Receipt logos: add support for black-and-white binary netpbm images.

quicktill/pdrivers.py

@@ -109,8 +109,10 @@ def __str__(self):
 
 
 class ImageElement(ReceiptElement):
-    def __init__(self, image):
+    def __init__(self, image, width, height):
         self.image_data = image
+        self.image_width = width
+        self.image_height = height
 
     def __str__(self):
         return "Image"
@@ -134,7 +136,9 @@ def printqrcode(self, data):
         self.story.append(QRCodeElement(data))
 
     def printimage(self, image):
-        self.story.append(ImageElement(image))
+        assert image.startswith(b"P4")  # only B&W PBM format currently supported
+        width, height = int(image[3:5]), int(image[6:8])
+        self.story.append(ImageElement(image[9:], width, height))
 
     def add_story(self, story):
         self.story += story
@@ -689,6 +693,9 @@ def process_canvas(self, canvas, f):
                         ("%s%s%s%s%s\n" % (
                             left, ' ' * padl, center, ' ' * padr, right))
                         .encode(self.coding))
+            elif hasattr(i, 'image_data'):
+                assert len(i.image_data * 8) == i.image_width * i.image_height
+                self._image(i.image_data, i.image_width, i.image_height, f)
             elif hasattr(i, 'qrcode_data'):
                 self._qrcode(i.qrcode_data, f)
             else:
@@ -701,6 +708,38 @@ def process_canvas(self, canvas, f):
                 f.write(escpos.ep_fullcut)
             f.flush()
 
+    def _image(self, data, width, height, f):
+        # Print a PBM bit-image
+        if width > self.dpl:
+            # Image too wide for paper
+            return
+
+        # Partition the bitmap into rows
+        rows = []
+        for line in range(height):
+            start = line * (width // 8)
+            end = start + (width // 8)
+            rows.append(data[start:end])
+
+        # Calculate padding required to center the image
+        padding = (self.dpl - width) // 2
+        padchars = bytes([False]) * padding
+
+        # Write the commands to render the padded image
+        f.write(escpos.ep_unidirectional_on)
+        for row in rows:
+            bits = []
+            for byte in row:
+                for bit in f"{int(byte):08b}":
+                    bits.extend([bool(int(bit))] * 3)
+            header = escpos.ep_bitimage_sd + bytes([len(bits), 1])
+            f.write(header + padchars + bytes(bits))
+            f.write(escpos.ep_half_dot_feed)
+        f.write(escpos.ep_unidirectional_off)
+
+        # Clear the line for subsequent content
+        f.write(escpos.ep_short_feed)
+
     def _qrcode_native(self, data, f):
         # Set the size of a "module", in dots.  The default is apparently
         # 3 (which is also the lowest).  The maximum is 16.

quicktill/printer.py

@@ -1,3 +1,5 @@
+import base64
+
 from . import td, ui, tillconfig, payment
 from decimal import Decimal
 from .models import Delivery, VatBand, Business, Transaction, PayType
@@ -25,6 +27,9 @@ def print_receipt(printer, transid):
     if not trans.lines:
         return
     with printer as d:
+        if tillconfig.publogo:
+            image = base64.b64decode(f"{tillconfig.publogo}")
+            d.printimage(image)
         d.printline(f"\t{tillconfig.pubname}", emph=1)
         for i in tillconfig.pubaddr().splitlines():
             d.printline(f"\t{i}", colour=1)

quicktill/tillconfig.py

@@ -29,6 +29,9 @@
 label_printers = []
 cash_drawer = None
 
+publogo = config.ConfigItem(
+    'core:sitelogo', None, display_name="Site logo",
+    description="Logo image to be printed on receipts.  To update it, use 'base64 logo.pbm | runtill config -s core:sitelogo'")
 pubname = config.ConfigItem(
     'core:sitename', "Default site name", display_name="Site name",
     description="Site name to be printed on receipts")