Merge 940306295c2aca973d87fe51f1e99d6c321d92e7 into d93e76e9040197da47832d88155940b5caa9bbfe

escpos/escpos.py

@@ -20,7 +20,7 @@ from exceptions import *
 class Escpos:
     """ ESC/POS Printer object """
     device    = None
-
+    img_cache = []
 
     def _check_image_size(self, size):
         """ Check and fix the size of the image to 32 bits """
@@ -33,13 +33,45 @@ class Escpos:
             else:
                 return (image_border / 2, (image_border / 2) + 1)
 
+    def cache_image(self, path_img):
+        """ Open image file and store in the printer's cache """
+
+        img_no = len(self.img_cache)
+
+        im_open = Image.open(path_img)
+        im = im_open.convert("RGB")
+        # Convert the RGB image into printable image
+        (pix_line, img_size) = self._convert_image(im)
+
+        # Convert the buffered data directly to the printer readable format
+        cache = ""
+        buffer = ""
+        i = 0
+        cont = 0
+
+        buffer = "%02X%02X%02X%02X" % (((img_size[0]/img_size[1])/8), 0, img_size[1], 0)
+        cache = buffer.decode('hex')
+        buffer = ""
+
+        while i < len(pix_line):
+            hex_string = int(pix_line[i:i+8],2)
+            buffer += "%02X" % hex_string
+            i += 8
+            cont += 1
+            if cont % 4 == 0:
+                cache += buffer.decode("hex")
+                buffer = ""
+                cont = 0
+
+        self.img_cache.append(cache)
+        return img_no
 
     def _print_image(self, line, size):
         """ Print formatted image """
         i = 0
         cont = 0
         buffer = ""
-       
+
         self._raw(S_RASTER_N)
         buffer = "%02X%02X%02X%02X" % (((size[0]/size[1])/8), 0, size[1], 0)
         self._raw(buffer.decode('hex'))
@@ -97,20 +129,25 @@ class Escpos:
                         break
                     elif im_color > (255 * 3 / pattern_len * pattern_len) and im_color <= (255 * 3):
                         pix_line += im_pattern[-1]
-                        break 
+                        break
             pix_line += im_right
             img_size[0] += im_border[1]
 
-        self._print_image(pix_line, img_size)
+        return pix_line, img_size
-
 
     def image(self,path_img):
-        """ Open image file """
+        """ Open and immediately print image file """
         im_open = Image.open(path_img)
         im = im_open.convert("RGB")
-        # Convert the RGB image in printable image
-        self._convert_image(im)
 
+        # Convert the RGB image in printable image
+        (pix_line, img_size) = self._convert_image(im)
+        self._print_image(pix_line, img_size)
+
+    def cached_image(self, index):
+        """ Prints an image from the image cache """
+        self._raw(S_RASTER_N)
+        self._raw(self.img_cache[index])
 
     def qr(self,text):
         """ Print QR Code for the provided string """

escpos/printer.py

@@ -18,6 +18,8 @@ from exceptions import *
 class Usb(Escpos):
     """ Define USB printer """
 
+    is_open = False
+
     def __init__(self, idVendor, idProduct, interface=0, in_ep=0x82, out_ep=0x01):
         """
         @param idVendor  : Vendor ID
@@ -36,9 +38,14 @@ class Usb(Escpos):
 
     def open(self):
         """ Search device on USB tree and set is as escpos device """
+        if self.is_open:
+            return  # Already open; no need to reopen
+
         self.device = usb.core.find(idVendor=self.idVendor, idProduct=self.idProduct)
         if self.device is None:
             print "Cable isn't plugged in"
+        else:
+            self.is_open = True
 
         if self.device.is_kernel_driver_active(0):
             try:
@@ -50,9 +57,21 @@ class Usb(Escpos):
             self.device.set_configuration()
             self.device.reset()
         except usb.core.USBError as e:
+            # Seems fatal when it occurs. Should the device be closed as a result?
+            #self.close()
             print "Could not set configuration: %s" % str(e)
 
