jSignature 插件实现手写电子签名

需求：需要在合同的最后加一个签名区，让用户能用鼠标或手指进行签名。

解决方案：jSignature 插件，依赖jquery。

index.html

    //#canvasDiv 就是书写区域，img 是书写完成后转为图片
	<div class="person" style="">
				乙方(持卡人及卡片使用人签字)：</br>
			    <div id="canvasDiv"></div>
	            <button id="btn_clear" style="">重写</button>
	            <button id="btn_submit">确定</button>
				<img id="qmimg" />
    </div>

index.js

<script src="./js/jquery-2.1.4.min.js"></script>
    <script src="./js/jSignature.min.js"></script>
    <script>
        $(function () {
                    
                    var param = {
                        width: '400px', //签名区域的宽
                        height: '100px', //签名区域的高
                       // cssclass: 'cans', //画布的类 可以写自定义的样式
                        UndoButton: true, //撤销按钮的状态 这个按钮的样式修改要去jSignature.js文件中去找
                        signatureLine: false, //去除默认画布上那条横线
                        lineWidth: '1' //画笔的大小
                    };
                  
                    //初始化
                    $("#canvasDiv").jSignature(param);
                    //jSignature提供了清除的API reset
                    $('#btn_clear').click(function () {
                        $("#canvasDiv").jSignature("reset");
                    });
                    //确认
                    $('#btn_submit').click(function () {
                            //获取签名生成的图片 默认是png的
                            var datapair = $("#canvasDiv").jSignature("getData", "image");
                            var i = new Image();
                            i.src = "data:" + datapair[0] + "," + datapair[1];
                            i.image = datapair[1];
                            // console.log(i.image);
                            //i.image 是一串字符串
                            $('#qmimg').attr('src',`data:image/png;base64,${i.image}`);
                            $("#canvasDiv").hide();
		 	                $("#btn_clear").hide();
		 	                $("#btn_submit").hide();
                           
                        })
                    })
	</script>

jSignature.min.js 文件，https://github.com/brinley/jSignature 这是github上的地址，也有这个文件

/*

jSignature v2 "2018-11-06T13:56" "commit ID 89c22b348ab2e1d92a928d8fd992f175e8bc5cbd"
Copyright (c) 2012 Willow Systems Corp http://willow-systems.com
Copyright (c) 2010 Brinley Ang http://www.unbolt.net
MIT License <http://www.opensource.org/licenses/mit-license.php>


Simplify.js BSD 
(c) 2012, Vladimir Agafonkin
mourner.github.com/simplify-js


base64 encoder
MIT, GPL
http://phpjs.org/functions/base64_encode
+   original by: Tyler Akins (http://rumkin.com)
+   improved by: Bayron Guevara
+   improved by: Thunder.m
+   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
+   bugfixed by: Pellentesque Malesuada
+   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
+   improved by: Rafal Kukawski (http://kukawski.pl)


jSignature v2 jSignature's Undo Button and undo functionality plugin


jSignature v2 jSignature's custom "base30" format export and import plugins.


jSignature v2 SVG export plugin.

*/
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总结：一开始有用过其他方法处理这个问题，那个方法最造成的问题是：在移动端放大页面来进行签名，签名区的滑动会导致整个页面进行滑动。
这个插件解决了这个问题。