capture_glitch.js

#!/usr/bin/env node

//http://vimeo.com/22429969

var fs = require('fs');
var spawn = require('child_process').spawn;

var cap = "/path/to/cap.jpg";
var glt = "/path/to/cap_glitch.jpg";

function changeDesktopPicture(){
  var scrt = (function(){/*
   
  tell application "Finder"
    set org to POSIX file "/path/to/cap.jpg" as string
    set desktop picture to file org    
    set pic to POSIX file "/path/to/cap_glitch.jpg" as string
    set desktop picture to file pic
  end tell
   
  */}).toString().replace(/^.*?\n/,'').replace(/\n.*?$/,'');
   
  var doing = spawn('osascript',['-e',scrt]);
}

function glitch(f){
  var v = (Math.random()>0.5)? 0.95 : Math.random()*1.5;
  var file = f;
  var buf = fs.readFileSync(file);
  
  for(var i=0; i<buf.length; i++){
    if(Math.random()>v){
      if(buf[i]==18){
        if(Math.random()>0.5){
          buf[i] = Math.floor(Math.random()*10);
        }else{
          buf[i] = buf[i+1];
        }
      }
    }
  }

  return buf
}

function capture(){
  var cmd = spawn('screencapture',['-W','-tjpeg',cap]);
  cmd.on('exit',function(){
    var buf = glitch(cap);
    fs.writeFile(glt,buf,function(err){
      if(err) throw err;
      changeDesktopPicture();
    });
  });
}

capture();