Apply formating, light linting

configuration/config.toml

@@ -1,11 +1,28 @@
 # Configuration file the LittlePrynter
 
 [defaults]
-signature = "Anonymous"
+signature = ""
+
 
 # Printer settings
 [printer]
 upload_folder = "src/static/uploads"
+# How long do we wait before giving up on waiting for a printer connexion
+waiting_time = 5
+
+[printer.epson]
+# Configurations for EPSON printers
+profile = "TM-T20III"
+label_type = 80 # 80 or 58 ( label width in mm )
+align_text = "center"
+text_max_length = 4096
+signature_max_length = 256
+
+[printer.brother]
+# Configurations for Brother printers
+label_type = "62" # See https://github.com/pklaus/brother_ql#usage for label types
+text_max_length = 4096
+signature_max_length = 256
 
 # Raspberry Pi Configuration
 [rpi]

configuration/config.toml.sample

@@ -5,8 +5,25 @@ signature = "Anonymous"
 
 # Printer settings
 [printer]
-vendor_id = "0x04b8"
-device_id = "0x0e28"
+# Where do we upload the pictures and such
+upload_folder = "src/static/uploads"
+
+# How long do we wait before giving up on waiting for a printer connexion
+waiting_time = 5
+
+[printer.epson]
+# Configurations for EPSON printers
+profile = "TM-T20III"
+label_type = 80 # 80 or 58 ( label width in mm )
+align_text = "center"
+text_max_length = 4096
+signature_max_length = 256
+
+[printer.brother]
+# Configurations for Brother printers
+label_type = 62 # See https://github.com/pklaus/brother_ql#usage for label types
+text_max_length = 4096
+signature_max_length = 256
 
 # Raspberry Pi Configuration
 [rpi]

src/main.py

@@ -111,7 +111,7 @@ web = Web(app, print_queue)
 # Create a pool of printers
 try:
     # comment: Find all printers connected to the system
-    printers_pool = Printers(app)
+    printers_pool = Printers(app, configuration_file)
 except Exception as e:
     app.logger.error("Could not create a pool of printers because %s", str(e))
     sys.exit(-1)
@@ -179,7 +179,13 @@ def web_print_sms():
         do_cut = False
 
     try:
-        web.print_sms(txt, sign, do_cut)
+        # Clamp value between 1 and
+        many = max(1, min(int(request.form["many"]), 20))
+    except werkzeug.exceptions.BadRequestKeyError:
+        many = 1
+
+    try:
+        web.print_sms(txt, sign, do_cut, many)
     except RuntimeError as e:
         app.logger.error("Whoops, we could not print an SMS because : %s ", str(e))
         flash("Whoops, we could not print an SMS because :" + str(e), "error")
@@ -233,9 +239,15 @@ def web_print_img():
     except werkzeug.exceptions.BadRequestKeyError:
         process_image = False
 
+    try:
+        # Clamp value between 1 and
+        many = max(1, min(int(request.form["many"]), 20))
+    except werkzeug.exceptions.BadRequestKeyError:
+        many = 1
+
     try:
         app.logger.debug("Sending the image to the printer.")
-        web.print_image(file, sign, do_cut, process_image)
+        web.print_image(file, sign, do_cut, process_image, many)
     except RuntimeError as e:
         app.logger.error("The image could not be printed because : %s ", str(e))
         flash("The image could not be printed because : " + str(e), "error")
@@ -286,9 +298,15 @@ def api_print_sms():
     except werkzeug.exceptions.BadRequestKeyError:
         do_cut = False
 
+    try:
+        # Clamp value between 1 and
+        many = max(1, min(int(request.form["many"]), 20))
+    except werkzeug.exceptions.BadRequestKeyError:
+        many = 1
+
     try:
         # comment: We try to print the SMS
-        web.print_sms(txt, sign, do_cut)
+        web.print_sms(txt, sign, do_cut, many)
     except RuntimeError as e:
         return str(e), 500
     # end try
@@ -331,9 +349,15 @@ def api_print_image():
     except werkzeug.exceptions.BadRequestKeyError:
         process_image = False
 
