H5自定义画布：（下面复制粘贴就能用了）HTML部分：<canvas id="canvas" style="border: 1px solid #999"></canvas>
    JS部分：        //画板var canvas = document.getElementById("canvas");var ctx = canvas.getContext("2d");ctx.lineWidth = 1.0;canvas.addEventListener('touchstart',function(event){//触摸点按下事件
            stopDefault();if (event.targetTouches.length == 1) {var touch = event.targetTouches[0];ctx.beginPath();ctx.moveTo(touch.clientX-canvas.offsetLeft,touch.clientY-canvas.offsetTop);canvas.addEventListener('touchmove',function (event) {//手机拖动触摸点事件var touche = event.targetTouches[0];ctx.lineTo(touche.clientX - canvas.offsetLeft, touche.clientY - canvas.offsetTop);ctx.stroke();},false)canvas.addEventListener('touchend',function (event) {//手机离开屏幕的事件
                    ctx.closePath();startDefault();},false)}},false)//清空画布$("#cx").click(function(){//重新设置高或宽，便能重置画布var c=document.getElementById("canvas");  var cxt=c.getContext("2d");  c.height=c.height;})    //将某段HTML通过canvas转化成图片显示例如：<div id="html">要转化成Image图片的HTML代码</div>   //要转化成Image图片的HTML代码<img id="img" src="" />   //通过该图片显示出来1.首先引入<script type="text/javascript" src="${pageContext.request.contextPath}/js/html2canvas.js"></script>2.通过下面代码获取到DOM对象，然后将其base64数据付给图片的src即可显示var DOM=document.getElementById("html");html2canvas(DOM).then(function(canvas) {var imageData = canvas.toDataURL();$("#img").attr("src",imageData);});//将某一个画布的内容，复制到另一块画布上
HTML部分：<canvas id="canvas" style="border: 1px solid #999">用户画的画布</canvas><canvas id="canvas_fz" style="border: 1px solid #999">要复制过去的画布</canvas>
JS部分：
var canvas=document.getElementById("canvas");//用户画的签名
var ctx=canvas.getContext("2d");
var imgData=ctx.getImageData(0,0,$("#canvas").width(),$("#canvas").height());//通过getImageData(左上角坐标,右上角坐标,获取的宽度,获取的高度)获取用户画的像素var canvas_fz=document.getElementById("canvas_fz");
$(canvas_fz).attr("width",$("#canvas").width()).attr("height",$("#canvas").height()); //设置要复制到画布的大小
var canvas_fz_context=canvas_fz.getContext("2d");
canvas_fz_context.putImageData(imgData,0,0);//通过putImageData()将画布附上
        通过canvas将图片进行压缩，获取base64数据<img id="image-1" />var img = new Image();//首先new一个Image对象img.src=base64;//这里的base64是要压缩的图片的base64数据var canvas = document.createElement("canvas");//获取画布对象var context = canvas.getContext("2d");canvas.width = ($("#image-1").width());设置画布大小，与显示的图片大小一样canvas.height = ($("#image-1").height());// 核心JS就这个context.drawImage(img,0,0,canvas.width,canvas.height);var data=canvas.toDataURL();//这样通过toDataURL()方法就获取到了压缩后的base64数据