Change the Printer class to implement multiple printer types

src/main.py

@@ -101,7 +101,6 @@ app.config["TEMPLATES_AUTO_RELOAD"] = True
 # Printer connection
 # Uses the class defined in the printer.py file
 printer = Printer(app, 0x04B8, 0x0E28)
-printer.init_printer()
 
 # Find out if we are running on a Raspberry Pi
 rpi = Raspberry(

src/printer.py

@@ -4,15 +4,54 @@ This class manages connexion to a Printer
 # import brother_ql
 from time import sleep
 import os.path
+from abc import ABC, abstractmethod
+
+from enum import Enum
+import uuid
 
 from PIL import Image, ImageEnhance
 import numpy as np
 
-# Importing the module to manage the connection to the printer.
+
+# Importing the modules needed for each supported printer Type
 import escpos.printer
+import brother_ql
+
+class PrinterCapabilities(Enum):
+    """
+    What are the capacities of a Printer ?
+    """
 
 
-class Printer():
+class Printer(ABC):
+    """
+    If it outputs printed paper and speaks like a printer, then it must be a printer.
+    """
+
+    def __init__(self, app, vendor_id, device_id):
+        """
+        We initialize a Printer via it's USB connexion, and generate a unique ID
+        """
+        self.id = uuid.uuid4()
+        self.app = app
+        self.vendor_id = vendor_id
+        self.device_id = device_id
+        self.ready = False
+
+    @abstractmethod
+    def _has_paper(self) -> bool:
+        """Check if the printer has papier"""
+
+    @abstractmethod
+    def _state(self) -> bool:
+        """Reports the state of the Printer"""
+
+    @abstractmethod
+    def print_task(self, task_type, data)-> None:
+        """Takes a PrintTask and executes it"""
+
+
+class EscPosPrinter(Printer):
     """
     # The connection is based on the ESC/POS library
 
@@ -29,47 +68,13 @@ class Printer():
     ## Annonce readyness : return a positive pong message.
     """
 
-    # Is the printer ready to accept a new print ?
+    def __init__(self, app):
-    ready = False
+        super().__init__(app, vendor_id="",device_id="")
-
-    def __init__(self, app, device_id, vendor_id):
-        super().__init__()
-        self.app = app
-        self.ready = False
         self.printer = None
-        self.device_id = device_id
-        self.vendor_id = vendor_id
         self.usb_args = {}
         self.usb_args["idVendor"] = self.device_id
         self.usb_args["idProduct"] = self.vendor_id
 
-    def check_paper(self) -> bool:
-        """
-        On printers that support it, we check that the printer has paper
-        """
-        self.app.logger.debug("Checking paper status...")
-        self.printer.open(self.usb_args)
-        status = self.printer.paper_status()
-        match status:
-            case 0:
-                self.app.logger.error("Printer has no more paper, aborting...")
-                self.printer.close()
-                raise RuntimeError("No more paper in the printer")
-            case 1:
-                self.app.logger.warning(
-                    "Printer needs paper to be changed very soon ! "
-                )
-                self.printer.close()
-            case 2:
-                self.app.logger.debug("Printer has paper, good to go")
-                self.printer.close()
-
-    def init_printer(self):
-        """
-        Check if the printer online ? Is the communication with the printer successfull ?
-        """
-
-        # TODO: This could happen directly when creating a new Printer class
         if os.getenv("FLASK_DEBUG"):
             waiting_elapsed = 3
         else:
@@ -77,14 +82,15 @@ class Printer():
 
         self.app.logger.debug("Waiting for printer to get online...")
 
