Added BarcodeScanner class which uses evdev to read input from /dev/input for

barcode scanner. The poll function is regularly called and when a ENTER key
is detected, the barcodeReceived signal is emitted with the ASCII string.

Implemented a primary and secondary barcode scanner in MainWindow. The
barcodeReceived signal is connected to a slot.

Author: addisonElliott

mainWindow.py

@@ -1,19 +1,35 @@
 import mainWindow_ui
+from scanner import BarcodeScanner
 from PyQt5.QtWidgets import QApplication, QWidget, QMainWindow
 from PyQt5.QtCore import *
 
-
 class MainWindow(QMainWindow, mainWindow_ui.Ui_MainWindow):
     def __init__(self, parent=None):
         super(MainWindow, self).__init__(parent)
         self.setupUi(self)
 
+        # TODO Load settings here. This will load the previously saved settings
+
         # Remove title bar to
         self.setWindowFlags(Qt.FramelessWindowHint)
 
         # Sets position to 0,0 on screen and sets window to fixed size
         self.setGeometry(0, 0, 800, 480)
 
+        # TODO The primary and secondary scanner should be defined based on prev
+        # settings
+        self.primaryScanner = BarcodeScanner(4);
+        self.primaryScanner.barcodeReceived.connect(self.primaryScanner_barcodeReceived)
+        self.secondaryScanner = BarcodeScanner(5);
+        self.secondaryScanner.barcodeReceived.connect(self.secondaryScanner_barcodeReceived)
+
+        # Setup timer to regularly poll for new barcodes from scanners
+        # TODO Consider having a constants file where I can set the interval for
+        # the scannerPoll timer. This doesnt need to be a setting however
+        self.scannerPoll = QTimer()
+        self.scannerPoll.timeout.connect(self.scannerPoll_ticked)
+        self.scannerPoll.start(2)
+
     @pyqtSlot()
     def keyPressEvent(self, event):
         # Pressing escape will kill the application since the title bar is absent
@@ -23,3 +39,16 @@ def keyPressEvent(self, event):
     @pyqtSlot()
     def on_pushButton_clicked(self):
         self.close()
+
+    @pyqtSlot()
+    def scannerPoll_ticked(self):
+        self.primaryScanner.poll()
+        self.secondaryScanner.poll()
+
+    @pyqtSlot(str)
+    def primaryScanner_barcodeReceived(self, barcode):
+        print("Primary barcode scanner got: %s" % barcode)
+        
+    @pyqtSlot(str)
+    def secondaryScanner_barcodeReceived(self, barcode):
+        print("Secondary barcode scanner got: %s" % barcode)

run.sh

@@ -1,10 +1,10 @@
 from exception import *
 from evdev import *
-from ecodes import *
+from evdev.ecodes import *
+from PyQt5.QtCore import QObject, pyqtSignal
 import re
 
 keycodeToASCII = {
-    # Scancode: ASCIICode
     KEY_1: ['1', '!'], KEY_2: ['2', '@'], KEY_3: ['3', '#'], KEY_4: ['4', '$'], KEY_5: ['5', '%'], KEY_6: ['6', '^'],
     KEY_7: ['7', '*'], KEY_8: ['8', '('], KEY_9: ['9', '('], KEY_0: ['0', ')'], KEY_MINUS: ['-', '_'], KEY_EQUAL: ['=', '+'],
     KEY_TAB: ['\t', '\t'], KEY_Q: ['q', 'Q'], KEY_W: ['w', 'W'], KEY_E: ['e', 'E'], KEY_R: ['r', 'R'], KEY_T: ['t', 'T'],
@@ -21,8 +21,12 @@
     KEY_KPPLUS: '+', KEY_KP1: '1', KEY_KP2: '2', KEY_KP3: '3', KEY_KP0: '0', KEY_KPDOT: '.', KEY_KPSLASH: '/'
 }
 
-class BarcodeScanner:
+class BarcodeScanner(QObject):
+    # Signal is emitted once a barcode has been scanned and received
+    barcodeReceived = pyqtSignal(str)
+    
     def __init__(self, usbPortNumber):
+        QObject.__init__(self)
         self.modifiers = {
             KEY_RIGHTMETA:  0,  # Right GUI - (usually the Windows key)
             KEY_RIGHTALT:   0,  # Right ALT
@@ -34,13 +38,18 @@ def __init__(self, usbPortNumber):
             KEY_LEFTCTRL:   0   # Left Control
         }
         self.state = {
-            LED_CAPSL:   0, # Caps Lock
-            LED_NUML:    0, # Num Lock
-            LED_SCROLLL: 0  # Scroll Lock
+            KEY_CAPSLOCK: 0,    # Caps Lock
+            KEY_NUMLOCK: 0,     # Num Lock
+            KEY_SCROLLLOCK: 0,  # Scroll Lock
         }
 
