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littleprynter/src/printer.py
2026-05-21 02:57:27 +02:00

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# import brother_ql
from time import sleep
import os.path
from PIL import Image, ImageEnhance
import numpy as np
# Importing the module to manage the connection to the printer.
import escpos.printer
class Printer(object):
"""
# The connection is based on the ESC/POS library
## Connection to the USB printer
## Making sure the printer is alive
## Making sure it has paper
## Define default print settings
## Print starting message, log time of first print, cut.
## Annonce readyness : return a positive pong message.
"""
# Is the printer ready to accept a new print ?
ready = False
def __init__(self, app, device_id, vendor_id):
super(Printer, self).__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 = 15
else:
waiting_elapsed = 10
self.app.logger.debug("Waiting for printer to get online...")
while not self.ready:
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 Exception as e:
self.app.logger.error(
"The USB device is not plugged in, trying again %s : %s",
waiting_elapsed,
str(e),
)
pass
try:
if p.is_online():
self.ready = True
self.app.logger.debug("Printer online !")
except Exception as e:
self.app.logger.error(
"Error while getting the printer online %s : %s",
waiting_elapsed,
str(e),
)
pass
sleep(1)
waiting_elapsed -= 1
if waiting_elapsed < 1:
self.app.logger.error(
"Printer took more than 30 seconds to get online, aborting..."
)
waiting_elapsed = 1 # Reset the waiting time for the next print.
return False
# Setting up the printing options.
p.set(
align="center",
font="a",
bold=False,
underline=0,
width=1,
height=1,
density=9,
invert=False,
smooth=False,
flip=False,
double_width=False,
double_height=False,
custom_size=False,
)
# Beware : if we print every time the printer becomes ready, it means
# we are printing before and after every print !
self.printer = p
self.ready = True
self.printer.close()
self.check_paper()
return True
def _print_sms(self, msg, signature="", bold=False):
if not isinstance(msg, str):
self.app.logger.error(
"It is not possible to print a " + str(type(msg)) + ", only strings."
)
raise ValueError
# We make sure that the signature is not something too goofy
clean_msg = str(msg) + "\n"
clean_signature = str(signature)
# Make checks on the size of the message being printed
if len(clean_msg) > 4096:
self.app.logger.warning(
"Could not print message of this length: " + str(len(clean_msg))
)
raise Exception(
"Could not print message of this length :"
+ str(len(clean_msg))
+ ", needs to be below 4096 caracters long."
)
if len(signature) > 256:
self.app.logger.warning(
"Could not print signature of this length: " + str(len(clean_signature))
)
raise Exception(
"Could not print signature of this length :"
+ str(len(clean_signature))
+ ", needs to be below 256 caracters long."
)
# Do the actual printing
# We would pop the next element in the queue here, if it's a sms type
try:
self.printer.open(self.usb_args)
self.printer.set(align="center", font="a", bold=bold)
self.printer.textln(clean_msg)
if clean_signature:
self.printer.textln(clean_signature)
self.printer.close()
except Exception as e:
self.app.logger.error("Unable to print because : " + str(e))
raise RuntimeError(
"Unable to print a SMS, the printer couldn't do it."
) from e
self.app.logger.info("Printed text")
return True
def _print_img(self, path, signature="", center=True, process=False):
clean_signature = str(signature)
if len(signature) > 256:
self.app.logger.warning(
"Could not print signature of this length: " + str(len(clean_signature))
)
raise ValueError(
"Could not print signature of this length :"
+ str(len(clean_signature))
+ ", needs to be below 256 caracters long."
)
if not os.path.isfile(str(path)):
self.app.logger.warning("File does not exist : " + str(path))
raise OSError(
"The file path for this image :"
+ str(path)
+ " wasn't found. Please try again."