+    try:
+        # Clamp value between 1 and
+        many = max(1, min(int(request.form["many"]), 20))
+    except werkzeug.exceptions.BadRequestKeyError:
+        many = 1
+
     try:
         app.logger.debug("Sending the image to the printer.")
-        web.print_image(file, sign, do_cut, process_image)
+        web.print_image(file, sign, do_cut, process_image, many)
     except RuntimeError as e:
         return str(e), 500
 
@@ -342,6 +366,7 @@ def api_print_image():
 
 # TODO: This might not depend on the Raspberry Pi
 @app.route("/api/camera/picture", methods=["GET"])
+@limiter.limit("6/minute", override_defaults=False)
 def camera_picture():
     """Returns a picture taken by the camera on a raspberry pi"""
     if RASPBERRY_PI_CONNECTED:
@@ -354,24 +379,28 @@ def camera_picture():
 
 
 @app.route("/api/queue", methods=["GET"])
+@limiter.limit("6/minute", override_defaults=False)
 def api_queue_status():
     """API endpoint for entire queue"""
     return jsonify(web.get_queue_state())
 
 
 @app.route("/api/queue/completed", methods=["GET"])
+@limiter.limit("6/minute", override_defaults=False)
 def api_queue_completed():
     """API endpoint that returns the finished tasks"""
     return jsonify(web.get_queue_completed())
 
 
 @app.route("/api/worker", methods=["GET"])
+@limiter.limit("6/minute", override_defaults=False)
 def api_worker_state():
     """API endpoint to get the worker state"""
     return jsonify(worker.current_state())
 
 
 @app.route("/api/worker/start")
+@limiter.limit("6/minute", override_defaults=False)
 def api_worker_start():
     """
     Enable to worker. This starts to process the print queue.
@@ -381,6 +410,7 @@ def api_worker_start():
 
 
 @app.route("/api/worker/stop")
+@limiter.limit("6/minute", override_defaults=False)
 def api_worker_stop():
     """
     Stops the print queue. This stops the processing of the print queue.
@@ -390,6 +420,7 @@ def api_worker_stop():
 
 
 @app.route("/api/printers")
+@limiter.limit("6/minute", override_defaults=False)
 def api_printers_info():
     """Returns the current state of every printers"""
     return jsonify(printers_pool.printers_info())

src/printer.py

@@ -10,9 +10,9 @@ import time
 from enum import Enum
 import uuid
 import threading
-import usb.core
 from pathlib import Path
 from uuid import uuid4
+import usb.core
 from PIL import Image, ImageEnhance, ImageDraw, ImageFont
 import numpy as np
 
@@ -107,7 +107,7 @@ class EscPosPrinter(Printer):
     Create a new ESC/POS based printer.
     """
 
-    def __init__(self, app, vendor_id, device_id):
+    def __init__(self, app, vendor_id, device_id, configuration_file):
         """
         Create a connexion to a ESC/POS Printer via USB,
         Making sure the printer is alive,
@@ -119,11 +119,14 @@ class EscPosPrinter(Printer):
         self.usb_args = {}
         self.usb_args["idVendor"] = self.vendor_id
         self.usb_args["idProduct"] = self.device_id
+        self.configuration_file = configuration_file
 
         try:
             # This also calls open(), which we need to close()
             # or else the device will appear as busy.
-            p = escpos.printer.Usb(self.vendor_id, self.device_id, 0, profile="TM-P80")
+            p = escpos.printer.Usb(
+                self.vendor_id, self.device_id, 0, profile=configuration_file["profile"]
+            )
         except escpos.exceptions.DeviceNotFoundError as e:
             self.app.logger.error(
                 "The USB device is not plugged in : %s",
@@ -140,9 +143,21 @@ class EscPosPrinter(Printer):
         except Exception as e:
             raise e
 
