poor man droid screencast

droidscreen.html

<canvas id="screencap" onclick="turn()"></canvas>
<script>
var angle = 0;
function turn() {
  angle = (angle + 90) % 360;
}

function readImage() {
  var img = new Image();
  img.onload = function () {
    var size = Math.max(img.width, img.height);

    var canvas = document.getElementById('screencap');
    canvas.width = size;
    canvas.height = size;

    var ctx = canvas.getContext('2d');
    ctx.save();
    ctx.translate(size / 2, size / 2);
    ctx.rotate(angle / 180 * Math.PI);
    ctx.translate(-img.width / 2, -img.height / 2);
    ctx.drawImage(img, 0, 0);
    ctx.restore();

    setTimeout(readImage, 50);
  };
  img.onerror = function () {
    setTimeout(readImage, 1000);
  };
  img.src = "http://localhost:8087/?r=" + Date.now()
}

readImage();
</script>

droidscreen.js

http = require('http');
exec = require('child_process').exec;

var isWindows = /^win/.test(require('os').platform());

var httpPort = 8087;
var bindAddress = '127.0.0.1';
var adbPath = isWindows ? 'adb.exe' : 'adb';

var currentImage = '';

http.createServer(function(req, res){
  res.writeHead(200, {'Content-Type': 'image/png' });
  res.end(currentImage, 'binary');
}).listen(httpPort, bindAddress);

function readScreen() {
  // getting image from the device per
  // http://blog.shvetsov.com/2013/02/grab-android-screenshot-to-computer-via.html
  exec(adbPath + ' shell screencap -p', {encoding: 'binary', maxBuffer : 4 * 1024 * 1024},
  function (error, output) {
    if (error) {
      console.log('error: ' + error);
      setTimeout(readScreen, 5000); // repeat in 5 sec
      return;
    }

    currentImage = output.replace(/\r\n/g, '\n'); // removing adb CR
    if (isWindows) {
      currentImage = currentImage.replace(/\r\n/g, '\n'); // removing windows CR
    }

    readScreen();
  });
}
readScreen();

You will need to install adb. These utilities can be found in the Android Developer Toolkit. (Or I found them at http://downloads.geeksphone.com/)

Run the HTML page in a browser(s), run node droidscreen.js and connect your device using USB port. Enjoy the show!