node.js 和 HTML5-Canvas 结合实现截图上传交互

楼主要做一个简单的图片上传服务器， node.js实现服务端，页面使用HTML5-Canvas实现截图。

为什么用Nodejs呢，因为用Js写后台很爽-。- 而且比较简单

为什么用canvas呢，其实我不想用的因为有些低版本的IE对HTML5的支持不好，

楼主本来想用 HTML2CANVAS 来实现截图并且上传到一个服务器上。（html2canvas 技术可以参照我另一篇博客【戳这里】）

但是这个技术对于一些复杂的DOM就不适用了，比如EXTJS drawComponent画出来的东西完全是渣啊~~所以退而求其次，我把呈现测试用

HTML5的Canvas呈现出来，然后保存图片。

╮(╯▽╰)╭ 具体用处是公司的秘密

推荐一个教程，写的很简单明了:

Node入门

下面的代码是我参照了这个教程的结构写的，如有雷同说明那货一定也是看了这个教程。

主页代码： Index.js

1 var server = require("./server");
2 var route  = require("./route");
3 server.start(route.route);

server代码：

var http = require("http");
var url = require("url");function start(route, handle) {function onRequest(request, response) {var postData = "";var pathname = url.parse(request.url).pathname;console.log("Request for " + pathname + " received.");request.setEncoding("utf8");request.addListener("data", function(postDataChunk) {postData += postDataChunk;console.log("Received POST data chunk '"+postDataChunk + "'.");});request.addListener("end", function() {route(pathname, response, postData);});}http.createServer(onRequest).listen(8888);console.log("Server has started.");
}exports.start = start;

route.js 代码：

 1 function route(pathname,response,postData){
 2     var requestHandler=require("./requestHandler");
 3     if (typeof requestHandler.handle[pathname] === 'function') {
 4          
 5              requestHandler.handle[pathname](response,postData);
 6          response.end();
 7      } 
 8     else {
 9         console.log("No request handler found for " +pathname);
10      response.writeHead(404, {"Content-Type": "text/plain"});
11         response.write("404 Not found");
12          
13       }
14 }
15 exports.route=route;

requestHandler.js　代码：

 1 function start(response,postData) {
 2   console.log("Request handler 'start' was called.");
 3     
 4     response.writeHead(200, {"Content-Type": "text/html"});
 5     var body = '<html>'+
 6     '<head>'+
 7     '<meta http-equiv="Content-Type" content="text/html; '+
 8     'charset=UTF-8" />'+
 9     '</head>'+
10     '<body>'+
11     '<canvas id="mycanvas" width=500 height=500 border=3 solid=#9C9898></canvas>'+'<script src="http://common.cnblogs.com/script/jquery.js" type="text/javascript"></script>'+'</body>'
12     +'<script type="text/javascript">window.onload = function(){var canvas=document.getElementById("mycanvas");var context = canvas.getContext("2d");context.beginPath();context.moveTo(100, 150);context.lineTo(450, 50);context.lineWidth = 10;context.strokeStyle ="#ff0000";context.stroke();$.ajax({url: "/upload",data:canvas.toDataURL("image/png"),type: "post",success: function( result ) {console.log( result );}});};</script>'+
13     
14     '</html>';
15        response.write(body);
16     response.end();
17 }
18 
19 function upload(response,postData) {
20     response.writeHead(200, {"Content-Type": "text/plain"});
21     var fs = require('fs');
22     var base64Data = postData.replace(/^data:image\/\w+;base64,/, "");
23     var dataBuffer = new Buffer(base64Data, 'base64');
24       console.log("Request handler 'upload' was called.");
25     fs.writeFile("out.png", dataBuffer, function(err) {
26         });
27      response.write("hello");
28     response.end();
29 }
30 var handle=[];
31 handle['/start']=start;
32 handle['/upload']=upload;
33 handle['/']=start;
34 exports.handle=handle;