)
else:
self.app.logger.debug("Printing file from " + str(path))
if process:
try:
self.app.logger.debug("Proccessing the image")
path = _process_image(self, path)
except RuntimeError as e:
self.app.logger.error(
"Error while processing the image, aborting print : %s", str(e)
)
raise e
else:
self.app.logger.warning("Not proccessing the image")
try:
self.printer.open(self.usb_args)
self.printer.image(path, center=center)
self.printer.textln(signature)
self.printer.close()
self.app.logger.debug("Printed an image : " + str(path))
except Exception as e:
self.app.logger.error(str(e))
raise RuntimeError("Could not print the picture") from e
finally:
try:
os.remove(path)
except OSError as e:
raise e
self.app.logger.debug("Removed image : " + str(path))
try:
self.printer.close()
except Exception as 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")
return True
def _qr(self, content):
try:
self.printer.open(self.usb_args)
self.printer.qr(content, center=True)
self.printer.close()
except Exception as e:
self.printer.close()
self.app.logger.error(str(e))
return False
self.app.logger.info("Printed a QR")
return True
def _cut(self):
try:
self.printer.open(self.usb_args)
self.printer.cut()
self.printer.close()
except Exception as e:
self.printer.close()
self.app.logger.error(str(e))
raise e
self.app.logger.info("Did a cut")
return True
def print_task(self, task_type, data):
"""Execute actual print based on task type"""
match (task_type.value):
case "text":
self._print_sms(data["txt"], signature=data["sign"])
case "image":
self._print_img(
data["img"], signature=data["sign"], process=data["process"]
)
case "cut":
self._cut()
case _:
raise RuntimeError("This task type is not supported")
def _process_image(self, path):
brightness_factor = 1.5 # Used only if image is too dark
brightness_threshold = 100 # Brightness threshold (0255)
contrast_factor = 0.6 # 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)
if original_img.mode in ("RGBA", "P"):
self.app.logger.debug("Converting the image to RGB from RGBA")
original_img = original_img.convert("RGB")
# Resize while maintaining aspect ratio
original_img.thumbnail((max_width, max_height), Image.Resampling.LANCZOS)
self.app.logger.debug("Resized the image")
# # Convert to grayscale for dithering
# dithered_img = original_img.convert("L").convert("1") # Dithering using default method (FloydSteinberg)
# self.app.logger.debug("Dithered the image")
# Compute brightness of original image (grayscale average)
grayscale = original_img.convert("L")
avg_brightness = np.array(grayscale).mean()
self.app.logger.debug(
"Average brightness of the image : " + str(avg_brightness)
)
# Dynamically compute brightness factor if too dark
if avg_brightness < brightness_threshold:
brightness_factor = (
1 + (brightness_threshold - avg_brightness) / brightness_threshold
)
brightness_factor = min(
max(brightness_factor, 1.1), 2.5
) # Clamp between 1.1 and 2.5
self.app.logger.debug(
f"Image too dark, increasing brightness by a factor of {brightness_factor:.2f}"
)
enhancer = ImageEnhance.Brightness(original_img)
original_img = enhancer.enhance(brightness_factor)
# # Reduce contrast
# contrast_enhancer = ImageEnhance.Contrast(original_img)
# original_img = contrast_enhancer.enhance(contrast_factor)
# Convert to JPEG and save
jpeg_path = os.path.splitext(path)[0] + "_processed.jpg"
original_img.save(jpeg_path, format="JPEG", quality=95, optimize=True)
self.app.logger.debug("Processed and saved image.")
return jpeg_path
def discover_printers():
"""
We try to find all the connected printers ( 0 or n ) to this system.
For every type of supported printer, we try to autodiscover them.
http://www.linux-usb.org/usb.ids A list of USB vendor IDs
04b8 Seiko Epson Corp.
04f9 Brother Industries, Ltd
"""
def find_and_parse_borther_ql_printer():
## We might be able to no use this because there is a `discover` command in https://github.com/pklaus/brother_ql#usage
## Code stolen from https://framagit.org/stickoeur/diagnostickoeur/-/blob/no-masters/printit.py?ref_type=heads
"""Find and parse Brother QL printer information."""
model_manager = ModelsManager()
# Debug print to show we're searching
# print("Searching for Brother QL printer...")
for backend_name in ["pyusb", "linux_kernel"]:
try:
# print(f"Trying backend: {backend_name}")
backend = backend_factory(backend_name)
available_devices = backend["list_available_devices"]()
# print(f"Found {len(available_devices)} devices with {backend_name} backend")
for printer in available_devices:
# print(f"Found device: {printer}")
identifier = printer["identifier"]
parts = identifier.split("/")
if len(parts) < 4:
# print(f"Skipping device with invalid identifier format: {identifier}")
continue
protocol = parts[0]
device_info = parts[2]
serial_number = parts[3]
try:
vendor_id, product_id = device_info.split(":")
except ValueError:
# print(f"Invalid device info format: {device_info}")
continue
# Default model
model = "QL-570"
# Try to match product ID to determine actual model
try:
product_id_int = int(product_id, 16)
for m in model_manager.iter_elements():
if m.product_id == product_id_int:
model = m.identifier
break
# print(f"Matched printer model: {model}")
except ValueError:
# print(f"Invalid product ID format: {product_id}")
continue
printer_info = {
"identifier": identifier,
"backend": backend_name,
"model": model,
"protocol": protocol,
"vendor_id": vendor_id,
"product_id": product_id,
"serial_number": serial_number,
}
# print(f"Found printer: {printer_info}")
return printer_info
except Exception as e:
# print(f"Error with backend {backend_name}: {str(e)}")
continue
print("No Brother QL printer found")
return None
def fint_and_parse_epson_printer():
pass