Using NowJS for Node.js with jQuery UI Draggable_问答_开发者

Using NowJS for Node.js with jQuery UI Draggable

开发者 https://www.devze.com 2023-04-06 16:46 出处：网络

I started with the code found at this post: http://www.bennadel.com/blog/2171-Realtime-Messaging-And-Synchronization-With-NowJS-And-Node-js.htm.

I tried refactoring the html so that the example would use jQuery UI Draggable. The code is pasted below; server side is unchanged. It works fine, but there is an issue with flickering when dragging. I assume this is a jQuery question, although I was thinking there might be a problem with the filtering on the server side?

Also, I was wondering about how I might create an "initialPosition" function so that o开发者_运维知识库pening a new page would put the draggable div in the proper position. I assume this is something that needs to be done on the server side, and ideally it would come from a database value that gets written after a drag ends.

Also, beyond that I was wondering what the code would look like if I had multiple draggable items on a page.

HTML

<!DOCTYPE html>
<html>
<head>
    <title>NowJS Draggable using jQuery UI</title>
    <style type="text/css">
        html, body { height: 100%; width: 100%; overflow: hidden; }
        #draggable { width: 150px; height: 150px; border: 1px solid black; }
    </style>
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js"/></script>
    <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.16/jquery-ui.min.js"/></script>
    <script type="text/javascript" src="/nowjs/now.js"></script>
    <script>
        $(function() {
            $( "#draggable" ).draggable();          
            $( "#draggable" ).bind( "drag", function( event ) {
                var newPosition = {
                    left: ( event.pageX ),
                    top: ( event.pageY ),
                };
                now.syncPosition( newPosition );
            });
            now.updatePosition = function( newPosition ){
                $( "#draggable" ).css( newPosition );
            };
        });
    </script>
</head>
<body>
    <div id="draggable"></div> 
</body>
</html>

NODE.JS (comments stripped out)

var sys = require( "sys" );
var http = require( "http" );
var url = require( "url" );
var path = require( "path" );
var fileSystem = require( "fs" );

var server = http.createServer(
    function( request, response ){
        fileSystem.readFile(
            __dirname+'/index.html',
            "binary",
            function( error, fileBinary ){
                if (error){
                    response.writeHead( 404 );
                    response.end();
                    return;
                }
                response.writeHead( 200 );
                response.write( fileBinary, "binary" );
                response.end();
            }
        );
    }
);

server.listen( 8080 );

(function(){
    var nowjs = require( "now" );
    var everyone = nowjs.initialize( server );
    var primaryKey = 0;
    everyone.connected(
        function(){
            this.now.uuid = ++primaryKey;
        }
    );
    everyone.now.syncPosition = function( position ){
        everyone.now.filterUpdateBroadcast( this.now.uuid, position );
    };
    everyone.now.filterUpdateBroadcast = function( masterUUID, position ){
        if (this.now.uuid == masterUUID){
            return;
        }
        everyone.now.updatePosition( position );
    };
})();

sys.puts( "Server is running on 8080" );