Change the way a Printer is used by the worker

src/printer.py

@@ -75,6 +75,7 @@ class Printer(ABC):
         self.ready = False
         self.printer_type = printer_type
         self._lock = threading.Lock()
+        self.used = False
 
     @abstractmethod
     def _has_paper(self) -> bool:
@@ -88,6 +89,13 @@ class Printer(ABC):
     def print_task(self, task_type, data) -> None:
         """Takes a PrintTask and executes it"""
 
+    def use_printer(self) -> None:
+        """Marks the printer as being used """
+        self.used = True
+
+    def free_printer(self) -> None:
+        """Marks the printer as being not used, it's available."""
+        self.used = False
 
 class EscPosPrinter(Printer):
     """
@@ -379,17 +387,19 @@ class BrotherPrinter(Printer):
 
     def __init__(self, app, vendor_id, device_id):
         super().__init__(
-            app, vendor_id="", device_id="", printer_type=PrinterType.BROTHER
+            app, vendor_id, device_id, printer_type=PrinterType.BROTHER
         )
         self.printer = None
         self.usb_args = {}
-        self.usb_args["idVendor"] = self.device_id
+        self.usb_args["idVendor"] = self.vendor_id
-        self.usb_args["idProduct"] = self.vendor_id
+        self.usb_args["idProduct"] = self.device_id
         self.model_manager = ModelsManager()
 
         # Code taken from https://github.com/5shekel/printit/blob/master/printer_utils.py
 
+        self.app.logger.debug("Creating backend for Brother")
         backend = backend_factory("pyusb")
+
         available_devices = backend["list_available_devices"]()
 
         for printer in available_devices:
@@ -408,14 +418,19 @@ class BrotherPrinter(Printer):
             serial_number = parts[3]
 
         try:
-            product_id_int = int(self.device_id, 16)
             for m in self.model_manager.iter_elements():
-                if m.product_id == product_id_int:
+                if m.product_id == self.device_id:
                     model = m.identifier
+
                     break
+
             self.app.logger.debug(f"Matched printer model: {model}")
-        except ValueError:
+        except ValueError as ve:
-            self.app.logger.warning(f"Invalid product ID format: {m.product_id}")
+            self.app.logger.warning("Invalid product ID format:"+ str(ve))
+            raise ve
+        except Exception as e:
+            self.app.logger.error("Error while finding a model ? : " + str(e))
+            raise e
 
         self.printer_info = PrinterInfo(
             identifier=identifier,
@@ -426,7 +441,7 @@ class BrotherPrinter(Printer):
             product_id=self.device_id,
             serial_number=serial_number,
         )
-
+        self.app.logger.debug("Created a Brother printer !")
         self.ready = True
 
     def _has_paper(self):
@@ -439,17 +454,19 @@ class BrotherPrinter(Printer):
         """
         Print a raster image via a Brother QL printer
         """
-        self.ready = False
         label_type = "102"
         rotate = 0
         dither = False
+
+        data = _process_image(self, path=data, max_width=720, max_height=720)
+
         try:
             # Prepare the image for printing
             qlr = BrotherQLRaster(self.printer_info["model"])
 
             instructions = convert(
                 qlr=qlr,
-                images=[data["img"]],
+                images=[data],
                 label=label_type,
                 rotate=rotate,
                 threshold=70,
@@ -486,6 +503,7 @@ class BrotherPrinter(Printer):
                 printer_identifier=self.printer_info["identifier"],
                 backend_identifier="pyusb",
             )
+            self.app.logger.debug("Status: " + str(status))
 
             if (
                 not status["did_print"]
@@ -494,10 +512,11 @@ class BrotherPrinter(Printer):
             ):
                 raise RuntimeError("Failed to print using Python API")
 
-            if status["printer_state"]:
+            # if status["printer_state"]:
-                self.ready = bool(status["printer_state"])
+            #     self.ready = bool(status["printer_state"])
-            else:
+            #     self.app.logger.debug("Printer is borky : " + str(self.ready))
-                self.ready = True
+            # else:
+            #     self.ready = True
 
         except usb.core.USBError as e:
             # Treat timeout errors as successful since they often occur after print completion
@@ -508,29 +527,29 @@ class BrotherPrinter(Printer):
                 self.app.logger.debug("Print completed (timeout is normal)")
                 self.ready = True
 