+        self.printer_info = PrinterInfo(
+            identifier=configuration_file["profile"],
+            backend="pyusb",
+            model=configuration_file["profile"],
+            protocol="ESC/POS",
+            vendor_id=self.vendor_id,
+            product_id=self.device_id,
+            serial_number="",
+            label_type=self.configuration_file["label_type"],
+        )
+
         # Setting up the printing options.
+        # TODO : Expose this to the web interface
         p.set(
-            align="center",
+            align=self.configuration_file["align_text"],
             font="a",
             bold=False,
             underline=0,
@@ -201,25 +216,25 @@ class EscPosPrinter(Printer):
         clean_signature = str(signature)
 
         # Make checks on the size of the message being printed
-        # TODO: make the max length configurable
-        if len(clean_msg) > 4096:
+        if len(clean_msg) > int(self.configuration_file["text_max_length"]):
             self.app.logger.warning(
                 "Could not print message of this length: " + str(len(clean_msg))
             )
             raise RuntimeError(
                 "Could not print message of this length :"
                 + str(len(clean_msg))
-                + ", needs to be below 4096 caracters long."
+                + ", needs to be below %s caracters long.",
+                str(self.configuration_file["text_max_length"]),
             )
-        # TODO: make the max length configurable
-        if len(signature) > 256:
+        if len(signature) > int(self.configuration_file["signature_max_length"]):
             self.app.logger.warning(
                 "Could not print signature of this length: " + str(len(clean_signature))
             )
             raise RuntimeError(
                 "Could not print signature of this length :"
                 + str(len(clean_signature))
-                + ", needs to be below 256 caracters long."
+                + ", needs to be below %s caracters long.",
+                str(self.configuration_file["signature_max_length"]),
             )
 
         # Do the actual printing
@@ -244,15 +259,15 @@ class EscPosPrinter(Printer):
     def _print_img(self, path, signature="", center=True, process=False):
         clean_signature = str(signature)
 
-        # TODO: make the max length configurable
-        if len(signature) > 256:
+        if len(signature) > int(self.configuration_file["signature_max_length"]):
             self.app.logger.warning(
                 "Could not print signature of this length: " + str(len(clean_signature))
             )
-            raise ValueError(
+            raise RuntimeError(
                 "Could not print signature of this length :"
                 + str(len(clean_signature))
-                + ", needs to be below 256 caracters long."
+                + ", needs to be below %s caracters long.",
+                str(self.configuration_file["signature_max_length"]),
             )
 
         if not os.path.isfile(str(path)):
@@ -287,22 +302,19 @@ class EscPosPrinter(Printer):
         except Exception as e:
             self.app.logger.error(str(e))
             raise RuntimeError("Could not print the picture") from e
-        finally:
-            try:
-                os.remove(path)
-                os.remove(processed_path)
-            except OSError as e:
-                raise e
-
-            self.app.logger.debug("Removed image : " + str(processed_path))
-            self.app.logger.debug("Removed image : " + str(path))
+        # finally:
+        #     try:
+        #         os.remove(path)
+        #         os.remove(processed_path)
+        #         self.app.logger.debug("Removed image : " + str(processed_path))
+        #         self.app.logger.debug("Removed image : " + str(path))
+        #     except OSError as e:
+        #         raise e
 
         try:
             self.printer.close()
         except Exception as e:
-                self.app.logger.error(
-                    "Could not close the printer connexion %s", str(e)
-                )
+            self.app.logger.error("Could not close the printer connexion %s", str(e))
             raise RuntimeError("Could not close the printer connexion. ") from e
 
         self.app.logger.info("Printed a picture")
@@ -392,7 +404,7 @@ class BrotherPrinter(Printer):
     Manages connexion and capabilities of a BrotherQL Printer
     """
 
