+ InvenTree
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+ + + ++ + + + + + +
+ InvenTree
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+ SergeoLacruz
+
+last modified: 29 Jan 2023
+Zebra Label Printer Plugin for Inventree
+ +This is a label printing plugin for InvenTree, which provides support for Zebra Label printers . +It supports printing to just GK420T with one label size (50x30) so far. So it is very simple. It uses the zpl library to +convert the png data provided by InvenTree to Zebras bitmap format.
+ +It can output the print data either to a local printer connected to the computer via USB or to a network printer +with an IP address. The output can be configured in the InvenTree plugin user interface. So the source code is +a good example for this.
+ +Error handling is very basic.
+ +Install this plugin using pip with the following command::
+ +pip install git+https://github.com/SergeoLacruz/inventree-zebra-plugin
+Here you can chose between Local printer or network printer. Default value is a local printer.
+ +In case you use an IP printer set the IPv4 address here.
+ +In case you use an IP printer set the port number here. The default port number is 9100.
+ +In case of a local printer set the device here. The plugin actually puts the data directly to the +device libe /dev/usb/lp0. No printer spooler is involved so far.
+ +First import all the stuff you need. Here we use the translation mechanism from django for multi language support. +The import the InvenTree libs and everything you need for plugin. Here we have zpl for the Zebra bitmaps and socket +for the IP connection to the printer.
+ +The next part is this:
+ +class ZebraLabelPlugin(LabelPrintingMixin, SettingsMixin, IntegrationPluginBase):
+
+ AUTHOR = "Michael Buchmann"
+ DESCRIPTION = "Label printing plugin for Zebra printers"
+ VERSION = ZEBRA_PLUGIN_VERSION
+ NAME = "Zebra"
+ SLUG = "zebra"
+ TITLE = "Zebra Label Printer"
+The name of the class can be freely chosen. You reference to it in the entry_points section of the setup.py file. +The parameters need to be like in the example. Then there is the description block. The keywords are fixed and +need to be like that. The values are found in the UI as shown in the pictures below.
+ +
+
Then we add the configuration parameters.
+SETTINGS = {
+ 'CONNECTION': {
+ 'name': _('Printer Interface'),
+ 'description': _('Select local or network printer'),
+ 'choices': [('local','Local printer e.g. USB'),('network','Network printer with IP address')],
+ 'default': 'local',
+ },
+ 'PORT': {
+ 'name': _('Port'),
+ 'description': _('Network port in case of network printer'),
+ 'default': '9100',
+ },
+ }
+
+We need to define a dict with the name SETTINGS. Please be aware the keys need to be in all CAPITAL letters like CONNECTION. +Simple parameters are just text strings like the port. We can set a default. The name and description shows up in the UI. +Instead of ta simple test we can also use choices. The first string like “local” it the key you use in the code. The second +one is the description in the UI. +After that we need to define a function:
+ +def print_label(self, **kwargs){
+The kwargs is a dict with the following keys:
+ +For the Zebra printer we use the png_file. This is a PIL (python Pillow) object with the graphic of the label in PNG format. +The PIL object is a greyscale image. Because the printer can just print pure BW we convert this to a BW picture.
+ +fn = lambda x : 255 if x > Threshold else 0
+label_image = label_image.convert('L').point(fn, mode='1')
+The threshold can by modified by a plugin parameter. 200 is a good starting value. This trick gives much better prints. +We can put the result this directly into the zpl library.
+ +l = zpl.Label(50,30,8)
+l.origin(0, 0)
+l.write_graphic(label_image, 50)
+l.endorigin()
+50,30 is the size of the label in millimeters. The third parameter is the resolution of the printer in +dots per mm. As the Zebra printer has 200dpi we put an eight here. write_graphic converts the pillow data +to zpl. 50 is the with of the image in mm.
+ +The plugin was tested with a label of 50x30 mm defined using css and html in InvenTree as shown below. The DPI scaling +can be chosen in the InvenTree settings. 400 is a good value because it is just double of the printers +resolution. If you save the pillow data to a png file you get a size of 788x473 which fits well to that data.
+ +<style>
+ @page {
+ width: 50mm;
+ height: 30mm;
+ padding: 0mm;
+ margin: 0px 0px 0px 0px;
+ background-color: white;
+ }
+The rest of the code is just output to the printer on different interfaces.
+ +License:
+
+ MIT
+
SergeoLacruz/inventree-zebra-plugin
+ SergeoLacruz
+
+ Zebra Label Printer Plugin for Inventree +
+ SergeoLacruz
+
+ Zebra Label Printer Plugin for Inventree +
+ SergeoLacruz
+
+ Zebra Label Printer Plugin for Inventree +
+ SergeoLacruz
+
+ Zebra Label Printer Plugin for Inventree +
++
+
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