置签名颜色
 
    eleSign.setBgColor('#333');//设置背景颜色
 
    //将当前实例签名的数据转化为json
    document.getElementById("getJson").addEventListener("click", function () {
        var jsonStr = eleSign.toJson();
        console.log(jsonStr);
        alert(jsonStr);
    })
 
    //下载png
    document.getElementById("downloadPng").addEventListener("click", function () {
        if (eleSign.isEmpty() === false) {
            var baseUrl = eleSign.toPng();
            var a = document.createElement("a");
            document.body.appendChild(a);
            a.setAttribute("href", baseUrl);
            a.setAttribute("download", "png图片");
            a.click();
            document.body.removeChild(a);
        } else {
            alert('请签名')
        }
 
    })
 
    //下载jpeg
    document.getElementById("downloadJpeg").addEventListener("click", function () {
        if (eleSign.isEmpty() === false) {
            var baseUrl = eleSign.toJpeg();
            var a = document.createElement("a");
            document.body.appendChild(a);
            a.setAttribute("href", baseUrl);
            a.setAttribute("download", "jpeg图片");
            a.click();
            document.body.removeChild(a);
        } else {
            alert('请签名')
        }
    })
 
    //撤销
    document.getElementById("undo").addEventListener("click", function () {
        eleSign.undo();
    })
    //清除
    document.getElementById("clear").addEventListener("click", function () {
        eleSign.clear();
    })
</script>