-    def __init__(self, app, vendor_id, device_id):
+    def __init__(self, app, vendor_id, device_id, configuration_file):
 
         super().__init__(app, vendor_id, device_id, printer_type=PrinterType.BROTHER)
         self.printer = None
@@ -446,7 +458,9 @@ class BrotherPrinter(Printer):
             vendor_id=vendor_id,
             product_id=self.device_id,
             serial_number=serial_number,
-            label_type="62",
+            label_type=configuration_file[
+                "label_type"
+            ],  # TODO: Implement automatic label type detection : https://framagit.org/stickoeur/diagnostickoeur/-/blob/no-masters/printit.py?ref_type=heads#L239
         )
         self.app.logger.debug("Created a Brother printer !")
         self.ready = True
@@ -462,10 +476,16 @@ class BrotherPrinter(Printer):
         self._print_img(text_to_image(msg))
         self._print_img(text_to_image(signature))
 
-    def _print_img(self, data, signature="", process=False):
+    def _print_img(
+        self,
+        data,
+        signature="",
+        process=False,
+    ):
         """
         Print a raster image via a Brother QL printer
         """
+        self.app.logger.debug("Printing an image %s via Brother printer", data)
         if process:
             try:
                 self.app.logger.debug("Proccessing the image")
@@ -478,6 +498,7 @@ class BrotherPrinter(Printer):
         else:
             processed_path = data
             self.app.logger.warning("Not proccessing the image")
+
         try:
             selected_backend = guess_backend(self.printer_info.identifier)
             BACKEND_CLASS = backend_factory(selected_backend)["backend_class"]
@@ -491,33 +512,93 @@ class BrotherPrinter(Printer):
         try:
             im = Image.open(processed_path)
             qlr = BrotherQLRaster(self.printer_info.model)
-            create_label(qlr, im, self.printer_info.label_type, cut=False, dither=True)
+            # create_label(qlr, im, self.printer_info.label_type, cut=False, dither=True)
 
             # noinspection PyCallingNonCallable
-            be = BACKEND_CLASS(BACKEND_STRING_DESCR)
-            be.write(qlr.data)
-            be.dispose()
-            del be
-        except Exception as e:
-            raise e
+            # be = BACKEND_CLASS(BACKEND_STRING_DESCR)
+            # be.write(qlr.data)
+            # be.dispose()
+            # del be
 
-        if signature != "":
-            try:
-                im = Image.open(text_to_image(signature))
-                qlr = BrotherQLRaster(self.printer_info.model)
-                create_label(
-                    qlr, im, self.printer_info.label_type, cut=False, dither=True
+            instructions = convert(
+                qlr=qlr,
+                images=[im],
+                label=self.printer_info.label_type,
+                dither=True,
+                compress=False,
+                dpi_600=False,
+                cut=False,
             )
 
-                # noinspection PyCallingNonCallable
-                be = BACKEND_CLASS(BACKEND_STRING_DESCR)
-                be.write(qlr.data)
-                be.dispose()
-                del be
+            success = send(
+                instructions=instructions,
+                printer_identifier=BACKEND_STRING_DESCR,
+                backend_identifier="pyusb",
+                blocking=False,
+            )
+
+            self.app.logger.debug(str(success))
+            self.app.logger.debug("Printed image")
+            time.sleep(2)
+
+        except usb.core.USBError as e:
+            if "timeout error" in str(e):
+                self.app.logger.error("USB Timeout Error %s", str(e))
         except Exception as e:
             raise e
+        # finally:
+        #     try:
+        #         os.remove(processed_path)
+        #         self.app.logger.debug("Removed image : " + str(processed_path))
+        #     except OSError as e:
+        #         raise e
+
+        if signature != "":
+            self.app.logger.debug("Printing signature for the image %s", data)
+            try:
+                signature_file = text_to_image(signature)
+                im = Image.open(signature_file)
+                qlr = BrotherQLRaster(self.printer_info.model)
+                # create_label(
+                #     qlr, im, self.printer_info.label_type, cut=False, dither=True
+                # )
+
+                # noinspection PyCallingNonCallable
+                # be = BACKEND_CLASS(BACKEND_STRING_DESCR)
+                # be.write(qlr.data)
+                # be.dispose()
+                # del be
+                instructions = convert(
+                    qlr=qlr,
+                    images=[signature_file],
+                    label=self.printer_info.label_type,
+                    dither=True,
+                    compress=False,
+                    dpi_600=False,
+                    cut=False,
+                )
+
+                success = send(
+                    instructions=instructions,
+                    printer_identifier=BACKEND_STRING_DESCR,
+                    backend_identifier="pyusb",
+                    blocking=False,
+                )
+                self.app.logger.debug(str(success))
+                self.app.logger.debug("Printed signature")
+                time.sleep(2)
+
+            except Exception as e:
+                raise e
+            finally:
+                try:
+                    # os.remove(signature_file)
+                    self.app.logger.debug("Removed image : " + str(signature_file))
+                except OSError as e:
+                    raise e
 
