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tf4pi.html

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    • screen.js 3.67 KiB 
    //
// screen.js
//    mjpeg content server
//    Neil Gershenfeld
//    2/9/17
// todo
//    standalone client content push
//    browser client content push
//    https
//    parse command line
//    add authentication
//    interframe compression
//    include audio
// uses maim for screen capture:
//    https://github.com/naelstrof/maim
//    https://github.com/naelstrof/maim/archive/master.zip
//    install libimlib2-dev libxrandr-dev libxfixes-dev cmake
//
// command line
//
if (process.argv.length != 5) {
   console.log("node screen.js server_port server_update_rate_ms client_update_rate_ms")
   process.exit()
   }
var port = parseInt(process.argv[2])
var server_delay = parseFloat(process.argv[3])
var client_delay = parseFloat(process.argv[4])
//
// requires
//
var http = require('http')
const spawn = require('child_process').spawn;
const spawnSync = require('child_process').spawnSync
const fork = require('child_process').fork
const fs = require('fs')
const events = require('events')
//
// globals
//
var img,newimg
var max=0
var last
//
// initialization
//
spawnSync('maim',['--showcursor','out.jpg'])
img = fs.readFileSync('out.jpg','binary')
var requests = [null]
//
// start http server
//
http.createServer(function(request,response) {
   var headers = request.headers
   var method = request.method
   var url = request.url
   if (url == '/') {
      fs.readFile('viewer.html',function(err,data){
         response.writeHead(200,{'Content-Type':'text/html'});
         response.end(data)
         })
      }
   else if (url == '/img') {
      requests.push(response)
      }
   else if (url == '/initvars') {
      var vars = {'client_delay':client_delay}
      response.writeHead(200,{'Content-Type':'text/plain'});
      response.end(JSON.stringify(vars))
      }
   else if (url == '/initimg') {
          response.writeHead(200,{'Content-Type':'application/octet-stream'})
      response.end(img,'binary')
      }
   else if (url == '/screen.js') {
      fs.readFile('screen.js',function(err,data){
         response.writeHead(200,{'Content-Type':'text/plain'});
         response.end(data)
         })
      }
   else if (url == '/viewer.html') {
      fs.readFile('viewer.html',function(err,data){
         response.writeHead(200,{'Content-Type':'text/plain'});
         response.end(data)
         })
      }
   else if (url == '/stats') {
      var resp = "<html>"
      resp += "<body>"
      resp += "last: "+last+"<br>"
      resp += "max: "+max+"<br>"
      response.writeHead(200,{'Content-Type':'text/html'});
      response.end(resp)
      }
  }).listen(port)
//
// start event loop
//
update()
//
// event loop
//
function update() {
   if (requests[0] == null) {
      const ps = spawn('maim',['--showcursor','out.jpg'])
      ps.on('close',function(code){
         fs.readFile('out.jpg','binary',function(err,data){
            var changed = false
            for (var i = 0; i < img.length; ++i) {
               if (img[i] != data[i]) {
                  changed = true 
                  break
                  }
               }
            if (changed == true) {
               if (requests.length > max)
                  max = requests.length
               last = requests.length
               img = data
               requests.splice(0,1)
               requests.push(null)
               //console.log('changed: '+requests.length)
               }
            //else
               //console.log('not changed: '+requests.length)
            })
         setTimeout(update,server_delay)
         })
      }
   else {
      requests[0].writeHead(200,{'Content-Type':'application/octet-stream'})
      requests[0].end(img,'binary')
      requests.splice(0,1)
      setTimeout(update,server_delay)
      }
   }