add function to print full images including resizing

escpos/__init__.py

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

escpos/escpos.py

@@ -7,8 +7,10 @@
 '''
 
 import Image
+import PIL.Image
 import time
 import os
+import operator
 
 from constants import *
 from exceptions import *
@@ -51,6 +53,42 @@ class Escpos:
                 buffer = ""
                 cont = 0
 
+    def fullimage(self, img, max_height=860, width=512, histeq=True):
+        """ Resizes and prints an arbitrarily sized image """
+        if isinstance(img, (Image.Image, PIL.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, current + bandsize)))
+            current += bandsize
+
 
     def image(self, img):
         """ Parse image and prepare it to a printable format """
@@ -61,7 +99,7 @@ class Escpos:
         switch   = 0
         img_size = [ 0, 0 ]
 
-        if isinstance(img, Image):
+        if isinstance(img, (Image.Image, PIL.Image.Image)):
             im = img.convert("RGB")
         else:
             im = Image.open(img).convert("RGB")

escpos/exceptions.py

@@ -14,6 +14,9 @@ class Error(Exception):
     def __str__(self):
         return self.msg
 
+class NotFoundError(Error):
+    """ Device wasn't found (not plugged in) """
+
 # Result/Exit codes
 # 0  = success
 # 10 = No Barcode type defined

escpos/printer.py

@@ -38,7 +38,7 @@ class Usb(Escpos):
         """ Search device on USB tree and set is 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 NotFoundError("Device not found or cable not plugged in.")
 
         if self.device.is_kernel_driver_active(0):
             try: