html代码:
1 <!DOCTYPE html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>Title</title> 6 <style> 7 * { 8 margin: 0; 9 padding: 0; 10 } 11 12 #myCanvas { 13 background: #abcdef; 14 } 15 </style> 16 </head> 17 <body> 18 <canvas id="myCanvas" width="550px" height="400px"></canvas> 19 <script src="main.js"></script> 20 </body> 21 </html>
js代码：
1 (function () { 2 3 var c = document.getElementById("myCanvas"); 4 var con = c.getContext("2d"); 5 6 c.onmousedown = function (e) { 7 c.onmousemove = function (e) { 8 con.beginPath(); 9 con.arc(e.pageX, e.pageY, 5, 0, 2 * Math.PI); 10 con.fillStyle = "white"; 11 con.fill(); 12 con.closePath(); 13 }; 14 c.onmouseup = function (e) { 15 c.onmousemove = ""; 16 } 17 18 } 19 20 })();
原文：http://www.cnblogs.com/chenluomenggongzi/p/5886281.html
