initial screen commit

04b234e2 · Neil Gershenfeld · 8934aaa8 · 04b234e2
Commit 04b234e2 authored May 19, 2017 by Neil Gershenfeld
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screen.js screen.js +135 -0

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--- a/screen.js
+++ b/screen.js
+//
+// 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)
+      }
+   }