     def _cut(self):
+        self.app.logger.debug("Cutting via Brother Printer")
         try:
             selected_backend = guess_backend(self.printer_info.identifier)
             BACKEND_CLASS = backend_factory(selected_backend)["backend_class"]
@@ -541,12 +622,13 @@ class BrotherPrinter(Printer):
             be.write(qlr.data)
             be.dispose()
             del be
+            self.app.logger.debug("Finished cutting via Brother Printer")
         except Exception as e:
             raise e
 
     def _qr(self):
         # This should not be reached by a print on a BrotherQL
-        raise NotImplementedError
+        raise NotImplementedError()
 
     def print_task(self, task_type, data):
         """Execute actual print based on task type"""

src/printers.py

@@ -18,11 +18,12 @@ class Printers:
     Finds and creates a set of Printer that can be used by the Workers to print.
     """
 
-    def __init__(self, app):
+    def __init__(self, app, configuration_file):
         """
         Discovers printers connected to the computer
         """
         self.app = app
+        self.configuration_file = configuration_file
         self.printers = list(self._discover_printers())
         self._lock = threading.Lock()
 
@@ -42,8 +43,7 @@ class Printers:
 
         printers = set()
 
-        # TODO : this could go in the config ?
-        waiting_time_for_printer = 5
+        waiting_time_for_printer = self.configuration_file["printer"]["waiting_time"]
 
         while True:
             # Find all connected USB devices
@@ -90,14 +90,18 @@ class Printers:
                 hex(dev.idProduct),
             )
 
-            if manufacturer == "EPSON":
+            match (manufacturer):
+                case "EPSON":
                     try:
                         # We create a new EscPosPrinter()
                         self.app.logger.debug("Trying to create a new EPSON printer")
                         prid = dev.idProduct
                         vendir = dev.idVendor
                         escpos_printer = EscPosPrinter(
-                        self.app, vendor_id=vendir, device_id=prid
+                            self.app,
+                            vendir,
+                            prid,
+                            self.configuration_file["printer"]["epson"],
                         )
                     except Exception as e:
                         raise e
@@ -105,19 +109,16 @@ class Printers:
                     # If the object creation is successfull, we add it to the list of Printers
                     printers.add(escpos_printer)
                     self.app.logger.debug("Found a %s printer", manufacturer)
-
-                # We already found the type of printer,
-                # we don't need an extra comparaison.
-                continue
-
-            # or a Brother Printer
-            if manufacturer == "Brother":
+                case "Brother":
                     try:
                         # We create a new BrotherPrinter()
                         self.app.logger.debug("Trying to create a new BROTHER printer")
 
                         brother_printer = BrotherPrinter(
-                        self.app, vendor_id=dev.idVendor, device_id=dev.idProduct
+                            self.app,
+                            dev.idVendor,
+                            dev.idProduct,
+                            self.configuration_file["printer"]["brother"],
                         )
                     except Exception as e:
                         self.app.logger.error(
@@ -131,6 +132,11 @@ class Printers:
                     # If the object creation is successfull, we add it to the list of Printers
                     printers.add(brother_printer)
                     self.app.logger.debug("Found a %s printer", manufacturer)
+                case _:
+                    self.app.logger.debug(
+                        "Found a printer of unknown manufacturer : %s", manufacturer
+                    )
+            # end match
 
         self.app.logger.debug("Found %s printers", len(printers))
 
