通过Node.js和Socket.io来实现手机的远程控制

Jun 19 2015

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用手机来实现远程控制是不是很酷？你不需要去写一个APP应用来实现这种功能-现在的手机浏览器已经支出了web socket技术，这提供了很多的可能。
这篇文章我们将用Node.js和Socket.io来实现手机控制PC的效果。

我们不必到处寻找基于HTML5的这种应用库。我们将使用Reveal.js-它来处理幻灯片动画效果，并支持键盘和触摸事件。

我们不必自己来实现远程控制的接口，我们将实现手机和电脑的同步。这样不仅能控制进度，也能同步的显示在你的手机上。

实现思路

技术上很简单。Reveal.js让当前的幻灯片序号在URL的hash上(e.g. http://example.com/#/1).我们将这个hash发送到所有连接的设备上，
对应的将会根据这个hash来自动的显示响应幻灯片。这样的话，别人可以方便的直接通过url来直接访问到显示的页面，所有我们需要输入一个验证码
在连接之前进行验证。

要说的是Reveal.js已经有一套API,我们可以直接调用来同步。但是hash变化的技术很简单，我们可以直接来实现。

运行

你可以本地运行示例，或者部署到能提供node.js环境的服务器上。本地运行更简单些，但是必须本地有node.js并执行npm install.

运行本地代码

• 下载示例代码
• 确保本地已经安装node.js。如果没有，请安装
• 解压刚才下载的代码包
• 打开终端进入相应的文件夹
• 运行npm install来安装依赖包
• 运行node app.js来启动应用
• PC端在浏览器打开http://localhost:8080，并输入连接码(默认是kittens)
• 在手机端浏览器打开http://<your computer’s local ip address>，并输入连接码
• 请享受

代码

思路说完，让我们来看看代码。这主要涉及2个js文件-app.js服务端控制，script.js浏览器端。你可以运行这个应用在Node.js 1.10+或者io.js.

后端，我们用到了express和Socket.io.它主要用来响应socket.io的事件监听。用express.static来让public下的文件可以访问到。
public/index.html文件保护显示的代码。express.static将会让它自动显示，所以我们不需要/来路由。

app.js

// This is the server-side file of our mobile remote controller app.
// It initializes socket.io and a new express instance.
// Start it by running 'node app.js' from your terminal.


// Creating an express server

var express = require('express'),
    app = express();

// This is needed if the app is run on heroku and other cloud providers:

var port = process.env.PORT || 8080;

// Initialize a new socket.io object. It is bound to
// the express app, which allows them to coexist.

var io = require('socket.io').listen(app.listen(port));


// App Configuration

// Make the files in the public folder available to the world
app.use(express.static(__dirname + '/public'));


// This is a secret key that prevents others from opening your presentation
// and controlling it. Change it to something that only you know.

var secret = 'kittens';

// Initialize a new socket.io application

var presentation = io.on('connection', function (socket) {

    // A new client has come online. Check the secret key and
    // emit a "granted" or "denied" message.

    socket.on('load', function(data){

        socket.emit('access', {
            access: (data.key === secret ? "granted" : "denied")
        });

    });

    // Clients send the 'slide-changed' message whenever they navigate to a new slide.

    socket.on('slide-changed', function(data){

        // Check the secret key again

        if(data.key === secret) {

            // Tell all connected clients to navigate to the new slide

            presentation.emit('navigate', {
                hash: data.hash
            });
        }
    });
});

console.log('Your presentation is running on http://localhost:' + port);

下面是前端的js文件，将监听hashchange事件，并发送socket.io消息到服务器端。

public/assets/js/script.js

$(function() {

    // Apply a CSS filter with our blur class (see our assets/css/styles.css)

    var blurredElements = $('.homebanner, div.reveal').addClass('blur');

    // Initialize the Reveal.js library with the default config options
    // See more here https://github.com/hakimel/reveal.js#configuration

    Reveal.initialize({
        history: true        // Every slide will change the URL
    });

    // Connect to the socket

    var socket = io();

    // Variable initialization

    var form = $('form.login'),
        secretTextBox = form.find('input[type=text]');

    var key = "", animationTimeout;

    // When the page is loaded it asks you for a key and sends it to the server

    form.submit(function(e){

        e.preventDefault();

        key = secretTextBox.val().trim();

        // If there is a key, send it to the server-side
        // through the socket.io channel with a 'load' event.

        if(key.length) {
            socket.emit('load', {
                key: key
            });
        }

    });

    // The server will either grant or deny access, depending on the secret key

    socket.on('access', function(data){

        // Check if we have "granted" access.
        // If we do, we can continue with the presentation.

        if(data.access === "granted") {

            // Unblur everything
            blurredElements.removeClass('blurred');

            form.hide();

            var ignore = false;

            $(window).on('hashchange', function(){

                // Notify other clients that we have navigated to a new slide
                // by sending the "slide-changed" message to socket.io

                if(ignore){
                    // You will learn more about "ignore" in a bit
                    return;
                }

                var hash = window.location.hash;

                socket.emit('slide-changed', {
                    hash: hash,
                    key: key
                });
            });

            socket.on('navigate', function(data){

                // Another device has changed its slide. Change it in this browser, too:

                window.location.hash = data.hash;

                // The "ignore" variable stops the hash change from
                // triggering our hashchange handler above and sending
                // us into a never-ending cycle.

                ignore = true;

                setInterval(function () {
                    ignore = false;
                },100);

            });

        }
        else {

            // Wrong secret key

            clearTimeout(animationTimeout);

            // Addding the "animation" class triggers the CSS keyframe
            // animation that shakes the text input.

            secretTextBox.addClass('denied animation');

            animationTimeout = setTimeout(function(){
                secretTextBox.removeClass('animation');
            }, 1000);

            form.show();
        }

    });

});

现在是幻灯片放映时间

手机远程访问控制已经可以了。希望你能从中得到有趣的体验。

参考：

http://tutorialzine.com/2015/02/smartphone-remote-control-for-presentations/
https://github.com/hakimel/reveal.js/wiki/Example-Presentations

Web技术

Node.js