add function to print full images including resizing and fix band printing

escpos/__init__.py

@@ -1 +1,2 @@
+import constants, escpos, exceptions, printer
 __all__ = ["constants", "escpos", "exceptions", "printer"]

escpos/escpos.py

@@ -18,6 +18,8 @@ import qrcode
 import time
 import textwrap
 import binascii
+import os
+import operator
 
 from .constants import *
 from .exceptions import *
@@ -161,6 +163,42 @@ class Escpos(object):
         # Convert the RGB image in printable image
         self._convert_image(im)
 
+    def fullimage(self, img, max_height=860, width=512, histeq=True):
+        """ Resizes and prints an arbitrarily sized image """
+        if isinstance(img, (Image, Image.Image)):
+            im = img.convert("RGB")
+        else:
+            im = Image.open(img).convert("RGB")
+
+        if histeq:
+            # Histogram equaliztion
+            h = im.histogram()
+            lut = []
+            for b in range(0, len(h), 256):
+                # step size
+                step = reduce(operator.add, h[b:b+256]) / 255
+                # create equalization lookup table
+                n = 0
+                for i in range(256):
+                    lut.append(n / step)
+                    n = n + h[i+b]
+            im = im.point(lut)
+
+        ratio = float(width) / im.size[0]
+        newheight = int(ratio * im.size[1])
+
+        # Resize the image
+        im = im.resize((width, newheight), Image.ANTIALIAS)
+        if im.size[1] > max_height:
+            im = im.crop((0, 0, im.size[0], max_height))
+
+        # Divide into bands
+        bandsize = 255
+        current = 0
+        while current < im.size[1]:
+            self.image(im.crop((0, current, width, min(im.size[1], current + bandsize))))
+            current += bandsize
+
     def direct_image(self, image):
         """ Send image to printer
 

escpos/exceptions.py

@@ -11,6 +11,7 @@ Result/Exit codes:
     - `60` = Invalid pin to send Cash Drawer pulse :py:exc:`~escpos.exceptions.CashDrawerError`
     - `70` = Invalid number of tab positions :py:exc:`~escpos.exceptions.TabPosError`
     - `80` = Invalid char code :py:exc:`~escpos.exceptions.CharCodeError`
+    - `90` = USB device not found :py:exc:`~escpos.exceptions.USBNotFoundError`
 
 :author: `Manuel F Martinez <manpaz@bashlinux.com>`_ and others
 :organization: Bashlinux and `python-escpos <https://github.com/python-escpos>`_
@@ -151,3 +152,17 @@ class CharCodeError(Error):
 
     def __str__(self):
         return "Valid char code must be set"
+
+class USBNotFoundError(Error):
+    """ Device wasn't found (probably not plugged in)
+
+    The USB device seems to be not plugged in.
+    Ths returncode for this exception is `90`.
+    """
+    def __init__(self, msg=""):
+        Error.__init__(self, msg)
+        self.msg = msg
+        self.resultcode = 90
+
+    def __str__(self):
+        return "USB device not found"

escpos/printer.py

@@ -43,7 +43,7 @@ class Usb(Escpos):
         """ Search device on USB tree and set it as escpos device """
         self.device = usb.core.find(idVendor=self.idVendor, idProduct=self.idProduct)
         if self.device is None:
-            print("Cable isn't plugged in")
+            raise USBNotFoundError("Device not found or cable not plugged in.")
 
         check_driver = None