-        while not self.ready:
+        online = False
+        while not online:
             try:
                 # This also calls open(), which we need to close()
                 # or else the device will appear as busy.
                 p = escpos.printer.Usb(
                     self.device_id, self.vendor_id, 0, profile="TM-P80"
                 )
-            except RuntimeError as e:
+            except escpos.exceptions.DeviceNotFoundError as e:
                 self.app.logger.error(
                     "The USB device is not plugged in, trying again %s : %s",
                     waiting_elapsed,
@@ -93,9 +99,9 @@ class Printer():
 
             try:
                 if p.is_online():
-                    self.ready = True
+                    online = True
                     self.app.logger.debug("Printer online !")
-            except RuntimeError as e:
+            except escpos.exceptions.DeviceNotFoundError as e:
                 self.app.logger.error(
                     "Error while getting the printer online %s : %s",
                     waiting_elapsed,
@@ -109,7 +115,7 @@ class Printer():
                     "Printer took more than 30 seconds to get online, aborting..."
                 )
                 waiting_elapsed = 1  # Reset the waiting time for the next print.
-                return False
+                raise RuntimeError("Could not get Printer %s online" % self.id)
 
         # Setting up the printing options.
         p.set(
@@ -130,14 +136,37 @@ class Printer():
         # Beware : if we print every time the printer becomes ready, it means
         # we are printing before and after every print !
         self.printer = p
+        self.printer.close() # We close the connexion to the Printer
+
+        try:
+            self._has_paper()
+        except Exception as e:
+            raise e
+
         self.ready = True
+
+    def _has_paper(self):
+        """Check if the printer has paper left"""
+        self.app.logger.debug("Checking paper status...")
+        self.printer.open(self.usb_args)
+        status = self.printer.paper_status()
+        match status:
+            case 0:
+                self.app.logger.error("Printer has no more paper, aborting...")
+                self.printer.close()
+                raise RuntimeError("No more paper in the printer")
+            case 1:
+                self.app.logger.warning(
+                    "Printer needs paper to be changed very soon ! "
+                )
+                self.printer.close()
+                return True
+            case 2:
+                self.app.logger.debug("Printer has paper, good to go")
                 self.printer.close()
-
-        self.check_paper()
-
                 return True
 
-    def _print_sms(self, msg, signature="", bold=False):
+    def _print_txt(self, msg, signature="", bold=False):
 
         if not isinstance(msg, str):
             self.app.logger.error(
@@ -255,14 +284,14 @@ class Printer():
         try:
             self.printer.open(self.usb_args)
             self.printer.qr(content, center=True)
+            self.printer.textln(content, center=True)
             self.printer.close()
         except RuntimeError as e:
             self.printer.close()
             self.app.logger.error(str(e))
-            return False
+            raise e
 
         self.app.logger.info("Printed a QR")
-        return True
 
     def _cut(self):
         try:
@@ -277,21 +306,45 @@ class Printer():
         self.app.logger.info("Did a cut")
         return True
 
+    def _state(self):
+        return self.printer.is_online() and self.ready and self._has_paper()
+
     def print_task(self, task_type, data):
         """Execute actual print based on task type"""
+        if self._state():
             match (task_type.value):
                 case "text":
-                self._print_sms(data["txt"], signature=data["sign"])
+                    self._print_txt(data["txt"], signature=data["sign"])
                 case "image":
                     self._print_img(
                         data["img"], signature=data["sign"], process=data["process"]
                     )
                 case "cut":
                     self._cut()
+                case "qr":
+                    self._qr(data["txt"])
                 case _:
                     raise RuntimeError("This task type is not supported")
 
 
+class BrotherPrinter(Printer):
+    """
+    Manages connexion and capabilities of a BrotherQL Printer
+    """
+
+    def __init__(self, app, vendor_id, device_id):
+        super().__init__(app, vendor_id="",device_id="")
+        self.printer = None
+        self.usb_args = {}
+        self.usb_args["idVendor"] = self.device_id
+        self.usb_args["idProduct"] = self.vendor_id
+
+    def _has_paper():
+
+    def _state():
+
+    def print_task():
+
 def _process_image(self, path):
     brightness_factor = 1.5  # Used only if image is too dark
     brightness_threshold = 100  # Brightness threshold (0–255)

src/printers.py

@@ -0,0 +1,18 @@
+"""
+A collection of Printers.
+
+It has methods to discover printers, and provides an interface for the methods expected from printers.
+"""
+
+from printer import Printer
+
+class Printers():
+    """
+    A collection of Printers
+    """
+    def __init__(self, name, age):
+        self.name = name
+        self.age = age
+
+    def _discover_printers(self):
+        pass