@@ -150,6 +156,8 @@ class Printers:
             return None
 
         with self._lock:
+            # So don't always look at the first printer available if need be
+            # this allows for a round-robin lookup
             for offset in range(len(printers)):
                 index = (start_index + offset) % len(printers)
                 printer = printers[index]
@@ -162,7 +170,18 @@ class Printers:
 
     def printers_info(self):
         """Return the current list of printers"""
-        return self.printers
+        printers_info_list = []
+        for i in self.printers:
+            printers_info_list.append(
+                [
+                    i.printer_type.name,
+                    "Used: " + str(i.used),
+                    "Ready: " + str(i.ready),
+                    i.printer_info,
+                ]
+            )
+
+        return printers_info_list
 
 
 class _FindClass:

src/templates/api.html

@@ -5,6 +5,6 @@
     <title>LittlePrynter API</title>
   </head>
   <body>
-    "Welcome to the printing software's API. Please see the index page to get started.
+    Welcome to the printing software's API. Please see the index page to get started.
   </body>
 </html>

src/templates/base.html

@@ -53,7 +53,7 @@
         <hr>
 
         <footer class="row">
-        <p class=" text-center">Little Prynter is built by <a href="https://n07070.xyz/about-me/">n07070</a> because it's fun :) | <a href="https://git.n07070.xyz/n07070/littleprynter">Source code - AGPLv3</a></p>
+        <p class=" text-center">Little Prynter is built by <a href="https://n07070.xyz/about-me/">n07070</a> because it's fun :) | <a href="/api">API interface</a> | <a href="https://git.n07070.xyz/n07070/littleprynter">Source code - AGPLv3</a></p>
         </footer>
     </body>
             <script src="https://cdn.socket.io/4.0.0/socket.io.min.js"></script>

src/templates/footer.html

@@ -1,5 +0,0 @@
-<hr>
-<footer>Little Prynter is built by <a href="https://n07070.xyz/about-me/">n07070</a> because it's fun :) | <a href="https://git.n07070.xyz/n07070/littleprynter/src/branch/epson-tm-t20iii">Source code - AGPLv3</a></footer>
-</div>
-</body>
-</html>

src/templates/index.html

@@ -9,14 +9,20 @@
           <textarea class="form-control" type="text" name="txt" placeholder="4096 caractères maximum " maxlength="4096"></textarea>
           <br>
           <input class="form-control" type="text" name="signature" placeholder="Signature ou pseudo" maxlength="200"><br>
+          <div class="input-group">
+            <span class="input-group-text">Combien ?</span>
+            <input type="number" aria-label="how-many" class="form-control" name="many" max="20" min="1" value="1">
+            <input class="btn btn-primary float-right" type="submit" value="Imprimer" name="imprimer">
+          </div>
+          <br>
           <div class="form-check">
             <input class="form-check-input" type="checkbox" value="True" id="flexCheckDefault" name="cut" checked>
             <label class="form-check-label" for="flexCheckDefault">
               Couper après impression ?
             </label>
           </div>
-          <br>
-          <input class="btn btn-primary float-right" type="submit" value="Imprimer" name="imprimer">
+
+
         </form>
       </div>
     </div>
@@ -29,6 +35,12 @@
         <form enctype="multipart/form-data" class="form-group" action="/web/print/img" method="post">
           <input class="form-control" type="file" name="img" required><br>
           <input class="form-control" type="text" name="signature" placeholder="Signature ou pseudo" maxlength="200"><br>
+          <div class="input-group">
+            <span class="input-group-text">Combien ?</span>
+            <input type="number" aria-label="how-many" class="form-control" name="many" max="20" min="1" value="1">
+            <input class="btn btn-primary float-right" type="submit" value="Imprimer" name="imprimer">
+          </div>
+          <br>
           <div class="form-check .form-check-inline">
             <input class="form-check-input" type="checkbox" value="True" id="flexCheckDefault" name="cut" checked>
             <label class="form-check-label" for="flexCheckDefault">
@@ -41,8 +53,7 @@
               Traiter l'image ?
             </label>
           </div>
-          <br>
-          <input class="btn btn-primary float-right" type="submit" value="Imprimer" name="imprimer">
+
         </form>
       </div>
     </div>

src/web.py

@@ -16,7 +16,7 @@ class Web:
         self.print_queue = print_queue
         self.app = app
 