-            error_msg = f"USBError encountered: {e}"
+            self.app.logger.debug(f"USBError encountered: {e}")
-            self.app.logger.debug(error_msg)
             raise RuntimeError from e
 
         except Exception as e:
-            error_msg = f"Unexpected error during printing: {str(e)}"
+            self.app.logger.debug(f"Unexpected error during printing: {str(e)}")
-            self.app.logger.debug(error_msg)
             raise RuntimeError from e
 
     def print_task(self, task_type, data):
         """Execute actual print based on task type"""
         with self._lock:
-            if self._state:
+            if self.ready:
-                self._state = False
+                try:
                     match (task_type.value):
                         case "image":
                             self._print_img(data["img"])
-                        self._state = True
                         case "cut":
                             # The cut happens by default on Brother QL printers.
-                        self._state = True
+                            pass
                         case _:
                             raise RuntimeError("This task type is not supported")
+                except Exception as e:
+                    raise e
+                # end try
             else:
                 raise RuntimeError("The printer is not ready to print yet !")
 
@@ -539,12 +558,10 @@ class BrotherPrinter(Printer):
         # raise NotImplementedError("This printer type is not implemented yet")
 
 
-def _process_image(self, path):
+def _process_image(self, path, max_width=575, max_height=1000):
     brightness_factor = 1.5  # Used only if image is too dark
     brightness_threshold = 100  # Brightness threshold (0–255)
     contrast_factor = 2  # Less than 1.0 = lower contrast
-    max_width = 575
-    max_height = 1000
 
     with Image.open(path) as original_img:
         # Convert to RGB if needed (JPEG doesn't support alpha)
@@ -553,7 +570,7 @@ def _process_image(self, path):
             original_img = original_img.convert("RGB")
 
         # Resize while maintaining aspect ratio
-        original_img.thumbnail((max_width, max_height), Image.Resampling.LANCZOS)
+        original_img = original_img.resize((max_width, max_height), Image.Resampling.LANCZOS)
         self.app.logger.debug("Resized the image")
 
         # # Convert to grayscale for dithering

src/printers.py

@@ -6,6 +6,7 @@ the methods expected from printers.
 """
 
 from collections.abc import Set
+import time
 import usb.core
 import usb.util
 from printer import Printer, EscPosPrinter, BrotherPrinter
@@ -41,7 +42,17 @@ class Printers:
 
         # Find all connected USB devices
         devices = usb.core.find(find_all=True, custom_match=_FindClass(7))
-        if not devices:
+        waiting_time_for_printer = 10
+        while not list(devices):
+            self.app.logger.warning(str(waiting_time_for_printer) + " Found no printers, waiting for a printer to connect to the system...")
+            time.sleep(1)
+            waiting_time_for_printer = waiting_time_for_printer - 1
+            devices = usb.core.find(find_all=True, custom_match=_FindClass(7))
+            if waiting_time_for_printer == 0:
+                break
+
+
+        if not list(devices):
             self.app.logger.warning(
                 "No USB devices of class 7 ( printers ) found or pyusb could not access the bus."
             )
@@ -60,6 +71,7 @@ class Printers:
                 product = usb.util.get_string(dev, dev.iProduct)
             except Exception:
                 product = "Unknown"
+
             self.app.logger.debug(
                 "Looking at %s %s (%s:%s)",
                 manufacturer,
@@ -71,7 +83,7 @@ class Printers:
             if manufacturer == "EPSON":
                 try:
                     # We create a new EscPosPrinter()
-                    self.app.logger.debug("Trying to creat a new EPSON printer")
+                    self.app.logger.debug("Trying to create a new EPSON printer")
                     prid = dev.idProduct
                     vendir = dev.idVendor
                     escpos_printer = EscPosPrinter(
@@ -92,11 +104,10 @@ class Printers:
             if manufacturer == "Brother":
                 try:
                     # We create a new BrotherPrinter()
-                    self.app.logger.debug("Trying to creat a new BROTHER printer")
+                    self.app.logger.debug("Trying to create a new BROTHER printer")
-                    prid = dev.idProduct
+
-                    vendir = dev.idVendor
                     brother_printer = BrotherPrinter(
-                        self.app, vendor_id=vendir, device_id=prid
+                        self.app, vendor_id=dev.idVendor, device_id=dev.idProduct
                     )
                 except Exception as e:
                     self.app.logger.error(

src/worker.py

@@ -5,6 +5,7 @@ This is the main printing thread. A worker thread consums Tasks from
 
 import threading
 import time
+import traceback
 from printers import Printers
 
 
@@ -13,7 +14,8 @@ class PrintWorker(threading.Thread):
     A thread used to consume Tasks added to a Print Queue.
 