 
+    def close(self):
+        """ Manually release USB interface """
+        self.is_open = False
+
+        if self.device:
+            usb.util.dispose_resources(self.device)
+
+        self.device = None
+
+
     def _raw(self, msg):
         """ Print any command sent in raw format """
         self.device.write(self.out_ep, msg, self.interface)
@@ -60,15 +79,15 @@ class Usb(Escpos):
 
     def __del__(self):
         """ Release USB interface """
-        if self.device:
+        self.close()
-            usb.util.dispose_resources(self.device)
-        self.device = None
 
 
 
 class Serial(Escpos):
     """ Define Serial printer """
 
+    is_open = False
+
     def __init__(self, devfile="/dev/ttyS0", baudrate=9600, bytesize=8, timeout=1):
         """
         @param devfile  : Device file under dev filesystem
@@ -84,15 +103,29 @@ class Serial(Escpos):
 
 
     def open(self):
-        """ Setup serial port and set is as escpos device """
+        """ Setup serial port and set it as escpos device """
+        if self.is_open:
+            return  # Already open; no need to reopen
+
         self.device = serial.Serial(port=self.devfile, baudrate=self.baudrate, bytesize=self.bytesize, parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=self.timeout, dsrdtr=True)
 
         if self.device is not None:
             print "Serial printer enabled"
+            self.is_open = True
         else:
             print "Unable to open serial printer on: %s" % self.devfile
 
 
+    def close(self):
+        """ Manually close Serial interface """
+        self.is_open = False
+
+        if self.device is not None:
+            self.device.close()
+
+        self.device = None
+
+
     def _raw(self, msg):
         """ Print any command sent in raw format """
         self.device.write(msg)
@@ -100,14 +133,14 @@ class Serial(Escpos):
 
     def __del__(self):
         """ Close Serial interface """
-        if self.device is not None:
+        self.close()
-            self.device.close()
-
 
 
 class Network(Escpos):
     """ Define Network printer """
 
+    is_open = False
+
     def __init__(self,host,port=9100):
         """
         @param host : Printer's hostname or IP address
@@ -120,11 +153,26 @@ class Network(Escpos):
 
     def open(self):
         """ Open TCP socket and set it as escpos device """
+        if self.is_open:
+            return  # Already open; no need to reopen
+
         self.device = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         self.device.connect((self.host, self.port))
 
         if self.device is None:
             print "Could not open socket for %s" % self.host
+        else:
+            self.is_open = True
+
+
+    def close(self):
+        """ Manually close TCP connection """
+        self.is_open = False
+
+        if self.device is not None:
+            self.device.close()
+
+        self.device = None
 
 
     def _raw(self, msg):
@@ -134,13 +182,15 @@ class Network(Escpos):
 
     def __del__(self):
         """ Close TCP connection """
-        self.device.close()
+        self.close()
 
 
 
 class File(Escpos):
     """ Define Generic file printer """
 
+    is_open = False
+
     def __init__(self, devfile="/dev/usb/lp0"):
         """
         @param devfile : Device file under dev filesystem
@@ -151,10 +201,25 @@ class File(Escpos):
 
     def open(self):
         """ Open system file """
+        if self.is_open:
+            return  # Already open; no need to reopen
+
         self.device = open(self.devfile, "wb")
 
         if self.device is None:
             print "Could not open the specified file %s" % self.devfile
+        else:
+            self.is_open = True
+
+
+    def close(self):
+        """ Manually close system file """
+        self.is_open = False
+
+        if self.device is not None:
+            self.device.close()
+
+        self.device = None
 
 
     def _raw(self, msg):
@@ -164,4 +229,4 @@ class File(Escpos):
 
     def __del__(self):
         """ Close system file """
-        self.device.close()
+        self.close()