-    def print_sms(self, texte, sign: str, do_cut: bool) -> bool:
+    def print_sms(self, texte, sign: str, do_cut: bool, many: int = 1) -> bool:
         """
         Get text and a signature, prints the text and cuts after that.
         """
@@ -28,19 +28,22 @@ class Web:
             # !! there is no garantee !! that both the SMS task and the Cut task
             # are added back to back, another task could be
             # inserted between the two.
+            for i in range(many):
                 sms = self.print_queue.enqueue(TextTask(content=texte, signature=sign))
                 self.app.logger.info("Added a SMS task at position %s", sms)
-
                 if do_cut:
                     cut = self.print_queue.enqueue(CutTask())
                     self.app.logger.info("Added a CUT task at position %s", cut)
+
         except Exception as e:
             self.app.logger.error(e)
             raise RuntimeError("Could not add SMS to queue, " + str(e)) from e
 
         return True
 
-    def print_image(self, image, sign: str, do_cut: bool, process_image: bool) -> bool:
+    def print_image(
+        self, image, sign: str, do_cut: bool, process_image: bool, many: int = 1
+    ) -> bool:
         """
         Get an image and a signature, prints the image and cuts after that.
         """
@@ -53,6 +56,7 @@ class Web:
         if file_uploaded:
             self.app.logger.debug("File has been uploaded, printing...")
             try:
+                for i in range(many):
                     img = self.print_queue.enqueue(
                         ImageTask(
                             os.path.join(

src/worker.py

@@ -6,7 +6,6 @@ This is the main printing thread. A worker thread consums Tasks from
 import threading
 import time
 import traceback
-from printers import Printers
 
 
 class PrintWorker(threading.Thread):
@@ -21,7 +20,7 @@ class PrintWorker(threading.Thread):
     tasks. TODO : Change that
     """
 
-    def __init__(self, app, print_queue, printers_pool):
+    def __init__(self, app, print_queue, printers_pool, printer_index=0):
         super().__init__(daemon=True)
         self.app = app
         self.print_queue = print_queue
@@ -33,7 +32,9 @@ class PrintWorker(threading.Thread):
         # All workers share the same pool of printers.
         self.printers = printers_pool
         self.printers_obj = self.printers.printers
-        self._printer_index = 0
+        # If we create several workers, we can assign an index
+        # so that we lookup the nth printer for the nth worker
+        self._printer_index = printer_index
 
         self.app.logger.debug("Worker initialized.")
         self.app.logger.debug("Printers connected:")
@@ -44,11 +45,15 @@ class PrintWorker(threading.Thread):
         self.app.logger.debug("Ho great, I'm alive... I'm ready to work another day...")
 
     def _acquire_available_printer(self):
-        result = self.printers.acquire_available_printer(self._printer_index)
+        result = self.printers.acquire_available_printer(
+            start_index=self._printer_index
+        )
         if result is None:
             return None
 
         index, printer = result
+        # In case we need to lookup another printer, we don't
+        # look at the same printer in the printer list
         self._printer_index = (index + 1) % len(self.printers_obj)
         return printer
 
@@ -128,7 +133,6 @@ class PrintWorker(threading.Thread):
                             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"
                         self.print_queue.mark_completed(task.task_id, "completed")
@@ -156,7 +160,10 @@ class PrintWorker(threading.Thread):
         """
         self.app.logger.debug("Giving the worker a break")
         self.state = "drinking-a-beer"
+        # Free the printer during the worker break
+        # so it can be used by someone else
         self.printer.free_printer()
+        self.printer = None
         self.running = False
 
     def start_worker(self):