odoo/addons/hw_scanner/controllers/main.py

# -*- coding: utf-8 -*-
import logging
import os
import time
from os import listdir
from os.path import join
from threading import Thread
from Queue import Queue, Empty
import openerp
import openerp.addons.hw_proxy.controllers.main as hw_proxy
from openerp.tools.translate import _

from openerp import http
from openerp.http import request

_logger = logging.getLogger(__name__)

try:
    import evdev
except ImportError:
    _logger.error('OpenERP module hw_scanner depends on the evdev python module')
    evdev = None

from select import select

class Scanner(Thread):
    def __init__(self):
        Thread.__init__(self)
        self.input_dir = '/dev/input/by-id/'
        self.keymap = {
            2: ("1","!"),
            3: ("2","@"),
            4: ("3","#"),
            5: ("4","$"),
            6: ("5","%"),
            7: ("6","^"),
            8: ("7","&"),
            9: ("8","*"),
            10:("9","("), 
            11:("0",")"), 
            12:("-","_"), 
            13:("=","+"), 
            # 14 BACKSPACE
            # 15 TAB 
            16:("q","Q"), 
            17:("w","W"),
            18:("e","E"),
            19:("r","R"),
            20:("t","T"),
            21:("y","Y"),
            22:("u","U"),
            23:("i","I"),
            24:("o","O"),
            25:("p","P"),
            26:("[","{"),
            27:("]","}"),
            # 28 ENTER
            # 29 LEFT_CTRL
            30:("a","A"),
            31:("s","S"),
            32:("d","D"),
            33:("f","F"),
            34:("g","G"),
            35:("h","H"),
            36:("j","J"),
            37:("k","K"),
            38:("l","L"),
            39:(";",":"),
            40:("'","\""),
            41:("`","~"),
            # 42 LEFT SHIFT
            43:("\\","|"),
            44:("z","Z"),
            45:("x","X"),
            46:("c","C"),
            47:("v","V"),
            48:("b","B"),
            49:("n","N"),
            50:("m","M"),
            51:(",","<"),
            52:(".",">"),
            53:("/","?"),
            # 54 RIGHT SHIFT
            57:(" "," "),
        }

    def get_device(self):
        try:
            if not evdev:
                return None
            devices   = [ device for device in listdir(self.input_dir)]
            keyboards = [ device for device in devices if 'kbd' in device ]
            scanners  = [ device for device in devices if ('barcode' in device.lower()) or ('scanner' in device.lower()) ]
            if len(scanners) > 0:
                return evdev.InputDevice(join(self.input_dir,scanners[0]))
            elif len(keyboards) > 0:
                return evdev.InputDevice(join(self.input_dir,keyboards[0]))
            else:
                _logger.error('Could not find the Barcode Scanner')
                return None
        except Exception as e:
            _logger.error('Found the Barcode Scanner, but unable to access it\n Exception: ' + str(e))
            return None

    @http.route('/hw_proxy/Vis_scanner_connected', type='json', auth='admin')
    def is_scanner_connected(self):
        return self.get_device() != None
    
    def get_barcode(self):
        """ Returns a scanned barcode. Will wait at most 5 seconds to get a barcode, and will
            return barcode scanned in the past if they are not older than 5 seconds and have not
            been returned before. This is necessary to catch barcodes scanned while the POS is
            busy reading another barcode
        """

        while True:
            try:
                timestamp, barcode = self.barcodes.get(True, 5)
                if timestamp > time.time() - 5: 
                    return barcode
            except Empty:
                return ''

    def run(self):
        """ This will start a loop that catches all keyboard events, parse barcode
            sequences and put them on a timestamped queue that can be consumed by
            the point of sale's requests for barcode events 
        """
        
        self.barcodes = Queue()
        
        barcode  = []
        shift    = False
        device   = None

        while True: # barcodes loop
            if device:  # ungrab device between barcodes and timeouts for plug & play
                try:
                    device.ungrab() 
                except Exception as e:
                    _logger.error('Unable to release barcode scanner\n Exception:'+str(e))
            device = self.get_device()
            if not device:
                time.sleep(5)   # wait until a suitable device is plugged
            else:
                try:
                    device.grab()
                    shift = False
                    barcode = []

                    while True: # keycode loop
                        r,w,x = select([device],[],[],5)
                        if len(r) == 0: # timeout
                            break
                        events = device.read()

                        for event in events:
                            if event.type == evdev.ecodes.EV_KEY:
                                #_logger.debug('Evdev Keyboard event %s',evdev.categorize(event))
                                if event.value == 1: # keydown events
                                    if event.code in self.keymap: 
                                        if shift:
                                            barcode.append(self.keymap[event.code][1])
                                        else:
                                            barcode.append(self.keymap[event.code][0])
                                    elif event.code == 42 or event.code == 54: # SHIFT
                                        shift = True
                                    elif event.code == 28: # ENTER, end of barcode
                                        self.barcodes.put( (time.time(),''.join(barcode)) )
                                        barcode = []
                                elif event.value == 0: #keyup events
                                    if event.code == 42 or event.code == 54: # LEFT SHIFT
                                        shift = False

                except Exception as e:
                    _logger.error('Could not read Barcode Scanner Events:\n Exception: '+str(e))

s = Scanner()
s.start()

class ScannerDriver(hw_proxy.Proxy):
    @http.route('/hw_proxy/is_scanner_connected', type='json', auth='admin')
    def is_scanner_connected(self):
        return s.get_device() != None
    
    @http.route('/hw_proxy/scanner', type='json', auth='admin')
    def scanner(self):
        return s.get_barcode()