This is a draft for a solution that enables a mobile device to control a mouse pointer. For convenience we will set the server as the phone, and the client as the device with the mouse.
We have a webpage that we will use in the device to get the rotation around two axes. We use an EventListener for deviceorientation.
function getData()
{
var dx = Math.round(data.beta); //Rotation around the x axis
var dy = Math.round(data.gamma); //Rotation around the y axis
var msg =
{
delta_x: dx,
delta_y: dy,
id: clientID,//enable device/user verification?
date: Date.now(),
};
...
// Send the data to the client
...
window.requestAnimationFrame(getData);
}It is advised not to directly update the data from the Event Listener.
==Issue== It creates lag if I want to bind the sensor to a viewable object on screen.
window.addEventListener('deviceorientation', function(event)
{
data = event;
getData();
});Sources:
https://developer.mozilla.org/en-US/docs/Web/API/DeviceMotionEvent
https://developers.google.com/web/fundamentals/native-hardware/device-orientation/
We will be using the Websockets protocol, with SSL.
url = protocol + "//" + window.location.host + window.location.pathname;
var ws = new WebSocket(url);protocol set to "wss:" because we will be setting ssl up in the client.
To send the message, we add this next to where the data is updated :
ws.addEventListener('open', function(event)
{
ws.send(JSON.stringify(msg));
}
);We launch can launch a node script or python script to create the connection, and receive all the messages sent by the server. the pointer won't be hooked directly to the sensor. I think we could set a range to watch for changes in dx/dy and update the pointer position only we enter that range. Refresh rate should be between 60 Hz and 165 Hz. This will be covered in the next section.
import logging
import asyncio
import websockets
import json
import ssl
import pathlib
log = logging.getLogger('websockets')
host = "localhost"
port = 443 #default for https/wss
async def hello(websocket, path):
while 42: # while connection open, server will be closed later (server side)
message = await websocket.recv()
message = json.loads(name) # name is a dict.
print(f"{name}")
ssl_context = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
ssl_context.load_cert_chain(pathlib.Path(__file__).with_name(host+'.pem'))
# Enable the connection
start_server = websockets.serve(hello, host, port, ssl=ssl_context)
log.setLevel(logging.INFO)
log.addHandler(logging.StreamHandler())
asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever()Sources:
http://websockets.readthedocs.io/en/stable/
==Issue== I get the error below when I try the websocket connection outside the localhost.
OSError: [Errno 49] error while attempting to bind on address
I think it has something to do with the deployment method (bitballoon doesn't allow port 443 ? or refuses the first handshake?)
This can be done, with a C program (or python) using the uinput kernel module. We can open a file descriptor and use system calls to write the Mouse position directly.
Sources :