     On initialisation, the worker will try to find Printers,
-    and on each print, choose an available Printer from a list of Printers.
+    and on each print, if the choosen Printer becomes unavailable, it
+    will choose an available Printer from a list of Printers.
 
     If a print fails, it's not retried, but will be added to a list of completed
     tasks.
@@ -30,8 +32,9 @@ class PrintWorker(threading.Thread):
 
         try:
             self.printers = Printers(self.app)
-            self.printers_obj = self.printers.printers
+            self.printers_obj = self.printers.printers # Get the number of printers connected to the system
-            self.printers = iter(self.printers.printers)
+            self.printers_list = iter(self.printers.printers)
+
         except RuntimeError as e:
             self.app.logger.warning("Could not get any Printers")
             raise e
@@ -53,11 +56,31 @@ class PrintWorker(threading.Thread):
             # we know about, and try to find one that is available.
             # When we find a printer, we acquire it
             # When we are finished with a printer, we release it to the world.
-            while not self.printer or not self.printer.ready:
+
+            # If we do not have a printer, we try to find one
+            while not self.printer:
                 time.sleep(1)
                 try:
-                    self.app.logger.debug("Changing printers")
+                    self.app.logger.debug("Trying to find a available printer for the worker.")
-                    self.printer = next(self.printers)
+
+                    # From the list of printer, we get one.
+                    # If no printer in the list is avaible, we try again from the start of the loop, that we reset.
+                    while self.printer.used or not self.printer:
+                        self.printer = next(self.printers_list)
+                        try:
+                            self.printer = next(self.printer)
+                        except StopIteration as e:
+                            self.app.error("We do not have any available printers. Resetting our list of printers and trying again. " + str(e))
+                            self.printers_list = iter(self.printers.printers)
+                            time.sleep(1)
+                            # TODO : Here, in case there is really no printer available, we will stay in a loop forever. Maybe after a number of tries, we should die.
+
+
+                    # Here, we must have found a Printer() that is
+                    # Printer.used = False, which means it's available.
+                    # Therefore, we mark it used, so no other worker uses it.
+                    self.printer.use_printer()
+
                     self.app.logger.debug(
                         "The worker got a %s printer and it's %s",
                         self.printer.printer_type,
@@ -67,6 +90,11 @@ class PrintWorker(threading.Thread):
                     self.app.logger.error("No printer detected" + str(e))
                     self.printer = None
 
+            # If the printer is not ready, we wait for it to become ready.
+            while not self.printer.ready:
+                self.app.debug("Waiting for our printer to become ready...")
+                time.sleep(1)
+
             if self.state != "idle":
                 self.app.logger("We are not idle, waiting...")
                 time.sleep(1)
@@ -80,6 +108,7 @@ class PrintWorker(threading.Thread):
                 except Exception as e:
                     self.app.logger.error("Could not get a new task ! %s ", str(e))
                     self.state = "idle"
+                    self.printer.free_printer()
                     raise RuntimeError(
                         "We could not get a new task because " + str(e)
                     ) from e
@@ -97,6 +126,8 @@ class PrintWorker(threading.Thread):
                         except RuntimeError as e:
                             self.state = "idle"
                             self.app.logger.error("Could not print : %s", str(e))
+                            self.app.logger.error(traceback.format_exc())
+                            self.printer.free_printer()
                             raise e
 
                         task.status = "completed"
@@ -125,6 +156,7 @@ class PrintWorker(threading.Thread):
         """
         self.app.logger.debug("Giving the worker a break")
         self.state = "drinking-a-beer"
+        self.printer.free_printer()
         self.running = False
 
     def start_worker(self):