Friday, July 20, 2012: Remote Camera Shutter for a Jailbroken iPad Powered by Node.js

Yesterday, I went to Chocolate Ville, a very beautiful restaurant, planning to take bunch of photos. I went with many friends, my MacBook Pro and my New iPad.

After the food is ordered, my friends went to look around and take more photos, while I and another friend were waiting for the food (someone has to look for our belongings), I then felt like oh it’s a nice idea to take photos of everyone.

…but instead of asking the waitress to take a photo for us, I think I’d make my MacBook press the shutter button on my iPad for me. So while waiting for the food, I quickly created a remote shutter in Node.js.

A Node.js server sending tap events to the iPad through Veency.

On the iPad

On the iPad, I installed “Veency”, which is a VNC server for the iPad, from Cydia. That’s all.

Make sure you enabled the server and set the password to something.

Then I used the normal camera app to take photos.

On My Laptop

First, I tried connecting my iPad to my MacBook through Bluetooth PAN, but the remote shutter works for like 2–3 meters and is so delayed. So I recommend you to set up an ad-hoc wireless network. Static IP is recommended because that makes these 2 devices see each other more quickly.

The Node.js Server

substack has made the excellent rfb module that lets Node connect to a VNC server. I also used connect so that I build the web server more quickly. So,

npm install rfb connect

And the app code (this code is refined to work better):

var RFB = require('rfb')
  , client = new RFB({
      host: process.argv[2]
    , password: process.argv[3]
    , securityType: 'vnc'
    })
  , connect = require('connect')

console.log('connecting')
client.dimensions(function(dim) {
  console.log('connected', dim)
  connect.createServer()
    .use(function(req, res, next) {
      var m = req.url.match(/click\/([\d\.]+)\/([\d\.]+)/)
      if (!m) return next()
      var x = parseFloat(m[1])
      var y = parseFloat(m[2])
      client.sendPointer(x * dim.width, y * dim.height, true)
      res.setHeader('Content-Type', 'text/plain')
      process.nextTick(function() {
        client.sendPointer(x * dim.width, y * dim.height, false)
        res.end('ok')
      })
    })
    .listen(2271)
})

Basically, what this code does is connecting to the VNC server, which is my iPad, and then starts a web server. If I go to:

http://localhost:2271/click/0.95/0.5

This will tap on the iPad at the point (0.95, 0.5) in the screen. The point in the screen is defined in range 0–1, where 0 is left/top and 1 is right/bottom.

Note that the coordinates are independent of the orientation of the device. The left side of the iPad screen is always the side that the home button resides. If you rotate your iPad, you have to rotate the numbers too if you want it to click on the same button.

Using It

Now, after the iPad and the laptop is in the same wireless network, run:

node app.js 192.168.43.42 vncpass1

Change the IP and your VNC password accordingly, then if it works, it should say “connected” along with the dimensions of the screen.

Then on the iPad, fire up the Camera app, and rotate your screen so that the lens are at the top, and the on-screen shutter button is on the same side as the home button.

Then fire the web browser to:

http://localhost:2271/click/0.05/0.5

The shutter button should act like it is actually tapped by a finger, and a photo should be taken, and the browser should say “ok”.

Now to take more photos, you just press Cmd+R on your keyboard and the shutter will be pressed again.

In closing, I think it is pretty amazing that with Node.js and the right module, it’s possible to make a working remote camera shutter in less than 30 lines of code and within 10 minutes while waiting for the food to be served.