+        # This regex expression identifies a device on a specified USB port number
+        # I am not entirely sure if this is Raspbian specific, Linux specific or what,
+        # but it works in this case
         rePhysicalLoc = re.compile("usb\-.*\..*\-1\.%i.*" % usbPortNumber)
 
+        # Loop through all available devices and search for a regex match
+        # First match found is the device we will use
         devices = [InputDevice(fn) for fn in list_devices()]
         self.device = None
         for device in devices:
@@ -54,36 +63,40 @@ def __init__(self, usbPortNumber):
 
         # Get the current state of the LED buttons; update self.state with the values that are on
         ledStates = self.device.leds()
-        for led in ledStates:
-            self.state[led] = 1
+        if LED_CAPSL in ledStates: self.state[KEY_CAPSLOCK] = 1
+        if LED_NUML in ledStates: self.state[KEY_NUMLOCK] = 1
+        if LED_SCROLLL in ledStates: self.state[KEY_SCROLLLOCK] = 1
+
+        # Set the current string buffer to none
+        self.curStr = ""
 
     def poll(self):
         try:
             # Read all of the events from the loop
-            events = self.device.read()
+            deviceEvents = self.device.read()
 
-            for event in events:
+            for event in deviceEvents:
+                # Only accept keyboard events
                 if event.type is EV_KEY:
                     keyEvent = util.categorize(event)
-
-                    if keyEvent.keycode in self.modifiers:
-                        if keyEvent.keystate is events.KeyEvent.key_down:
-                            self.modifiers[keyEvent.keycode] = 1
-                        elif keyEvent.keystate is events.KeyEvent.key_up:
-                            self.modifiers[keyEvent.keycode] = 0
-                    elif keyEvent.keycode in self.state:
-                        if keyEvent.keystate is events.KeyEvent.key_down:
-                            self.state[keyEvent.keycode] = 1
-                        elif keyEvent.keystate is events.KeyEvent.key_up:
-                            self.state[keyEvent.keycode] = 0
-                    elif keyEvent.keystate is events.KeyEvent.key_down or \
-                        keyEvent.keystate is events.KeyEvent.key_hold:
-                        if keyEvent.keycode in keycodeToASCII:
+                    
+                    if keyEvent.scancode in self.modifiers:
+                        if keyEvent.keystate is events.KeyEvent.key_down: self.modifiers[keyEvent.scancode] = 1
+                        elif keyEvent.keystate is events.KeyEvent.key_up: self.modifiers[keyEvent.scancode] = 0
+                    elif keyEvent.scancode in self.state:
+                        if keyEvent.keystate is events.KeyEvent.key_down: self.state[keyEvent.scancode] = 1
+                        elif keyEvent.keystate is events.KeyEvent.key_up: self.state[keyEvent.scancode] = 0
+                    elif keyEvent.keystate is events.KeyEvent.key_down or keyEvent.keystate is events.KeyEvent.key_hold:
+                        if keyEvent.scancode is KEY_ENTER:
+                            #print("Current str: %s" % self.curStr)
+                            self.barcodeReceived.emit(self.curStr)
+                            self.curStr = ""
+                        elif keyEvent.scancode in keycodeToASCII:
                             shift = (self.modifiers[KEY_LEFTSHIFT] or self.modifiers[KEY_RIGHTSHIFT])
-                            str = keycodeToASCII[keyEvent.keycode][shift]
-                        elif keyEvent.keycode in numpadcodeToASCII:
-                            str = numpadcodeToASCII[keyEvent.keycode]
+                            self.curStr += keycodeToASCII[keyEvent.scancode][shift]
+                        elif keyEvent.scancode in numpadcodeToASCII and self.state[KEY_NUMLOCK]:
+                            str = numpadcodeToASCII[keyEvent.scancode]
         except BlockingIOError:
             # If no events are available, this is thrown
             # No actual error, move on
-            pass
+            pass